Tag Archives: physicists

CERN physicists witness exceptionally rare hyperon decay

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A hyperon is a particle that contains three quarks, like a proton or a neutron, and one or more strange quarks. Physicists from the LHCb collaboration at the Large Hadron Collider (LHC) at CERN say they have observed a hyperon decay Σ+→pμ+μ- in proton-proton collisions.

A view of the LHCb detector. Image courtesy of CERN.

“Rare decays of known particles are a promising tool for exploring physics beyond the Standard Model of particle physics,” said the LHCb physicist.

“In the Standard Model, the Σ+ → pμ+μ- process is only possible through a loop diagram, meaning that the decay does not occur directly, but intermediate states have to be exchanged within the loop.”

“In quantum field theory, the probability of such a process occurring is the sum of the probabilities of all particles, both known and unknown, that can possibly be exchanged in this loop.”

“This is what makes such processes sensitive to new phenomena.”

“If a discrepancy is observed between experimental measurements and theoretical calculations, it may be caused by the contribution of some unknown particle.”

“These particles can either be exchanged within the loop or directly mediate this decay, interacting with the quarks and decaying into pairs of muons.”

“In the latter case, the new particle would leave a signature on the properties of the two muons.”

The study of the Σ+ → pμ+μ- decay has been particularly exciting thanks to hints of structure observed in the properties of muon pairs by the HyperCP collaboration in 2005.

With only three occurrences the structure was far from conclusive, and it was hoped that new research would shed light on the situation.

Finally, the LHCb data did not show any significant peak structure in the two-muon mass region highlighted by HyperCP, thus refuting the hint.

However, the new study observes the decay with a high degree of significance, followed by precise measurements of the decay probability and other parameters, which will allow further investigation of the discrepancy with the Standard Model predictions.

“In data collected in Run 2 of pp collisions at the LHCb experiment, the Σ+ → pμ+μ− decay is observed with very high significance, with a yield of NΣ+→pμ+μ− = 279 ± 19,” the authors write in their paper. paper.

“We do not see any structure in the two-muon invariant mass distribution that is consistent with the Standard Model predictions.”

“The collected signal yield allows for measurements of integral and differential branching rates, as well as other measurements such as charge-parity symmetry breaking and front-to-back asymmetry.”

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LHCb Collaboration. 2024. Observation of rare Σ+→pμ+μ− decays at LHCb. CERN-LHCb-CONF-2024-002

Source: www.sci.news

Quantum entanglement used by physicists to measure Earth’s rotation

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Physicists at the University of Vienna have used a maximally entangled quantum state of light paths in a large interferometer to experimentally measure the speed of the Earth’s rotation.

Silvestri othersThey have demonstrated the largest and most precise quantum-optical Sagnac interferometer to date, sensitive enough to measure the Earth’s rotation rate. Image courtesy of Marco Di Vita.

For over a century, interferometers have been key instruments for experimentally testing fundamental physical questions.

They disproved the ether as a light-transmitting medium, helped establish the theory of special relativity, and made it possible to measure tiny ripples in space-time itself known as gravitational waves.

Recent technological advances allow interferometers to work with a variety of quantum systems, including electrons, neutrons, atoms, superfluids, and Bose-Einstein condensates.

“When two or more particles are entangled, only the overall state is known; the states of the individual particles remain uncertain until they are measured,” said co-first author Dr. Philip Walther and his colleagues.

“Using this allows us to get more information per measurement than we would without it.”

“But the extremely delicate nature of quantum entanglement has prevented the expected leap in sensitivity.”

For their study, the authors built a large fiber-optic Sagnac interferometer that was stable with low noise for several hours.

This allows the detection of entangled photon pairs with a sufficiently high quality to exceed the rotational precision of conventional quantum-optical Sagnac interferometers by a factor of 1000.

“In a Sagnac interferometer, two particles moving in opposite directions on a rotating closed path reach a starting point at different times,” the researchers explained.

“When you have two entangled particles, you get a spooky situation: they behave like a single particle testing both directions simultaneously, accumulating twice the time delay compared to a scenario where no entanglement exists.”

“This unique property is known as super-resolution.”

In the experiment, two entangled photons propagated through a 2 km long optical fiber wound around a giant coil, creating an interferometer with an effective area of ​​more than 700 m2.

The biggest hurdle the team faced was isolating and extracting the Earth’s stable rotation signal.

“The crux of the problem lies in establishing a measurement reference point where light is not affected by the Earth’s rotation,” said Dr Raffaele Silvestri, lead author of the study.

“Since we can’t stop the Earth’s rotation, we devised a workaround: split the optical fiber into two equal-length coils and connect them through an optical switch.”

“By switching it on and off, we were able to effectively cancel the rotation signal, which also increased the stability of larger equipment.”

“We’re basically tricking light into thinking it’s in a non-rotating universe.”

The research team succeeded in observing the effect of the Earth’s rotation on a maximally entangled two-photon state.

This confirms the interplay between rotating reference systems and quantum entanglement, as described in Einstein’s special theory of relativity and quantum mechanics, and represents a thousand-fold improvement in precision compared to previous experiments.

“A century after the first observations of the Earth’s rotation using light, this is an important milestone in that the entanglement of individual quanta of light is finally in the same region of sensitivity,” said co-first author Dr Haokun Yu.

“We believe that our findings and methods lay the foundation for further improving the rotational sensitivity of entanglement-based sensors.”

“This could pave the way for future experiments to test the behaviour of quantum entanglement through curves in space-time,” Dr Walther said.

Team work Published in a journal Scientific advances.

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Raffaele Silvestri others2024. Experimental Observation of Earth’s Rotation through Quantum Entanglement. Science Advances 10(24); doi: 10.1126/sciadv.ado0215

Source: www.sci.news

Physicists Investigate True Tauonium: The Heaviest and Smallest QED Atom

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Quantum Electrodynamics (QED) Atoms are composed of unstructured point-like lepton pairs held together by electromagnetic forces.

An artist's impression of a true tauonium. Image credit: Fu other., doi: 10.1016/j.scib.2024.04.003.

“QED atom “Like hydrogen, which is formed from protons and electrons, it is formed from lepton pairs through electromagnetic interactions,” said physicist Jinghan Hu of Peking University and colleagues.

“Their properties have been studied for things like testing QED theory, fundamental symmetries, gravity, and exploring physics beyond the Standard Model.”

“The first QED atom was discovered in 1951. It was in a bonded state and was named positronium.”

“The second one, discovered in 1960, was in a captive state and was named Muonium.”

“No other QED atoms have been discovered in the past 64 years.”

“A new collider is proposed to discover true muonium, which decays to its final state with electrons and photons,” they said.

