Saturday, June 11, 2022

It's Always the Last Place You Look

Livescience, Physicists discover never-before seen particle sitting on a tabletop. "This newly-discovered particle could account for dark matter."

Researchers have discovered a new particle that is a magnetic relative of the Higgs boson. Whereas the discovery of the Higgs boson required the tremendous particle-accelerating power of the Large Hadron Collider (LHC), this never-before-seen particle  —  dubbed the axial Higgs boson — was found using an experiment that would fit on a small kitchen countertop.

As well as being a first in its own right, this magnetic cousin of the Higgs boson  —  the particle responsible for granting other particles their mass  —  could be a candidate for dark matter, which accounts for 85%t of the total mass of the universe but only reveals itself through gravity.

"When my student showed me the data I thought she must be wrong," Kenneth Burch, a professor of physics at Boston College and lead researcher of the team that made the discovery, told Live Science. "It’s not every day you find a new particle sitting on your tabletop."

The axial Higgs boson differs from the Higgs boson, which was first detected by the ATLAS and CMS detectors at the LHC a decade ago in 2012 ,  because it has a magnetic moment, a magnetic strength or orientation that creates a magnetic field. As such, it requires a more complex theory to describe it than its non-magnetic mass-granting cousin.

In the Standard Model of particle physics, particles emerge from different fields that permeate the universe, and some of these particles shape the universe’s fundamental forces. For example photons mediate electromagnetism, and hefty 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 weak force were one thing and all of these particles were nearly identical. As the universe cooled, the electroweak force split, causing the W and Z bosons to gain mass and to behave very differently from photons, a process physicists have called "symmetry breaking." But how exactly did these weak-force-mediating particles get so heavy?

It turns out that these particles interacted with a separate field, known as the Higgs field. Perturbations in that field gave rise to the Higgs boson and lent the W and Z bosons their heft.

It seems odd to me that a particle that could be detected with a simple tabletop experiment was discovered after the Higgs boson, which required massive experiment using the CERNs Large Hadron Collider. Shouldn't science seek the lower hanging fruit first, and then build up to the hard stuff?

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