Nonresonant Semileptonic Heavy Quark Decay

TL;DR

This paper investigates nonresonant semileptonic heavy quark decays, demonstrating their significant production rate in the heavy quark limit and analyzing the fragmentation and suppression factors affecting their contribution.

Contribution

It introduces a calculation of nonresonant decay channels using an unquenched quark model and explores duality-violating effects in heavy quark decays.

Findings

Nonresonant decays are produced at a significant rate in the heavy quark limit.

The total nonresonant decay rate is highly fragmented among many channels.

Duality-violating suppression factors reduce the nonresonant rate to a few percent of the total.

Abstract

In both the large N_c limit and the valence quark model, semileptonic decays are dominated by resonant final states. Using Bjorken's sum rule in an "unquenched" version of the quark model, I demonstrate that in the heavy quark limit nonresonant final states should also be produced at a significant rate. By calculating the individual strengths of a large number of exclusive two-body nonresonant channels, I show that the total rate for such processes is highly fragmented. I also describe some very substantial duality-violating suppression factors which reduce the inclusive nonresonant rate to a few percent of the total semileptonic rate for the finite quark masses of B decay, and comment on the importance of nonresonant decays as testing grounds for very basic ideas on the structure, strength, and significance of the quark-antiquark sea and on quark-hadron duality in QCD.