Dr. Patricia Ball (Fermi National Accelerator Laboratory)

Monday, February 24, 1997 at 4:00 pm in 144 Loomis

The Decay B => Rho e nu from Light-Cone Sum Rules


Theoretical predictions for the decay B => rho e nu show a large model-dependence. This is essentially due to the fact that the hadronicform factors depend on the momentum transfer, t between the B and the rho, which assumes values in the large range 0 < t < 20.3 GeV^2. We propose to determine the relevant form factorsincluding their functional dependence on t from a suitably definedcorrelation function. We show that this correlation function is determinedby its behaviour on and near the light-cone. We then perform a light-coneexpansion in terms of hadron distribution amplitudes of fixed twist, whichare similar to the parton distribution functions familiar from deepinelastic scattering. The form factors are expressed in terms of sum rulesover the distribution amplitudes. The theoretical uncertainties associatedwith our approach are investigated in detail. With present knowledge ofthe distribution amplitudes and sum rules, V_ub can be extracted fromthe spectrum dGamma/dt with a theoretical error of less than 20%.