No abstract

The semileptonic process, B −→ π lν, is studied via full QCD lattice simulations. We use unquenched gauge configurations generated by the MILC collaboration. These include the effect of vacuum polarization from three quark flavors: the s quark and two very light flavors (u/d) of variable mass allowing extrapolations to the physical chiral limit. We employ Nonrelativistic QCD to simulate the b quark and a highly improved staggered quark action for the light sea and valence quarks. We calculate the form factors f+(q 2 ) and f0(q 2 ) in the chiral limit for the range 16 GeV 2 ≤ q 2 < q 2 max and obtain q 2 (2006)). Results for the form factor f+(q 2 ) in the chiral limit have changed significantly. The last two sentences in this abstract should now read; "We calculate the form factors f+(q 2 ) and f0(q 2 ) in the chiral limit for the range 16 GeV 2 ≤ q 2 < q 2 max and obtain q 2 max 16GeV 2 [ dΓ/dq 2 ] dq 2 / |V ub | 2 = 2.07(57) ps −1 . Combining this with a preliminary average by the Heavy Flavor Averaging Group (HFAG'05) of recent branching fraction data for exclusive B semileptonic decays from the BaBar, Belle and CLEO collaborations, leads to |V ub | = 3.55(25)(50) × 10 −3 ."

One-loop matching of heavy-light currents is carried out for a highly improved lattice action, including the effects of mixings with dimension 4 O(1/M ) and O(a) operators. We use the NRQCD action for heavy quarks, the Asqtad improved naive action for light quarks, and the Symanzik improved glue action. As part of the matching procedure we also present results for the NRQCD self-energy and for massless Asqtad quark wave function renormalization with improved glue.

No abstract

The semileptonic process, B −→ π lν, is studied via full QCD lattice simulations. We use unquenched gauge configurations generated by the MILC collaboration. These include the effect of vacuum polarization from three quark flavors: the s quark and two very light flavors (u/d) of variable mass allowing extrapolations to the physical chiral limit. We employ Nonrelativistic QCD to simulate the b quark and a highly improved staggered quark action for the light sea and valence quarks. We calculate the form factors f+(q 2 ) and f0(q 2 ) in the chiral limit for the range 16 GeV 2 ≤ q 2 < q 2 max and obtainCombining this with a preliminary average by the Heavy Flavor Averaging Group (HFAG'05) of recent branching fraction data for exclusive B semileptonic decays from the BaBar, Belle and CLEO collaborations, leads to |V ub | = 4.22(30)(51) × 10 −3 . PLEASE NOTE APPENDIX B with an ERRATUM, to appear in Physical Review D, to the published version of this e-print (Phys.Rev.D 73, 074502 (2006)). Results for the form factor f+(q 2 ) in the chiral limit have changed significantly. The last two sentences in this abstract should now read; "We calculate the form factors f+(q 2 ) and f0(q 2 ) in the chiral limit for the range 16 GeV 2 ≤ q 2 < q 2 max and obtainCombining this with a preliminary average by the Heavy Flavor Averaging Group (HFAG'05) of recent branching fraction data for exclusive B semileptonic decays from the BaBar, Belle and CLEO collaborations, leads to |V ub | = 3.55(25)(50) × 10 −3 ."