Physicists discover elusive new particles through tabletop experiments

Axial Higgs mode

An interdisciplinary team led by a physicist at Boston University has discovered a new particle, known as the axial Higgs mode, which is a magnetic relative of the Higgs boson that defines mass, or a previously undetectable quantum excitation. Credit: Nature

Materials containing the axial Higgs mode may act as quantum sensors to help evaluate other quantum systems and answer persistent questions in particle physics.

According to the Standard Model of particle physics, the current best theory of scientists explaining the most basic components of the universe is the particles called quarks (which make up protons and neutrons) and leptons (which contain electrons). Consists of all known substances. Force-carrying particles belonging to the wider boson group affect quarks and leptons.

Despite the success of the Standard Model that describes the universe, it has its limits. Dark matter and dark energy are two examples, and new particles that have not yet been discovered may eventually solve these mysteries.

Today, a team of interdisciplinary scientists led by physicists at the University of Boston discover a new particle known as the axial Higgs mode, a magnetic relative of the Higgs boson that defines mass, or a previously undetectable quantum excitation. Announced that it was done.The team published the report today (June 8, 2022) in the online version of the journal. Nature..

The long-awaited detection of the Higgs boson 10 years ago was central to our understanding of mass. Unlike the parent, the axial Higgs mode has a magnetic moment, and a more complex form of theory is needed to explain its properties. Quantum path interference in RTe3.. “

The theory that predicted the existence of such a mode was called to explain the “dark matter”, the almost invisible matter that makes up most of the universe, but only by gravity, Birch said. Said.

The Higgs boson is an elementary particle related to the Higgs field that gives mass to other elementary particles such as electrons and quarks. The mass of a particle determines how much it resists a change in velocity or position when it encounters a force.

The team focused on RTe, while the Higgs boson was revealed by experiments on a giant particle collider.3Or the rare earth triterlide, a well-studied quantum material that can be examined at room temperature in a “tabletop” experimental format.

“It’s not every day that we find new particles sitting on the table top,” says Birch.

RTe3 According to Birch, it has properties that mimic the theory of producing the axial Higgs mode. However, he said, the central challenge in finding the Higgs boson in general is weak binding to experimental probes such as light rays. Similarly, revealing the subtle quantum properties of particles usually requires fairly complex experimental settings such as giant magnets and high power lasers, while cooling the sample to cryogenic temperatures.

The team reports that they have overcome these challenges by using light scattering on their own and choosing the right quantum simulator. This is essentially a material that mimics the properties needed for research.

Specifically, researchers focused on “charge density waves,” a compound that has long been known to have a state in which electrons self-assemble at periodic densities in space, Birch. He said.

He added that the basic theory of this wave mimics the components of the Standard Model of particle physics. However, in this case, the charge density wave is very special, much higher than room temperature, with modulation of both charge density and atomic orbital. This allows the Higgs boson associated with this charge density wave to have additional components. That is, it can be axial. That is, it may contain angular momentum.

To reveal the subtle nature of this mode, Burch explained that the team used light scattering. In this case, the laser illuminates the material, which can change not only the polarization but also the color. The color change is caused by light producing Higgs bosons in the material, but polarization is sensitive to the symmetry component of the particles.

In addition, with proper choice of incident and output polarization, you can create particles with a variety of components, including non-magnetic and upward components. They took advantage of the basic aspects of quantum mechanics to take advantage of the fact that these components are canceled in one configuration. However, if the configuration is different, add it.

“Therefore, we were able to uncover the hidden magnetic components and prove the discovery of the first axial Higgs mode,” Birch said.

“The detection of the axial Higgs was predicted in high-energy particle physics to explain dark matter,” Birch said. “But it has never been observed. Its appearance in condensed matter physics is completely amazing and heralds the discovery of an unexpected new symmetry breaking state. To observe new particles. Unlike the extreme conditions normally required for this, this was a tabletop experiment that achieved quantum control of the mode simply by changing the polarization of the light, and was done at room temperature. “

Birch said the seemingly accessible and simple experimental method developed by the team could be applied to research in other areas.

“Many of these experiments were done by undergraduates in my lab,” Birch said. “This approach can be applied directly to the quantum properties of many aggregate phenomena, such as superconductors, magnets, ferroelectrics, charge density wave modes. In addition, quantum interference of materials with correlated and / or topological phases. Bring your research to room temperature and overcome the difficulties of extreme experimental conditions.

In addition to Burch, co-authors at Boston University included undergraduate student Grant McNamara, recent PhD graduate Yiping Wang, and postdoctoral fellow Md Mofazzel Hosen. Wang won the best paper on magnetism from the American Physical Society as part of her work on the project, Birch said.

Birch said it is important to utilize a wide range of expertise among BC researchers at Harvard University.[{” attribute=””>Princeton University, the University of Massachusetts, Amherst, Yale University, University of Washington, and the Chinese Academy of Sciences.

“This shows the power of interdisciplinary efforts in revealing and controlling new phenomena,” Burch said. “It’s not every day you get optics, chemistry, physical theory, materials science and physics together in one work.”

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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