R. Sugar

Semileptonic D→π/K and B→π/D decays in 2+1 flavor lattice QCD

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 c d | , | V c s | , | V c b | and | v u b | . We also check CKM unitarity, for the first time, using only lattice QCD as the theoretical input.

B→Kl+l−decay form factors from three-flavor lattice QCD

We compute the form factors for the B → Kl+l- semileptonic decay process in lattice QCD using gauge-field ensembles with 2+1 flavors of sea quark, generated by the MILC Collaboration. The ensembles span lattice spacings from 0.12 to 0.045 fm and have multiple sea-quark masses to help control the chiral extrapolation. The asqtad improved staggered action is used for the light valence and sea quarks, and the clover action with the Fermilab interpretation is used for the heavy b quark. We present results for the form factors f+(q2), f0(q2), and fT(q2), where q2 is the momentum transfer, together with a comprehensive examination of systematic errors. Lattice QCD determines the form factors for a limited range of q2, and we use the model-independent z expansion to cover the whole kinematically allowed range. We present our final form-factor results as coefficients of the z expansion and the correlations between them, where the errors on the coefficients include statistical and all systematic uncertainties. Lastly, we use this complete description of the form factors to test QCD predictions of the form factors at high and low q2.

Kaon semileptonic form factors with Nf = 2+1+1 HISQ fermions and physical light quark masses

a CAFPE and Departamento de Física Teórica y del Cosmos, Universidad de Granada, ‖Granada, Spain bPhysics Department, Brookhaven National Laboratory,∗∗Upton, NY, USA cDepartment of Physics, Washington University, St. Louis, MO, USA dDepartment of Physics, The Ohio State University, Columbus, Ohio, USA ePhysics Department, University of Utah, Salt Lake City, UT, USA f Physics Department, University of Illinois, Urbana, IL, USA gLiberal Arts Department, School of the Art Institute of Chicago, Chicago, Illinois, USA hDepartment of Physics, Indiana University, Bloomington, IN, USA iAmerican Physical Society, One Research Road, Ridge, NY, USA jDepartment of Physics, University of Arizona, Tucson, AZ, USA kFermi National Accelerator Laboratory,††Batavia, IL, USA lSUPA, School of Physics & Astronomy, University of Glasgow, Glasgow, UK mDepartment of Physics, University of California, Santa Barbara, USA