A Study of the Decays D^0 --> pi^- e^+ nu_e, D^0 --> K^- e^+ nu_e, D^+ --> pi^0 e^+ nu_e, and D^+ --> barK^0 e^+ nu_e

TL;DR

This paper measures branching fractions and form factors for specific D meson semileptonic decays using a large data sample, and extracts CKM matrix elements |Vcd| and |Vcs| by combining experimental results with lattice calculations.

Contribution

It provides new precise measurements of branching fractions and form factors for D meson semileptonic decays, and determines CKM matrix elements using combined experimental and lattice data.

Findings

Branching fractions for four D meson decays are precisely measured.

Form factors are studied through q^2-dependent partial branching fractions.

CKM matrix elements |Vcd| and |Vcs| are extracted with improved accuracy.

Abstract

Using 1.8 million DDbar pairs and a neutrino reconstruction technique, we have studied the decays D^0 -> K^- e^+ nu_e, D^0 -> pi^- e^+ nu_e, D^+ -> Kbar^0 e^+ nu_e, and D^+ -> pi^0 e^+ nu_e. We find B(D^0 -> pi^- e^+ nu_e) = 0.299(11)(9)%, B(D^+ -> pi^0 e^+ nu_e) = 0.373(22)(13)%, B(D^0 -> K^- e^+ nu_e) = 3.56(3)(9)%, and B(D^+ -> Kbar^0 e^+ nu_e) = 8.53(13)(23)%. In addition, form factors are studied through fits to the partial branching fractions obtained in five q^2 ranges. By combining our results with recent unquenched lattice calculations, we obtain |Vcd| = 0.217(9)(4)(23) and |Vcs| = 1.015(10)(11)(106).