Physicists unveil ground-breaking rare decay process shedding light on the Higgs boson and our universe.
What is a Higgs boson?
The origin of mass in subatomic particles, such as electrons and protons, is attributed to their interaction with the Higgs boson. The strength of this interaction determines the particle's mass, with electrons having a certain mass, protons having more, and neutrons slightly more than protons. The Higgs boson, a force-carrying subatomic particle, can also interact with other Higgs bosons, indicating its greater mass compared to protons or neutrons. It serves as a carrier of the force experienced by particles when moving through the Higgs field, present throughout the universe. Understanding the coupling strength of different particle types with Higgs bosons and the properties of the bosons themselves offers insights into the universe. However, the lack of mass in photons, which do not interact with Higgs bosons, raises questions about how a Higgs boson could decay into a Z boson and a photon. Exploring this question involves delving into the realm of spacetime.
The results of the study
According to quantum field theory, space at the subatomic level is not empty but filled with fleeting virtual particles that leave behind detectable effects. The Large Hadron Collider (LHC) generates a Higgs boson by colliding high-energy protons, resulting in a release of energy that condenses into various particles. Due to its heaviness, the Higgs boson is unstable and undergoes decay into lighter particles. The Standard Model, a theory describing fundamental particles, predicts the probability of specific decay paths. For instance, the theory suggests that the Higgs boson will decay to a Z boson and a photon approximately 0.1% of the time. To observe such decays, a substantial number of Higgs bosons must be produced. Researchers estimate that at least 1,000 Higgs bosons needed to be created to spot a single decay to a Z boson and a photon. Similarly, the Z boson itself is unstable and decays to two muons around 3% of the time. To detect the simultaneous production of muon pairs and a photon, it was estimated that the LHC would have had to produce at least 30,000 Higgs bosons. Therefore, even though the Higgs boson was discovered over a decade ago, it is now that physicists are confirming these specific decay pathways.
The implications
Previously, the ATLAS and CMS detectors had separately observed the decay of a Higgs boson to a Z boson and a photon in 2018 and 2020. However, in their latest breakthrough, the two teams combined their data from 2015 to 2018, significantly enhancing the statistical precision and search capabilities, as stated by CERN. Nevertheless, the statistical significance is still not strong enough for the teams to claim the Higgs boson decayed to a Z boson and a photon with absolute certainty, highlighting the rarity of this decay pathway. The meticulous pursuit of detecting such decays is driven by the predictions of the Standard Model, which suggests that the Higgs boson should follow this path approximately 0.1% of the time, given its mass of 125 billion eV/c². While the Standard Model has successfully predicted numerous phenomena, it falls short in explaining mysteries like dark matter and the unusually heavy mass of the Higgs boson. By rigorously testing these predictions, physicists hope to uncover any deviations and explore new physics theories that could provide answers to these unresolved questions. Discovering a higher rate of decay through this pathway at the LHC could potentially pave the way for ground-breaking scientific advancements.
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