Semileptonic D->pi/K and B->pi/D decays in 2+1 flavor lattice QCD

TL;DR

This paper computes form factors for semileptonic D and B meson decays using 2+1 flavor lattice QCD, reducing systematic errors and extracting CKM matrix elements, including a novel unitarity check.

Contribution

It provides improved lattice QCD results for semileptonic decay form factors and extracts CKM matrix elements, including the first unitarity test solely based on lattice QCD data.

Findings

Agreement of D decay results with experiments

Preliminary B decay results obtained

First CKM unitarity check using only lattice QCD

Abstract

We present results for form factors of semileptonic decays of $D$ and $B$ mesons in 2+1 flavor lattice QCD using the MILC gauge configurations. With an improved staggered action for light quarks, we successfully reduce the systematic error from the chiral extrapolation. The results for $D$ decays are in agreement with experimental ones. The results for B decays are preliminary. Combining our results with experimental branching ratios, we then obtain the CKM matrix elements $|V_{cd}|$, $|V_{cs}|$, $|V_{cb}|$ and $|V_{ub}|$. We also check CKM unitarity, for the first time, using only lattice QCD as the theoretical input.