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T: Fachverband Teilchenphysik
T 105: Flavor IX
T 105.2: Talk
Thursday, March 23, 2023, 16:05–16:20, HSZ/0401
Search for the lepton flavour violating decay τ+→µ+µ−µ+ with the LHCb experiment — •Giulia Frau1, Flavio Archilli2, and Rowina Caspary1 — 1Physikalisches Institut, Heidelberg University,Germany — 2Università di Roma Tor Vergata, Rome, Italy
As lepton flavour violating, the τ+→µ+µ−µ+ decay is forbidden in the Standard Model (SM) at the tree level. The combination of the SM with neutrino oscillations predicts for this decay a branching ratio (BR) of the order of 10−55, well below our current and foreseen experimental sensitivity. Improving the existing limit on the BR of this decay would allow to constrain theories of Physics beyond the SM. Especially lepto-quark models which are often discussed in the context of the recently observed flavor anomalies predict τ→µµµ BR which are testable with the current available data set. In this talk, I will show the different steps of the analysis performed to evaluate the limit on the BR using data collected by LHCb during Run 2, by focusing on the improvements introduced with respect to the previous LHCb analysis, which was conducted by analyzing Run 1 data. With the increasing luminosity and cross section of Run 2 and a more sophisticated analysis, we expect the LHCb limit to improve by at least a factor of two, making our results competitive with the current best experimental limit.