latest research quarks

Physicists Just Found 4 New Subatomic Particles That May Test The Laws of Nature

This month is a time to celebrate. CERN has just announced the discovery of four brand new particles at the Large Hadron Collider (LHC) in Geneva.

This means that the LHC has now found a total of 59 new particles , in addition to the Nobel prize-winning Higgs boson , since it started colliding protons – particles that make up the atomic nucleus along with neutrons – in 2009.

Excitingly, while some of these new particles were expected based on our established theories, some were altogether more surprising.

The LHC's goal is to explore the structure of matter at the shortest distances and highest energies ever probed in the lab – testing our current best theory of nature: the Standard Model of Particle Physics . And the LHC has delivered the goods – it enabled scientists to discover the Higgs boson , the last missing piece of the model. That said, the theory is still far from being fully understood.

One of its most troublesome features is its description of the strong force which holds the atomic nucleus together. The nucleus is made up of protons and neutrons, which are in turn each composed of three tiny particles called quarks (there are six different kinds of quarks: up, down, charm, strange, top and bottom).

If we switched the strong force off for a second, all matter would immediately disintegrate into a soup of loose quarks – a state that existed for a fleeting instant at the beginning of the universe.

Don't get us wrong: the theory of the strong interaction, pretentiously called " quantum chromodynamics ", is on very solid footing. It describes how quarks interact through the strong force by exchanging particles called gluons. You can think of gluons as analogues of the more familiar photon, the particle of light and carrier of the electromagnetic force.

However, the way gluons interact with quarks makes the strong force behave very differently from electromagnetism. While the electromagnetic force gets weaker as you pull two charged particles apart, the strong force actually gets stronger as you pull two quarks apart.

As a result, quarks are forever locked up inside particles called hadrons – particles made of two or more quarks – which includes protons and neutrons. Unless, of course, you smash them open at incredible speeds, as we are doing at Cern.

To complicate matters further, all the particles in the standard model have antiparticles which are nearly identical to themselves but with the opposite charge (or other quantum property). If you pull a quark out of a proton, the force will eventually be strong enough to create a quark-antiquark pair, with the newly created quark going into the proton.

You end up with a proton and a brand new "meson", a particle made of a quark and an antiquark. This may sound weird but according to quantum mechanics, which rules the universe on the smallest of scales, particles can pop out of empty space.

This has been shown repeatedly by experiments – we have never seen a lone quark. An unpleasant feature of the theory of the strong force is that calculations of what would be a simple process in electromagnetism can end up being impossibly complicated. We therefore cannot (yet) prove theoretically that quarks can't exist on their own.

Worse still, we can't even calculate which combinations of quarks would be viable in nature and which would not.

When quarks were first discovered, scientists realized that several combinations should be possible in theory. This included pairs of quarks and antiquarks (mesons); three quarks (baryons); three antiquarks (antibaryons); two quarks and two antiquarks (tetraquarks); and four quarks and one antiquark (pentaquarks) – as long as the number of quarks minus antiquarks in each combination was a multiple of three.

For a long time, only baryons and mesons were seen in experiments. But in 2003, the Belle experiment in Japan discovered a particle that didn't fit in anywhere. It turned out to be the first of a long series of tetraquarks.

In 2015, the LHCb experiment at the LHC discovered two pentaquarks .

The four new particles we've discovered recently are all tetraquarks with a charm quark pair and two other quarks. All these objects are particles in the same way as the proton and the neutron are particles. But they are not fundamental particles: quarks and electrons are the true building blocks of matter.

Charming new particles

The LHC has now discovered 59 new hadrons. These include the tetraquarks most recently discovered, but also new mesons and baryons. All these new particles contain heavy quarks such as "charm" and "bottom".

These hadrons are interesting to study. They tell us what nature considers acceptable as a bound combination of quarks, even if only for very short times.

They also tell us what nature does not like. For example, why do all tetra- and pentaquarks contain a charm-quark pair (with just one exception)? And why are there no corresponding particles with strange-quark pairs? There is currently no explanation.

Another mystery is how these particles are bound together by the strong force. One school of theorists considers them to be compact objects, like the proton or the neutron.

Others claim they are akin to "molecules" formed by two loosely bound hadrons. Each newly found hadron allows experiments to measure its mass and other properties, which tell us something about how the strong force behaves. This helps bridge the gap between experiment and theory. The more hadrons we can find, the better we can tune the models to the experimental facts.

These models are crucial to achieve the ultimate goal of the LHC: find physics beyond the standard model. Despite its successes, the standard model is certainly not the last word in the understanding of particles. It is for instance inconsistent with cosmological models describing the formation of the universe.

The LHC is searching for new fundamental particles that could explain these discrepancies. These particles could be visible at the LHC, but hidden in the background of particle interactions. Or they could show up as small quantum mechanical effects in known processes.

Patrick Koppenburg , Research Fellow in Particle Physics, Dutch National Institute for Subatomic Physics and Harry Cliff , Particle physicist, University of Cambridge .

This article is republished from The Conversation under a Creative Commons license. Read the original article .

Cern Large Hadron Collider scientists observe three 'exotic' particles for first time

Scientists working with the Large Hadron Collider (LHC) have discovered three subatomic particles never seen before as they work to unlock the building blocks of the universe, the European nuclear research centre CERN said on Tuesday.

The 27 kilometre-long (16.8 mile) LHC at CERN is the machine that found the Higgs boson particle, which along with its linked energy field is thought to be vital to the formation of the universe after the Big Bang 13.7 billion years ago.

Now scientists at CERN say they have observed a new kind of “pentaquark” and the first-ever pair of “tetraquarks,” adding three members to the list of new hadrons found at the LHC.

They will help physicists better understand how quarks bind together into composite particles.

Quarks are elementary particles that usually combine in groups of twos and threes to form hadrons such as the protons and neutrons that make up atomic nuclei.

More rarely, however, they can also combine into four-quark and five-quark particles, or tetraquarks and pentaquarks.

“The more analyses we perform, the more kinds of exotic hadrons we find,” physicist Niels Tuning  said  in a statement.

“We’re witnessing a period of discovery similar to the 1950s, when a ‘particle zoo’ of hadrons started being discovered and ultimately led to the quark model of conventional hadrons in the 1960s. We’re creating ‘particle zoo 2.0’.”

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This is the first known particle with four of the same kind of quark.

The exotic particle could be a unique testing ground for ideas about how quarks interact

A newly discovered four-quark particle (illustrated) is the first to contain all heavy quarks, and more than two quarks of the same kind.

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By Maria Temming

July 7, 2020 at 10:57 am

In a never-before-seen particle, four quarks of a feather flock together.

Physicists think they have detected the first conglomerate of four quarks incorporating more than two of the same kind. This tetraquark contains four quarks of the charm variety : two charm quarks and their antimatter counterparts, called anticharm quarks, researchers report online at arXiv.org on June 30.

Quarks — fundamental building blocks of matter — typically make up three-quark particles, like protons and neutrons, or quark-antiquark pairs, like pions and kaons. Physicists have observed some more exotic quark quartets ( SN: 4/11/14 ) and even quintets ( SN: 7/14/15 ). But the new four-quark particle, dubbed X(6900), is the first four-quark particle with all of the same type. Since charm quarks and their anticharm counterparts are among the heaviest types of quarks, it is also the first tetraquark to include more than two heavy quarks.

“It’s a pretty exciting finding,” says physicist Matthew Shepherd of Indiana University Bloomington, who wasn’t involved in the work.

Quarks are bound together by the strong force. Discovering new, exotic quark arrangements “tells us something about the types of patterns of quarks that the strong interaction generates, which tells us something about the strong interaction,” Shepherd says. A deeper knowledge of that fundamental force of nature could give insight not only into quirky particles like X(6900) but also common quark-based particles, like the protons and neutrons in atomic nuclei.

