Measurement of direct CP-asymmetry in the B⁰->K⁺π^- decays in 355 pb^-1.

This webpage collects the links to the CDF public note and the relevant supporting plots of the measurement of direct CP-asymmetry measurement
in self tagging decay B⁰→K⁺π^- .
The result have been blessed at the CDF B-Physics meeting on Thursday March 09, 2006.

Abstract

We present the measurement of the direct CP asymmetry in B⁰→K⁺π^- decays to the new B⁰_(s)→h⁺h'^- sample collected by the Two Track Trigger, and corresponding to about 355 pb^-1 of integrated luminosity. This is an improvement of the measurement performed on the first 180 pb^-1 described here. Besides the larger statistics, and an higher-resolution tracking, the analysis includes a few improvements in the selection of the sample and in the fitting technique. The measured asymmetry is:
.

This result is 1.5σ different from 0 and can be compared with current world best measurements from B-factories
A_CP(B⁰→K⁺π^-)_BaBar=-0.133± 0.030 ± 0.009 (PRL 93,131801(2004)) and
A_CP(B⁰→K⁺π^-)_Belle=-0.113 ± 0.022 ± 0.008 (hep-ex/0507045) and
with the current world world-average A_CP(B⁰→K⁺π^-)=-0.115± 0.018 (HFAG April 2006).
Although the statistical resolution of current CDF result is not yet competitive with the B-factories, we have smaller systematics uncertainty. This is very encouraging in view of the next iteration of the anlysis, in which we expect less than 2.5% statistical uncertainty in the 1 fb^-1 sample already on tape.