Direct observation of time.reversal violation in B mesons at BABAR

3rd Symposium on Prospects in the Physics of Discrete Symmetries

Villanueva-Pérez, Pablo^1,2

IFIC, Universitat de València-CSIC, E-46071, Paterna (Valencia), Spain^1

Department of Theoretical Physics, Universitat de València, E-46100 Burjassot Valencia, Spain^2

关键词: B factory;    BaBar detector;    CP violations;    Direct observations;    Final state;    Time evolutions;    Time reversal;    Time-differences;   

Others  :  https://iopscience.iop.org/article/10.1088/1742-6596/447/1/012024/pdf
DOI  :  10.1088/1742-6596/447/1/012024

来源: IOP

【 摘 要 】

Although CP violation in the B meson system has been well established by the B factories, there has been no direct observation of time-reversal violation. The decays of entangled neutral B mesons into definite flavour states (B0or0), and J/ψK0L or cK0s final states (referred to as B+ or B-), allow comparisons between the probabilities of four pairs of T-conjugated transitions, for example,0→ B- and B- →0, as a function of the time difference between the two B decays. Using 468 million B pairs produced in Upsilon(4S) decays collected by the BABAR detector at SLAC, T-violating parameters in the time evolution of neutral B mesons have been measured, yielding ΔS+T = -1.37 ± 0.14 (stat.) ± 0.06 (syst.) and ΔS-T 1.17 ± 0.18 (stat.) ± 0.11 (syst.) [1]. These non-zero results represent the first direct observation of T violation through the exchange of initial and final states in transitions that can only be connected by a T-symmetry transformation.