Evidence of the new tetraquark was lurking in data collected from 2009 to 2018 at the Large Hadron Collider, or LHC, near Geneva. In these experiments, physicists used the LHC to smash protons together and observe the particles forged in the collisions.

The LHC data contained signatures of a particle with the mass expected for a quartet of charm quarks: around 6,900 million electron volts. That particle decayed into two J/psi particles, each containing a charm and an anticharm quark, suggesting it was originally a tetraquark with two charm and two anticharm quarks. Like other known tetraquarks, X(6900) could be either a single entity, composed of four quarks all tightly bundled together, or a pair of two-quark particles that are more loosely bound — like a set of atoms in a molecule ( SN: 6/7/19 ).

“We need to do many kinds of checks to confirm that it’s really there,” says study coauthor Liupan An, a particle physicist at the Italian National Institute of Nuclear Physics in Florence. Those checks could include collecting more data with the LHC or seeing if other particle collision experiments produce similar results.

Assuming that the evidence for this exotic quark cluster holds up, the strange new particle offers “a sort of stress tester” for ideas about how quarks construct matter, says study coauthor Chris Parkes, a physicist at the University of Manchester in England. He compares using this tetraquark for studying particle physics to biologists looking at extremophile creatures, like tardigrades, to understand the limits of biology — or to astronomers using black holes to see whether theories about gravity hold up in such intense environments ( SN: 4/16/20 ).

It may be easier to study quark interactions in X(6900) than its other four-quark relatives, which contain lighter quarks, Shepherd says. That’s because it’s notoriously challenging to accurately predict the complex, fast-moving behavior of light quarks. When it comes to the four heavy quarks in X(6900), on the other hand, physicists could potentially build simpler models to predict quark behavior.

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• 10 August 2021
• Correction 17 August 2021

Exotic four-quark particle spotted at Large Hadron Collider

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The Large Hadron Collider (LHC) is also a big hadron discoverer. The atom smasher near Geneva, Switzerland, is most famous for demonstrating the existence of the Higgs boson in 2012, a discovery that slotted into place the final keystone of the current classification of elementary particles. But the LHC has also netted dozens of the non-elementary particles called hadrons — those that, like protons and neutrons, are made of quarks.

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doi: https://doi.org/10.1038/d41586-021-02174-6

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Correction 17 August 2021 : An earlier version of the ‘Particle discoveries’ graphic erroneously included ‘2021’ twice on the x axis.

Karliner, M. & Rosner, J. L. Phys. Rev. Lett. 119 , 202001 (2017).

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April 27, 2023

Physicists See ‘Strange Matter’ Form inside Atomic Nuclei

New research attempts to discern how bizarre particles of strange matter form in the nuclei of atoms

By Stephanie Pappas

koto_feja/Getty Images

A new physics result two decades in the making has found a surprisingly complex path for the production of strange matter within atoms.

Strange matter is any matter containing the subatomic particles known as strange quarks. “Strange” here refers, in part, to a profound remoteness from our everyday lives: strange matter only seems to show up in truly extreme circumstances such as high-energy particle collisions and perhaps the enormously dense and pressurized cores of neutron stars . Probing the details of strange matter’s emergence is part of a broader effort by nuclear physicists to understand the fundamentals of how subatomic particles form. In this particular case, a group of researchers focused on one variety of strange matter, called lambda particles.

“This data is the first time we study the lambda in the [atomic] nucleus, and we look at what we call hadronization, the process of producing hadrons,” says study co-author Kawtar Hafidi, associate laboratory director for physical sciences and engineering at Argonne National Laboratory.

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Hadrons are subatomic particles that are made of quarks and subject to the strong force. This is the force that binds quarks together to make larger particles such as protons and neutrons and that holds those protons and neutrons within an atom’s nucleus. Lambda particles are baryons, which means they’re a type of hadron made of three quarks: one up quark, one down quark and one strange quark. The vast majority of quarks are of the up or down varieties, says Lamiaa El Fassi, lead author of the new study and an associate professor of experimental nuclear physics at Mississippi State University. Strange quarks are heavier, rarer beasts than their up and down siblings, and the particles they form are correspondingly far less stable, tending to decay very quickly.

The scarce, slippery nature of strange quarks is precisely what makes them so appealing for researchers, says Daniel Brandenburg, an assistant professor of physics at the Ohio State University, who was not involved in the new work. “Our naive picture of a proton and a neutron is that they involve up and down quarks,” he says. “So part of the reason that strange quarks are interesting is because, at least in this naive picture, they’re not there at the beginning. You have to create them somehow.”

Lambda particles have been studied before, but in the new paper, the researchers relied on a special process called semi-inclusive deep inelastic scattering to create them inside a nucleus. This involves shooting an electron beam at a nucleus, which transfers energy to the quarks within the protons and neutrons inside, stimulating lambda production.

Yet despite these elaborate efforts, the arcane laws of quantum mechanics dictate that, even here, the electrons do not interact directly with the quarks. Instead the impinging electrons release “virtual” photons, so called because they scarcely exist at all : these photons are reabsorbed by the quarks almost as fast as they are emitted. The resulting energetic kick can send quarks pinballing through the nucleus, where they combine with other quarks to create lambdas and other “composite” particles.

This subatomic alchemy took place at the Thomas Jefferson National Accelerator Facility way back in 2004. At the time, El Fassi was conducting separate research with the dataset, but she eventually chose to seek evidence of lambda particles within it as well. Teasing out the subtle signal of lambda decay—the particles are too short-lived for direct detection—required more than 10 years of effort. “It is a long journey,” El Fassi says. She and her colleagues reported their findings in the journal Physical Review Letters.

By studying the energy and momentum of the particles produced by the decaying lambdas, El Fassi and her colleagues could piece together  exactly what happened to the freed quarks running rampant through the nucleus. Interactions with other subatomic particles sapped the quarks’ energy to varying degrees, and they experienced changes in momentum as they linked up with other quarks to form hadrons.

Most strikingly, the researchers saw differences between the production of lambda particles with high and low energies that suggest these particles sometimes form in an unexpected way. Instead of a virtual photon hitting one quark and freeing it to go find two new quarks to bond with, as theorists have long assumed, the virtual photon sometimes seemed to interact with a quark pair, known as a diquark. Likely composed of the mundane up and down quarks that are so plentiful in the nucleus, this diquark would then go in search of a third quark, ultimately bonding with a strange quark. When this happens, the result is a lambda particle. The findings not only reveal how these strange and unusual particles form, Brandenburg says. Because the particles’ final energies and momenta contain information about what they encountered on their journey through the nucleus, they can also help uncover what’s happening in the hidden hearts of atoms.

Not all physicists are convinced that this diquark hypothesis reflects how lambdas really form, however. There are alternative models that could explain the energy and momentum patterns the researchers observed, says Jen-Chieh Peng, a professor of nuclear physics at the University of Illinois at Urbana-Champaign, who was not involved in the new study. For example, he says, patterns of momentum transfer between particles that the researchers attribute to the diquark’s dynamics could instead be the result of a single quark picking up two quarks separately. That would mean the original “quark-by-quark” conception of how tripartite particles such as lambdas form is correct. “Their data is interesting but the interpretation, I think, is a very long shot,” Peng says.

Better measurements will likely settle the debate in the near future. The electron beam at Jefferson Lab is twice as powerful today as it was in 2004, El Fassi says, and new hadronization experiments are planned for next year. The Electron-Ion Collider, a particle accelerator now being planned at Brookhaven National Laboratory, will also be a powerful new tool for similar experiments, Brandenburg says.

“Because we’re still building it,” he says, “we can really fine-tune it for the measurements we know are important.”

New Research

What Is a Pentaquark and Why Are Physicists so Excited About It?

For fifty years scientists have thought they existed, and now they finally have proof

Helen Thompson

This week researchers at CERN’s Large Hadron Collider (LHC) in Switzerland announced evidence of a new type of particle called a pentaquark, Ian Sample reports for The Guardian .

