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HYPER (HighlY Interactive ParticlE Relics) – A New Model for Dark Matter

January 24, 2023 Admin Leave a comment

A team of researchers has now proposed a new candidate for dark matter: HYPER, or “HighlY Interactive ParticlE Relics.”

Phase transition in early universe changes strength of interaction between dark and normal matter.

Dark matter remains one of the greatest mysteries of modern physics. It is clear that it must exist, because without dark matter, for example, the motion of galaxies cannot be explained. But it has never been possible to detect dark matter in an experiment.

Currently, there are many proposals for new experiments: They aim to detect dark matter directly via its scattering from the constituents of the atomic nuclei of a detection medium, i.e., protons and neutrons.

A team of researchers—Robert McGehee and Aaron Pierce of the University of Michigan and Gilly Elor of Johannes Gutenberg University of Mainz in Germany—has now proposed a new candidate for dark matter: HYPER, or “HighlY Interactive ParticlE Relics.”

In the HYPER model, sometime after the formation of dark matter in the early universe, the strength of its interaction with normal matter increases abruptly—which on the one hand, makes it potentially detectable today and at the same time can explain the abundance of dark matter.

This NASA Hubble Space Telescope image shows the distribution of dark matter in the center of the giant galaxy cluster Abell 1689, containing about 1,000 galaxies and trillions of stars.
Dark matter is an invisible form of matter that accounts for most of the universe’s mass. Hubble cannot see the dark matter directly. Astronomers inferred its location by analyzing the effect of gravitational lensing, where light from galaxies behind Abell 1689 is distorted by intervening matter within the cluster.
Researchers used the observed positions of 135 lensed images of 42 background galaxies to calculate the location and amount of dark matter in the cluster. They superimposed a map of these inferred dark matter concentrations, tinted blue, on an image of the cluster taken by Hubble’s Advanced Camera for Surveys. If the cluster’s gravity came only from the visible galaxies, the lensing distortions would be much weaker. The map reveals that the densest concentration of dark matter is in the cluster’s core.
Abell 1689 resides 2.2 billion light-years from Earth. The image was taken in June 2002.
Credit: NASA, ESA, D. Coe (NASA Jet Propulsion Laboratory/California Institute of Technology, and Space Telescope Science Institute), N. Benitez (Institute of Astrophysics of Andalusia, Spain), T. Broadhurst (University of the Basque Country, Spain), and H. Ford (Johns Hopkins University)

The new diversity in the dark matter sector

Since the search for heavy dark matter particles, or so-called WIMPS, has not yet led to success, the research community is looking for alternative dark matter particles, especially lighter ones. At the same time, one generically expects phase transitions in the dark sector—after all, there are several in the visible sector, the researchers say. But previous studies have tended to neglect them.

“There has not been a consistent dark matter model for the mass range that some planned experiments hope to access. “However, our HYPER model illustrates that a phase transition can actually help make the dark matter more easily detectable,” said Elor, a postdoctoral researcher in theoretical physics at JGU.

The challenge for a suitable model: If dark matter interacts too strongly with normal matter, its (precisely known) amount formed in the early universe would be too small, contradicting astrophysical observations. However, if it is produced in just the right amount, the interaction would conversely be too weak to detect dark matter in present-day experiments.

“Our central idea, which underlies the HYPER model, is that the interaction changes abruptly once—so we can have the best of both worlds: the right amount of dark matter and a large interaction so we might detect it,” McGehee said.

And this is how the researchers envision it: In particle physics, an interaction is usually mediated by a specific particle, a so-called mediator—and so is the interaction of dark matter with normal matter. Both the formation of dark matter and its detection function via this mediator, with the strength of the interaction depending on its mass: The larger the mass, the weaker the interaction.

The mediator must first be heavy enough so that the correct amount of dark matter is formed and later light enough so that dark matter is detectable at all. The solution: There was a phase transition after the formation of dark matter, during which the mass of the mediator suddenly decreased.

“Thus, on the one hand, the amount of dark matter is kept constant, and on the other hand, the interaction is boosted or strengthened in such a way that dark matter should be directly detectable,” Pierce said.

New model covers almost the full parameter range of planned experiments

“The HYPER model of dark matter is able to cover almost the entire range that the new experiments make accessible,” Elor said.

Specifically, the research team first considered the maximum cross-section of the mediator-mediated interaction with the protons and neutrons of an atomic nucleus to be consistent with astrological observations and certain particle-physics decays. The next step was to consider whether there was a model for dark matter that exhibited this interaction.

“And here we came up with the idea of the phase transition,” McGehee said. “We then calculated the amount of dark matter that exists in the universe and then simulated the phase transition using our calculations.”

There are a great many constraints to consider, such as a constant amount of dark matter.

“Here, we have to systematically consider and include very many scenarios, for example, asking the question whether it is really certain that our mediator does not suddenly lead to the formation of new dark matter, which of course must not be,” Elor said. “But in the end, we were convinced that our HYPER model works.”

The research is published in the journal Physical Review Letters.

