On the nonperturbative charm effects in inclusive B -> X_c l\nu decays
Abstract
We address the nonperturbative effects associated with soft charm quarks in inclusive B decays. Such corrections are allowed by the OPE, but have largely escaped attention so far. The related four-quark `double heavy' expectation values of the form <B|\bar{b}c \bar{c}b|B> are computed in the 1/m_c expansion by integrating out the charm field to one and two loops. A significant enhancement of the two-loop coefficients has been noted. A method is suggested for evaluating the expectation values of the higher-order b-quark operators required to calculate charm expectation values, free from the overly large ambiguities of dimensional analyses. The soft-charm effects were found generally at the level of 0.5% in \Gamma_{sl}(b->c); however, as a result of cancellations the net impact should be smaller. We propose a direct way to search for such effects in the data. Finally, we discuss the relation of the soft charm corrections in inclusive decays with the `Intrinsic Charm' ansatz.
Keywords
Cite
@article{arxiv.hep-ph/0511158,
title = {On the nonperturbative charm effects in inclusive B -> X_c l\nu decays},
author = {I. I. Bigi and N. Uraltsev and R. Zwicky},
journal= {arXiv preprint arXiv:hep-ph/0511158},
year = {2008}
}
Comments
32 pages, LaTeX, 3 figures. Revised: A number of inconsistencies and typos corrected including the $1/m_c^2$ matrix elements. The effect on \Gamma_sl is estimated about 0.003, not changing the conclusions. A new reference [9] has been added