Precise measurement of the CP violation parameter sin2phi_1 in B0-->(c\bar c)K0 decays

TL;DR

This paper reports a highly precise measurement of the CP violation parameter sin2phi_1 in B0 decays, using a large data sample from the Belle experiment, confirming the Standard Model predictions with improved accuracy.

Contribution

It provides the most precise measurement of sin2phi_1 and A_f in B0 decays to date, utilizing a large dataset and refined analysis techniques.

Findings

sin2phi_1=0.667±0.023(stat)±0.012(syst)

A_f=0.006±0.016(stat)±0.012(syst)

Results are consistent with Standard Model expectations.

Abstract

We present a precise measurement of the CP violation parameter sin2phi_1 and the direct CP violation parameter A_f using the final data sample of 772x10^6 B\bar B pairs collected at the Upsilon(4S) resonance with the Belle detector at the KEKB asymmetric-energy e+e- collider. One neutral B meson is reconstructed in a J/psi K0S, psi(2S) K0S, chi_c1 K0S or J/psi K0L CP-eigenstate and its flavor is identified from the decay products of the accompanying B meson. From the distribution of proper time intervals between the two B decays, we obtain the following CP violation parameters: sin2phi_1=0.667+-0.023(stat)+-0.012(syst) and A_f=0.006+-0.016(stat)+-0.012(syst).