Measurement ofCPviolation inB0→D*−π+andB0→D−π+decays

Abstract

We report measurements of time-dependent decay rates for B{sup 0}{yields}D{sup (*)-}{pi}{sup +} decays and extraction of CP violation parameters that depend on {phi}{sub 3}. Using fully reconstructed D{sup (*)}{pi} events and partially reconstructed D*{pi} events from a data sample that contains 386x10{sup 6} BB pairs that was collected near the {upsilon}(4S) resonance, with the Belle detector at the KEKB asymmetric energy e{sup +}e{sup -} collider, we obtain the CP violation parameters S{sup +}(D{sup (*)}{pi}) and S{sup -}(D{sup (*)}{pi}). We obtain S{sup +}(D*{pi})=0.049{+-}0.020(stat){+-}0.011(sys), S{sup -}(D*{pi})=0.031{+-}0.019(stat){+-}0.011(sys), and S{sup +}(D{pi})=0.031{+-}0.030(stat){+-}0.012(sys), S{sup -}(D{pi})=0.068{+-}0.029(stat){+-}0.012(sys). These results are an indication of CP violation in B{sup 0}{yields}D*{sup -}{pi}{sup +} and B{sup 0}{yields}D{sup -}{pi}{sup +} decays at the 2.5{sigma} and 2.2{sigma} levels, respectively. If we use the values of R{sub D{sup (*}}{pi}} that are derived using assumptions of factorization and SU(3) symmetry, branching fraction measurements for the B{yields}D{sub s}{sup (*)}{pi} modes, and lattice QCD calculations, we can restrict the allowed region of |sin(2{phi}{sub 1}+{phi}{sub 3})| to be above 0.44 and 0.52 at 68% confidence level from the D*{pi} and D{pi} modes, respectively.