Quarks are tiny particles that bind together to form different types of larger particles you might be more familiar with. Three quarks make a proton, for example. And, when five quarks combine, that’s called a pentaquark. This might not seem all that exciting, but for physicists it is. 

“The pentaquark is not just any new particle,” Guy Wilkinson , a physicist and spokesperson for the LHC experiment, said in a statement . “Studying its properties may allow us to understand better how ordinary matter, the protons and neutrons from which we’re all made, is constituted.”

Quarks come in six “ flavors ”: up, down, top, bottom, strange and charm. Anti-quarks also come the same six flavors. A pentaquark seems to consist of two up quarks, one down quark, a charm quark and an anti-charm quark. 

The discovery confirms 50 years scientists’ suspicions that more exotic particles might exist, Tia Ghose explains for Live Science:

In 1964, physicist Murray Gell-Mann proposed that a group of particles known as baryons, which include protons and neutrons, are actually made up of three even tinier charged subatomic particles known as quarks. Meanwhile, the theory went, another group of particles called mesons were composed of quarks and their antimatter partners, antiquarks.

Gell-Mann’s theory implied that even more complex quark structures could form larger particles, Ghose explains . If a trio of quarks make a proton, then what could five or six or seven quarks form? There were earlier hints at evidence of a pentaquark, but nothing conclusive.

The LHC researchers were studying how baryons (another particle made of three quarks) break down, but during the particle decay the quarks were forming intermediate structures. Based on the signal patterns they received, these intermediate structures had to be pentaquarks, the researchers report in the journal Physical Review Letters .

So far, physicists have only observed this one type of pentaquark in the LHC data, but there could be many other varieties.

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Helen Thompson writes about science and culture for Smithsonian . She's previously written for NPR, National Geographic News , Nature and others.

CERN Experiment Reveals “Spooky Action at a Distance” Persists Between Top Quarks

Quantum entanglement in top quarks has been demonstrated, according to physicists at CERN who say the discovery offers new insights into the behavior of fundamental particles and their interactions at distances that cannot be attained by light-speed communication.

The research, led by University of Rochester professor Regina Demina , extends the phenomenon known as “spooky action at a distance” to the heaviest particles recognized by physicists and offers important new insights into high-energy quantum mechanics.

Initially discovered almost three decades ago, top quarks are the most massive elementary particles that have been observed. The mass of these unique particles originates from their coupling to the Higgs boson, the famous particle predicted in theory regarding the unification of the weak and electromagnetic interactions. According to the Standard Model of particle physics, this coupling is the largest that occurs at the scale of the weak interactions and those above it.

In the past, quantum entanglement has been observed in stable particles, including electrons and photons. In their new research, Demina and her team demonstrate entanglement between unstable top quarks and their antimatter counterparts, revealing spin correlations that occur over distances that extend beyond the transfer of information at light speed.

The findings present new challenges to existing models and expand our understanding of particle behavior at extreme energies.  

The experiment was conducted at the European Center for Nuclear Research (CERN) as part of the Compact Muon Solenoid (CMS) Collaboration. CERN is home to the famous Large Hadron Collider (LHC), a device that propels high-energy particles at speeds nearing those of light across a 17-mile underground track.

Given the amount of energy required for the production of top quarks, such processes can only be achieved at facilities like CERN . The results of Demina’s recent study could help to shed some light on how long entanglement persists, as well as whether it can be extended to “daughter” particles or decay products. The research also may help determine whether entanglement between particles can be broken.

Presently, it is believed that the universe was in an entangled state following its initial fast expansion stage. The revelation of entanglement in top quarks may help scientists like Demina better understand what factors may have contributed to the quantum connection in our world becoming diminished over time, ultimately leading to the state in which our reality exists today.

Magic Mushrooms May Help Stop Opioid Addiction, New Research Suggests

Additionally, the experiment’s results could have applications in the growing area of quantum information science. While top quarks are not a good fit for use with quantum computers, the recent findings may nonetheless be helpful in providing researchers a better understanding of their entanglement properties, which could also shed light on how quantum connections are either maintained or disrupted.

Ultimately, the new findings made possible by CERN could challenge our current widely accepted understanding of quantum mechanics while setting the pace for future studies of quantum phenomena that may help add missing pieces to the puzzle of our cosmic origins and the fundamental laws that govern reality.

Micah Hanks is the Editor-in-Chief and Co-Founder of The Debrief. He can be reached by email at   [email protected] . Follow his work at  micahhanks.com  and on X:  @MicahHanks .

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Never Been Done Before – A New Way To Study Quarks

By University of Tokyo January 20, 2023

Quarks are elementary particles and a fundamental constituent of matter. They are the smallest things we know of and are not made up of anything smaller or simpler. Quarks come in six different “flavors”: up, down, charm, strange, top, and bottom. They are never found alone in nature, but are always found in combination with other quarks to form protons and neutrons in the nucleus of an atom, and other subatomic particles like mesons. Quarks are believed to be the building blocks of protons and neutrons, which make up the majority of the matter in the universe.

Scientists are investigating how matter gets its mass by confining quarks.

A novel method for investigating quarks, the fundamental particles that make up the protons and neutrons in atomic nuclei, has been proposed. This innovative approach has never been attempted before and could provide answers to many fundamental questions in physics, particularly the origin of mass in matter.

The study of matter can seem a bit like opening a stack of Russian matryoshka dolls, each level down revealing another familiar, yet different, arrangement of components smaller and harder to explore than the one before. At our everyday scale, we have objects we can see and touch. Whether water in a glass or the glass itself, these are mostly arrangements of molecules too small to see. The tools of physics, microscopes, particle accelerators, and so forth, let us peer deeper to reveal molecules are made from atoms. But it doesn’t stop there — atoms are made from a nucleus surrounded by electrons.

The nucleus in turn is an arrangement of nucleons (protons and neutrons), which gives the atom its properties and its mass. But it doesn’t end here either; the nucleons are further composed of less familiar things known as quarks and gluons. . And it’s at this scale that limits to our knowledge of fundamental physics present a block. As to explore quarks and gluons, they must ideally be isolated from each other; however, at present, this seems to be impossible. When particle accelerators smash atoms and create showers of atomic debris, quarks and gluons bind again too quickly for researchers to explore them in detail. New research from the University of Tokyo’s Department of Physics suggests we could soon open up the next layer of the matryoshka doll.

“To better understand our material world, we need to do experiments and to improve upon experiments, we need to explore new approaches to the way we do things,” said Professor Kenji Fukushima. “We have outlined a possible way to identify the mechanism responsible for quark confinement. This has been a longstanding problem in physics, and if realized, could unlock some deep mysteries about matter and the structure of the universe.”

The mass of subatomic quarks is incredibly small: Combined, the quarks in a nucleon make up less than 2% of the total mass, and gluons appear to be entirely massless. So, physicists suggest the majority of atomic mass actually comes from the way in which quarks and gluons are bound, rather than from the things themselves. They are bound by the so-called strong force, one of the four fundamental forces of nature, including electromagnetism and gravity, and it’s believed the strong force itself endows a nucleon with mass. This is part of a theory known as quantum chromodynamics (QCD), where “chromo” comes from the Greek word for color, which is why you sometimes hear quarks referred to as being red, green, or blue, despite the fact they’re colorless.

“Rigorous proof that the strong force gives rise to mass remains out of reach,” said Fukushima. “The obstacle is that QCD describes things in such a way that makes theoretical calculations hard. Our achievement is to demonstrate that the strong force, within a special set of circumstances, can realize quark confinement. We did this by interpreting some observed parameters of quarks as a new variable we call the imaginary angular velocity. Though purely mathematical in nature, it can be converted back into real values of things we can control. This should lead to a means to realize an exotic state of rapidly rotating quark matter once we learn how to turn our idea into an experiment.”

