Improving bounds on γ in B±→DK± and B±,0→DXs±,0

Michael Gronau

doi:10.1016/s0370-2693(03)00192-8

Abstract

In view of recent experimental progress in rate and CP asymmetry measurements in B±→DK±, we reconsider information on the weak phase γ which can be obtained from these processes. Model-independent inequalities are proven for sin2γ in terms of two ratios of partial rates for B±,0→DXs±,0, where Xs is any multiparticle charmless state carrying strangeness ±1. Good prospects are shown to exist for using these inequalities and CP asymmetry measurements in two body and multibody decays in order to improve present bounds on γ.

Highlights

The observation of CP violation in decays of B mesons to J/ψ and neutral kaons [1] is in good agreement with the prediction of the the Standard Model, in which CP violation originates in a single phase γ ≡ ArgVu∗b of the Cabibbo-Kobayashi-Maskawa (CKM) matrix
Further measurements of CP asymmetries in other B decay processes are needed in order to establish the CKM hypothesis for CP violation on a firm ground, or to observe deviations from this simple picture
One of the very early proposals for a clean measurement of γ is based on decays of the type B± → DXs± [3], where Xs± stands for a charged kaon or any few particle state with the same flavor quantum numbers as a charged kaon, e.g. Xs = K, K∗, Kπ, K∗π

Summary

Introduction

The observation of CP violation in decays of B mesons to J/ψ and neutral kaons [1] is in good agreement with the prediction of the the Standard Model, in which CP violation originates in a single phase γ ≡ ArgVu∗b of the Cabibbo-Kobayashi-Maskawa (CKM) matrix. In the absence of color-suppression in most multibody decays, which implies larger values of corresponding r parameters in these processes, these bounds are likely to provide stronger constraints on γ than in the case of two body decays. A corresponding strong phase difference between isospin amplitudes in B → Dπ decays was measured recently [19] in the range 16◦ − 38◦.

Results

Conclusion