Measurement of D0 -> pilnu (Klnu) Form Factors and Absolute Branching Fractions

TL;DR

This study precisely measures the absolute branching fractions and form factors for D0 decays to K-l+nu and pi-l+nu using Belle data, providing key parameters for understanding charm semileptonic decays.

Contribution

It presents the first high-precision measurements of D0 semileptonic decay branching fractions and form factors using a novel reconstruction method with excellent neutrino momentum resolution.

Findings

Branching fraction for D0 -> K-l+nu: 3.45%

Branching fraction for D0 -> pi-l+nu: 0.255%

Form factors at zero momentum transfer: f+^K(0)=0.695, f+^pi(0)=0.624

Abstract

Using a 282 1/fb data sample collected by the Belle experiment at the KEKB e+e- collider, we study D0 decays to K-l+nu and pi-l+nu final states. The D0 flavor and momentum are tagged through a full reconstruction of the recoiling charm meson and additional mesons from fragmentation. The reconstruction method provides very good resolution in neutrino momentum and in q^2 = (p_l+p_nu)^2. Normalizing to the total number of D0 tags, we measure the absolute branching fractions to be B(D0 -> Klnu) =(3.45 +- 0.07stat +- 0.20syst)% and B(D0 -> pilnu) = (0.255 +- 0.019stat +- 0.016syst)% and the semi-leptonic form factors (within the modified pole model) f+^K(0) = 0.695 +- 0.007stat +- 0.022syst and f+^pi(0) = 0.624 +- 0.020stat +- 0.030syst.