Reference: “Perturbative Confinement in Thermal Yang-Mills Theories Induced by Imaginary Angular Velocity” by Shi Chen, Kenji Fukushima and Yusuke Shimada, 8 December 2022, Physical Review Letters . DOI: 10.1103/PhysRevLett.129.242002

The study was funded by the Japan Society for the Promotion of Science. 

More on SciTechDaily

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New Insight Into How Quarks Combine by Tracking Particles Containing Charm Quarks

New Subatomic Particle Zc(3900) Hints at Four-Quark Matter

Science Made Simple: What Are Quarks and Gluons?

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Extreme State of Matter: Evidence of Top Quarks in Collisions at the Large Hadron Collider

U.S. RHIC Atom Smasher Reveals a Surprising Preference in Particle Spin Alignment

New type of entanglement lets nuclear physicists “see” inside atomic nuclei, 2 comments on "never been done before – a new way to study quarks".

Rotation is associated in the dynamics of quarks and gluon.Mathematical Theory is present.

Refreshing, here are my notes https://docs.google.com/document/d/1ofotN7rdbg1-Abz-YPf2Jh3Mh7gzCikH3RdE1h17u_k/edit?usp=drivesdk @Redjflamez

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The Science

Quarks are the basic particles that make up visible matter in the universe. The most intriguing and most puzzling property of quarks is that they are never found in isolation. Instead, they can only be observed when confined inside composite particles such as protons . Nuclear physicists use giant particle accelerators to produce various types of quarks and study how they evolve to form observable particles. Groups of three quarks form composite particles called baryons (such as protons and neutrons ), while pairs of quarks form mesons. New measurements from the Large Hadron Collider beauty (LHCb) experiment show surprising variations in the rate at which baryons are produced, defying previous expectations.

The atomic nuclei that form all visible matter are composed of baryons (specifically, protons and neutrons), which scientists believe formed in the early universe . Baryons inside nuclei are stable particles that do not undergo radioactive decay. However, all mesons are unstable, and they rapidly decay into lighter particles that cannot form atoms. The existence of stable baryons versus unstable mesons is therefore what makes the existence of atoms and the universe as we know it possible. The LHCb experiment has shown that the rate of quarks forming into baryons versus mesons depends greatly on the density of their environment. This finding helps to explain the creation of the first stable particles in the early universe.

The fact that quarks must be confined is the defining feature of the strong interaction, as described by the theory of quantum chromodynamics (QCD). Calculations using QCD can predict the total number of heavy bottom quarks produced in particle collisions but cannot describe the fraction that emerge as baryons rather than mesons. Typically, researchers tune models to match data from previous experiments involving collisions of electrons with positrons, assuming that the baryon production rate is universal.

An important difference in this new research relative to previous experiments is that collisions of protons and/or nuclei at the Large Hadron Collider produce an environment with a much higher quark density. In this research, nuclear physicists from the LHCb experiment found that the number of baryons containing b quarks depends on the environment following the collisions, and increases with higher particle densities. This shows that scientists’ assumption of the universality of baryon production is incorrect, and that interactions between the produced quarks during their evolution into visible matter influences how many baryons emerge. These new results prove that additional theoretical mechanisms for producing baryons are required in dense collision systems, which may have been especially important when the first protons were formed in the early universe.

J. Matthew Durham Los Alamos National Laboratory [email protected] Julie L. M. Berkey Los Alamos National Laboratory [email protected]

This research was supported by the Department of Energy Office of Science, Nuclear Physics program.

Publications

Aaij, R., et al. (LHCb Collaboration), Enhanced production of baryons in high-multiplicity pp collisions at  = 13 TeV . Physical Review Letters 132, 081901 (2024). [DOI: 10.1103/PhysRevLett.132.081901 ]

Related Links

Three’s Company for Bottom Quarks, APS Physics Magazine

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The Higgs particle could have ended the universe by now — here’s why we’re still here

Although our universe may seem stable, having existed for a whopping 13.7 billion years, several experiments suggest that it is at risk – walking on the edge of a very dangerous cliff. And it’s all down to the instability of a single  fundamental particle : the  Higgs boson .

In  new research  by me and my colleagues, just accepted for publication in Physical Letters B, we show that some models of the early universe, those which involve objects called light primordial black holes, are unlikely to be right because they would have triggered the Higgs boson to end the cosmos by now.

The Higgs boson is  responsible for the mass and interactions  of all the particles we know of. That’s because particle masses are a consequence of elementary particles  interacting with a field , dubbed the Higgs field. Because the Higgs boson exists, we know that the field exists.

You can think of this field as a perfectly still water bath that we soak in. It has identical properties across the entire universe. This means we observe the same masses and interactions throughout the cosmos. This uniformity has allowed us to observe and describe the same physics over several millennia (astronomers typically look backwards in time).

But the Higgs field isn’t likely to be in the lowest possible energy state it could be in. That means it could theoretically change its state, dropping to a lower energy state in a certain location. If that happened, however, it would alter the laws of physics dramatically.

Such a change would represent what physicists call a phase transition. This is what happens when water turns into vapour, forming bubbles in the process. A phase transition in the Higgs field would similarly create low-energy bubbles of space with completely different physics in them.

In such a bubble, the mass of electrons would suddenly change, and so would its interactions with other particles. Protons and neutrons – which make up the atomic nucleus and are made of quarks – would suddenly dislocate. Essentially, anybody experiencing such a change would likely no longer be able to report it.

Constant risk

Recent measurements of particle masses  from the Large Hadron Collider (LHC) at Cern suggest that such an event might be possible. But don’t panic; this may only occur in a few thousand billion billion years after we retire. For this reason, in the corridors of particle physics departments, it is usually said that the universe is not unstable but rather “meta-stable”, because the world’s end will not happen anytime soon.

To form a bubble, the Higgs field needs a good reason. Due to quantum mechanics, the theory which governs the microcosmos of atoms and particles, the energy of the Higgs is always fluctuating. And it is statistically possible (although unlikely, which is why it takes so much time) that the Higgs forms a bubble from time to time.

However, the story is different in the presence of external energy sources like  strong gravitational fields  or  hot plasma  (a form of matter made up of charged particles): the field can borrow this energy to form bubbles more easily.

Therefore, although there is no reason to expect that the Higgs field forms numerous bubbles today, a big question in the context of cosmology is whether the extreme environments shortly after the Big Bang could have triggered such bubbling.

However, when the universe was very hot, although energy was available to help form Higgs bubbles,  thermal effects also stabilised the Higgs  by modifying its quantum properties. Therefore, this heat could not trigger the end of the universe, which is probably why we are still here.

Primordial black holes

In our new research, we showed there is one source of heat, however, that would constantly cause such bubbling (without the stabilising thermal effects seen in the early days after the Big Bang). That’s primordial black holes, a type of black hole which emerged in the early universe from the collapse of overly dense regions of spacetime. Unlike normal black holes, which form when stars collapse, primordial ones could be tiny – as light as a gram.

The existence of such light black holes is a prediction of many theoretical models that describe the evolution of the cosmos shortly after the Big Bang. This includes  some models of inflation , suggesting the universe blew up hugely in size after the Big Bang.

However, proving this existence comes with a big caveat: Stephen Hawking demonstrated in the 1970s that, because of quantum mechanics, black holes evaporate slowly by emitting radiation through their event horizon (a point at which not even light can escape).

Hawking showed that black holes behave like heat sources in the universe, with a  temperature inversely proportional to their mass . This means that light black holes are much hotter and evaporate more quickly than massive ones. In particular, if primordial black holes lighter than a few thousands billion grams formed in the early universe (10 billion times smaller than the Moon’s mass), as many models suggest, they would have evaporated by now.

In the  presence of the Higgs field , such objects would behave like impurities in a fizzy drink – helping the liquid form gas bubbles by contributing to its energy via the effect of gravity (due to the mass of the black hole) and the ambient temperature (due to its Hawking radiation).

When primordial black holes evaporate,  they heat the universe locally . They would evolve in the middle of hot spots that could be much hotter than the surrounding universe, but still colder than their typical Hawking temperature. What we showed, using a combination of analytical calculations and numerical simulations, is that, because of the existence of these hot spots, they would constantly cause the Higgs field to bubble.

