Form Factors for Semileptonic B -> pi and D -> pi Decays from the Omnes Representation

Abstract

We use the Omnes representation to obtain the q-squared dependence of the form factors f+ and f0 for semileptonic H -> pi decays from the elastic pi H -> pi H scattering amplitudes, where H denotes a B or D meson. The scattering amplitudes used satisfy elastic unitarity and are calculated from two-particle irreducible amplitudes obtained using tree-level heavy meson chiral perturbation theory (HMChPT). The q-squared dependences for the form factors agree with lattice QCD results when the HMChPT coupling constant, g, takes values smaller than 0.32, and confirm the milder dependence of f0 on q-squared found in sumrule calculations.

9 pages latex, 5 figures, uses graphicx package. Version accepted for publication (discussion extended, one extra figure)

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• Open-charm meson resonances with negative strangeness
• Two-pole structure of the $D_0^{\ast }(2400)$
• Study of the q^2-Dependence of B --> pi ell nu and B --> rho(omega)ell nu Decay and Extraction of |V_ub|
• Semileptonic $B\to \pi$ Decays from an Omnès Improved Nonrelativistic Constituent Quark Model
• Extracting |V(ub)| from B->pi l nu Decays Using a Multiply-subtracted Omnes Dispersion Relation
• |Vub| from Exclusive Semileptonic B--> rho Decays
• |Vub| from Exclusive Semileptonic B to pi Decays
• Ward Identities, B-> ρForm Factors and |V_ub|
• Determination of |Vub|