25 research outputs found
Subleading Power Factorization in
We analyze the factorization to subleading power in the flavor changing
neutral current process . In particular, we
compute the so-called resolved contributions and explore the numerical impact
on observables. In these contributions the virtual photon couples to light
partons instead of connecting directly to the effective weak-interaction
vertex. They represent an irreducible uncertainty in the inclusive decay which cannot be removed by relaxing the experimentally
necessary cuts in the hadronic mass spectrum.Comment: 32 pages,18 figure
Taming the higher power corrections in semileptonic B decays
We study the effect of dimension 7 and 8 operators on inclusive semileptonic
B decays and the extraction of |Vcb|. Using moments of semileptonic B decay
spectra and information based on the Lowest-Lying State saturation
Approximation (LLSA) we perform a global fit of the nonperturbative parameters
of the heavy quark expansion including for the first time the O(1/mb^{4,5})
contributions. Higher power corrections appear to have a very small effect on
the extraction of |Vcb|, independently of the weight we attribute to the LLSA.Comment: 6 pages, 3 figures, small changes to match accepted publication in
PL
Non-cancellation of electroweak logarithms in high-energy scattering
We study electroweak Sudakov corrections in high energy scattering, and the
cancellation between real and virtual Sudakov corrections. Numerical results
are given for the case of heavy quark production by gluon collisions involving
the rates . Gauge boson virtual corrections are related to real
transverse gauge boson emission, and Higgs virtual corrections to Higgs and
longitudinal gauge boson emission. At the LHC, electroweak corrections become
important in the TeV regime. At the proposed 100 TeV collider, electroweak
interactions enter a new regime, where the corrections are very large and need
to be resummed.Comment: 11 pages, 12 figures, 1 table. v2: Journal versio
A proposal to solve some puzzles in semileptonic B decays
Some long-standing problems in the experimental data for semileptonic b -> c
l nu decay rates have resisted attempts to resolve them, despite substantial
efforts. We summarize the issues, and propose a possible resolution, which may
alleviate several of these tensions simultaneously, including the "1/2 vs. 3/2
puzzle" and the composition of the inclusive decay rate in terms of exclusive
channels.Comment: 5 pages, 4 figure