Talk presented by Massimo di Pierro

Parallel Session: Heavy Quarks V

Friday July 2nd, 15.30 - 15.50, Pacinotti Room

Lattice determination of the $B^\ast B \pi$ coupling

Abstract: The coupling $g_{B^\ast B \pi}$ is related to the form factor at zero momentum of the axial current between $B^\ast$- and $B$-states. This form factor has been evaluated on the lattice using static heavy quarks and light quark propagators determined by a stochastic inversion of the fermionic bilinear. The $\gBBP$ coupling is related to the coupling $g$ between heavy mesons and low-momentum pions in the effective heavy meson chiral lagrangian. The coupling of the effective theory can therefore be computed by numerical simulations. We found the value $g = 0.42(4)(8)$. Besides its theoretical interest, this quantity has phenomenological implications, under the assumpion of vector meson dominance, in $B \rightarrow \pi + l \bar l$ decays.

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