Analysis of theD+→K−π+e+νedecay 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 + νe decay channel are analyzed. This decay mode is dominated by the K * (892) 0 contribution. We determine the K * (892) 0 parameters:2) MeV/c 2 and the Blatt-Weisskopf parameter rBW = 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 (rV = V (0)A 1 (0) = 1.463±0.017±0.031, r2 = A 2 (0) A 1 (0) = 0.801±0.020±0.020) and the value of the axial-vector pole mass parameterizing the q 2 variation of A1 and A2: mA = (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 + νe) = (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 A1 at q 2 = 0: A1(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 Kπ mass. These results confirm those obtained with Kπ production at small momentum transfer in fixed target experiments.

Study of the decay D0→K¯0π−e+νe

“…The form factors can be expanded into partial waves including S-wave (F 10 ), P-wave (F i1 ) and D-wave (F i2 ), to show their explicit dependences on θK0. Analyses of the decay D þ → K þ π − e þ ν e by using much higher statistics performed by the BABAR [5] and BESIII [6] collaborations do not observe a D-wave component and hence it is not considered in this analysis. Consequently, the form factors can be written as…”

“…where the term A S ðmÞ corresponds to the mass-dependent S-wave amplitude, and the same expression of A S ðmÞ ¼ r S PðmÞe iδ S ðmÞ as in Refs. [5,6] is adopted, in which…”

“…The relative simplicity of theoretical description of the SL decay D →Kπe þ ν e [3] makes it a optimal place to study thē Kπ system, and to further determine the hadronic transition form factors. Measurements ofKπ resonant and nonresonant amplitudes in the decay D þ → K − π þ e þ ν e have been reported by the CLEO [4], BABAR [5] and BESIII [6] collaborations. In these studies a nontrival S-wave component is observed along with the dominant P-wave one.…”

“…A study of the dynamics in the isospin-symmetric mode D 0 →K 0 π − e þ ν e will provide complementary information on theKπ system. Furthermore, the form factors in the D → Ve þ ν e transition, where V refers to a vector meson, have been measured in decays of D þ →K Ã0 e þ ν e [4][5][6], D → ρe þ ν e [7] and D þ → ωe þ ν e [8], while no form factor in D 0 → K Ã ð892Þ − e þ ν e has been studied yet. Therefore, the study of the dynamics in the decay D 0 → K Ã ð892Þ − e þ ν e provides essentially additional information on the family of D → Ve þ ν e decays.…”

B s → K (*)ℓ$ \overline{\nu} $, angular analysis, S-wave contributions and |V ub |

“…Considering the momentum dependence of the K * decay, we have the running width 4) and the Blatt-Weisskopf parameter R = (2.1 ± 0.5 ± 0.5)GeV −1 [73]. In the following, we will suppress the dependence on the q 2 , m Kπ , and the polar angle θ K for simplicity.…”