Measurement of indirect CP asymmetries in D[superscript 0] → K[superscript −] K[superscript +] and D[superscript 0] → π[superscript −] π[superscript +] decays using semileptonic B decays

摘要

Time-dependent CP asymmetries in the decay rates of the singly Cabibbo-suppressed decays D[superscript 0] → K[superscript −] K[superscript +] and D[superscript 0] → π[superscript −] π[superscript +] are measured in pp collision data corresponding to an integrated luminosity of 3.0 fb[superscript −1] collected by the LHCb experiment. The D[superscript 0] mesons are produced in semileptonic b-hadron decays, where the charge of the accompanying muon is used to determine the initial state as D[superscript 0] or [bar over D][superscript 0]. The asymmetries in effective lifetimes between D[superscript 0] and [bar over D][superscript 0] decays, which are sensitive to indirect CP violation, are determined to beA[subscript Γ](K[superscript −]K[superscript +]) = (−0.134 ± 0.077[−0.026 over −0.034])%, A[subscript Γ](π[superscript −]π[superscript +]) = (−0.092 ± 0.145[−0.025 over −0.033])%,where the first uncertainties are statistical and the second systematic. This result is in agreement with previous measurements and with the hypothesis of no indirect CP violation in D[superscript 0] decays.