Reference: “Maximizing Direct Detection with Highly Interactive Particle Relic Dark Matter” by Gilly Elor, Robert McGehee and Aaron Pierce, 20 January 2023, Physical Review Letters.
DOI: 10.1103/PhysRevLett.130.031803

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Light shaped as a smoke ring that behaves like a particle

January 19, 2023 Admin Leave a comment

Light can be shaped into a structure resembling a twisted smoke ring. Credit: Y. Shen and Z. Zhu.

We can frequently find in our daily lives a localized wave structure that maintains its shape upon propagation—picture a smoke ring flying in the air. Similar stable structures have been studied in various research fields and can be found in magnets, nuclear systems, and particle physics. In contrast to a ring of smoke, they can be made resilient to perturbations. This is known in mathematics and physics as topological protection.

A typical example is the nanoscale hurricane-like texture of a magnetic field in magnetic thin films, behaving as particles—that is, not changing their shape—called skyrmions. Similar doughnut-shaped (or toroidal) patterns in 3D space, visualizing complex spatial distributions of various properties of a wave, are called hopfions. Achieving such structures with light waves is very elusive.

Recent studies of structured light revealed strong spatial variations of polarization, phase, and amplitude, which enable the understanding of—and open up opportunities for designing—topologically stable optical structures behaving like particles. Such quasiparticles of light with control of diversified topological properties may have great potential, for example as next-generation information carriers for ultra-large-capacity optical information transfer, as well as in quantum technologies.

As reported in Advanced Photonics, collaborating physicists from UK and China recently demonstrated the generation of polarization patterns with designed topologically stable properties in three dimensions, which, for the first time, can be controllably transformed and propagated in free space.

(a) The parameter-space sphere which represents spin: the longitude and latitude degrees (α and β) of a parametric 2-sphere are represented by hue color and its lightness (dark towards the south pole, where spin is down, and bright towards the north pole, where spin is up). Each point on a parametric 2-sphere corresponds to a closed iso-spin line located in a 3D Euclidean space. (b) The lines projected from the selected points of the same latitude β and different longitude α on the hypersphere (highlighted by the solid dots with the corresponding hue colors), form torus knots covering a torus (with different tori corresponding to different β). (c) The real-space visualization of a Hopf fibration as a full stereographic mapping from a hypersphere: torus knots arranged on a set of coaxially nested tori, with each torus corresponding to different latitude β of a parametric 2-sphere. The black circle corresponds to the south pole (spin down) and the axis of the nested tori corresponds to the north pole (spin up) in (a). (d) The 3D spin distribution in a hopfion, corresponding to the isospin contours in (c) with each spin vector colored by its α and β parameters of a parametric sphere in (a) as shown in the insert. (e, f) The cross-sectional view of the spin distribution in (d): (e) xy (z = 0) and (f) yz (x = 0) cross-sections show skyrmion-like structures with the gray arrows marking the vorticity of the skyrmions. Color scale is the same as that corresponding to the spin direction in (d). Credit: Shen et al., doi 10.1117/1.AP.5.1.015001

As a consequence of this insight, several significant advances and new perspectives are offered. “We report a new, very unusual, structured-light family of 3D topological solitons, the photonic hopfions, where the topological textures and topological numbers can be freely and independently tuned, reaching far beyond previously described fixed topological textures of the lowest order,” says Yijie Shen of University of Southampton in the UK, the lead author of the paper.

“Our results illustrate the immense beauty of light structures. We hope they will inspire further investigations towards potential applications of topological protected light configurations in optical communications, quantum technologies, light–matter interactions, superresolution microscopy, and metrology,” says Anatoly Zayats, professor at King’s College London and project lead.

This work provides a theoretical background describing the emergence of this family of hopfions and their experimental generation and characterization, revealing a rich structure of topologically protected polarization textures. In contrast to previous observations of hopfions localized in solid-state materials, this work demonstrates that, counterintuitively, an optical hopfion can propagate in free space with topological protection of the polarization distribution.

The robust topological structure of the demonstrated photonic hopfions upon propagation is often sought in applications.

This newly developed model of optical topological hopfions can be easily extended to other higher-order topological formations in other branches of physics. The higher order hopfions are still a great challenge to observe in other physics communities, from high-energy physics to magnetic materials. The optical approach proposed in this work may provide a deeper understanding of this complex field of structures in other branches of physics.

More information:
Yijie Shen et al, Topological transformation and free-space transport of photonic hopfions, Advanced Photonics (2023). DOI: 10.1117/1.AP.5.1.015001

Citation:
Photonic hopfions: Light shaped as a smoke ring that behaves like a particle (2023, January 19)
retrieved 20 January 2023
from https://phys.org/news/2023-01-photonic-hopfions-particle.html

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Oddities in nuclear reactor measurements not due to a new particle

January 11, 2023 Admin Leave a comment

Enlarge / A diagram of the array of detectors in STEREO (left) and its location near a nuclear reactor (right).

Loris Scola – CEA

Neutrinos are probably the strangest particles we know about. They’re far, far lighter than any other particle with mass and only interact with other matter via the weak force—which means they barely ever interact with anything. Three types (or flavors) of neutrinos have been identified, and any individual particle doesn’t have a fixed identity. Instead, it can be viewed as a quantum superposition of all three flavors and will oscillate among these identities.