But we are still here. This means that such objects are highly unlikely to ever have existed. In fact, we should rule out all of the cosmological scenarios predicting their existence.

That’s of course unless we discover some evidence of their past existence in ancient radiation or gravitational waves. If we do, that may be even more exciting. That would indicate that there’s something we don’t know about the Higgs; something that protects it from bubbling in the presence of evaporating primordial black holes. This may, in fact, be brand new particles or forces.

Either way, it is clear that we still have a lot to discover about the universe on the smallest and biggest scales.

Princeton Plasma Physics Laboratory

Heating for fusion: why toast plasma when you can microwave it.

An artist's metaphoric depiction of a fusion plasma in a microwave, with a toaster in the background. (Illustration credit: Kyle Palmer / PPPL Communications Department)

Carving a new path forward for compact fusion vessels

Some believe the future of fusion in the U.S. lies in compact, spherical fusion vessels. A smaller  tokamak , it is thought, could offer a more economical fusion option. The trick is squeezing everything into a small space. New research suggests eliminating one major component used to heat the  plasma , freeing up much-needed space.

Scientists at the U.S.  Department of Energy ’s (DOE)  Princeton Plasma Physics Laboratory (PPPL), the private company  Tokamak Energy and  Kyushu University in Japan have proposed a design for a compact, spherical fusion pilot plant that heats the plasma using only microwaves. Typically, spherical tokamaks also use a massive coil of copper wire called a solenoid, located near the center of the vessel, to heat the plasma. Neutral beam injection, which involves applying beams of uncharged particles to the plasma, is often used as well. But much like a tiny kitchen is easier to design if it has fewer appliances, it would be simpler and more economical to make a compact tokamak if it has fewer heating systems.

The new approach eliminates ohmic heating, which is the same heating that happens in a toaster and is standard in tokamaks. “A compact, spherical tokamak plasma looks like a cored apple with a relatively small core, so one does not have the space for an ohmic heating coil,” said  Masayuki Ono , a principal research physicist at PPPL and lead author of  the paper detailing the new research. “If we don’t have to include an ohmic heating coil, we can probably design a machine that is easier and cheaper to build.”  

VIDEO: Tokamak shapes

The video below provides some basic facts about spherical and doughnut-shaped tokamaks.

Identifying the ideal beam angle and heating mode

Microwaves are a form of electromagnetic radiation that can be generated using a device known as a gyrotron. The gyrotrons would sit on the outside of the tokamak — metaphorically speaking, just outside the apple skin — aimed toward the core. As the gyrotrons emitted powerful waves into the plasma, they would generate a current by moving negatively charged particles known as electrons. This process, known as electron cyclotron current drive (ECCD), both drives a current in and heats up the plasma. The heating process is not as simple as just turning on some gyrotrons, however. The researchers need to model different scenarios and determine various details, such as the best angle to aim the gyrotrons so the microwaves penetrate the plasma properly.

Using a computer code called TORAY coupled with one called TRANSP, the team scanned the aiming angles and saw what gave the highest efficiency. The goal is to use as little power as possible to drive the necessary current. “Also, you have to try to avoid any of the power that you’re putting into the plasma coming back out,” said  Jack Berkery , a co-author on the paper and the deputy director of research for the  National Spherical Torus Experiment-Upgrade (NSTX-U). This can happen when the microwaves are reflected off the plasma or when they enter the plasma but exit without changing the plasma’s current or temperature. “There were a lot of scans of different parameters to find the best solution,” Berkery said.

The research team also determined which mode of ECCD would work best for each phase of the heating process. There are two modes: ordinary mode, known as O mode, and extraordinary mode, known as X mode. The researchers see X mode as the best fit for ramping up the temperature and current of the plasma, while O mode is the best choice after the ramp-up, when the plasma temperature and current simply need to be maintained.

“O mode is good for a high-temperature, high-density plasma. But we found that O mode efficiency becomes very poor at lower temperatures, so you need something else to take care of the low-temperature regime,” said Ono.  

Considering the impact of impurities

The authors, including postdoctoral researcher Kajal Shah, also investigated how power would radiate away from the plasma. Such radiation could be significant in a plasma as big as one needed for commercial fusion.  Luis Delgado-Aparicio , the Lab’s head of the Advanced Projects Department and a co-author on the paper, notes that it will be particularly important to minimize the number of impurities from elements with a high atomic number, which is also known as a Z number, in the periodic table. Those are the elements with many positively charged particles, known as protons. The more protons an element has, the higher its Z number and the more it can contribute to heat loss. Tungsten and molybdenum, for example, have Z numbers, so their use inside a compact spherical tokamak would need to be carefully considered with an eye toward running the reactor in ways that would reduce impurity transfer into the plasma.

While the strong magnetic fields largely confine the plasma inside a tokamak in a particular shape, sometimes plasma can come close to the interior walls of the tokamak. “When this happens, atoms from the walls can sputter off and enter the plasma, cooling it,” said Delgado-Aparicio. “Even a relatively small amount of an element with a high Z number can cause the temperature of the plasma to cool significantly.” So, it is particularly important to keep impurities out of the plasma — as much as possible — particularly while the temperature is still ramping up.  

Private-public partnerships: The future of fusion

The heating simulations are part of a design project known as the Spherical Tokamak Advanced Reactor or STAR. The project is a strategic initiative to develop plans for a pilot power plant. Berkery said the project provides PPPL researchers with an opportunity to apply their expertise in physics, engineering and working with the computer codes for fusion simulations while working in partnership with private firms on their plans for fusion power plants with a spherical tokamak design.

Vladimir Shevchenko, a co-author on the paper and a senior technical adviser at Tokamak Energy, said he plans to run experiments at the end of next year in the company’s fusion vessel, ST40, to compare to the simulation results presented in the paper. “Other heating systems have very, very serious problems,” Shevchenko said. “I see this as the future for tokamak heating systems.”

Shevchenko thinks the project benefits from the public-private partnership between PPPL and Tokamak Energy, one of the companies selected for the DOE milestone-based fusion development program. “PPPL has a lot of experienced specialists in different areas related to plasma physics and tokamak technologies. Their contribution in terms of modeling and advising is very valuable for a private company like Tokamak Energy,” he said.

Other PPPL researchers on this project include Nicola Bertelli, Syun’ichi Shiraiwa, Jon Menard and Álvaro Sánchez Villar. This research was completed with funding from the DOE under contract number DE-AC02-09CH11466.

PPPL is mastering the art of using plasma — the fourth state of matter — to solve some of the world's toughest science and technology challenges. Nestled on Princeton University’s Forrestal Campus in Plainsboro, New Jersey, our research ignites innovation in a range of applications including fusion energy, nanoscale fabrication, quantum materials and devices, and sustainability science. The University manages the Laboratory for the U.S. Department of Energy’s Office of Science, which is the nation’s single largest supporter of basic research in the physical sciences. Feel the heat at https://energy.gov/science  and  https://www.pppl.gov .  

Quantum Scale Sensors used to Measure Planetary Scale Magnetic Fields

Magnetic fields are everywhere in our solar system. They originate from the Sun, planets, and moons, and are carried throughout interplanetary space by solar wind. This is precisely why magnetometers—devices used to measure magnetic fields—are flown on almost all missions in space to benefit the Earth, Planetary, and Heliophysics science communities, and ultimately enrich knowledge for all humankind. These instruments can remotely probe the interior of a planetary body to provide insight into its internal composition, structure, dynamics, and even evolution based on the magnetic history frozen into the body’s crustal rock layers. Magnetometers can even discover hidden oceans within our solar system and help determine their salinity, thereby providing insight into the potential habitability of these icy worlds.

