Search for CP violation in [Tau] decays at BABAR




Choi, Hervé Hiu Fai

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According to the Big Bang Theory, matter and antimatter were produced in equal amounts at the beginning. Over time the antimatter disappeared, leaving galactic struc- tures composed only of matter. Therefore, there is some process in nature that proceeds at different rates for matter and antimatter due to the violation of the CP symmetry. CP violation has been observed in strange and bottom quark meson decays. However, a direct CP violation is predicted in the τ lepton sector. Specifically, the charge asymmetry due to CP violation in the decay τ − → π−K0S (≥ 0π0) ντ is predicted to be (+0.33 ± 0.01)%. In this work the charge asymmetry of the decay τ − → π−K0S (≥ 0π0) ντ is measured using a dataset of 437 million τ lepton pairs collected by the BABAR experiment at the SLAC Na- tional Accelerator Laboratory. The charge asymmetry induced by CP violation is found to be A = (−0.45 ± 0.24 ± 0.11) %, consistent with prediction.



Particle physics, CP violation, BABAR, High energy physics