Constraining New Physics with the CDF Measurement of CP Violation in $B \to \psi K_S$

TL;DR

This paper analyzes how recent CDF measurements of CP violation in B meson decays constrain possible new physics contributions to B-Bbar mixing, providing bounds on the phase and implications for CP asymmetries.

Contribution

It introduces a new bound on the phase of new physics contributions to B-Bbar mixing based on recent experimental data.

Findings

Derived a bound: sin2θ_d ≳ -0.6 at 1σ

Bound tightens to sin2θ_d ≳ -0.87 at 95% CL

Discussed implications for CP asymmetry in semileptonic B decays

Abstract

Recently, the CDF collaboration has reported a measurement of the CP asymmetry in the $B\to\psi K_S$ decay: $a_{\psi K_S}=0.79^{+0.41}_{-0.44}$. We analyze the constraints that follow from this measurement on the size and the phase of contributions from new physics to $B-\barB$ mixing. Defining the relative phase between the full $M_{12}$ amplitude and the Standard Model contribution to be $2\theta_d$, we find a new bound: $\sin2\theta_d\gsim-0.6 (-0.87)$ at one sigma (95% CL). Further implications for the CP asymmetry in semileptonic B decays are discussed.