2019/01/25 by Li, Ruizi, Bazavov, A., Bernard, C. W. +17
#FOS: Physical sciences #High Energy Physics - Lattice (hep-lat) #High Energy Physics - Phenomenology (hep-ph)
paper · doi:10.48550/arxiv.1901.08989
We discuss preliminary results for the vector form factors f+^\π,K\ at zero-momentum transfer for the decays D→πℓν and D→ K ℓν using MILC's Nf = 2+1+1 HISQ ensembles at four lattice spacings, a ≈ 0.042, 0.06, 0.09, and 0.12 fm, and various HISQ quark masses down to the (degenerate) physical light quark mass. We use the kinematic constraint f+(q2)= f0(q2) at q2 = 0 to determine the vector form factor from our study of the scalar current, which yields f0(0). Results are extrapolated to the continuum physical point in the framework of hard pion/kaon SU(3) heavy-meson-staggered χPT and Symanzik effective theory. Our calculation improves upon the precision achieved in existing lattice-QCD calculations of the vector form factors at q2=0. We show the values of the CKM matrix elements |Vcs| and |Vcd| that we would obtain using our preliminary results for the form factors together with recent experimental results, and discuss the implications of these values for the second row CKM unitarity.