Instruct: Identify the main and secondary category of Arxiv papers based on the titles and abstracts
Query: Threshold resummation for exclusive B meson decays   We argue that double logarithmic corrections $\alpha_s\ln^2 x$ need to be
resumed in perturbative QCD factorization theorem for exclusive $B$ meson
decays, when the end-point region with a momentum fraction $x\to 0$ is
important. These double logarithms, being of the collinear origin, are absorbed
into a quark jet function, which is defined by a matrix element of a quark
field attached by a Wilson line. The factorization of the jet function from the
decay $B\to\gamma l\bar\nu$ is proved to all orders. Threshold resummation for
the jet function leads to a universal, {\it i.e.}, process-independent, Sudakov
factor, whose qualitative behavior is analyzed and found to smear the end-point
singularities in heavy-to-light transition form factors.

35
The categories of this paper are: mtrl-th
1
The categories of this paper are: cs
25
The categories of this paper are: patt-sol
32
The categories of this paper are: atom-ph
6
The categories of this paper are: astro-ph
33
The categories of this paper are: plasm-ph
26
The categories of this paper are: bayes-an
24
The categories of this paper are: dg-ga
14
The categories of this paper are: math-ph
2
The categories of this paper are: math
10
The categories of this paper are: q-bio
34
The categories of this paper are: chem-ph
13
The categories of this paper are: quant-ph
3
The categories of this paper are: physics
15
The categories of this paper are: nucl-ex
36
The categories of this paper are: cmp-lg