Sensitivity study of the charged lepton flavour violating mode B+ to K+ tau+ e- at Belle II.

Sumitted to PubDB: 2022-03-30

Category: Master Thesis, Visibility: Public

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Authors	Steven Robertson, Trevor Shillington
Date	2021-01-01
Belle II Number	BELLE2-MTHESIS-2022-006
Abstract	Belle II is a B factory experiment for the SuperKEKB electron-positron collider located at the KEK laboratory in Tsukuba, Japan, operating near the Upsilon(4S) resonance, at an energy of 10.58 GeV. In this thesis we outline our analysis searching for the ultra-rare charged lepton flavour violating (CLFV) decay B+ to K+ tau+ e-. This decay is far below experimental sensitivity if we assume the decay rate predicted by the Standard Model. However, many extensions of the Standard Model, specifically those attempting to incorporate the recent "B physics anomalies", predict much larger branching fractions which are potentially within the reach of experiments. Discovery of this mode would be explicit evidence of physics beyond the Standard Model, while a null result would allow us to place strict constraints on these models. A previous search was done at BaBar in 2012, setting a 90% CL upper limit branching fraction of a few x 10^-5. The much larger integrated luminosity dataset at Belle II can be exploited to improve the analysis sensitivity by at least an order of magnitude. A sensitivity study is performed based on a dataset of 200 fb^-1, and a data/MC comparison is done.
Conference	Montreal, QC