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• Physics 16, s91
New information from observations of B-meson decay once more vindicate the usual mannequin of particle physics.
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Newly launched information taken utilizing the Belle II experiment at KEK in Japan and the LHCb experiment at CERN in Switzerland present no signal of a potential anomaly that researchers suppose may present a path to overturning the usual mannequin of particle physics [1–3].
In response to the usual mannequin, electrons, muons, and tau leptons ought to all behave identically when subjected to any of the basic forces of nature. Over a decade in the past, researchers started questioning the validity of this assumption—often called lepton universality—after they noticed high-energy particle decays that deviated from standard-model predictions. Particularly, the observations involved the decay of B mesons into varied leptons, with the experiments hinting that a number of extra tau leptons have been being produced than anticipated. Pleasure constructed amongst particle physicists, who hoped they have been on the cusp of discovering the long-sought standard-model violation that will uncover new bodily phenomena. Hopes rose additional as different experiments discovered hints of lepton-universality violations within the decay of B mesons into electrons and muons, however the alerts remained too small to rule out experimental artifacts.
Then on the finish of final yr, hopes started to fade when the LHCb Collaboration launched information for B-meson decays involving electrons and muons that precisely matched standard-model predictions [2, 3]. Now information from the Belle II Collaboration for a distinct B-meson decay involving electrons and muons dim these hopes additional [1]. The research present a few of the most stringent lepton-universality exams but in such decays. However researchers haven’t but given up on leptons unlocking a door to new physics, says Belle II Collaboration member Henrik Junkerkalefeld of the College of Bonn, Germany. He notes that, though the outcomes present new constraints on the choices for undiscovered physics, they don’t utterly rule all of them out.
–Katherine Wright
Katherine Wright is the Deputy Editor of Physics Journal.
References
- L. Aggarwal et al. (Belle II Collaboration), “Take a look at of light-lepton universality within the charges of inclusive semileptonic B-meson decays at Belle II,” Phys. Rev. Lett. 131, 051804 (2023).
- R. Aaij et al. (LHCb Collaboration), “Take a look at of lepton universality in decays,” Phys. Rev. Lett. 131, 051803 (2023).
- R. Aaij et al. (LHCb Collaboration), “Measurement of lepton universality parameters in and decays,” Phys. Rev. D 108, 032002 (2023).
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