ISSN - 15507998, Physical Review D - Particles, Fields, Gravitation and Cosmology, 2002, vol. 66, p. -
Improved measurement of mixing-induced CP violation in the neutral B meson system
We present an improved measurement of the standard model CP violation parameter sin 2φ1 (also known as sin 2β) based on a sample of 85× 106 BB̄ pairs collected at the Y (4S) resonance with the Belle detector at the KEKB asymmetric-energy e+e- collider. One neutral B meson is reconstructed in J/ψKS 0, ψ(2S)KS 0, χc1K S 0, ηcKS 0, J/ψ/K*0, or J/ψ/KL 0 CP-eigenstate decay channel and the flavor of the accompanying B meson is identified from its decay products. From the asymmetry in the distribution of the time interval between the two B meson decay points, we obtain sin 2φ1=0. 719±0.074(stat)±0.035(syst). © 2002 The American Physical Society.