Measurement of CP Asymmetries in the Three-Body Charmless Decay Neutral B Meson Decays to Neutral Kaon(S) Neutral Kaon(S) Neutral Kaon(S)

摘要

In this dissertation, a measurement of CP-violating effects in decays of neutral B mesons is presented. The data sample for this measurement consists of about 272 million (Upsilon)(4S) (yields) B(bar B) decays collected between 1999 and 2004 with the BABAR detector at the PEP-II asymmetric-energy e(sup +)e(sup -) collider, located at the Stanford Linear Accelerator Center. One neutral B meson is fully reconstructed in the CP eigenstate B(sup 0) (yields) K(sub S)(sup 0) K(sub S)(sup 0) K(sub S)(sup 0). The other B meson is determined to be either a B(sup 0) or a (bar B)(sup 0), at the time of its decay, from the properties of its decay products. The proper time (Delta)t elapsed between the decay of the two mesons is determined by reconstructing their decay vertices, and by measuring the distance between them. A novel technique for determining the B vertex of the decay to the CP eigenstate B(sup 0) (yields) K(sub S)(sup 0) K(sub S)(sup 0) K(sub S)(sup 0) has been applied since the tracks in the final state do not originate from the B decay vertex. The time-dependent CP asymmetry amplitudes are determined by the distributions of (Delta)t in events with a reconstructed B meson in the CP eigenstate. The detector resolution and the b flavor tagging parameters are constrained by the (Delta)t distributions of events with a fully reconstructed flavor eigenstate. Because of the special topology of this decay, the detector resolution on (Delta)t must be checked for consistency with decays with tracks which originate from the B decay. From a maximum likelihood fit to the (Delta)t distributions of all selected events, the value of the CP violating asymmetries are measured to be S(sub 3K(sub S)(sup 0)) = -0.71(sub -0.32)(sup +0.38) (+-) 0.04 and C(sub 3K(sub S)(sup 0)) = -0.34(sub -0.25)(sup +0.28) (+-) 0.05. Fixing C = 0 we measure the time-dependent CP asymmetry amplitude sin 2(beta) = -S(sub 3K(sub S)(sup 0)) = 0.79(sub -0.36)(sup +0.39) (+-) 0.04. The value of sin 2(beta) is in agreement with Standard Model predictions.