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Category: particle physics – Page 11

How an atomic nucleus can have two different shapes with only slightly different energy levels

A team of researchers at the Facility for Rare Isotope Beams (FRIB) at Michigan State University (MSU) has discovered that cobalt-70 isotopes form different nuclear shapes when their energy levels differ only slightly. The findings, published in Nature Communications Physics, shed light on the dynamic, complex nature of exotic nuclear particles.

The team included Artemis Spyrou, professor of physics at the Facility for Rare Isotope Beams (FRIB) and in the MSU Department of Physics and Astronomy, Sean Liddick, associate professor of chemistry at FRIB and in the MSU Department of Chemistry and Experimental Nuclear Science Department head at FRIB, Alex Brown, professor of physics at FRIB, and Cade Dembski, former FRIB student research assistant. Dembski, now working on his Ph.D. at the University of Notre Dame, served as the paper’s lead author.

“When we first started this project, it was motivated by the astrophysical side of nuclear science research, instead of focusing on ,” Dembski said. “As we continued with our , though, we couldn’t quite understand all of the patterns we were seeing. It turned out the reason was due to some interesting nuclear structure effects that we were not expecting, and we ended up writing the paper about those effects.”

Out of the string theory swampland: New models may resolve problem that conflicts with dark energy

String theory has long been touted as physicists’ best candidate for describing the fundamental nature of the universe, with elementary particles and forces described as vibrations of tiny threads of energy. But in the early 21st century, it was realized that most of the versions of reality described by string theory’s equations cannot match up with observations of our own universe.

In particular, conventional ’s predictions are incompatible with the observation of dark energy, which appears to be causing our universe’s expansion to speed up, and with viable theories of quantum gravity, instead predicting a vast ‘swampland’ of impossible universes.

Now, a new analysis by FQxI physicist Eduardo Guendelman, of Ben-Gurion University of the Negev, in Israel, shows that an exotic subset of string models—in which the of strings is generated dynamically—could provide an escape route out of the string theory swampland.

“Like the Birth of Everything”: Scientists Recreate First Microseconds of Universe to Unveil Wild Behavior of Quark-Gluon Plasma

IN A NUTSHELL 🌌 Quark-gluon plasma dominated the universe’s earliest microseconds, shaping the cosmos we know today. 🔬 Researchers used lattice QCD and Monte Carlo simulations to unravel the complexities of the strong nuclear force. 📈 The study revealed that even at extreme temperatures, the strong force influenced particle behavior more than previously believed. 📚

Why are some rocks on the moon highly magnetic?

A large impact could have briefly amplified the moon’s weak magnetic field, creating a momentary spike that was recorded in some lunar rocks. Scientists may have solved the mystery of why the moon shows ancient signs of magnetism although it has no magnetic field today. An impact, such as from a large asteroid, could have generated a cloud of ionized particles that briefly enveloped the moon and amplified its weak magnetic field.

Where did the moon’s magnetism go? Scientists have puzzled over this question for decades, ever since orbiting spacecraft picked up signs of a high magnetic field in lunar surface rocks. The moon itself has no inherent magnetism today.

Now, MIT scientists may have solved the mystery. They propose that a combination of an ancient, weak magnetic field and a large, plasma-generating impact may have temporarily created a strong magnetic field, concentrated on the far side of the moon.

New measurement of the mass of the Z boson from the Large Hadron Collider

The LHCb experiment has taken a leap in precision physics at the Large Hadron Collider (LHC). In a new paper submitted to Physical Review Letters and currently available on the arXiv preprint server, the LHCb collaboration reports the first dedicated measurement of the Z boson mass at the LHC, using data from high-energy collisions between protons recorded in 2016 during the collider’s second run.

The Z boson is a massive, electrically neutral particle that mediates the weak nuclear force—one of nature’s fundamental forces. With a mass of about 91 billion electronvolts (GeV), it ranks among the heaviest known elementary particles.

