Measurements of time-dependent $C P$ violation in $B^{0} \to ψ (2 S) K_{S}^{0}$ decays

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13 May 2008

journal article
research article
Published by American Physical Society (APS) in Physical Review D

Vol. 77 (9) , 091103
https://doi.org/10.1103/physrevd.77.091103

Abstract

We report improved measurements of time-dependent

C P

violation parameters for

B^{0} ({\bar{B}}^{0}) \to ψ (2 S) K_{S}^{0}

. This analysis is based on a data sample of

657 \times 10^{6}

B \bar{B}

pairs collected at the

Υ (4 S)

resonance with the Belle detector at the KEKB energy-asymmetric

e^{+} e^{-}

collider. We fully reconstruct one neutral

B

meson in the

ψ (2 S) K_{S}^{0}

C P

-eigenstate decay channel, and the flavor of the accompanying

B

meson is identified to be either

B^{0}

or

{\bar{B}}^{0}

from its decay products.

C P

violation parameters are obtained from the asymmetries in the distributions of the proper-time intervals between the two

B

decays:

S_{ψ (2 S) K_{S}^{0}} = + 0.72 \pm 0.09 (stat) \pm 0.03 (syst)

,

A_{ψ (2 S) K_{S}^{0}} = + 0.04 \pm 0.07 (stat) \pm 0.05 (syst)

. These results are in agreement with results from measurements of

B^{0} \to J / ψ K^{0}

.

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