“The heaviest and smallest QED atoms are tauonium, ditauonium, or true tauonium”

in new paper in a diary science bulletinphysicists introduce a new method to identify true tauonium.

“Tauonium, which consists of tauon and its antiparticle, has a Bohr radius of only 30.4 femtometers, which is about 1/1741 times smaller than the Bohr radius of a hydrogen atom,” the researchers said.

“This means that tauonium can test the fundamental principles of quantum mechanics and QED on a smaller scale, providing a powerful tool for exploring the mysteries of the microscopic world of matter.”

“We will observe taunium by collecting data at 1.5 ab-1, which is close to the threshold for tauon pair production, in an electron-positron collider and selecting signal events containing charged particles accompanied by undetected neutrinos carrying away energy. We have demonstrated that the significance exceeds 5σ.

“This provides strong experimental evidence for the presence of tauonium.”

“We also found that by using the same data, the accuracy of measuring the tau lepton mass can be improved to an unprecedented level of 1 keV, two orders of magnitude higher than the best accuracy achieved in current experiments.”

“This result not only contributes to the accurate verification of the electroweak theory in the Standard Model, but also has profound implications for fundamental physics questions such as the universality of leptonic flavors.”

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Jin Hung Fu other. A new method for determining the heaviest QED atoms. science bulletin, published online on April 4, 2024. doi: 10.1016/j.scib.2024.04.003

Source: www.sci.news

Physicists at CERN release data on the discovery of the Higgs particle

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Physicist from CMS cooperation at CERN just published the combination of CMS measurements that helped establish the discovery of the Higgs boson in 2012.

CMS event display showing a Higgs boson candidate decaying into two photons. It is one of two decay channels that were key to the particle’s discovery. Image credit: CERN.

“Physical measurements based on data from CERN’s Large Hadron Collider (LHC) are typically reported as central values and corresponding uncertainties,” the CMS physicists said.

“For example, shortly after observing the Higgs boson in the LHC’s proton-proton collision data, CMS determined its mass to be 125.3 plus or minus 0.6 GeV (the mass of a proton is about 1 GeV).”

“But this figure is just a quick summary of the measurements, and is like the title of a book.”

In measurement, the complete information extracted from the data is encoded into a mathematical function known as a likelihood function. This function includes measurements of quantities and dependence on external factors.

“For CMS measurements, these factors include the calibration of the CMS detector, the accuracy of the CMS detector simulation used to facilitate the measurements, and other systematic effects,” the researchers said.

“To fully understand the nasty collisions that occur at the LHC, many aspects need to be determined, so the likelihood function for measurements based on LHC data can be complex.”

“For example, the likelihood function for the combined CMS Higgs boson discovery measurement that CMS just released in electronic form has nearly 700 parameters for a fixed value of the Higgs boson mass.”

“Only one of these, the number of Higgs bosons found in the data, is an important physical parameter, and the rest model systematic uncertainties.”

“Each of these parameters corresponds to a dimension of a multidimensional abstract space in which the likelihood function can be drawn.”

“It is difficult for humans to visualize spaces that contain multiple dimensions, much less spaces that contain many dimensions.”

The new release of the CMS Higgs boson discovery measurement likelihood function, the first publicly available likelihood function from this collaboration, allows researchers to avoid this problem.

Using a publicly accessible likelihood function, physicists outside the CMS Collaboration can now accurately incorporate CMS Higgs boson discovery measurements into their studies.

“The release of this likelihood function and the Combine software used to model likelihood and fit data marks another milestone in CMS’s 10-year commitment to fully open science.” said the people.

“This joins hundreds of open access publications, the release of nearly 5 petabytes of CMS data on the CERN Open Data Portal, and the publication of the entire software framework on GitHub.”

Source: www.sci.news

Physicists at CERN successfully measure a key parameter of the Standard Model

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Physicists from the CMS Collaboration at CERN’s Large Hadron Collider (LHC) have successfully measured the effective leptonic electroweak mixing angle. The results were presented at the annual general meeting. Rencontre de Morion Conference is the most accurate measurement ever made at the Hadron Collider and is in good agreement with predictions from the Standard Model of particle physics.

Installation of CMS beam pipe. Image credit: CERN/CMS Collaboration.

The Standard Model is the most accurate description of particles and their interactions to date.

Precise measurements of parameters, combined with precise theoretical calculations, provide incredible predictive power that allows us to identify phenomena even before we directly observe them.

In this way, the model has succeeded in constraining the masses of the W and Z particles, the top quark, and recently the Higgs boson.

Once these particles are discovered, these predictions serve as a consistency check on the model, allowing physicists to explore the limits of the theory’s validity.

At the same time, precise measurements of the properties of these particles provide a powerful tool for exploring new phenomena beyond the standard model, so-called “new physics.” This is because new phenomena appear as mismatches between different measured and calculated quantities.

The electroweak mixing angle is a key element of these consistency checks. This is a fundamental parameter of the Standard Model and determines how unified electroweak interactions give rise to electromagnetic and weak interactions through a process known as electroweak symmetry breaking.

At the same time, we mathematically connect the masses of the W and Z bosons that transmit weak interactions.

Therefore, measurements of W, Z, or mixed angles provide a good experimental cross-check of the model.

The two most accurate measurements of the weak mixing angle were made by experiments at CERN’s LEP collider and by the SLD experiment at the Stanford Linear Accelerator Center (SLAC).

These values ​​have puzzled physicists for more than a decade because they don’t agree with each other.

The new results are in good agreement with standard model predictions and are a step towards resolving the discrepancy between standard model predictions and measurements of LEP and SLD.

“This result shows that precision physics can be performed at the Hadron Collider,” said Dr. Patricia McBride, spokesperson for the CMS Collaboration.

“The analysis had to deal with the challenging environment of LHC Run 2, with an average of 35 simultaneous proton-proton collisions.”

“This paves the way for even more precise physics, where more than five times as many proton pairs collide simultaneously at the high-luminosity LHC.”

Precise testing of Standard Model parameters is a legacy of electron-positron collider such as CERN’s LEP, which operated until 2000 in the tunnel that now houses the LHC.

Electron-positron collisions provide a clean environment ideal for such high-precision measurements.

Proton-proton collisions at the LHC are more challenging for this type of research, even though the ATLAS, CMS, and LHCb experiments have already yielded numerous new ultra-high-precision measurements.

This challenge is primarily due to the vast background from physical processes other than those studied, and the fact that protons, unlike electrons, are not subatomic particles.

With the new results, it seemed impossible to reach accuracy similar to that of the electron-positron collider, but now it has been achieved.

The measurements presented by CMS physicists use a sample of proton-proton collisions collected from 2016 to 2018 at a center of mass energy of 13 TeV and a total integrated luminosity of 137 fb.−1 or about 11 billion collisions.

