Evidence for decay $B_s^0 o D_s^(*)D_s^(*)$ and a measurement of $DeltaGamma_s^CP/Gamma_s$

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 _s16/- 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 _s16/- 0.010(stat) _s16/- 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 _s16/- 0.021(stat) _s16/- 0.022(syst).