Shape Functions from B -> X_c \ell \nu
摘要
We study inclusive semi-leptonic (B -> X_c \ell \nu) decay using the power counting m_c ~ \sqrt{Lambda_{QCD} m_b}. Assuming this scaling for the charm-quark mass, the decay kinematics can be chosen to access the shape-function region even in b -> c transitions. To apply effective field theory methods in this region we extend SCET to describe massive collinear quarks. We calculate the tree-level decay rate, including O(Lambda_{QCD}/m_b) power corrections, and show that it factorizes into a convolution of jet and shape functions. We identify a certain kinematical variable whose decay spectrum is proportional to the universal leading-order shape function familiar from b -> u decay, and speculate as to whether information about this shape function can be extracted from data on b -> c decay.
引用
@article{arxiv.hep-ph/0504005,
title = {Shape Functions from B -> X_c \ell \nu},
author = {H. Boos and Th. Feldmann and T. Mannel and B. D. Pecjak},
journal= {arXiv preprint arXiv:hep-ph/0504005},
year = {2009}
}
备注
18 pages, 1 figure, version to appear in PRD