“The mixing angle is obtained through analysis of the angular distribution in collisions in which pairs of electrons or muons are produced,” the researchers said.

“This is the most accurate measurement ever made at the Hadron Collider and improves on previous measurements by ATLAS, CMS, and LHCb.”

Source: www.sci.news

Physicists puzzled by the 1919 total solar eclipse

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Total solar eclipse in August 2017 over Jefferson City, Missouri

(NASA/Rami Daoud)

The following is an excerpt from the monthly Launchpad newsletter, where resident space expert Leah Crane travels through the solar system and beyond. You can sign up for Launchpad for free here.

It was in 1919 that the moon did something completely natural and blocked our view of the sun, forever changing our understanding of the universe. Observing from the African island of Principe, astronomer Arthur Eddington observed the positions of stars and planets that became visible in the eerie darkness of the day. Because most of the sun’s light was dimmed, he was able to see how light from distant stars is distorted when it is deflected by the sun’s gravity, an effect called gravitational lensing.

He confirmed his sightings with those of another expedition in Brazil, and these observations provided some of the first evidence for Albert Einstein’s relatively new theory of general relativity. This explanation of how massive objects distort the fabric of space-time is now considered fundamental, but at the time it was a revelation. It changed all the way we think about gravity and the universe.

It also led to my results Favorite newspaper headline most of all time, published in of new york times Later that year, “All the light in the heavens is slanted.” Scientists are more or less puzzled over the observations of solar eclipses. Triumph of Einstein’s theory The stars were determined by where they were visible and by calculation It’s not where it was, but no one needs to worry.”

“No one needs to worry” may seem like a bit of a stretch, but watching a total solar eclipse can certainly make you nervous in ways you can’t explain. I watched it for the first time in 2017. It was truly unforgettable. You might think of a solar eclipse as being like a cloudy day when clouds drift in front of the sun. After all, what’s happening is simply the moon passing in front of the sun and casting a shadow on Earth. But it’s surprisingly different.

The first thing you notice during a total solar eclipse is the moon’s shadow hurtling toward you across the ground at speeds of over 1,500 miles per hour. The extent of the shadow for April’s eclipse will be approximately 185 kilometers, but this can vary slightly based on the exact orientation of the Sun and Moon. As the shadow approaches, it looks like the moon has bitten the sun, and its light has a mysterious, foggy quality.

Suddenly, the area becomes dark. This is wholeness. Temperatures can drop up to 10 degrees. The only light comes from the sun’s outermost layer, called the corona, and ripples beyond the moon’s silhouette. It was completely dark, and some stars were visible in the sky. Many animals, including birds and insects, naturally seem to think it is night, and the otherworldly twilight becomes silent, except for the chirps of awakened nocturnal insects. I can’t tell you how you feel, but for me it was a mixture of awe and some strange primal fear. The sun disappeared, and even though my mind knew why, my body panicked at the loss.

solar eclipse 2024

On April 8th, a total solar eclipse will pass over Mexico, the United States, and Canada. Our special series covers everything you need to know, from how and when to see a solar eclipse to the strangest solar eclipse experience of all time.

This seems to be a fairly common reaction, not just in humans. Researchers who studied animals during past total solar eclipses found that while some animals simply finished their evening routine early, many showed signs of anxiety and were aimless during total solar eclipses. I discovered that they run and huddle together.

Then, just a few minutes later, the total star will retreat as quickly as it arrived. The shadows rush away, the sun comes out again, and the birds and insects sing again. Astronomers look up from their solar telescopes, dazed but excited by the treasure trove of data they’ve collected.

Humans have been observing solar eclipses for thousands of years, and we’ve learned some very interesting things. When the sun’s disc is covered by the moon, its faint corona becomes visible, making solar eclipses the perfect time to study the sun’s outer reaches. For example, scientists first discovered helium during a total solar eclipse. A solar eclipse is also a great time to observe the plumes of radiation and material emitted from the sun’s surface through the corona. The coronavirus itself is very strange, and there is still much to understand about how it works. Despite being far removed from the sun’s core fusion, the corona is millions of degrees hotter than the sun’s surface, and we still don’t know why.

Even if you haven’t studied the sun’s mysterious layers, it’s worth watching a total solar eclipse. More than 100 years ago, newspaper editors got it right. More or less, you will be confused.

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Source: www.newscientist.com

Physicists suggest that the capture and annihilation of dark matter could reignite dormant neutron stars

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A team of particle physicists from the University of Melbourne, Australian National University, King’s College London, and Fermi National Accelerator Laboratory has discovered that the energy transferred when dark matter particles collide and annihilate inside a cold neutron star. They calculated that the star could be heated rapidly. Previously, this heating was thought to be irrelevant because this energy transfer takes a very long time, in some cases longer than the age of the universe itself.

An artist’s impression of a neutron star.

A number of recent studies have focused on trapping dark matter in neutron stars as sensitive probes of the interaction of dark matter with ordinary matter.

This could potentially be used to test dark matter interactions in a way that is highly complementary to experiments on Earth, especially since dark matter is accelerated to relativistic speeds during a fall into a neutron star. there is.

In some cases, neutron star technology may be able to probe interactions that are difficult or impossible to observe with direct dark matter detection experiments. These include dark matter, which is too light to leave a detectable signal in nuclear recoil experiments, and interactions where non-relativistic scattering cross sections are momentum suppressed.

It was recently pointed out that an isolated old neutron star near the Sun could be heated by the capture of dark matter, increasing its temperature by 2000 K.

Once older than 10 million years, an isolated neutron star is expected to cool to temperatures below this unless reheated by standard matter accretion or internal heating mechanisms.

As a result, observations of local neutron stars may place severe constraints on dark matter interactions. Importantly, neutron stars with temperatures in this range produce near-infrared radiation that could be detected by future telescopes.

“Our new calculations show for the first time that most of the energy is stored in just a few days,” said Professor Nicole Bell from the University of Melbourne, lead author of the study.

“The search for dark matter is one of science’s greatest detective stories.”

“Dark matter makes up 85% of the matter in the universe, but we can’t see it.”

“It doesn’t interact with light. It doesn’t absorb, reflect, or emit light.”

“This means that even if we know it exists, we can’t directly observe it with our telescopes.”

“Rather, its attraction to an object that we can see tells us that it must be there.”

“Predicting dark matter theoretically and observing it experimentally are two different things.”

“Earth-based experiments are limited by the technical challenges of building a large enough detector.”

“But neutron stars act as huge natural dark matter detectors, collecting dark matter over astronomically long timescales, so they are a good place to focus our efforts.”

“Neutron stars form when supermassive stars run out of fuel and collapse,” Professor Bell said.

“They have a similar mass to our sun and are squeezed into a sphere just 20km wide. If they got any denser, they would become black holes.”