Discovered at CERN more than 40 years ago, alongside the W boson, the Z boson played a central role in confirming the Standard Model of particle physics—a breakthrough that led to the 1984 Nobel Prize in Physics. Measuring its mass precisely remains essential for testing the Standard Model and searching for signs of new physics.

Probing hyperon potential to resolve a longstanding puzzle in neutron stars

A research team led by Prof. Yong Gaochan from the Institute of Modern Physics (IMP) of the Chinese Academy of Sciences has proposed a novel experimental method to probe the hyperon potential, offering new insights into resolving the longstanding “hyperon puzzle” in neutron stars. These findings were published in Physics Letters B and Physical Review C.

According to conventional theories, the extreme densities within neutron stars lead to the production of hyperons containing strange quarks (e.g., Λ particles). These hyperons significantly soften the equation of state (EoS) and reduce the maximum mass of neutron stars. However, have discovered neutron stars with masses approaching or even exceeding twice that of the sun, contradicting theoretical predictions.

Hyperon potential refers to the interaction potential between a hyperon and a nucleon. Aiming to resolve the “neutron star hyperon puzzle,” the study of hyperon potential has emerged as a frontier topic in the interdisciplinary field of nuclear and astrophysics. Currently, it is believed that if hyperon potentials exhibit stronger repulsion at high densities, they could counteract the softening effect of the EoS, thereby allowing massive to exist.

Magnetic surface enables precise atomic migration at near absolute zero

Adatoms are single atoms that get adsorbed onto the surface of a solid material and are known to hop randomly from one spot to another. In a recent study published in Nature Communications, a group of scientists from Germany demonstrated that single atoms can be steered in a chosen direction at near absolute zero temperatures (4 Kelvin), provided the surface being used is magnetic in nature—a discovery that can open up new possibilities for precise control of atomic motion, a sought-after ability in the field of nanotechnology, data storage and functional materials.

The researchers placed individual cobalt, rhodium, and iridium atoms on a 1-atom-thick manganese surface to create a magnetically well-defined surface and studied the migration behavior of adatoms using a scanning tunneling microscope (STM) at a temperature of 4 K.

According to established findings from nonmagnetic surfaces, atomic movement is usually governed by surface symmetry. In a hexagonal manganese monolayer like the one used in the study, atoms would be expected to migrate randomly in any of six directions. Yet in a surprising twist, researchers found that when a short, localized voltage pulse from the STM was applied, the atoms consistently moved in just one direction.

Study predicts existence of Type-III multiferroics, which exhibit ferroelectricity-driven magnetism

Multiferroics are materials that exhibit more than one ferroic property, typically ferroelectricity (i.e., a spontaneous electric polarization that can be reversed by electric fields) and ferromagnetism (i.e., the spontaneous magnetic ordering of electron spins). These materials have proved promising for the development of various new technologies, including spintronics, devices that exploit the spin of electrons to process and store information.

So far, physicists and material scientists have uncovered two distinct types of multiferroics, dubbed Type-I and Type-II multiferroics. In Type-I multiferroics, ferroelectricity and arise independently from distinct physical mechanisms, while in Type-II multiferroics, ferroelectricity is driven by magnetic ordering.

Researchers at Nanjing University of Science and Technology recently predicted the existence of a third type of multiferroics, referred to as Type-III multiferroics, in which magnetism is driven by ferroelectricity. Their paper, published in Physical Review Letters, could inspire future efforts aimed at identifying materials with the characteristics they described, which could be highly advantageous for the advancement of spintronics as well as other memory and information processing systems.

Physicists observe a new form of magnetism for the first time

MIT physicists have demonstrated a new form of magnetism that could one day be harnessed to build faster, denser, and less power-hungry “spintronic” memory chips.

The new magnetic state is a mash-up of two main forms of magnetism: the ferromagnetism of everyday fridge magnets and compass needles, and antiferromagnetism, in which materials have magnetic properties at the microscale yet are not macroscopically magnetized.

Now, the MIT team has demonstrated a new form of magnetism, termed “p-wave magnetism.”