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Published November 21, 2012 | Supplemental Material + Published
Journal Article Open

Observation of Time-Reversal Violation in the B^0 Meson System


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 flavor states (B^0 or B^0), and J/ψK_L^0 or cc K_S^0 final states (referred to as B_+ or B_-), allow comparisons between the probabilities of four pairs of T-conjugated transitions, for example, B^0→B_- and B_-→B^0, as a function of the time difference between the two B decays. Using 468×10^6 BB pairs produced in Υ(4S) decays collected by the BABAR detector at SLAC, we measure T-violating parameters in the time evolution of neutral B mesons, yielding ΔS_T^+=-1.37±0.14(stat)±0.06(syst) and ΔS_T^-=1.17±0.18(stat)±0.11(syst). These nonzero 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.

Additional Information

© 2012 American Physical Society. Received 24 July 2012; published 19 November 2012. We are grateful for the excellent luminosity and machine conditions provided by our PEP-II colleagues, and for the substantial dedicated effort from the computing organizations that support BABAR. The collaborating institutions wish to thank SLAC for its support and kind hospitality. This work is supported by DOE and NSF (USA), NSERC (Canada), CEA and CNRS-IN2P3 (France), BMBF and DFG(Germany), INFN (Italy), FOM (The Netherlands), NFR (Norway), MES (Russia), MINECO (Spain), STFC (United Kingdom). Individuals have received support from the Marie Curie EIF (European Union), the A. P. Sloan Foundation (USA) and the Binational Science Foundation (USA-Israel).

Attached Files

Published - PhysRevLett.109.211801.pdf

Supplemental Material - README.TXT

Supplemental Material - epaps.pdf


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August 19, 2023
October 20, 2023