Analysis of D+ to K- pi+ e+ nu_e and D+ to K- pi+ mu+ nu_mu Semileptonic Decays

TL;DR

This paper presents precise measurements of form factors and branching fractions for D+ semileptonic decays into K- pi+ e+ nu_e and mu+ nu_mu, testing theoretical models and exploring non-resonant contributions.

Contribution

It provides the first non-parametric measurement of the mass-suppressed form factor and tests spectroscopic pole dominance without relying on prior assumptions.

Findings

Branching fractions consistent with world averages.

Helicity form factors align with spectroscopic pole dominance.

First non-parametric measurement of mass-suppressed form factor.

Abstract

Using a large sample (~11800 events) of D^+ into K^- pi^+ e^+ nu_e and D^+ into K^- pi^+ mu^+ nu_mu decays collected by the CLEO-c detector running at the psi(3770), we measure the helicity basis form factors free from the assumptions of spectroscopic pole dominance and provide new, accurate measurements of the absolute branching fractions for D^+ into K^- pi^+ e^+ nu_e and D^+ into K^- pi^+ mu^+ nu_mu decays. We find branching fractions which are consistent with previous world averages. Our measured helicity basis form factors are consistent with the spectroscopic pole dominance predictions for the three main helicity basis form factors describing D^+ into anti-K*0 ell^+ nu_mu decay. The ability to analyze D^+ into K^- pi^+ mu^+ nu_mu allows us to make the first non-parametric measurements of the mass-suppressed form factor. Our result is inconsistent with existing Lattice QCD calculations. Finally, we measure the form factor that controls non-resonant s-wave interference with the D^+ into anti-K*0 ell^+ nu_mu amplitude and search for evidence of possible additional non-resonant d-wave or f-wave interference with the anti-K*0.