Fluxgates are the most widely used magnetometers for missions in space due to their proven performance and simplicity. However, the conventional size, weight, and power (SWaP) of fluxgate instruments can restrict them from being used on small platforms like CubeSats and sometimes limit the number of sensors that can be used on a spacecraft for inter-sensor calibration, redundancy, and spacecraft magnetic field removal. Traditionally, a long boom is used to distance the fluxgate magnetometers from the contaminate magnetic field generated by the spacecraft, itself, and at least two sensors are used to characterize the falloff of this field contribution so it can be removed from the measurements. Fluxgates also do not provide an absolute measurement, meaning that they need to be routinely calibrated in space through spacecraft rolls, which can be time and resource intensive.

An SMD-funded team at NASA’s Jet Propulsion Laboratory in Southern California has partnered with NASA’s Glenn Research Center in Cleveland, Ohio to prototype a new magnetometer called the silicon carbide (SiC) magnetometer, or SiCMag, that could change the way magnetic fields are measured in space. SiCMag uses a solid-state sensor made of a silicon carbide (SiC) semiconductor. Inside the SiC sensor are quantum centers—intentionally introduced defects or irregularities at an atomic scale—that give rise to a magnetoresistance signal that can be detected by monitoring changes in the sensor’s electrical current, which indicate changes in the strength and direction of the external magnetic field. This new technology has the potential to be incredibly sensitive, and due to its large bandgap (i.e., the energy required to free an electron from its bound state so it can participate in electrical conduction), is capable of operating in the wide range of temperature extremes and harsh radiation environments commonly encountered in space.

Team member David Spry of NASA Glenn indicates, “Not only is the SiC material great for magnetic field sensing, but here at NASA Glenn we’re further developing robust SiC electronics that operate in hot environments far beyond the upper temperature limitations of silicon electronics. These SiC-based technologies will someday enable long-duration robotic scientific exploration of the 460 °C Venus surface.”

SiCMag is also very small— the sensor area is only 0.1 x 0.1 mm and the compensation coils are smaller than a penny. Consequently, dozens of SiCMag sensors can easily be incorporated on a spacecraft to better remove the complex contaminate magnetic field generated by the spacecraft, reducing the need for a long boom to distance the sensors from the spacecraft, like implemented on most spacecraft, including Psyche (see figure below).

SiCMag has several advantages when compared to fluxgates and other types of heritage magnetometers including those based on optically pumped atomic vapor. SiCMag is a simple instrument that doesn’t rely on optics or high-frequency components, which are sensitive to temperature variations. SiCMag’s low SWaP also allows for accommodation on small platforms such as CubeSats, enabling simultaneous spatial and temporal magnetic field measurements not possible with single large-scale spacecraft. This capability will enable planetary magnetic field mapping and space weather monitoring by constellations of CubeSats. Multiplatform measurements would also be very valuable on the surface of the Moon and Mars for crustal magnetic field mapping, composition identification, and magnetic history investigation of these bodies.

SiCMag has a true zero-field magnetic sensing ability (i.e., SiCMag can measure extremely weak magnetic fields), which is unattainable with most conventional atomic vapor magnetometers due to the requisite minimum magnetic field needed for the sensor to operate. And because the spin-carrying electrons in SiCMag are tied up in the quantum centers, they won’t escape the sensor, meaning they are well-suited for decades-long journeys to the ice-giants or to the edges of the heliosphere. This capability is also an advantage of SiCMag’s optical equivalent sibling, OPuS-MAGNM, an optically pumped solid state quantum magnetometer developed by Hannes Kraus and matured by Andreas Gottscholl of the JPL solid-state magnetometry group. SiCMag has the advantage of being extremely simple, while OPuS-MAGNM promises to have lower noise characteristics, but uses complex optical components.

According to Dr. Andreas Gottscholl, “SiCMag and OPuS-MAGNM are very similar, actually. Progress in one sensor system translates directly into benefits for the other. Therefore, enhancements in design and electronics advance both projects, effectively doubling the impact of our efforts while we are still flexible for different applications.”

SiCMag has the ability to self-calibrate due to its absolute sensing capability, which is a significant advantage in the remote space environment. SiCMag uses a spectroscopic calibration technique that atomic vapor magnetometers also leverage called magnetic resonance (in the case of SiCMag, the magnetic resonance is electrically detected) to measure the precession frequency of electrons associated with the quantum centers, which is directly related to the magnetic field in which the sensor is immersed. This relationship is a fundamental physical constant in nature that doesn’t change as a function of time or temperature, making the response ideal for calibration of the sensor’s measurements. “If we are successful in achieving the sought-out sensitivity improvement we anticipate using isotopically purer materials, SiC could change the way magnetometry is typically performed in space due to the instrument’s attractive SWaP, robustness, and self-calibration ability,” says JPL’s Dr. Corey Cochrane, principal investigator of the SiCMag technology.

NASA has been funding this team’s solid-state quantum magnetometer sensor research through its PICASSO (Planetary Instrument Concepts for the Advancement of Solar System Observations) program since 2016. A variety of domestic partners from industry and academia also support this research, including NASA’s Glenn Research Center in Cleveland, Penn State University, University of Iowa, QuantCAD LLC, as well as international partners such as Japan’s Quantum Materials and Applications Research Center (QUARC) and Infineon Technologies.

Acknowledgment: The research was carried out at the Jet Propulsion Laboratory, California Institute of Technology, under a contract with the National Aeronautics and Space Administration (80NM0018D0004) and the NASA Glenn Research Center.

Project Lead(s):

Dr. Corey Cochrane, Dr. Hannes Kraus, Jet Propulsion Laboratory/California Institute of Technology

Dr. Phil Neudeck, David Spry, NASA Glenn Research Center

Sponsoring Organization(s):

Science Mission Directorate PICASSO, JPL R&D fund

Related Terms

• Glenn Research Center
• Jet Propulsion Laboratory
• Planetary Science
• Science-enabling Technology
• Technology Highlights

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Perceptions

Collection Pérez Art Museum, Miami.

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CERN Accelerating science

The Standard Model

The Standard Model explains how the basic building blocks of matter interact, governed by four fundamental forces.

The theories and discoveries of thousands of physicists since the 1930s have resulted in a remarkable insight into the fundamental structure of matter: everything in the universe is found to be made from a few basic building blocks called fundamental particles, governed by four fundamental forces. Our best understanding of how these particles and three of the forces are related to each other is encapsulated in the Standard Model of particle physics. Developed in the early 1970s, it has successfully explained almost all experimental results and precisely predicted a wide variety of phenomena. Over time and through many experiments, the Standard Model has become established as a well-tested physics theory.

Particles of the Standard Model of particle physics (Image: Daniel Dominguez/CERN)

Matter particles

All matter around us is made of elementary particles, the building blocks of matter. These particles occur in two basic types called quarks and leptons. Each group consists of six particles, which are related in pairs, or “generations”. The lightest and most stable particles make up the first generation, whereas the heavier and less-stable particles belong to the second and third generations. All stable matter in the universe is made from particles that belong to the first generation; any heavier particles quickly decay to more stable ones. The six quarks are paired in three generations – the “up quark” and the “down quark” form the first generation, followed by the “charm quark” and “strange quark”, then the “top quark” and “bottom (or beauty) quark”. Quarks also come in three different “colours” and only mix in such ways as to form colourless objects. The six leptons are similarly arranged in three generations – the “electron” and the “electron neutrino”, the “muon” and the “muon neutrino”, and the “tau” and the “tau neutrino”. The electron, the muon and the tau all have an electric charge and a sizeable mass, whereas the neutrinos are electrically neutral and have very little mass.

Forces and carrier particles

There are four fundamental forces at work in the universe: the strong force, the weak force, the electromagnetic force, and the gravitational force. They work over different ranges and have different strengths. Gravity is the weakest but it has an infinite range. The electromagnetic force also has infinite range but it is many times stronger than gravity. The weak and strong forces are effective only over a very short range and dominate only at the level of subatomic particles. The weak force is weaker than the strong force and the electromagnetic force, but it is still much stronger than gravity. The strong force, as the name suggests, is the strongest of all four fundamental interactions.