“Dark matter is the main type of matter in the universe, but it is very difficult to detect because it interacts very weakly with normal matter.”

“In fact, dark matter is so weak that it can pass straight through the Earth and even the Sun.”

“But neutron stars are different. Because neutron stars are so dense, dark matter particles are much more likely to interact with the star.”

“If dark matter particles collide with neutrons inside a star, they lose energy and become trapped.”

“Over time, this will lead to an accumulation of dark matter within the star.”

“We expect this to cause old, cold neutron stars to heat up to a point where they can be observed in the future, or even cause the star to collapse into a black hole,” said the University of Melbourne doctor. candidate Michael Vilgat, co-author of the study.

“If the energy transfer happens quickly enough, the neutron star will heat up.”

“For this to happen, the dark matter would have to collide within the star many times, transferring more and more of the dark matter’s energy until all the energy is stored in the star.”

“Until now it was unknown how long this process takes, because as dark matter particles become less and less energetic, they become less and less likely to interact again.”

“As a result, it was thought that it would take a very long time to transfer all the energy, in some cases longer than the age of the universe.”

Instead, the researchers calculated that 99% of the energy is transferred in just a few days.

“This is good news, because it means dark matter can potentially heat neutron stars to detectable levels,” Birgat said.

“As a result, observations of cold neutron stars will provide important information about the interactions between dark matter and ordinary matter and shed light on the nature of this elusive matter.”

“If we are to understand the ubiquity of dark matter, it is important to use every technology at our disposal to understand what the hidden matter in our universe actually is.” .”

of study Published in Journal of Cosmology and Astroparticle Physics.

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Nicole F. Bell other. 2024. Thermalization and extinction of dark matter in neutron stars. JCAP 04,006; doi: 10.1088/1475-7516/2024/04/006

Source: www.sci.news

Physicists successfully transfer electron spin to photon

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A team of physicists led by Dr. Yuan Lu of the Jean Lamour Institute at the University of Lorraine used electrical pulses to manipulate magnetic information into polarized signals. This discovery could revolutionize long-distance optical communications, including between Earth and Mars. This breakthrough involves the field of spintronics, which aims to manipulate the spin of electrons to store and process information.

Structure of SOT Spin LED: Control of emission intensity and charging current is the basis of information transfer and processing. In contrast, robust information storage and magnetic random access memory are implemented using carrier spins and their associated magnetizations in ferromagnets. The missing link between the respective fields of photonics, electronics, and spintronics is modulating the circular polarization of emitted light rather than its intensity through electrically controlled magnetization.Dynon other. demonstrated that this missing link is established in light-emitting diodes at room temperature in the absence of an applied magnetic field through the transfer of angular momentum between photons, electrons, and ferromagnets.Image credit: Dynon other., doi: 10.1038/s41586-024-07125-5.

Spintronics has been successfully used in magnetic computer hard drives, where information is represented by the direction of electron spin and its proxy, magnetization.

Ferromagnetic materials such as iron and cobalt have an unequal number of electrons, with their spins oriented either along or against the magnetization axis.

Electrons with spins aligned with the magnetization move smoothly in a ferromagnetic material, while electrons with spins in the opposite direction bounce. This represents binary information of 0’s and 1’s.

The resulting change in resistance is a key principle in spintronic devices, where magnetic states can be maintained indefinitely, which can be considered stored information.

Just as a refrigerator magnet requires no power to stick to a door, spintronic devices require much less power than traditional electronics.

But like pulling a fish out of water, when an electron is removed from a ferromagnetic material, the spin information is quickly lost and can no longer travel far.

This major limitation can be overcome by utilizing circularly polarized light, also known as helicity, as another spin carrier.

Just as humans used homing pigeons centuries ago to carry written communication farther and faster than on foot, the trick is to transfer the spin of an electron to a photo, a quantum of light. That’s probably true.

Such transfer is possible due to the presence of spin-orbit coupling, which causes spin information loss outside the ferromagnetic material.

The key missing link is to electrically modulate the magnetization and thereby change the helicity of the emitted light.

“The concept of spin LEDs was first proposed at the end of the last century,” Dr. Lu said.

“But to move into practical use, it must meet three important criteria: it must operate at room temperature, it does not require a magnetic field, and it must be able to be electrically controlled.”

“After more than 15 years of dedicated work in this field, our collaborative team has managed to overcome all obstacles.”

In their research, Dr. Lu and his colleagues succeeded in switching the magnetization of a spin injector using an electric pulse that uses spin-orbit torque.

The electron spin is rapidly converted into information contained in the helicity of the emitted photon, allowing seamless integration of magnetization dynamics and photonic technology.

This electrically controlled spin-to-photon conversion is currently realized with electroluminescence in light-emitting diodes.

In the future, through implementation in semiconductor laser diodes, so-called spin lasers, this highly efficient information encoding will pave the way for high-speed communication across interplanetary distances, since the polarization of light is preserved in spatial propagation. It is possible and could potentially make it possible. The fastest mode of communication between Earth and Mars.

It also has significant benefits for the development of a variety of advanced technologies on Earth, including photonic quantum communications and optical computing, neuromorphic computing for artificial intelligence, and ultra-fast and highly efficient optical transmitters for data centers and light-fidelity applications. will bring about.

“The realization of spin-orbit torque spin injectors is a decisive step in the development of ultrafast and energy-efficient spin lasers for next-generation optical communications and quantum technologies,” said Professor Nils Gerhardt of Ruhr University. ” he said.

team's work It was published in the magazine Nature.

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PA Dynon other. 2024. Optical helicity control by electromagnetic switching. Nature 627, 783-788; doi: 10.1038/s41586-024-07125-5

Source: www.sci.news

Physicists at CERN witness the creation of two tau leptons from two photons during a proton-proton collision

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According to physicists, CMS cooperation This is the first time this process has been observed in proton-proton collisions at CERN's Large Hadron Collider (LHC). This is also the most accurate measurement of tau's anomalous magnetic moment and provides a new way to constrain the existence of new physics.

We reproduced candidate events of the γγ →ττ process in proton-proton collisions measured by the CMS detector. Tau can decay into muons (red), charged pions (yellow), and neutrinos (not visible). Energy is stored in green in an electromagnetic calorimeter and cyan in a hadronic calorimeter. Image credit: CMS Collaboration.

of TauIt is a special particle of the lepton family, also called tauon.

In general, leptons, together with quarks, constitute the matter content of the Standard Model.

Tau was first discovered in the 1970s, and its associated neutrino (tau neutrino) was discovered by Fermilab's DONUT collaboration in 2000 to complete the tangible matter part.

However, tau has a very short lifetime and can remain stable for only 290*10 hours, making it quite difficult to study it accurately.-15 seconds.

