Charm semileptonic decays and |V_{cs(d)}| from heavy clover quarks and 2+1 flavor asqtad staggered ensembles

TL;DR

This paper combines experimental data and lattice QCD calculations to determine CKM matrix elements |V_{cs}| and |V_{cd}| from charm semileptonic decays, using advanced computational techniques on multiple lattice ensembles.

Contribution

It presents a new calculation of form factors for D to K and D to pi decays using Fermilab charm quarks and asqtad staggered ensembles, with a detailed extrapolation to physical quark masses and continuum limit.

Findings

Preliminary form factor shapes agree with experimental data.

Quantitative estimates of |V_{cs}| and |V_{cd}| are obtained.

Error analysis and systematic uncertainties are discussed.

Abstract

By combining experimentally measured partial branching fractions for the semileptonic decays D to K l nu and D to pi l nu with lattice calculations of the form factors f_+^{D to K}(q^2) and f_+^{D to pi}(q^2), one can extract the CKM matrix elements |V_{cs}| and |V_{cd}|. We are calculating the form factors by using Fermilab charm and asqtad staggered light and strange quarks on 2+1 flavor asqtad staggered ensembles generated by the MILC Collaboration. We vary the light valence quark masses from 0.4m_s to 0.05m_s (m_s is the strange sea-quark mass), and the lattice spacings, from about 0.12 fm to about 0.045 fm. We extrapolate to the physical light-quark mass and the continuum limit using heavy-light meson staggered chiral perturbation theory about the SU(2) and SU(3) limits, compare the resulting (preliminary) form factor shapes with experiment, and discuss our errors.