As if all that weren’t enough, a set of strange measurements has suggested that there could be a fourth type of neutrino that doesn’t even interact via the weak force, making it impossible to detect. These “sterile neutrinos” could potentially explain the tiny masses of the other neutrinos, as well as the existence of dark matter, but the whole “impossible to detect” thing makes it difficult to address their existence directly.

The strongest hints of their presence come from odd measurement results in experiments with other flavors of neutrinos. But a new study today rules out sterile neutrinos as an explanation for one of these oddities—even while confirming that the anomalous results are real.

Spotting the undetectable

We can detect the existence of particles in two ways: They either interact with other matter directly, or they decay into one or more particles that do. That’s what makes sterile neutrinos undetectable. They’re fundamental particles and shouldn’t decay into anything. They also only interact with other matter via gravity, and their low masses make detection via this route an impossibility.

Instead, we can potentially detect them via the oscillations of neutrinos. You can set up an experiment that produces a specific type of neutrinos at a known rate and then try to detect those neutrinos. If there are sterile neutrinos, some of the neutrinos you produced will oscillate into that identity and, thus, go undetected. So you end up measuring fewer neutrinos than you’d expect.

That’s exactly what has been happening at nuclear reactors. One of the products of a radioactive decay (which is driven by the weak force) is a neutrino, so nuclear reactors produce copious amounts of these particles. Measurements with detectors placed nearby, however, picked up about 6 percent fewer neutrinos than expected. A rapid oscillation into sterile neutrinos could explain that discrepancy.

But these experiments are really difficult. Neutrinos interact with detectors so rarely that only a tiny fraction of those produced get registered. And nuclear reactors are incredibly complex environments. Even if you start with a pure sample of a single radioactive isotope, decays quickly turn things into a complicated mix of new elements, some radioactive, some not. The neutrons released can also convert the reactor equipment into new isotopes that may be radioactive. So, it’s tough to know exactly how many neutrinos you’re producing to start with and the exact fraction of the ones you produce that will get registered by your detector.

For all those reasons, it’s tough to be certain that any anomalies in neutrino measurements are real. Physicists tend to take a wait-and-see attitude toward indications that something strange is going on.

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Completing Einstein’s Theories – A Particle Physics Breakthrough

November 28, 2022 Admin Leave a comment

More than a century after it was first theorized, scientists have completed Einstein’s homework on special relativity in electromagnetism.

Osaka University researchers show the relativistic contraction of an electric field produced by fast-moving charged particles, as predicted by Einstein’s theory, which can help improve radiation and particle physics research.

Over a century ago, one of the most renowned modern physicists, Albert Einstein, proposed the ground-breaking theory of special relativity. Most of everything we know about the universe is based on this theory, however, a portion of it has not been experimentally demonstrated until now. Scientists from Osaka University’s Institute of Laser Engineering utilized ultrafast electro-optic measurements for the first time to visualize the contraction of the electric field surrounding an electron beam traveling at near the speed of light and demonstrate the generation process.

According to Einstein’s theory of special relativity, one must use a “Lorentz transformation” that combines space and time coordinates in order to accurately describe the motion of objects passing an observer at speeds near the speed of light. He was able to explain how these transformations resulted in self-consistent equations for electric and magnetic fields.

While different effects of relativity have been proved numerous times to a very high degree of experimental

Illustration of the formation process of the planar electric field contraction that accompanies the propagation of a near-light-speed electron beam (shown as an ellipse in the figure). Credit: Masato Ota, Makoto Nakajima

Now, the research team at Osaka University has demonstrated this effect experimentally for the first time. They accomplished this feat by measuring the profile of the Coulomb field in space and time around a high-energy electron beam generated by a linear particle accelerator. Using ultrafast electro-optic sampling, they were able to record the electric field with extremely high temporal resolution.

It has been reported that the Lorentz transformations of time and space as well as those of energy and momentum were demonstrated by time dilation experiments and rest mass energy experiments, respectively. Here, the team looked at a similar relativistic effect called electric-field contraction, which corresponds to the Lorentz transformation of electromagnetic potentials.

“We visualized the contraction of an electric field around an electron beam propagating close to the speed of light,” says Professor Makoto Nakajima, the project leader. In addition, the team observed the process of electric-field contraction right after the electron beam passed through a metal boundary.

When developing the theory of relativity, it is said that Einstein used thought experiments to imagine what it would be like to ride on a wave of light. “There is something poetic about demonstrating the relativistic effect of electric fields more than 100 years after Einstein predicted it,” says Professor Nakajima. “Electric fields were a crucial element in the formation of the theory of relativity in the first place.”

This research, with observations matching closely to Einstein’s predictions of special relativity in electromagnetism, can serve as a platform for measurements of energetic particle beams and other experiments in high-energy physics.

Reference: “Ultrafast visualization of an electric field under the Lorentz transformation” by Masato Ota, Koichi Kan, Soichiro Komada, Youwei Wang, Verdad C. Agulto, Valynn Katrine Mag-usara, Yasunobu Arikawa, Makoto R. Asakawa, Youichi Sakawa, Tatsunosuke Matsui and Makoto Nakajima, 20 October 2022,

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The Particle Accelerator Experiment That Could Rewrite the History of the Printing Press

August 14, 2022 Admin Leave a comment

I’m a little nervous. In my right hand, I’m holding a priceless piece of human history. And that’s not hyperbole. It’s a weathered black binder, emblazoned with gold text on the front. In Gothic-style text it reads “A Leaf of The Gutenberg Bible (1450 – 1455).”

