1,462 research outputs found
Conceptual aspects of QCD factorization in hadronic B decays
I review the meaning of ``QCD factorization'' in hadronic two-body B decays
and then discuss recent results of theoretical (rather than phenomenological)
nature: the proof of factorization at two loops; the identification of
``chirally enhanced'' power corrections; and the role of annihilation
contributions.Comment: 10 pages, LaTeX. Based on talks presented at the UK Phenomenology
Workshop on Heavy Flavour and CP Violation, 17 - 22 September 2000, Durham,
proceedings to appear in J. Phys. G; the 5th International Symposium on
Radiative Corrections (RADCOR2000), Carmel, California, September 11 - 15,
2000; the 4th Workshop on Continuous Advances in QCD, Minneapolis, 12-14 May
2000; the Vth International Workshop on Heavy Quark Physics, Dubna, 6-8 April
200
Next-to-next-to-leading soft-gluon corrections for the top quark cross section and transverse momentum distribution
I present results for top quark production in hadronic collisions at LHC and
Tevatron energies. The soft-gluon corrections to the differential cross section
are resummed at next-to-next-to-leading-logarithm (NNLL) accuracy via the
two-loop soft anomalous dimension matrices. Approximate
next-to-next-to-leading-order (NNLO) differential and total cross sections are
calculated. Detailed theoretical predictions are shown for the t tbar cross
section and the top quark p_T distribution at the Tevatron and the LHC.Comment: 23 pages, 14 figures; additional results and figure
Obtaining Bounds on The Sum of Divergent Series in Physics
Under certain circumstances, some of which are made explicit here, one can
deduce bounds on the full sum of a perturbation series of a physical quantity
by using a variational Borel map on the partial series. The method is
illustrated by applying it to various examples, physical and mathematical.Comment: 33 pages, Journal Versio
Planning Your Pork Production
Hog raisers know that pork prices have their ups and downs. But they don\u27t always give enough attention to the way in which these prices change. Hog prices usually follow a more or less definite pattern from year to year
Taking Guesswork Out og Hog Raising
If you raise hogs, you have to take some gambles. But you\u27ll have a better chance of winning if you know how to figure your odds
The weak angle gamma from one-particle inclusive CP asymmetries in the B(s) system
We compute CP asymmetries of one-particle inclusive B(s) --> D(s) X decay
rates. We find that the weak angle gamma could in principle be extracted from
these asymmetries although they are very small. Taking the decay width
difference into account, we find that the time integrated CP asymmetries are of
the order A=1.4 10^(-4) sin(gamma). Some large uncertainties remain due to the
lack of experimental data.Comment: 12 page
Power Corrections in Charmless B Decays
In this paper, we focus on the role of power corrections in QCD
factorization(QCDF) method in charmless two-body nonleptonic meson decays.
We use the ratio of the branching fraction of to
that of , for which the theoretical uncertainties are
greatly reduced, to show clearly that the power corrections in charmless B
decays are probably large. With other similar ratios considered, for example,
for the decay, it is very likely that, among various
sources of power corrections, annihilation topology plays an indispensable role
at least for penguin dominated channels. We also consider some
selective ratios of direct CP asymmetries. Among these, we find that, if power
corrections other than the chirally enhanced power corrections and annihilation
topology were negligible, QCDF would predict the direct CP asymmetry of to be about 3 times larger than that of ,
with opposite sign. Experimentally any significant deviation from this
prediction would suggest either new physics or possibly the importance of
long-distance rescattering effects.Comment: references and note added, to appear in Phys. Rev.
On the Universality of the Leading, Power Corrections in QCD
We discuss corrections to hard processes in QCD where is a large
mass parameter like the total energy in annihilation. The main problem
we address ourselves to is whether these corrections to different processes
(concentrating for definiteness on the Thrust and the Drell-Yan cross section)
can be related to each other in a reliable way so that the phenomenology of the
corrections can be developed. We derive first the relation valid to
lowest order using both the renormalon and finite-gauge-boson mass techniques
to check its independence on the infrared cut- off procedure. We then argue
that the corrections are due to soft gluons which factorize into a
universal factor such that the lowest order relations are preserved in higher
orders.Comment: 12 page
Soft-Collinear Messengers: A New Mode in Soft-Collinear Effective Theory
It is argued that soft-collinear effective theory for processes involving
both soft and collinear partons, such as exclusive B-meson decays, should
include a new mode in addition to soft and collinear fields. These
"soft-collinear messengers" can interact with both soft and collinear particles
without taking them far off-shell. They thus can communicate between the soft
and collinear sectors of the theory. The relevance of the new mode is
demonstrated with an explicit example, and the formalism incorporating the
corresponding quark and gluon fields into the effective Lagrangian is
developed.Comment: 22 pages, 5 figures. Extended Section 6, clarifying the relevance of
different types of soft-collinear interaction
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