Two other charged leptons, electrons and muons, are fairly well studied.

Much is also known about their magnetic moments and their associated anomalous magnetic moments.

The former can be understood as the strength and direction of a virtual bar magnet within the particle.

However, this measurable quantity requires correction at the quantum level resulting from the virtual particles pulling on the magnetic moment and deviates from the predicted value.

The quantum correction, called the anomalous magnetic moment, is about 0.1%.

If the theoretical and experimental results do not agree, this anomalous magnetic momentIopens the door to physics beyond the Standard Model.

The anomalous magnetic moment of the electron is one of the most accurately known quantities in particle physics and is in perfect agreement with models.

Its muon counterpart, on the other hand, is one of the most studied, and research is ongoing.

So far, theory and experiment are largely in agreement, but recent results raise tensions that require further investigation.

But for Tau, the race is still on. Its anomalous magnetic moment is particularly difficult to measure.τThis is because tau has a short lifespan.

The first attempt wasτ After the discovery of tau, there was an uncertainty 30 times higher than the size of the quantum correction.

Experimental efforts at CERN improved the constraints and reduced the uncertainty to 20 times the size of the quantum correction.

In collisions, physicists look for special processes. That is, two photons interact to produce two tau leptons (also called a ditau pair), which then decay into muons, electrons, or charged pions, and neutrinos.

So far, both ATLAS and CMS collaborations have observed this in ultraperipheral lead-to-lead collisions.

Now, CMS physicists report: first observation The same process occurs during proton-proton collisions.

These collisions provide greater sensitivity to physics over the standard model, as new physical effects increase with collision energy.

Taking advantage of the superior tracking capabilities of the CMS detector, the collaboration will isolate this particular process from other processes by selecting events that produce a tau with no other tracking within a distance of just 1 mm. I was able to separate it.

“This remarkable achievement in detecting proton-proton collisions in the super-periphery sets the stage for many breakthrough measurements of this kind from CMS experiments,” said Dr. Michael Pitt, a member of the CMS team. said.

This new method provided a new way to constrain tau's anomalous magnetic moments, and the CMS Collaboration quickly put it to the test.

Future driving data will likely improve the significance, but their new measurements impose the tightest constraints to date, with greater precision than ever before.

This reduces the prediction uncertainty to just three times the size of the quantum correction.

“We're really excited to finally be able to narrow down some of the fundamental properties of the elusive tau lepton,” said CMS team member Dr. Isaac Neutelings.

“This analysis introduces a new approach to investigating tau g-2 and revitalizes a measurement that has been stagnant for more than 20 years,” said CMS team member Dr. Xuelong Qin.

Source: www.sci.news

Physicists are delving into quantum gravity using the concept of gravitational rainbows

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The fans roar to life, pumping air upwards at 260 kilometers per hour. Wearing a baggy blue jumpsuit, red helmet, and plastic goggles, claudia de rum When you step into the glass room… Whoosh! Suddenly, she was suspended in the air, her wide grin on her face excited by her simulated experience of free fall.

I persuaded de Lamme, a theoretical physicist at Imperial College London, to go indoor skydiving with me at iFLY London. It seemed appropriate, given that much of her life has been dedicated to exploring the limits and true nature of gravity. At least on this occasion, jumping out of the plane wasn't an option for her.

As she explains in her new book, the beauty of falling, de Rum trained to be a pilot and then an astronaut, but medical problems ruined his chance for the ultimate escape from gravity. But as a theorist, she continued to delve deeper into this most familiar and mysterious force, making her mark by asking her fundamental question: “What is the weight of gravity?” Ta.

That means she is a graviton, a hypothetical particle that is thought to carry this force. If it had mass, as de Rum suspects, that would open a new window on gravity. Among other things, we may finally discover a “gravitational rainbow” that betrays the existence of gravitons. Along with gravitons, it will also become possible to provide a quantum description of gravity, which has been sought for many years.

When De Rum is suspended in the air, she makes it look easy. She will ascend soon…

Source: www.newscientist.com

Physicists discover first natural unconventional superconductor

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Solid state chemistry has led to the creation of numerous materials with unique properties not found in nature. For instance, the high-temperature superconductivity of copper oxide compounds known as cuprates is so distinct from the superconductivity of naturally occurring metals and alloys that it is often referred to as “unconventional.” Unconventional superconductivity is also present in other synthetic compounds like iron-based superconductors and heavy fermion superconductors. Physicists at Ames National Laboratory have uncovered strong evidence of unconventional superconductivity in synthetic samples of Rh17S15, a mineral that exists in nature as miassite.

Miasite is one of only four minerals found in nature that act as a superconductor when grown in the laboratory, and is the only mineral ever known to exhibit unconventional superconductivity in its clean synthetic form. It is the only mineral that exists. Image credit: Paul Canfield.

Superconductivity is the ability of a material to conduct electricity without any loss of energy.

Superconductors have various applications including medical MRI machines, power cables, and quantum computers.

Conventional superconductors are well understood but have low critical temperatures.

The critical temperature is the highest temperature at which a material displays superconductivity.

In the 1980s, scientists discovered unconventional superconductors with significantly higher critical temperatures, all of which were manufactured in a lab, challenging the notion that unconventional superconductivity is not a natural occurrence, as stated by Ruslan Prozorov, a researcher at Ames National Laboratory.

“Miasite is a fascinating mineral due to its intricate chemical composition,” he added.

Continued efforts to grow miasite crystals as part of a broader exploration into compounds combining elements with high melting points and volatile elements have led to the discovery of unconventional superconductors in the Rh-S system.

Professor Paul Canfield highlighted the unique process of growing crystals at low temperatures with minimal vapor pressure in elements like Rh, contrary to pure elements found in nature.

Further tests confirmed that miasite functions as an unconventional superconductor, enhancing the understanding of superconductors.

For more information on this discovery, refer to the article published in Communication Materials.

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H. Kim et al. 2024. Nodal superconductivity in miasite Rh17S15. Communication Materials 5, 17; doi: 10.1038/s43246-024-00456-w

Source: www.sci.news

Physicists at CERN Discover Intriguing New Decay Mode of Mesons

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Physicists from LHCb collaboration at CERN’s Large Hadron Collider (LHC) have made the first observation of the collapse of the Bc+ meson. This results in a J/ψ charm-anticharm quark bound state (consisting of two heavy quarks, b and c) and a pair of pions π+π0. This new decay process shows a contribution from an intermediate particle, the ρ+ meson, which forms for a short time and then decays into π+π0 pairs.

September 2016, LHCb experimental cave at LHC IP8. Image courtesy of CERN.

The Bc+ is the heaviest meson and decays only through weak interactions due to the decay of one heavy constituent quark.

