An axial Higgs mode has been spotted within the collective quantum excitations of a solid material. Kenneth Burch at Boston College and colleagues in the US and China, discovered the quasiparticle cousin of the Higgs boson in a relatively simple tabletop experiment carried out at room temperature.
In 2012, the discovery of the Higgs boson at CERN’s Large Hadron Collider confirmed a prediction made nearly 50 years earlier about the mechanism by which some fundamental particles acquire mass. The Higgs mechanism is triggered by spontaneous symmetry breaking and was originally devised to explain how photons acquire mass in superconductors. As a result, analogues of the Higgs boson – collective excitations (or quasiparticles) called Higgs modes – can be found in superconductors.
Theory predicts that further symmetry breaking could lead to the emergence of a new type of excitation called the “axial Higgs mode”, which unlike the Higgs mode, has intrinsic angular momentum.
Now Burch and colleagues have observed an axial Higgs mode in rare-earth tritellurides. These are layered materials that harbour charge density waves (CDWs) in which chains of electrons form standing waves. These electrons behave in a highly correlated manner and a CDW is described as a quantum fluid – a category of materials that also includes superconductors.
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