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June 18, 2021
A new study shows that a class of new unknown particles that could account for the muon’s magnetism, known as leptoquarks, also affects the Higgs boson’s transformation into muons
Image above: Displays of candidate events for a Higgs boson decaying into two muons, as recorded by CMS (left) and ATLAS (right). (Image: CERN).
Zoom into an online particle physics conference, and the chances are you’ll hear the term muon anomaly. This is a longstanding tension with the Standard Model of particle physics, seen in the magnetism of a heavier cousin of the electron called a muon, that has recently been strengthened by measurements made at Fermilab in the US.
In a paper accepted for publication in Physical Review Letters, a trio of theorists including Andreas Crivellin of CERN shows that a class of new unknown particles that could account for the muon anomaly, known as leptoquarks, also affects the transformation, or “decay”, of the Higgs boson into muons.
Leptoquarks are hypothetical particles that connect quarks and leptons, the two types of particles that make up matter at the most fundamental level. They are a popular explanation for the muon anomaly and other anomalies seen in certain decays of particles called B mesons.
In their new study, Crivellin and his colleagues explored how two kinds of leptoquarks that could explain the muon anomaly would affect the rare decay of the Higgs boson into muons, of which the ATLAS and CMS experiments recently obtained the first indications.
They found that one of the two kinds of leptoquarks increases the rate at which this Higgs decay takes place, while the other one decreases it.
“The current measurements of the Higgs decay to muons are not sufficient to see this increase or decrease, and the muon anomaly has yet to be confirmed,” says Crivellin. “But if future measurements, at the LHC or future colliders, display such a change, and the muon anomaly is confirmed, it will be possible to pick out which of the two kinds of leptoquarks would be more likely to explain the muon anomaly.”
Note:
CERN, the European Organization for Nuclear Research, is one of the world’s largest and most respected centres for scientific research. Its business is fundamental physics, finding out what the Universe is made of and how it works. At CERN, the world’s largest and most complex scientific instruments are used to study the basic constituents of matter — the fundamental particles. By studying what happens when these particles collide, physicists learn about the laws of Nature.
The instruments used at CERN are particle accelerators and detectors. Accelerators boost beams of particles to high energies before they are made to collide with each other or with stationary targets. Detectors observe and record the results of these collisions.
Founded in 1954, the CERN Laboratory sits astride the Franco–Swiss border near Geneva. It was one of Europe’s first joint ventures and now has 23 Member States.
Related article:
ALICE finds that charm hadronisation differs at the LHC
https://orbiterchspacenews.blogspot.com/2021/06/alice-finds-that-charm-hadronisation.html
Related links:
Strengthened by measurements made at Fermilab in the US: https://news.fnal.gov/2021/04/first-results-from-fermilabs-muon-g-2-experiment-strengthen-evidence-of-new-physics/
Physical Review Letters: https://arxiv.org/abs/2008.02643
Standard Model: https://home.cern/science/physics/standard-model
Higgs boson: https://en.wikipedia.org/wiki/Higgs_boson
CMS experiment: https://home.cern/science/experiments/cms
ATLAS experiment: https://home.cern/science/experiments/atlas
Large Hadron Collider (LHC): https://home.cern/science/accelerators/large-hadron-collider
For more information about European Organization for Nuclear Research (CERN), Visit: https://home.cern/
Image (mentioned), Text, Credits: CERN/By Ana Lopes.
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