Measurements of branching fraction ratios and CP-asymmetries in suppressed B^- -> D(-> K^+ pi^-)K^- and B^- -> D(-> K^+ pi^-)pi^- decays

TL;DR

This paper reports the first measurement of suppressed B^- decays involving D mesons in hadron collisions, providing insights into CP violation and CKM phase gamma using data from the CDF II detector.

Contribution

It presents the first reconstruction and measurement of suppressed B^- decay modes in hadron collisions, including branching fraction ratios and CP asymmetries, using Tevatron data.

Findings

Significant signal for B^- -> D(-> K^+ pi^-)K^- decay with 3.2 sigma significance.

Measured ratios of suppressed to favored branching fractions for B^- decays.

Observed direct CP asymmetry in the suppressed decay mode.

Abstract

We report the first reconstruction in hadron collisions of the suppressed decays B^- -> D(-> K^+ pi^-)K^- and B^- -> D(-> K^+ pi^-)pi^-, sensitive to the CKM phase gamma, using data from 7 fb^-1 of integrated luminosity collected by the CDF II detector at the Tevatron collider. We reconstruct a signal for the B^- -> D(-> K^+ pi^-)K^- suppressed mode with a significance of 3.2 standard deviations, and measure the ratios of the suppressed to favored branching fractions R(K) = [22.0 \pm 8.6(stat)\pm 2.6(syst)]\times 10^-3, R^+(K) = [42.6\pm 13.7(stat)\pm 2.8(syst)]\times 10^-3, R^-(K)= [3.8\pm 10.3(stat)\pm 2.7(syst]\times 10^-3, as well as the direct CP-violating asymmetry A(K) = -0.82\pm 0.44(stat)\pm 0.09(syst) of this mode. Corresponding quantities for B^- -> D(-> K^+ pi^-)pi^- decay are also reported.