Evidence for the decay B_s^0 --> D_s^(*)D_s^(*) and a measurement of Delta_Gamma_s^CP/Gamma_s

TL;DR

This paper reports evidence for the decay B_s^0 --> D_s^(*)D_s^(*) and measures the width difference Delta_Gamma_s^CP/Gamma_s, providing insights into B_s^0 meson properties and CP violation.

Contribution

First measurement of B_s^0 --> D_s^(*)D_s^(*) decay with evidence and a new estimate of the width difference Delta_Gamma_s^CP/Gamma_s.

Findings

Branching ratio Br(B_s^0 --> D_s^(*)D_s^(*)) = 0.035 +/- 0.010 (stat) +/- 0.011 (syst)

Evidence with 3.2 sigma significance for the decay

Width difference Delta_Gamma_s^CP/Gamma_s = 0.072 +/- 0.021 (stat) +/- 0.022 (syst)

Abstract

We search for the semi-inclusive process B_s^0 --> D_s^(*)D_s^(*) using 2.8 fb^-1 of ppbar collisions at s^(1/2) = 1.96 TeV recorded by the D0 detector operating at the Fermilab Tevatron Collider. We observe 26.6 +/- 8.4 signal events with a significance above background of 3.2 standard deviations yielding a branching ratio of Br(B_s^0 --> D_s^(*)D_s^(*)) = 0.035 +/- 0.010(stat) +/- 0.011(syst). Under certain theoretical assumptions, these double-charm final states saturate CP-even eigenstates in the B_s^0 decays resulting in a width difference of Delta_Gamma_s^CP/Gamma_s = 0.072 +/- 0.021(stat) +/- 0.022(syst).