Three of the fundamental forces result from the exchange of force-carrier particles, which belong to a broader group called “bosons”. Particles of matter transfer discrete amounts of energy by exchanging bosons with each other. Each fundamental force has its own corresponding boson – the strong force is carried by the “gluon”, the electromagnetic force is carried by the “photon”, and the “ W and Z bosons” are responsible for the weak force. Although not yet found, the “graviton” should be the corresponding force-carrying particle of gravity. The Standard Model includes the electromagnetic, strong and weak forces and all their carrier particles, and explains well how these forces act on all of the matter particles. However, the most familiar force in our everyday lives, gravity, is not part of the Standard Model, as fitting gravity comfortably into this framework has proved to be a difficult challenge. The quantum theory used to describe the micro world, and the general theory of relativity used to describe the macro world, are difficult to fit into a single framework. No one has managed to make the two mathematically compatible in the context of the Standard Model. But luckily for particle physics, when it comes to the minuscule scale of particles, the effect of gravity is so weak as to be negligible. Only when matter is in bulk, at the scale of the human body or of the planets for example, does the effect of gravity dominate. So the Standard Model still works well despite its reluctant exclusion of one of the fundamental forces.

So far so good, but...

...it is not time for physicists to call it a day just yet. Even though the Standard Model is currently the best description there is of the subatomic world, it does not explain the complete picture. The theory incorporates only three out of the four fundamental forces, omitting gravity. There are also important questions that it does not answer, such as “ What is dark matter? ”, or “ What happened to the antimatter after the big bang? ”, “Why are there three generations of quarks and leptons with such a different mass scale?” and more. Last but not least is a particle called the Higgs boson , an essential component of the Standard Model.

On 4 July 2012, the ATLAS and CMS experiments at CERN's Large Hadron Collider (LHC) announced they had each observed a new particle in the mass region around 126 GeV. This particle was consistent with the Higgs boson but it took further work to determine whether or not it was the Higgs boson predicted by the Standard Model. The Higgs boson, as proposed within the Standard Model, is the simplest manifestation of the Brout-Englert-Higgs mechanism. Other types of Higgs bosons are predicted by other theories that go beyond the Standard Model.

On 8 October 2013 the Nobel prize in physics was awarded jointly to François Englert and Peter Higgs “for the theoretical discovery of a mechanism that contributes to our understanding of the origin of mass of subatomic particles, and which recently was confirmed through the discovery of the predicted fundamental particle, by the ATLAS and CMS experiments at CERN's Large Hadron Collider”.

So although the Standard Model accurately describes the phenomena within its domain, it is still incomplete. Perhaps it is only a part of a bigger picture that includes new physics hidden deep in the subatomic world or in the dark recesses of the universe. New information from experiments at the LHC will help us to find more of these missing pieces.

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Why Dropping the E in DEI Is a Mistake

• Enrica N. Ruggs
• Oscar Holmes IV

The Society for Human Resource Management’s decision to remove “equity” from its DEI framework sets a dangerous precedent that flies in the face of decades of research.

The Society for Human Resource Management (SHRM) has decided to remove “equity” from its inclusion, equity, and diversity (IE&D) framework, now promoting “inclusion and diversity” (I&D) instead. This decision sets a dangerous precedent that flies in the face of decades of research about DEI in the workplace. It undermines efforts to create equitable workplaces and ignores the vital role of equity in fostering fairness and addressing systemic barriers faced by marginalized groups. Instead of scaling back their focus on equity, companies should: 1) Commit to achievable equity goals; 2) Implement and track evidence-based DEI policies and practices; and 3) Establish accountability and transparency.

Recently, the Society for Human Resource Management (SHRM), a leading voice of HR professionals, announced that it was abandoning the acronym “IE&D” — inclusion, equity, and diversity — in favor of “I&D.”

• Enrica N. Ruggs , PhD is an associate professor of management in the C. T. Bauer College of Business at the University of Houston. She is a workplace diversity scholar who conducts research on reducing discrimination and bias in organizations and improving workplace experiences for individuals with marginalized identities.
• Oscar Holmes IV , PhD, SHRM-SCP is an associate professor of management at Rutgers University-Camden and the creator and host of the podcast Diversity Matters . In his research he examines how leaders can maximize productivity and well-being by fostering more inclusive workplaces.

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La partícula de Higgs podría haber acabado ya con el universo: ¿por qué seguimos aquí?

Postdoctoral Research Associate, King's College London

Disclosure statement

Lucien Heurtier does not work for, consult, own shares in or receive funding from any company or organisation that would benefit from this article, and has disclosed no relevant affiliations beyond their academic appointment.

King's College London provides funding as a member of The Conversation UK.

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A pie de Tierra, el universo parecer estable. No podría ser de otro modo. Hace al menos la friolera de 13 700 millones de años que persiste. Sin embargo, a medida que los expertos indagan más sobre las partículas cuánticas y su papel en el cosmos, la estabilidad se tambalea. Los experimentos sobre la partícula de Higgs (o bosón de Higgs) y el campo de Higgs muestran que algo pudo y podría salir mal.

Aún hoy la inestabilidad de una única partícula fundamental , el bosón de Higgs , nos coloca ante la inquietante posibilidad de que el cosmos llegue a su fin convirtiéndose en en burbujas.

De qué se ocupa el bosón de Higgs

El bosón de Higgs es responsable de la masa y las interacciones de todas las partículas que conocemos.

Y esa masa depende de la interacción de partículas elementales con un campo , denominado campo de Higgs.

Como el bosón de Higgs existe, sabemos que ese campo fundamental para que las partículas interacciones entre ellas existe.

El campo en el que nos sumergimos

Se puede pensar en este campo como en un baño de agua perfectamente inmóvil en el que nos sumergimos. Tiene propiedades idénticas en todo el universo. Esto significa que observamos las mismas masas e interacciones en todo el cosmos. Esta uniformidad nos ha permitido observar y describir la misma física a lo largo de varios milenios (los astrónomos suelen mirar hacia atrás en el tiempo).

Pero lo más inquietante es que este campo fundamental tiene que ser exactamente como es. Si su estado energético fuera el más bajo posible, según los físicos, en teoría, podría cambiar de estado y si eso ocurriera las leyes de la física se alterarían drásticamente.

Tal cambio es lo que ocurre cuando el agua se convierte en vapor, formando burbujas en el proceso, es lo que los físicos llaman una transición de fase. Si este cambio se produjera, el campo de Higgs crearía burbujas de espacio de baja energía con una física completamente diferente.

En una burbuja así, la masa de los electrones cambiaría de repente, al igual que sus interacciones con otras partículas. Los protones y neutrones, que componen el núcleo atómico y están formados por quarks, se dislocarían de repente. Esencialmente, si se experimentara un cambio así nadie ni nada quedaría por aquí para contarlo.

El riesgo de cambio es constante

Mediciones recientes de masas de partículas en el Gran Colisionador de Hadrones (LHC) del CERN sugieren que tal evento podría ser posible. Pero que no cunda el pánico; es posible, sí, pero en unos miles de miles de millones de años. Por eso, en los pasillos de los departamentos de física de partículas se suele decir que el universo no es inestable, sino más bien “metaestable”, porque el fin del mundo probablemente llegará, pero no llegará pronto.

Para formar una burbuja, el campo de Higgs necesita una buena razón. Debido a la mecánica cuántica, la teoría que rige el microcosmos de átomos y partículas, la energía del Higgs siempre fluctúa. Y es estadísticamente posible (aunque improbable, por eso llevaría tanto tiempo que ocurriera) que el Higgs forme una burbuja de vez en cuando.

¿Y si entra en juego una energía extra?

La historia es diferente, y ya no sería tanta la improbabilidad, en presencia de fuentes de energía externas como campos gravitatorios fuertes o plasma caliente (una forma de materia compuesta de partículas cargadas). El campo de Higgs podría tomar prestada esta energía extra para formar burbujas más fácilmente.

