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4-11 July 2012
Melbourne Convention and Exhibition Centre
Australia/Melbourne timezone
ICHEP2012 - 36th International Conference for High Energy Physics

|Vub| determination in Lattice QCD

7 Jul 2012, 09:45
Room 220 (Melbourne Convention and Exhibition Centre)

Room 220

Melbourne Convention and Exhibition Centre

Melbourne Australia
Parallel Sessions Track 10. Lattice QCD Room 220 Lattice QCD / B-Physics / CP Violation, etc -TR5&7&10


Dr Fabio Bernardoni (DESY (DE))


At present there is a tension at the level of 3 \sigma between two exclusive determinations of |Vub|. They are obtained combining the experimental branching ratios of B -> \tau \nu and B -> \pi l \nu (respectively) with a theoretical computation of the hadronic matrix elements f_B and the B to \pi form factor f_+(q^2). To understand the tension, improved precision and a careful analysis of the systematics involved are necessary. We report the results of the ALPHA collaboration for f_B from the Lattice with N_f=2 O(a) improved Wilson fermions. We employ HQET, including 1/m_b corrections, with pion masses ranging down to ~250 MeV. Renormalization and matching were performed non-perturbatively, and three lattice spacings reaching a^-1~4.1 GeV are used in the continuum extrapolation. We also present progress towards a computation of f_+(q^2), to directly compare two independent exclusive determinations of |Vub| with each other and with inclusive determinations. Additionally, we report on preliminary results for f_Bs, which is needed to determine |Vtd| and |Vts|.

Primary authors

Presentation materials