Yes, that Gutenberg Bible. These original pages, that date back to the 15th century, have come to the SLAC National Accelerator Laboratory in Northern California to be blasted by a high-powered X-ray. Along with the Bible pages, a 15th-century Korean Confucian text, a page from the Canterbury Tales written in the 14th century and other western and eastern documents are set to endure the barrage. Researchers are hoping that within the pages of these priceless documents lie clues to the evolution of one humankind’s most important inventions: the printing press.

A page from an original Gutenberg Bible (1450-1455 AD) is scanned by a beam from SLAC’s synchrotron particle accelerator.

SLAC National Accelerator Laboratory

“What we’re trying to learn is the elemental composition of the inks, the papers, and perhaps any residues of the typefaces that are used in these Western and Eastern printings,” said imaging consultant Michael Toth.

For centuries, it was commonly believed Johannes Gutenberg invented the printing press around 1440 AD in Germany. He’s thought to have printed 180 Bibles (fewer than 50 are known to exist today). But more recently, historians have uncovered evidence that Korean Buddhists began printing around 1250 AD.

A page of the Gutenberg Bible from the First and Second Epistles of Peter, mid-15th century.

Jacqueline Ramseyer Orrell/SLAC National Accelerator Laboratory

“What is not known is whether those two inventions were completely separate, or whether there was an information flow,” said Uwe Bergmann, a professor of physics at the University of Wisconsin. “If there was an information flow, it would have been, of course, from Korea, to the west to Gutenberg.”

To put it more plainly: Was Gutenberg’s invention based, at least in part, on Eastern technology? That’s where the Stanford Synchrotron Radiation Light Source comes in.

The Spring and Autumn Annals, Confucius, c. 1442.

Jacqueline Ramseyer Orrell/SLAC National Accelerator Laboratory

A synchrotron is a particle accelerator that fires electrons into a massive ring shaped tunnel in order to generate X-rays (as opposed to SLAC’s more famous linear particle accelerator, the two-mile long LCLS). These X-rays give scientists the ability to study the structural and chemical properties of matter. To see exactly how they’re using SSRL to study the priceless documents, watch the video above.

By firing the SSRL’s thinner-than-a-human-hair X-ray beam at a block of text on a document, researchers can create two-dimensional chemical maps that detail elements present in each pixel. It’s a technique called X-ray fluorescence imaging, or XRF.

The Stanford Synchrotron Radiation Lightsource (SSRL) at the SLAC National Accelerator Laboratory.

SLAC National Accelerator Laboratory

“The atoms in that sample emit light, and we can track which elements that light must have come from on the periodic table,” said Minhal Gardezi, a PhD student working on the project.

Though the SSRL’s X-rays are powerful, they don’t damage the documents, giving scientists a holistic view of the molecules that make up the ancient texts. They also give them the ability to look for trace metals that historians say should not be in the ink. That would indicate they probably came from the printing press themselves. “That would mean we could learn something about the alloys which were used in Korea and by Gutenberg and then maybe later by others,” Bergmann said.

Scientists can use X-rays to create two-dimensional chemical maps of ancient texts like this Confucian document.

Mike Toth/SLAC National Accelerator Laboratory

If they find similarities in the chemical compositions of the documents, that could contribute to ongoing research into the differences and similarities of the printing technologies, and whether there was an exchange of information from East Asian cultures to the West.

However, every scientist I talked with on the project made it clear that even if similarities between the two documents are found, it wouldn’t definitively prove one technology influenced the other.

The documents are on loan from private collections, the Stanford Library and archives in Korea. The research at SLAC is part of a larger project led by UNESCO called From Jikji to Gutenberg. The findings will be presented at the Library of Congress next April.

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Explained: What is the Large Hadron Collider, now readying to seek answers to fundamental questions of particle physics?

July 5, 2022 Admin Leave a comment

The world’s most powerful particle collider, the Large Hadron Collider (LHC), will begin smashing protons into each other at unprecedented levels of energy beginning July 5.

Scientists will record and analyse the data, which are expected to throw up evidence of “new physics” — or physics beyond the Standard Model of Particle Physics, which explains how the basic building blocks of matter interact, governed by four fundamental forces.

The LHC

The Large Hadron Collider is a giant, complex machine built to study particles that are the smallest known building blocks of all things.

Structurally, it is a 27-km-long track-loop buried 100 metres underground on the Swiss-French border. In its operational state, it fires two beams of protons almost at the speed of light in opposite directions inside a ring of superconducting electromagnets.

The magnetic field created by the superconducting electromagnets keeps the protons in a tight beam and guides them along the way as they travel through beam pipes and finally collide.

“Just prior to collision, another type of magnet is used to ‘squeeze’ the particles closer together to increase the chances of collisions. The particles are so tiny that the task of making them collide is akin to firing two needles 10 km apart with such precision that they meet halfway,” according to the European Organisation for Nuclear Research (originally Conseil Européen pour la Recherche Nucléaire, or CERN, in French), which runs the particle accelerator complex that houses the LHC.