Por lo tanto, aunque no hay razón para esperar que el campo de Higgs forme numerosas burbujas hoy en día, una gran pregunta en el contexto de la cosmología es si los ambientes extremos poco después del Big Bang podrían haber desencadenado tal burbujeo.

Los datos apuntan a que en ese momento, cuando el universo estaba muy caliente y había energía disponible para ayudar a formar las destructivas burbujas de Higgs, esos efectos térmicos también sirvieron al mismo tiempo para estabilizar el Higgs modificando sus propiedades cuánticas. Así que este calor no pudo desencadenar el fin del universo, que es probablemente la razón por la que todavía estamos aquí.

El dilema de los agujeros negros primordiales

Nuestra nueva investigación que acaba de ser aceptada para su publicación en Physical Letters , demuestra que existe una fuente de calor que provocaría constantemente ese burbujeo indeseable del campo de Higgs (sin los efectos térmicos estabilizadores observados en los primeros días tras el Big Bang). La fuente de este calor podrían ser agujeros negros primordiales, un tipo de agujero negro que hipotéticamente surgió en el universo primitivo a partir del colapso de regiones demasiado densas del espacio-tiempo.

A diferencia de los agujeros negros normales, que se forman cuando las estrellas colapsan, los primordiales podrían ser diminutos, tan ligeros como un gramo.

La existencia de estos agujeros negros ligeros es una predicción de muchos modelos teóricos que describen la evolución del cosmos poco después del Big Bang. Esto incluye algunos modelos de inflación , que sugieren que el universo aumentó enormemente de tamaño tras el Big Bang.

El dilema y la solución

Sin embargo, demostrar esta existencia conlleva una gran advertencia: Stephen Hawking demostró en los años 70 que, debido a la mecánica cuántica, los agujeros negros se evaporan lentamente emitiendo radiación a través de su horizonte de sucesos (un punto al que ni siquiera la luz puede escapar).

Hawking demostró que los agujeros negros se comportan como fuentes de calor en el universo, con una temperatura inversamente proporcional a su masa . Esto significa que los agujeros negros ligeros son mucho más calientes y se evaporan más rápidamente que los masivos. En particular, si en el universo primitivo se formaron agujeros negros primordiales más ligeros que unos pocos miles de miles de millones de gramos (10 000 millones de veces más pequeños que la masa de la Luna), como sugieren muchos modelos, ya se habrían evaporado.

En presencia del campo de Higgs , tales objetos se comportarían como impurezas en una bebida gaseosa, ayudando al líquido a formar burbujas de gas al contribuir a su energía mediante el efecto de la gravedad (debido a la masa del agujero negro) y la temperatura ambiente (debido a su radiación Hawking).

Cuando los agujeros negros primordiales se evaporan, calientan el universo localmente . Evolucionarían en medio de puntos que podrían ser mucho más calientes que el universo circundante, pero aún más fríos que la temperatura Hawking típica.

Lo que demostramos, utilizando una combinación de cálculos analíticos y simulaciones numéricas, es que estos puntos calientes harían burbujear constantemente el campo de Higgs. Y, con esto, el fin.

Pero todavía estamos aquí. Así que hay que mirar lo observado desde un punto de vista radicalmente distinto. Esto significa que es muy improbable que tales objetos hayan existido alguna vez. De hecho, deberíamos descartar todos los escenarios cosmológicos que predicen la existencia de agujeros negros primordiales.

Eso, por supuesto, a menos que descubramos alguna prueba de su existencia pasada en la radiación antigua o en las ondas gravitacionales. Si se encuentra puede ser aún más emocionante. Eso indicaría que hay algo que no sabemos sobre el bosón de Higgs; algo que lo protege de burbujear en presencia de agujeros negros primordiales en evaporación. Podría tratarse, de hecho, de partículas o fuerzas completamente nuevas.

En cualquier caso, está claro que aún nos queda mucho por descubrir sobre el inquietante universo en las escalas más pequeñas y más grandes.

This article was originally published in English

• bosón de Higgs
• origen del universo

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How Alzheimer’s disease could be reversed through lifestyle changes: new research

• A plant-based diet, strength training exercise and meditation can help reverse the disease’s symptoms, study says

It is not often you hear a hopeful story or read an encouraging study about dementia, given the sobering statistics about the disease.

Someone in the world develops dementia every three seconds, according to the non-profit Alzheimer’s Disease International. More than 55 million people worldwide lived with dementia in 2020, a number that is expected to double every 20 years, reaching 78 million in 2030 and 139 million in 2050.

Dr Dean Ornish, a professor of medicine at the University of California San Francisco and founder and president of the non-profit Preventive Medicine Research Institute, also in California, paints a brighter picture in a paper published in June in the journal Alzheimer’s Research & Therapy.

He suggests that radical lifestyle changes might not only slow the progression of dementia, but could even reverse it.

It sounds too good to be true given the less encouraging stories of a cure for the disease. But Ornish has reason to be optimistic.

“People talk about Alzheimer’s disease today just like they used to talk about heart disease,” he said in a recent podcast from the non-profit Us Against Alzheimer’s. “Forty-five years ago, the best that was hoped for was that the progression of heart disease might be slowed, not reversed altogether.”

It has since been proven to be reversible.

Ornish’s rules for health – and a healthy brain – as we age are simple: “Eat well, move more, stress less and love more.”

Ornish’s study – admittedly a small study sample – reviewed 51 adults in their 70s who all had signs of mild cognitive impairment or early Alzheimer’s.

At the end of the five-month study period, 70 per cent of the control group had worse cognitive function. Of the group who engaged in healthy interventions, 70 per cent were either stable or markedly improved.

The changes in some individuals were significant. Several participants whose symptoms had seen them stop reading began to read again; a musician remembered his music; a businessman who had not been able to manage his affairs was able to again; and a number of people who had struggled to follow complicated movie plots were able to enjoy films again.

The positive changes among participants who undertook interventions were astonishing given the short length of the study, the authors said.

Cici Zerbe, a Californian now in her mid-80s, was one of the patients in the control group. Her dementia appeared to worsen during the study but by the end, she committed to changing her lifestyle radically.

Five years later, in the documentary The Last Alzheimer’s Patient made for CNN by Dr Sanjay Gupta, Zerbe opens the door to Gupta and greets him by name.

In the documentary, Zerbe says her symptoms have been reversed after changes she made following the end of the study. She now walks every day and admits to a big change in her diet. “I haven’t had a breaded veal cutlet in years,” she laughs.

Gupta, who has Alzheimer’s in his family, is acutely aware of his own risk and had his profile analysed for the documentary.

In the course of assessing his risk, he spoke to neurologist and researcher Dr Richard Isaacson, director of the Florida Atlantic University Centre for Brain Health.

Isaacson, who also has the disease in his family, describes the recent case of Simon Nicholls. Nicholls lost his mother to Alzheimer’s and, at 55, was concerned about his memory. He spent a year under Isaacson’s care to manage his risk.

“His brain grew and his belly size got smaller,” Isaacson notes in the documentary.

Gupta’s tests were all normal. Isaacson calls him a “walking modifiable risk factor for Alzheimer’s” – in other words, he can keep managing his lifestyle to minimise his chance of developing the disease.

There were no signs or amyloid plaques or tau tangles in his brain, but as Gupta notes, he still has to watch for them.

Isaacson’s tips for best brain health in old age include eating a mostly plant-based diet; exercising regularly; taking brisk walks, particularly while wearing a weighted belt; and wearing a glucose monitor to keep an eye on blood sugar fluctuations.

Ornish – who designed a diet that experts recognised as being among the top healthy diets in the world in 2024 – says the problem with Alzheimer’s disease at the moment is that it can isolate a person, which further hastens the development of the disease.

Changing the way you live now – whatever your age – for better brain health later is a message of hope, he says, not despair.