Exact light-cone wavefunction representation of matrix elements of electroweak currents Original Research Article

The matrix elements of electroweak currents which occur in exclusive decays of heavy hadrons are evaluated in the non-perturbative light-cone Fock representation. In general, each semileptonic exclusive decay amplitude receives two contributions, a diagonal Δn = 0 parton-number-conserving amplitude and a Δn = −2 contribution in which a qaurk and an antiquark from the initial hadron Fock state annihilate to the leptonic current. The general formalism can be used as a basis for systematic approximations to heavy hadron decay amplitudes such as hard perturbative QCD contributions. We illustrate the general formalism using a simple perturbative model of composite hadrons. Our analysis demonstrates the occurrence of “zero-mode” endpoint contributions to matrix elements of the “bad” j− currents in the Drell-Yan frame when q+ → 0.