Since the LHC’s powerful electromagnets carry almost as much current as a bolt of lightning, they must be kept chilled. The LHC uses a distribution system of liquid helium to keep its critical components ultracold at minus 271.3 degrees Celsius, which is colder than interstellar space. Given these requirements, it is not easy to warm up or cool down the gigantic machine.

Latest upgrade

Three years after it shut down for maintenance and upgrades, the collider was switched back on this April. This is the LHC’s third run, and from Tuesday, it will operate round-the-clock for four years at unprecedented energy levels of 13 tera electron volts. (A TeV is 100 billion, or 10-to-the-power-of-12, electon volts. An electron volt is the energy given to an electron by accelerating it through 1 volt of electric potential difference.)

“We aim to be delivering 1.6 billion proton-proton collisions per second” for the ATLAS and CMS experiments, CERN’s head of accelerators and technology Mike Lamont said, according to an AFP report. This time, the proton beams will be narrowed to less than 10 microns — a human hair is around 70 microns thick — to increase the collision rate, he said.

(ATLAS is the largest general purpose particle detector experiment at the LHC; the Compact Muon Solenoid (CMS) experiment is one of the largest international scientific collaborations in history, with the same goals as ATLAS, but which uses a different magnet-system design.)

Previous runs & ‘God Particle’ discovery

Ten years ago, on July 4, 2012, scientists at CERN had announced to the world the discovery of the Higgs boson or the ‘God Particle’ during the LHC’s first run. The discovery concluded the decades-long quest for the ‘force-carrying’ subatomic particle, and proved the existence of the Higgs mechanism, a theory put forth in the mid-sixties.

This led to Peter Higgs and his collaborator François Englert being awarded the Nobel Prize for physics in 2013. The Higgs boson and its related energy field are believed to have played a vital role in the creation of the universe.

The LHC’s second run (Run 2) began in 2015 and lasted till 2018. The second season of data taking produced five times more data than Run 1.

The third run will see 20 times more collisions as compared to Run 1.

‘New Physics’

After the discovery of the Higgs boson, scientists have started using the data collected as a tool to look beyond the Standard Model, which is currently the best theory of the most elementary building blocks of the universe and their interactions.

Scientists at CERN say they don’t know what Run 3 will reveal; the hope is to use the collisions to further the understanding of so-called “dark matter”.

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This hard-to-detect, hoped-for particle is believed to make up most of the universe, but is completely invisible as it does not absorb, reflect, or emit light.

Luca Malgeri, a scientist with the CERN, told Reuters: “CERN scientists hope that it might be spotted, even fleetingly, in the debris of the billions of collisions, just as the Higgs boson was.”

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10th anniversary of the Higgs Boson discovery: What have we learned from the ‘God Particle’?

July 4, 2022 Admin Leave a comment

Many Americans will mark the country’s birthday today, but physicists and science nerds will also celebrate the tenth anniversary of the discovery of the Higgs Boson – also known as the ‘God Particle’ – on July 4.

You may not be familiar with physicist Peter Higgs, who first predicted the existence of the new particle in the 1960s and theorized that we are surrounded by an ocean of quantum information known as the Higgs Field, but his Nobel Prize-winning discovery makes everything else in our universe possible.

The existence of the Higgs Boson is one reason why everything we see, including ourselves, all planets and stars, has mass and exists – hence why it was called the ‘God Particle.’

The particle that Higgs and fellow physicists hypothesized in 1964 could only gain mass by interacting with a field that permeates the entire universe. Meaning that if the field did not exist, the particles would simply float freely and move at the speed of light.

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The discovery of the Higgs Boson in July 2012 forms the basis for the existence of all elementary particles in our universe. Pictured above is a visualization of an event recorded at the CMS detector at the Large Hadron Collider at CERN. It shows the characteristics expected from the decay of the SM Higgs Boson to a pair of photons

Unlike a lot of other notable discoveries, the Higgs Boson can’t simply be ‘found’ in a traditional sense – it must be created. Once it’s created, evidence of its decay is looked for in data collected at the Large Hadron Collider at CERN.

At the world’s largest particle accelerator – where protons are smashed together near the speed of light in a vast, racetrack-like 27-kilometer tunnel that sits 300 feet underground in at the border of France and Switzerland – scientists knew that they had found evidence of its decay in 2012.

Many technologies were advanced – in healthcare, industry and computing – in the decade since the Higgs Boson was first observed.

Since the announcement of its discovery on July 4, 2012, physicists have been analyzing how the Higgs Boson interacts with other particles in order to see if it lines up with what’s known as the Standard Model of physics.

The existence of the Higgs Boson, which is a subatomic particle that is the carrier particle for the Higgs Field, was first proposed by British physicist Peter Higgs in 1964. Pictured above is Higgs, who received a Nobel Prize in physics for proposing the existence of the Higgs Boson, at CERN in July 2012

THE HIGGS BOSON CARRIES MASS AND IS A FUNDAMENTAL PART OF THE STANDARD MODEL OF PARTICLE PHYSICS

The Higgs boson is an elementary particle – one of the building blocks of the universe according to the Standard Model of particle physics.

It was named after physicist Peter Higgs as part of a mechanism that explains why particles have mass.

