Resolving a discrete ambiguity in the CKM angle beta through B-u,B-d - J/psi K* and B-s - J/psi phi decays

摘要

It is well known that sin(2 beta), where beta is one of the angles of the unitarity triangle of the CKM matrix, can be determined in a theoretically clean way by measuring mixing-induced CP violation in the decay B-d --> J/psi K-s. Another clean extraction of this CKM angle is provided by the time-dependent angular distribution for the decay products of B-d --> J/psi (--> l(+)l(-)) K * (0)(--> pi(0)K(s)), where we have more observables at our disposal than in the case of B-d --> J/psi K-s, so that in addition to sin(2 beta) also cos(2 beta) can be probed in a direct way. Unfortunately a sign ambiguity remains in cos(2 beta). If it could be resolved, a discrete ambiguity in the extraction of the CKM angle beta could be resolved as well, which would allow a more incisive test of the CKM model of CP violation. This note shows that detailed time-dependent studies of B-u,B-d,--> J/psi K * and B-s --> J/psi phi decay processes can determine the sign of cos(2 beta), thereby removing the corresponding ambiguity in the extraction of the CKM angle beta. (C) 1998 Elsevier Science B.V. All rights reserved. References: 19