Researchers have discovered a new particle that is a magnetic relative of the Higgs boson. While the discovery of the Higgs boson required the enormous particle-accelerating power of the Large Hadron Collider (LHC), this never-before-seen particle – dubbed the axial Higgs boson – was discovered using an experiment that could stand on a small kitchen counter. .
In addition to being a first in itself, this magnetic cousin of the Higgs boson – the particle responsible for giving mass to other particles – could be a candidate for black matter, which represents 85% of the total mass of the universe but is only revealed by gravity.
“When my student showed me the data, I thought she must be wrong,” Kenneth Burch, a Boston College physics professor and principal investigator on the team that made the discovery, told Live Science. “It’s not every day that you find a new particle on your table.”
The axial Higgs boson differs from the Higgs boson, which was first detected by the ATLAS and CMS detectors at the LHC ten years ago in 2012, because it has a magnetic moment, magnetic force, or orientation that creates a magnetic field. As such, it requires a more complex theory to describe it than its non-magnetic, mass-tuning cousin.
In the standard model of particle physics, particles emerge from different fields that permeate the universe, and some of these particles shape the fundamental forces of the universe. For example, photons mediate electromagnetism, and large particles known as W and Z bosons mediate the weak nuclear force, which governs nuclear decay at subatomic levels. When the universe was young and hot, however, electromagnetism and the weak force were one thing, and all of those particles were nearly identical. As the universe cooled, the electroweak force split, causing the W and Z bosons to gain mass and behave very differently from photons, a process physicists have called ” symmetry breaking. But how exactly did these weak force mediator particles become so heavy?
It turns out that these particles interacted with a separate field, known as the Higgs field. Perturbations in this domain gave rise to the Higgs boson and gave their weight to the W and Z bosons.
The Higgs boson is produced in nature whenever such a symmetry is broken, . “However, typically only one symmetry is broken at a time, and so the Higgs is simply described by its energy,” Burch said.
The theory behind the axial Higgs boson is more complicated.
“In the case of the axial Higgs boson, it appears that multiple symmetries are broken together, leading to a new form of theory and a Higgs mode [the specific oscillations of a quantum field like the Higgs field] which requires several parameters to describe it: in particular, energy and magnetic moment,” Burch said.
Burch, who along with his colleagues described the new magnetic cousin of the Higgs in a study published Wednesday, June 8 in the journal Nature, explained that the original Higgs boson does not couple directly with light, meaning it must be created by crushing other particles with huge magnets and powerful lasers while cooling the samples to extremely hot temperatures. cold. It is the disintegration of these original particles into others which appear fleetingly in existence which reveals the presence of the Higgs.
The axial Higgs boson, on the other hand, arose when quantum materials at room temperature mimicked a specific set of oscillations, called the axial Higgs mode. The researchers then used light scattering to observe the particle.
“We found the axial Higgs boson using a tabletop optics experiment that sits on a table measuring about 1 x 1 meter by focusing on a material with a unique combination of properties,” Burch continued. . “Specifically, we used the rare-earth tritelluride (RTe3) [a quantum material with a highly 2D crystal structure]. The electrons in RTe3 self-organize into a wave where the charge density is periodically increased or decreased.”
The size of these charge density waves, which emerge above room temperature, can be modulated over time, producing the axial Higgs mode.
In the new study, the team created the axial Higgs mode by beaming laser light of one color into the RTe3 crystal. The light scattered and changed to a lower frequency color in a process known as Raman scattering, and the energy lost in the color change created the axial Higgs mode. The team then spun the crystal and discovered that the axial Higgs mode also controls the angular momentum of electrons, or how fast they move in a circle, in the material, which means this mode must also be magnetic.
“Originally, we were just studying the light scattering properties of this material. By carefully examining the symmetry of the response – how it differed as we rotated the sample – we discovered anomalous changes that were the first clues to something new,” Burch explained. “As such, it is the first magnetic Higgs of its kind to be discovered and indicates that the collective behavior of electrons in RTe3 is unlike any state previously observed in nature.”
Particle physicists had previously predicted an axial Higgs mode and even used it to explain dark matter, but this is the first time it has been observed. It is also the first time that scientists have observed a state with multiple broken symmetries.
Symmetry breaking occurs when a symmetrical system that appears the same in all directions becomes asymmetrical. University of Oregon suggests thinking of this as a rotating coin that has two possible states. The coin eventually falls on its head or back side, releasing energy and becoming asymmetrical.
The fact that this double symmetry breaking still fits with current physical theories is exciting, as it could be a way to create hitherto unseen particles that could explain dark matter.
“The basic idea is that to explain dark matter, you need a theory that is consistent with existing particle experiments, but produces new particles that haven’t been seen yet,” Burch said.
Adding this extra symmetry breaking via the axial Higgs mode is one way to achieve this, he said. Although predicted by physicists, the observation of the axial Higgs boson came as a surprise to the team, and they spent a year trying to verify their findings, Burch said.
Originally posted on Live Science.