According to the Standard Model our universe is made of 12 matter particles – including six quarks and six leptons.

It also has four forces – gravity, electromagnetism, strong and weak.

Each force has a corresponding carrier particle known as a boson that acts on the matter.

The theory went that the Higgs boson was responsible for transferring mass.

It was first proposed in 1964 and wasn’t discovered until 2012 – during a run of the Large Hadron Collider.

The discovery was significant as if it had been shown not to exist then it would have meant tearing up the Standard Model and going back to the drawing board.

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The Standard Model is a guiding theory that accounts for three of the four main forces of the universe – electromagnetism, the weak force and the strong force – but it excludes gravity.

There are other aspects of our universe, such as dark matter and dark energy, that are not yet explained by the standard model.

Scientists have been studying how the Higgs Boson interacts with other particles and what these so-called ‘couplings’ can produce – this was achieved by conducting many experiments and analyzing a lot of data.

By 2018, scientists had determined that 58 percent of Higgs bosons decay into b quarks, also known as beauty or bottom quarks.

Although CERN has been the center of the action when it comes to the Higgs Boson, many people aren’t aware that at one point the United States could have been home to what would have been the largest ever particle accelerator in the world – called the Tevatron.

Planned in the 1980s for a site deep beneath Waxahachie, Texas, that particle accelerator would have been 87 kilometers long with the ability to slam protons together at higher energy levels than are currently possible at CERN.

However, a combination of bureaucratic unease with the project’s cost and discomfort among scientists and religious-minded people alike over the phrase ‘God Particle’ led to the project being canceled in 1993.

CERN, which was founded on September 29, 1954, is the focal point of a community of 10,000 scientists from all over the world and it’s also the birthplace of the World Wide Web. It has 23 member states, however the US only has observer status at CERN – which means it isn’t part of CERN’s governing council that makes important decisions about its science.

In 2012, Higgs and his collaborator Francois Englert won the Nobel Prize for the ‘theoretic discovery of a mechanism that contributes to our understanding of the origin of mass of subatomic particles.’

There are many questions that scientists still hope to answer in the coming years and decades at CERN.

What can the Higgs Boson tell us about the earliest moments of our universe?

Could dark matter and dark matter, which make up 68 and 27 percent of the universe respectively, be found from interactions with the Higgs Boson?

Is it possible to open microscopic black holes and could energy one day be pulled through them?

Can we uncover more information about b or beauty quarks and what their significance is for the singularity?

What could we learn about M-theory, which posits that instead of just three dimension of space plus time, there could in fact be at least 11 dimensions composed not of the particles we know but of teeny vibrating strings that all interact with each other.

The launch of the Large Hadron Collider’s Run 3 will be broadcast live on all of CERN’s social media channels starting at 4 pm on Tuesday, July 5.

The Higgs Field is best thought of as a field of energy or information that permeates everything around us. Pictured above is an artistic view of that field released by CERN

Physicist Peter Higgs first posited the existence of the Higgs Field and the Higgs Boson in 1964. Pictured above is the scientific paper in which he laid out that case

CERN is one of the largest scientific institutions in the world, home to over 2,000 scientists working on many physics projects. Pictured above is a chain of LHC dipole magnets inside a tunnel at the end of the second long shutdown, when the facility at CERN was updated for a few years so that protons could be slammed together at much higher energy ranges when run 3 begins in July

Future experiments at CERN will attempt to unravel mysteries such as dark matter and dark energy. Pictured above is a chain of dipole magnets inside a tunnel at the Large Hadron Collider at CERN

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A ‘Very Exciting’ Anomaly Detected in Major Experiment Could Be Huge News For Physics

June 17, 2022 Admin Leave a comment

A strange gap between theoretical predictions and experimental results in a major neutrino research project could be a sign of the elusive ‘sterile’ neutrino – a particle so quiet, it can only be detected by the silence it leaves in its wake.

It’s not the first time the anomaly has been seen, adding to previous experimental data hinting at something odd in the world of neutrino research. This time around, it’s been detected at the Baksan Experiment on Sterile Transitions (BEST).

Unambiguous evidence of the hypothetical sterile neutrino could provide physicists with a solid candidate for the Universe’s mysterious supply of dark matter. On the other hand, it could simply all come down to a problem in the models used to describe the quirky behaviors of old school neutrinos.

Which would also make for a significant moment in the history of physics.

“The results are very exciting,” says Los Alamos National Laboratory physicist Steve Elliott.

“This definitely reaffirms the anomaly we’ve seen in previous experiments. But what this means is not obvious. There are now conflicting results about sterile neutrinos. If the results indicate fundamental nuclear or atomic physics are misunderstood, that would be very interesting, too.”

In spite of ranking among the most abundant particles in the Universe, neutrinos are notoriously difficult to catch. When you’ve got barely any mass, no electric charge, and only make your presence known through the weak nuclear force, it’s easy to slip through even the densest of materials unimpeded.

The neutrino’s ghost-like movement isn’t its only interesting quality. Each particle’s quantum wave morphs as it zips along, oscillating between characteristic ‘flavors’ that echo their negatively charged particle cousins – the electron, muon, and tau.