It decays into an odd number of optical hadrons, and J/ψ (or another attractive and anti-attractive quark-bound state called Charmonia) has been intensively studied and found to be in remarkable agreement with theoretical predictions.

The decay of Bc+ to J/ψ and π+π0 pairs is the simplest decay to charmonium and even-numbered optical hadrons.

This has never been observed before. The main reason for this is that in the LHC proton-proton collision environment, it is very difficult to accurately reconstruct low-energy π0 mesons through their decay into a pair of photons.

“Accurate measurements of the Bc+→J/ψπ+π0 decay will allow us to better understand its possible contribution as a background source for the study of other decays of Bc mesons and rare decays of B0 mesons,” said the LHCb physicist.

From a theoretical point of view, J/ψ and the decay of Bc into an even number of pions are closely related to the decay of the τ lepton into an even number of pions and the e+e- annihilation into an even number of pions.

Accurate measurements of e+e- annihilation into two pions in the ρ mass region (like the Bc decay discussed here) are possible using the Fermilab G-2 experiment, which measures the anomalous magnetic dipole moment of the muon and is important for interpreting the results. The annihilation of low-energy e+e- into hadrons is an important source of uncertainty in g-2 measurements.

The ratio of the probability of a new decay to the probability of a decay from Bc+ to J/ψπ+ has been calculated by various theorists over the past 30 years.

Now these predictions can finally be compared with experimental measurements. Most predictions agree with the new result 2.80±0.15±0.11±0.16.

The large number of b quarks produced in LHC collisions and the excellent detectors allow LHCb researchers to study the formation, decay, and other properties of Bc+ mesons in detail.

“Since the discovery of the meson by the Tevatron Collider’s CDF experiment, 18 new Bc+ decays (with more than 5 standard deviations) have been observed, all from the LHCb,” the researchers said.

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LHCb collaboration. 2024. Observation of B+c→J/ψπ+π0 collapse. arXiv: 2402.05523

Source: www.sci.news

Physicists showcase novel technique for pinpointing 3D location of individual atoms

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Developed by a team of physicists from the University of Bonn and the University of Bristol, this new method makes it possible to precisely determine the position of atoms in 3D in a single image and is based on an original physical principle.

The different directions of rotation of the various “dumbbells” indicate that the atoms are in different planes. Image credit: Institute of Applied Physics, University of Bonn.

“If you have ever used a microscope to study plant cells in your biology class, you can probably recall a similar situation,” said Tanguy Legrand and colleagues at the University of Bonn.

“It's easy to see that a particular chloroplast is located above and to the right of the nucleus. But are they both on the same plane?”

“However, when we adjust the focus of the microscope, we find that the images of the nuclei become clearer, while the images of the chloroplasts become blurred.”

“One of them has to be a little higher than the other, and the other a little lower than the other. However, this method doesn't give you exact details about the vertical position.”

“The principle is very similar if you want to observe individual atoms rather than cells. So-called quantum gas microscopes can be used for this purpose.”

“This allows us to directly determine the x and y coordinates of atoms.”

“However, it is much more difficult to measure its z-coordinate, and thus its distance to the objective lens. To find out in which plane an atom lies, we need to take multiple images by moving the focus to various different planes. I need to take a picture of a plane. This is a complex and time-consuming process. ”

“We have developed a method that completes this process in one step,” Dr. Legrand said.

“To achieve this, we use an effect that was already known in theory since the 1990s but had not yet been used in quantum gas microscopy.”

To experiment with atoms, you must first cool them down significantly until they barely move.

It is then possible to confine them to a standing wave of laser light, for example.

The egg then slides into the trough of the waves so that it fits inside the egg box.

After being captured, it is exposed to an additional laser beam and stimulated to emit light to reveal its location.

The resulting fluorescence appears as slightly blurred round spots in quantum gas microscopy.

“We have now developed a special method to transform the wavefront of light emitted by atoms,” said Dr. Andrea Alberti, also from the University of Bonn.

“Instead of a typical round spot, the deformed wavefront produces a dumbbell shape on the camera, which rotates itself.”

“The direction this dumbbell points is determined by the distance light travels from the atom to the camera.”

Professor Dieter Meschede from the University of Bonn said: “The dumbbell acts like a compass needle, and depending on its direction we can read the Z coordinate.”

This new method could be used to develop new quantum materials with special properties.

“For example, we can find out what quantum mechanical effects occur when atoms are arranged in a particular order,” said physicist Dr Carrie Widener from the University of Bristol.

“This allows us to simulate the properties of three-dimensional materials to some extent without having to synthesize them.”

team's work It was published in the magazine Physical review A.

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Tanguy Legrand other. 2024. His three-dimensional imaging of single atoms in optical lattices by helical point spread function engineering. Physics. Rev.A 109 (3): 033304; doi: 10.1103/PhysRevA.109.033304

Source: www.sci.news

Physicists Create New Isotopes of Osmium and Tungsten through Synthesis

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A team of Chinese physicists has synthesized two new isotopes: osmium-160 and tungsten-156.

Location of the new isotopes osmium-160 and tungsten-156 on the nuclide chart. Image credit: Huabin Yang.

“The magic numbers of protons and neutrons make the nucleus particularly stable. The traditional magic numbers are 8, 20, 28, 50, 82, and 126,” said Dr. Huabin Yang, a physicist at the Institute of Modern Physics, Chinese Academy of Sciences. said the colleague.

“In previous research, physicists discovered that traditional magic numbers disappear and new magic numbers appear on the neutron-rich side of the nuclide chart.”

“Will other traditional magical numbers also disappear in the nuclear region where there is an extreme lack of neutrons?”

“Further exploration is critical to enriching and developing nuclear theory and improving our understanding of nuclear forces.”

In the new study, Dr. Yang's team conducted experiments at the Gas-Filled Recoil Separator Spectrometer for Heavy Atom and Nuclear Structures (SHANS) in Lanzhou, China.

Researchers have synthesized two new isotopes, osmium-160 and tungsten-156, using nuclear fusion vaporization reactions.

They measured the energy of the alpha particle and the half-life of the alpha-emitting isotope osmium-160.

On the other hand, the daughter nucleus, tungsten-156, was found to be a β+ emitter with a half-life of 291 ms.

The researchers used the newly measured alpha decay data to derive the alpha decay reduction for osmium-160 and compared it to other nuclei with 84 neutrons and fewer protons.

They discovered a surprising trend: the higher the number of protons, the lower the decay rate.

“This trend is interpreted as evidence of enhanced closure of the 82 neutron shell towards the proton drip line, which is supported by the increase in the neutron shell gap predicted by the theoretical model,” Dr. Yang said. said.

