ISSN - 15507998, Physical Review D - Particles, Fields, Gravitation and Cosmology, 2013, vol. 87, p. -
Precise measurement of the branching fractions for Bs0→Ds(*) +Ds(*)-and first measurement of the Ds*+Ds*-polarization using e+e- collisions
We have made a precise measurement of the absolute branching fractions of Bs0→Ds(*)+Ds(*)- decays using 121.4 fb-1 of data recorded by the Belle experiment running at the Υ(5S) resonance. The results are B(Bs0→Ds+Ds-)=(0.58-0.09+0.11±0.13)%, B(Bs0→Ds*±Dsâ̂)=(1.76-0.22+0.23±0.40)%, and B(Bs0→Ds*+Ds*-)=(1.98-0.31-0.50+0.33+0.52)%; the sum is B(Bs0→Ds(*)+Ds(*)-)=(4.32-0.39-1.03+0.42+1.04)%. Assuming Bs0→Ds(*)+Ds(*)- saturates decays to CP-even final states, the branching fraction constrains the ratio ΔΓs/ cosâ¡12, where ΔΓs is the difference in widths between the two Bs-B̄s mass eigenstates, and 12 is the CP-violating phase in Bs-B ̄s mixing. We also measure for the first time the longitudinal polarization fraction of Bs0→Ds*+Ds*-; the result is 0.06-0.17+0.18±0.03. © 2013 American Physical Society.