Studies on the oscillations of neutrinos at the US Los Alamos National Laboratory in the 1990s noticed gaps in the timing of this flip-flopping that left room for a fourth flavor, one that wouldn’t make so much as a ripple in the weak nuclear field.

Cloaked in silence, the sterile flavor of neutrino would only be conspicuous by a brief pause in its interactions.

BEST is shielded from cosmic neutrino sources beneath a mile of rock in Russia’s Caucasus Mountains. It features a double-chambered tank of liquid gallium which patiently collects neutrinos erupting from a core of irradiated chromium.

After measuring the amount of gallium that had transformed into a germanium isotope in each tank, the researchers could work backwards to determine the number of direct collisions with neutrinos while they were oscillating through their electron flavor.

Similar to the Los Alamos experiment’s own ‘gallium anomaly’, researchers calculated a fifth to a quarter less germanium than expected, hinting at a deficit in the expected number of electron neutrinos.

This isn’t to say with certainty that the neutrinos had briefly adopted a sterile flavor. Many other searches for the pale little particle come up empty-handed, leaving open the possibility that the models used to predict the transformations are on some level misleading.

That isn’t itself a bad thing. Corrections in the basic framework of nuclear physics could have significant ramifications, potentially revealing gaps in the Standard Model which could lead to explanations for some of science’s big remaining mysteries.

If this is indeed the mark of the sterile neutrino, we might at last have evidence of a material that exists in tremendous quantities, yet makes only a gravitational dimple in the fabric of space.

Whether that is the sum of dark matter or a mere piece of its puzzle would depend on further experimentation on the most ghostliest of ghost particles.

This research was published in Physics Review Letters and Physical Review C.

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Researchers Discovered a New Kind of Higgs Relative in The Unlikeliest of Places

June 11, 2022 Admin Leave a comment

Sometimes the discovery of new physics demands insane levels of energy. Big machines. Fancy equipment. Countless hours of sifting through reams of data.

And then sometimes the right combination of materials can open a doorway to invisible realms in a space little bigger than a tabletop.

Take this new kind of relative to the Higgs boson, for example. It was found lurking in a room temperature chunk of layered tellurium crystals. Unlike its famous cousin, it didn’t take years of smashing up particles to spot it, either. Just a clever use of some lasers and a trick for unweaving their photon’s quantum properties.

“It’s not every day you find a new particle sitting on your tabletop,” says Kenneth Burch, a Boston College physicist and the lead co-author of the study announcing the discovery of the particle.

Burch and his colleagues caught sight of what’s known as an axial Higgs mode, a quantum wiggle that technically qualifies as a new kind of particle.

Like so many discoveries in quantum physics, observing theoretical quantum behaviors in action get us closer to uncovering potential cracks in the Standard Model and even helps us hone in on solving some of the remaining big mysteries.

“The detection of the axial Higgs was predicted in high-energy particle physics to explain dark matter,” says Burch.

“However, it has never been observed. Its appearance in a condensed matter system was completely surprising and heralds the discovery of a new broken symmetry state that had not been predicted.”

It’s been 10 years since the Higgs boson was formally identified amid the carnage of particle collisions by CERN researchers. This not only ended the hunt for the particle but loosely closed the final box in the Standard Model – the zoo of fundamental particles making up nature’s complement of bricks and mortar.

With the Higgs field’s discovery, we could, at last, confirm our understanding of how components of the model gained mass while at rest. It was a huge win for physics, one we’re still using to understand the inner mechanics of matter.

While any single Higgs particle exists for barely a fraction of a second, it’s a particle in the truest sense of the word, blinking briefly into reality as a discrete excitation in a quantum field.

There are, however, other circumstances in which particles can bestow mass. A break in the collective behavior of a surge of electrons called a charge density wave, for example, would do the trick.

This ‘Frankenstein’s monster’ version of Higgs, called a Higgs mode, can also appear with traits that aren’t seen in its less patchwork cousin, such as a finite degree of angular momentum (or spin).

A spin-1 or axial Higgs mode not only does a similar job to the Higgs boson under very specific circumstances, it (and quasiparticles like it) could provide interesting grounds for studying the shadowy mass of dark matter.

As a quasiparticle, the axial Higgs mode can only be seen emerging from the collective behaviors of a crowd. Spotting it requires knowing its signature amid a wash of quantum waves and then having a way to sift it out of the chaos.

By sending perfectly coherent beams of light from two lasers through such material and then watching for telltale patterns in their alignment, Burch and his team uncovered the echo of an axial Higgs mode in layers of rare-earth tritelluride.

“Unlike the extreme conditions typically required to observe new particles, this was done at room temperature in a table top experiment where we achieve quantum control of the mode by just changing the polarization of light,” says Burch.

It’s possible there could be plenty of other such particles emerging from the tangle of body parts making up exotic quantum materials. Having a means of easily catching a glimpse of their shadow in the light of a laser could reveal a whole litany of new physics.

This research was published in Nature.

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Physicists Discover Elusive New Particle Through Tabletop Experiment

June 8, 2022 Admin Leave a comment

An interdisciplinary team led by Boston College physicists has discovered a new particle – or a previously undetectable quantum excitation – known as the axial Higgs mode, a magnetic relative of the mass-defining Higgs Boson particle, the team reports in the journal Nature. Credit: Nature

Materials that contain the axial Higgs mode could serve as quantum sensors to evaluate other quantum systems and help answer persistent questions in particle physics.