“The increased stability of the 82 neutron shell closure is thought to be due to the increasing proximity of the double magic nucleus lead 164, which may be a stable atomic nucleus with 82 protons and 82 neutrons. Masu.”

“Although lead-164 is predicted to cross the proton drip line, enhanced shell effects could make it a bonded or quasi-bonded nucleus.”

of study It was published in the magazine physical review letter.

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HB Yang other. 2024. Discovery of new isotopes 160with oz 156W: Reveals improved stability of N=82 shell closure on the neutron-deficient side. Physics.pastor rhett 132 (7): 072502; doi: 10.1103/PhysRevLett.132.072502

Source: www.sci.news

Physicists witness real-time movement of electrons in liquid water for the first time

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A research team led by physicists at Argonne National Laboratory isolated the energetic motion of electrons while “freezing” the motion of the much larger atoms they orbit in a sample of liquid water.

Shuai other. Synchronized attosecond X-ray pulse pairs (pictured here in pink and green) from an X-ray free electron laser were used to study the energetic response of electrons (gold) in liquid water on the attosecond time scale. On the other hand, hydrogen (white) and oxygen (red) atoms are “frozen” over time. Image credit: Nathan Johnson, Pacific Northwest National Laboratory.

“The radiation-induced chemical reactions we want to study are the result of targeted electronic reactions that occur on the attosecond time scale,” said lead author of the study, Professor Linda Young, a researcher at Argonne National Laboratory. said.

Professor Young and colleagues combined experiment and theory to reveal the effects of ionizing radiation from an X-ray source when it hits material in real time.

Addressing the timescales over which actions occur will provide a deeper understanding of the complex radiation-induced chemistry.

In fact, researchers originally came together to develop the tools needed to understand the effects of long-term exposure to ionizing radiation on chemicals found in nuclear waste.

“Attosecond time-resolved experiments are one of the major R&D developments in linac coherent light sources,” said study co-author Dr. Ago Marinelli, a researcher at the SLAC National Accelerator Laboratory.

“It's exciting to see these developments applied to new types of experiments and moving attosecond science in new directions.”

Scientists have developed a technique called X-ray attosecond transient absorption spectroscopy in liquids that allows them to “watch” electrons energized by X-rays move into an excited state before larger nuclei move on. “We were able to.

“In principle, we have tools that allow us to track the movement of electrons and watch newly ionized molecules form in real time,” Professor Young said.

The discovery resolves a long-standing scientific debate about whether the X-ray signals observed in previous experiments are the result of different structural shapes or motifs in the mechanics of water or hydrogen atoms.

These experiments conclusively demonstrate that these signals are not evidence of two structural motifs in the surrounding liquid water.

“Essentially, what people were seeing in previous experiments was a blur caused by the movement of hydrogen atoms,” Professor Young explained.

“By recording everything before the atoms moved, we were able to eliminate that movement.”

To make this discovery, the authors used a technique developed at SLAC to spray an ultrathin sheet of pure water across the pulse path of an X-ray pump.

“We needed a clean, flat, thin sheet of water that could focus the X-rays,” said study co-author Dr. Emily Nienhaus, a chemist at Pacific Northwest National Laboratory.

Once the X-ray data was collected, the researchers applied their knowledge of interpreting X-ray signals to recreate the signals observed at SLAC.

They modeled the response of liquid water to attosecond X-rays and verified that the observed signal was indeed confined to the attosecond timescale.

“Using the Hyak supercomputer, we developed cutting-edge computational chemistry techniques that enable detailed characterization of transient high-energy quantum states in water,” study co-authors from the University of Washington said Xiaosong Li, a researcher at Pacific Northwest National University. Laboratory.

“This methodological breakthrough represents a pivotal advance in our quantum-level understanding of ultrafast chemical transformations, with extraordinary precision and atomic-level detail.”

The team worked together to peer into the real-time movement of electrons in liquid water.

“The methodology we have developed enables the study of the origin and evolution of reactive species produced by radiation-induced processes encountered in space travel, cancer treatment, nuclear reactors, legacy waste, etc.,” Professor Young said. Stated.

The team's results were published in a magazine science.

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L. Shuai other. 2024. Attosecond Pump Attosecond Probe X-ray Spectroscopy of Liquid Water. science, published online on February 15, 2024. doi: 10.1126/science.adn6059

Source: www.sci.news

Physicists conclude the shape factor of a proton’s Grunick gravitational force

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Protons are one of the main building blocks of all visible matter in the universe. Its unique properties include charge, mass, and spin. These properties emerge from the complex dynamics of its basic building blocks, quarks and gluons, explained by the theory of quantum chromodynamics. The charge and spin of protons shared between quarks has been previously studied using electron scattering. One example is the high-precision measurement of the charge radius of protons. In contrast, little is known about the internal mass density of protons, which is dominated by the energy carried by gluons. In a new study, a team of physicists led by Argonne National Laboratory used a small colored dipole to probe the gravitational density of gluons through threshold photogeneration of J/ψ (J/Psi) particles.

Proton valence quarks (blue, red, green), quark and antiquark pairs, and gluons (springs). Scalar gluon activity (pink) extends beyond the charge radius (orange) surrounding the gluon energy core (yellow). Image credit: Argonne National Laboratory.

For many years, nuclear physicists have determined the size of protons by precisely measuring their charge response. This is a result of the proton's charged constituent quarks.

However, determining the size of matter by the size of its protons is a more difficult task. This is because part of the proton's mass is driven by the elusive neutral gluon, rather than by the mass or motion of charged quarks. These gluons combine themselves with quarks within the proton.

The new discovery provides a view of this mass region produced by gluon interactions.

This measurement not only reveals the mass radius resulting from the strong force, but also its confinement effect on quarks that extend far beyond the proton's charge radius.

“A key detail of the proton's structure is its size,” said lead author Dr. Zein Eddin Meziani, a physicist at Argonne National Laboratory, and his colleagues.

“The most commonly used measure of a proton's size is its charge radius, which uses electrons to measure the spherical size of the proton's charge.”

The new measurements come from the J/Ψ -007 experiment at the Thomas Jefferson National Accelerator Facility.

This differs in that a small colored dipole ( ) was used to reveal the sphere size and position of the gluon mass and its range of influence on the gluon within the proton.

In the experiment, physicists used a high-energy beam of electrons to create J/Ψ particles from protons. The J/Ψ particle provides information about the distribution of gluons inside the proton.

Experimenters inserted these measurements into a theoretical model and analyzed them.

As a result, the mass radius of the gluon inside the proton was determined.

Furthermore, the area of ​​influence of a strong force called a confinement scalar cloud, which also affects proton quarks, was also shown.

“This study paves the way for a deeper understanding of the prominent role of gluons in imparting gravitational mass to visible matter,” the authors concluded.

