Progress on charm semileptonic form factors from 2+1 flavor lattice QCD

TL;DR

This paper reports progress in lattice QCD calculations of charm semileptonic form factors, aiming to improve the precision of CKM matrix element determinations and validate bottom decay form factors.

Contribution

It introduces improved methods for calculating charm form factors using 2+1 flavor lattice QCD with Fermilab quarks and details progress towards reducing theoretical uncertainties.

Findings

Reduced uncertainties in |V(cs)| and |V(cd)| from 10.5% and 11% to about 7%.

Enhanced calculation techniques for charm semileptonic form factors.

Progress towards validating bottom decay form factor calculations.

Abstract

Lattice calculations of the form factors for the charm semileptonic decays D to K l nu and D to pi l nu provide inputs to direct determinations of the CKM matrix elements |V(cs)| and |V(cd)| and can be designed to validate calculations of the form factors for the bottom semileptonic decays B to pi l nu and B to K l l-bar. We are using Fermilab charm (bottom) quarks and asqtad staggered light quarks on the 2+1 flavor asqtad MILC ensembles to calculate the charm (bottom) form factors. We outline improvements to the previous calculation of the charm form factors and detail our progress. We expect our current round of data production to allow us to reduce the theoretical uncertainties in |V(cs)| and |V(cd)| from 10.5% and 11%, respectively, to about 7%.