According to the Standard Model of Particle Physics, scientists’ current best theory to describe the most basic building blocks of the universe, particles called quarks (which make up protons and neutrons) and leptons (which include electrons) make up all known matter. Force-carrying particles, which belong to a broader group of bosons, influence the quarks and leptons.

Despite the success of the Standard Model at explaining the universe, it has its limitations. Dark matter and dark energy are two examples, and it is possible that new particles, yet to be discovered, could eventually solve these enigmas.

Today, an interdisciplinary team of scientists led by Boston College physicists announced that they have discovered a new particle – or previously undetectable quantum excitation – known as the axial Higgs mode, a magnetic relative of the mass-defining Higgs Boson particle. The team published their report today (June 8, 2022) in the online edition of the journal Nature.

The detection a decade ago of the long-sought Higgs Boson became central to the understanding of mass. Unlike its parent, axial Higgs mode has a magnetic moment, and that requires a more complex form of the theory to explain its properties, said Boston College Professor of Physics Kenneth Burch, a lead co-author of the report “Axial Higgs Mode Detected by Quantum Pathway Interference in RTe₃.”

Theories that predicted the existence of such a mode have been invoked to explain “dark matter,” the nearly invisible material that makes up much of the universe, but only reveals itself via gravity, Burch said.

The Higgs boson is the fundamental particle associated with the Higgs field, a field that gives mass to other fundamental particles such as electrons and quarks. A particle’s mass determines how much it resists changing its speed or position when it encounters a force.

Whereas Higgs Boson was revealed by experiments in a massive particle collider, the team focused on RTe₃, or rare-earth tritelluride, a well-studied quantum material that can be examined at room temperature in a “tabletop” experimental format.

“It’s not every day you find a new particle sitting on your tabletop,” Burch said.

RTe₃ has properties that mimic the theory that produces the axial Higgs mode, Burch said. But the central challenge in finding Higgs particles in general is their weak coupling to experimental probes, such as beams of light, he said. Similarly, revealing the subtle quantum properties of particles usually requires rather complex experimental setups including enormous magnets and high-powered lasers, while cooling samples to extremely cold temperatures.

The team reports that it overcame these challenges through the unique use of the scattering of light and proper choice of quantum simulator, essentially a material mimicking the desired properties for study.

Specifically, the researchers focused on a compound long known to possess a “charge density wave,” namely a state where electrons self-organize with a density that is periodic in space, Burch said.

The fundamental theory of this wave mimics components of the standard model of particle physics, he added. However, in this case, the charge density wave is quite special, it emerges far above room temperature and involves modulation of both the charge density and the atomic orbits. This allows for the Higgs Boson associated with this charge density wave to have additional components, namely it could be axial, meaning it contains angular momentum.

In order to reveal the subtle nature of this mode, Burch explained that the team used light scattering, where a laser is shined on the material and can change color as well as polarization. The change in color results from the light creating the Higgs Boson in the material, while the polarization is sensitive to the symmetry components of the particle.

In addition, through proper choice of the incident and outgoing polarization, the particle could be created with different components – such as one absent magnetism, or a component pointing up. Exploiting a fundamental aspect of quantum mechanics, they used the fact that for one configuration, these components cancel. However, for a different configuration they add.

“As such, we were able to reveal the hidden magnetic component and prove the discovery of the first axial Higgs mode,” Burch said.

“The detection of the axial Higgs was predicted in high-energy particle physics to explain dark matter,” Burch said. “However, it has never been observed. Its appearance in a condensed matter system was completely surprising and heralds the discovery of a new broken symmetry state that had not been predicted. Unlike the extreme conditions typically required to observe new particles, this was done at room temperature in a tabletop experiment where we achieve quantum control of the mode by just changing the polarization of light.”

Burch said the seemingly accessible and straightforward experimental techniques deployed by the team can be applied to study in other areas.

“Many of these experiments were performed by an undergraduate in my lab,” Burch said. “The approach can be straightforwardly applied to the quantum properties of numerous collective phenomena including modes in superconductors, magnets, ferroelectrics, and charge density waves. Furthermore, we bring the study of quantum interference in materials with correlated and/or topological phases to room temperature overcoming the difficulty of extreme experimental conditions.

In addition to Burch, Boston College co-authors on the report included undergraduate student Grant McNamara, recent doctoral graduate Yiping Wang, and post-doctoral researcher Md Mofazzel Hosen. Wang won the Best Dissertation in Magnetism from the American Physical Society, in part for her work on the project, Burch said.

Burch said it was crucial to draw on the broad range of expertise among researchers from BC, Harvard University,

Reference: “Axial Higgs mode detected by quantum pathway interference in RTe₃” by Yiping Wang, Ioannis Petrides, Grant McNamara, Md Mofazzel Hosen, Shiming Lei, Yueh-Chun Wu, James L. Hart, Hongyan Lv, Jun Yan, Di Xiao, Judy J. Cha, Prineha Narang, Leslie M. Schoop and Kenneth S. Burch, 8 June 2022, Nature.
DOI: 10.1038/s41586-022-04746-6

Funding: U.S. Department of Energy

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