Search for direct CP violation in D0 -> h- h+ modes using semileptonic B decays

TL;DR

This paper searches for direct CP violation in D0 decays to K- K+ and pi- pi+ using semileptonic B decays, finding no significant evidence for CP violation within the measured uncertainties.

Contribution

It introduces a novel method of using semileptonic B decays to tag D0 mesons for CP violation studies in charm decays.

Findings

Measured difference in CP asymmetries: (0.49 +- 0.30 +- 0.14)%

Result does not confirm previous evidence of CP violation in charm sector

Analysis uses 1.0 fb^-1 of data collected at 7 TeV by LHCb

Abstract

A search for direct CP violation in D0 -> h- h+ (where h=K or pi) is presented using data corresponding to an integrated luminosity of 1.0 fb^-1 collected in 2011 by LHCb in pp collisions at a centre-of-mass energy of 7 TeV. The analysis uses D0 mesons produced in inclusive semileptonic b-hadron decays to the D0 mu X final state, where the charge of the accompanying muon is used to tag the flavour of the D0 meson. The difference in the CP-violating asymmetries between the two decay channels is measured to be Delta A_CP = A_CP(K-K+) - A_CP(pi-pi+) = (0.49 +- 0.30 (stat) +- 0.14 (syst)) % . This result does not confirm the evidence for direct CP violation in the charm sector reported in other analyses.