Non-Valence Fock States in Heavy-to-Light Form Factors at Large Recoil

Abstract

We studied three-particle Fock state contributions to heavy-to-light form factors in the context of soft-collinear effective theory and found that they enter at leading power. These contributions are non-factorizable due to the appearance of endpoint singularities, however they do not violate spin-symmetry relations at leading power. In this talk I present their numerical estimation in a crude model in which the "soft overlap" contribution is cut off and find that they might lower the standard values for the form factors at maximum recoil significantly. Furthermore I briefly discuss the role of soft-collinear messenger modes in the region of soft overlap.

Comments: 3 pages, 2 figures, invited talk at the international conferences QCD '03, Montpellier, France, and EPS '03, Aachen, Germany