$$B\to\pi\ell\nu$$ semileptonic form factors from unquenched lattice QCD and determination of $$|V_{ub}|$$
We compute the $$B\to\pi\ell\nu$$ semileptonic form factors and update the determination of the CKM matrix element $$|V_{ub}|$$. We use the MILC asqtad ensembles with $$N_f=2+1$$ sea quarks at four different lattice spacings in the range $$a \approx 0.045$$~fm to $0.12$~fm. The lattice form factors are extrapolated to the continuum limit using SU(2) staggered chiral perturbation theory in the hard pion limit, followed by an extrapolation in $q^2$ to the full kinematic range using a functional $$z$$-parameterization. The extrapolation is combined with the experimental measurements of the partial branching fraction to extract $$|V_{ub}|$$. Our preliminary result is $$|V_{ub}|=(3.72\pm 0.14)\times 10^{-3}$$, where the error reflects both the lattice and experimental uncertainties, which are now on par with each other.
- Research Organization:
- Fermi National Accelerator Lab. (FNAL), Batavia, IL (United States); Brookhaven National Lab. (BNL), Upton, NY (United States)
- Sponsoring Organization:
- USDOE Office of Science (SC), High Energy Physics (HEP)
- Contributing Organization:
- Fermilab Lattice; MILC
- DOE Contract Number:
- AC02-07CH11359
- OSTI ID:
- 1327265
- Report Number(s):
- arXiv:1411.6038; FERMILAB-CONF-14-518-T; 1329797
- Journal Information:
- PoS, Vol. LATTICE2014; Conference: 32nd International Symposium on Lattice Field Theory, Brookhaven, NY, USA, 06/23-06/28/2014
- Country of Publication:
- United States
- Language:
- English
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