Their paper It was published in the magazine Nature.

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B. Duran other. 2023. Determination of the Grunick gravitational shape factor of protons. Nature 615, 813-816; doi: 10.1038/s41586-023-05730-4

Source: www.sci.news

Physicists’ Discovery Unveils Distribution of Strong Forces Within Protons

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The physics of proton gravitational form factors and their understanding in quantum chromodynamics have advanced significantly over the past two decades through both theory and experiment.a new paper inside modern physics review We provide an overview of this progress, highlighting the physical insights revealed by studies of the gravitational form factor and reviewing its interpretation in terms of the mechanical properties of protons.

A 2D representation of the quark contribution to the force distribution within the proton as a function of distance from the proton center. Light gray shading and long arrows indicate areas of stronger force, while dark gray shading and short arrows indicate areas of weaker force. Left panel: Normal force as a function of distance from center. The arrows change size and always point radially outward. Right panel: tangential force as a function of distance from center. The force changes direction and magnitude as indicated by the direction and length of the arrow. The sign of the force changes around 0.4 fm from the proton center. Image credit: Burkert other., doi: 10.1103/RevModPhys.95.041002.

“This measurement reveals insight into the environment experienced by the proton's components,” said Volker Burkert, principal investigator at the Jefferson Institute.

“A proton is made up of three quarks held together by a strong force.”

“At its peak, this amounts to more than four tons of force that would have to be applied to the quark to pull it out of the proton.”

“Of course, it is not possible in nature to separate just one quark from a proton because quarks have a property called color.”

“Protons have three colors mixed with quarks, and appear colorless from the outside. This is a requirement for them to exist in the universe.”

“When you try to extract a colored quark from a proton, the energy you invested in separating the quarks is used to create a meson, a pair of colorless quark and antiquark, leaving behind a colorless proton (or neutron).”

“In other words, the number four tons represents the strength of the force inherent in protons.”

The result is only the second of the mechanical properties of the protons to be measured.

Mechanical properties of protons include internal pressure (measured in 2018), mass distribution (physical size), angular momentum, and shear stress (shown here).

This result was made possible by predictions from half a century ago and data from 20 years ago.

In the mid-1960s, nuclear physicists realized that if they could observe how gravity interacted with subatomic particles like protons, such experiments could directly reveal the mechanical properties of protons. It was theorized that

“But at the time, we had no choice. For example, if you compare gravity to electromagnetic forces, there's a difference of 39 orders of magnitude. So it's pretty hopeless, right?” said Latifa El-Adhriri, a staff scientist at the Jefferson Institute. .

This data comes from experiments conducted at the Continuous Electron Beam Accelerator Facility (CEBAF) at the Jefferson Research Institute.

A typical CEBAF experiment involves a high-energy electron interacting with another particle by exchanging a packet of energy and a unit of angular momentum called a virtual photon with the particle. The energy of an electron determines which particles it interacts with in this way and how it reacts.

In the experiment, a high-energy beam of electrons interacting with protons inside a target of liquefied hydrogen gas exerted a much greater force on the protons than the four tons needed to pull out the quark/antiquark pair.

“We have developed a program to study deep virtual Compton scattering,” said Dr. El-Adrili.

“This is where electrons exchange virtual photons with protons.”

“And in the final state, the proton stays the same but recoils, and you actually produce one very high-energy photon, and you also get a scattered electron.”

“At the time we acquired the data, we did not know that beyond the intended 3D imaging with these data, we were also collecting the data needed to access the mechanical properties of the protons.”

“It turns out that this particular process, the highly virtual Compton scattering, may be related to how gravity interacts with matter.”

“A general version of this relationship is stated in Einstein's 1973 textbook on general relativity.gravityWritten by Charles W. Meisner, Kip S. Thorne, and John Archibald Wheeler. ”

“In it, they say, “A massless spin 2 field would give rise to a force indistinguishable from gravity, because a massless spin 2 field would couple with a stress-energy tensor in the same way as a gravitational interaction.'' It is written as 'It is from.'.'.

“Thirty years later, theorist Maxim Polyakov continued this idea and established a theoretical foundation linking deep virtual Compton scattering processes and gravitational interactions.”

“This theoretical breakthrough establishes a relationship between measurements of deep virtual Compton scattering and the gravitational shape factor.”

“And we were able to take advantage of that for the first time and bring out the pressure that we gave during the game.” Nature A paper was published in 2018 and now normal and shear forces are being studied,” Dr. Burkert said.

“A more detailed explanation of the relationship between deep virtual Compton scattering processes and gravitational interactions is provided in a new paper describing the first results obtained from this study.”

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V.D. Burkert other. 2023. Colloquium: Gravitational shape factor of protons. Rev.Mod. Physics 95(4):041002; doi: 10.1103/RevModPhys.95.041002

Source: www.sci.news

Physicists have successfully captured direct images of noble gas nanoclusters at room temperature

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For the first time, physicists have directly imaged small clusters of noble gas atoms at room temperature. This result opens up exciting possibilities for fundamental research in condensed matter physics and applications in quantum information technology.

Xenon nanoclusters between two graphene layers. Sizes range from 2 to 10 atoms. Image credit: Manuel L'Engle.

“When I was researching the use of ion irradiation to modify the properties of graphene and other two-dimensional materials, I noticed something unusual. They can become trapped between the sheets,” the University of Vienna said. Dr. Jani Kotaski and his colleagues.

“This happens when noble gas ions pass through the first graphene layer fast enough to pass through, but not the second graphene layer.”

“Once trapped between the layers, the noble gases are free to move because they do not form chemical bonds.”

“But to accommodate the noble gas atoms, the graphene bends to form tiny pockets.”

“Here, two or more noble gas atoms can meet and form two-dimensional noble gas nanoclusters that are ordered and densely packed.”

The researchers' method overcomes the difficulty that noble gases do not form stable structures under experimental conditions at ambient temperatures.

“We observed these clusters using a scanning transmission electron microscope, and they are really fascinating and very fun to look at,” said Dr. Manuel L'Engle, a physicist at the University of Vienna.

“They rotate, jump, grow, and shrink as we imagine them.”

“Getting the atoms between the layers was the most difficult part of the job.”

“Achieving this gives us a simple system to study fundamental processes related to the growth and behavior of materials.”

“The next step is to study the properties of clusters containing different noble gases and how they behave at low and high temperatures,” Dr Kotasky added.

“With the use of noble gases in light sources and lasers, these new structures may enable future applications such as quantum information technology.”

a paper The findings were published in this week's magazine Natural materials.

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M. Langre other. Two-dimensional few atomic noble gas clusters within a graphene sandwich. nut.meter, published online on January 11, 2024. doi: 10.1038/s41563-023-01780-1

Source: www.sci.news