Analysis of the D+→K−π+e+νe decay channel

Abstract

Using 347.5 fb − 1 of data recorded by the BABAR detector at the PEP-II electron-positron collider, 244 × 10 3 signal events for the D + → K − π + e + ν e decay channel are analyzed. This decay mode is dominated by the ¯¯¯¯ K ∗ ( 892 ) 0 contribution. We determine the ¯¯¯¯ K ∗ ( 892 ) 0 parameters: m K ∗ ( 892 ) 0 = ( 895.4 ± 0.2 ± 0.2 ) MeV / c 2 , Γ 0 K ∗ ( 892 ) 0 = ( 46.5 ± 0.3 ± 0.2 ) MeV / c 2 , and the Blatt-Weisskopf parameter r BW = 2.1 ± 0.5 ± 0.5 ( GeV / c ) − 1 , where the first uncertainty comes from statistics and the second from systematic uncertainties. We also measure the parameters defining the corresponding hadronic form factors at q 2 = 0 ( r V = V ( 0 ) A 1 ( 0 ) = 1.463 ± 0.017 ± 0.031 , r 2 = A 2 ( 0 ) A 1 ( 0 ) = 0.801 ± 0.020 ± 0.020 ) and the value of the axial-vector pole mass parametrizing the q 2 variation of A 1 and A 2 : m A = ( 2.63 ± 0.10 ± 0.13 ) GeV / c 2 . The S -wave fraction is equal to ( 5.79 ± 0.16 ± 0.15 ) % . Other signal components correspond to fractions below 1%. Using the D + → K − π + π + channel as a normalization, we measure the D + semileptonic branching fraction: B ( D + → K − π + e + ν e ) = ( 4.00 ± 0.03 ± 0.04 ± 0.09 ) × 10 − 2 , where the third uncertainty comes from external inputs. We then obtain the value of the hadronic form factor A 1 at q 2 = 0 : A 1 ( 0 ) = 0.6200 ± 0.0056 ± 0.0065 ± 0.0071 . Fixing the P -wave parameters, we measure the phase of the S wave for several values of the K π mass. These results confirm those obtained with K π production at small momentum transfer in fixed target experiments.