147,403 research outputs found
The SCET_II and factorization
We reformulate the soft-collinear effective theory which includes the
collinear quark and soft gluons. The quark form factor is used to prove that
SCET reproduces the IR physics of the full theory. We give a
factorization proof in deep inelastic lepton-hadron scattering by use of the
position space formulation.Comment: 14 pages. The revised version which modifies largely will appear in
PL
Power corrections in heavy-to-light decays at large recoil energy
I briefly present recent work on QCD power corrections in heavy-to-light
meson decays, using an effective field theory approach.Comment: 4 pages, 1 figure. Talk given at ICHEP 2002, Amsterdam, July 200
Reparameterization Invariance for Collinear Operators
We discuss restrictions on operators in the soft-collinear effective theory
(SCET) which follow from the ambiguity in the decomposition of collinear
momenta and the freedom in the choice of light-like basis vectors and . Invariance of SCET under small changes in and/or implies a
symmetry of the effective theory that constrains the form of allowed operators
with collinear fields. The restrictions occur at a given order in the power
counting as well as between different orders. As an example, we present the
complete set of higher order operators that are related to the collinear quark
kinetic term.Comment: 11 page
Microscopic Approach to Nucleon Spectra in Hypernuclear Non-Mesonic Weak Decay
A consistent microscopic diagrammatic approach is applied for the first time
to the calculation of the nucleon emission spectra in the non-mesonic weak
decay of Lambda-hypernuclei. We adopt a nuclear matter formalism extended to
finite nuclei via the local density approximation, a one--meson exchange weak
transition potential and a Bonn nucleon-nucleon strong potential. Ground state
correlations and final state interactions, at second order in the
nucleon--nucleon interaction, are introduced on the same footing for all the
isospin channels of one- and two-nucleon induced decays. Single and
double--coincidence nucleon spectra are predicted for 12_Lambda^C and compared
with recent KEK and FINUDA data. The key role played by quantum interference
terms allows us to improve the predictions obtained with intranuclear cascade
codes. Discrepancies with data remain for proton emission.Comment: 11 pages, 6 figures, 2 tables. To be published in Physics Letters
Infrared regulators and SCETII
We consider matching from SCETI, which includes ultrasoft and collinear
particles, onto SCETII with soft and collinear particles at one loop. Keeping
the external fermions off their mass shell does not regulate all IR divergences
in both theories. We give a new prescription to regulate infrared divergences
in SCET. Using this regulator, we show that soft and collinear modes in SCETII
are sufficient to reproduce all the infrared divergences of SCETI. We explain
the relationship between IR regulators and an additional mode proposed for
SCETII.Comment: 9 pages. Added discussion about relationship between IR regulators
and messenger mode
SCET approach to top quark decay
In this work we study QCD corrections to the top quark doubly decay rate with
a detected hadron containing a quark. We focus on the regime among
which the emitted boson nearly carries its maxim energy. The tool that we
use here is the soft-collinear effective theory (SCET). The factorization
theorem based on SCET indicates a novel fragmenting jet function. We calculate
this function to next-to-leading order in . Large logarithms due to
several well separated scale are summed up using the renormalization group
equation (RGE). Finally we reach an analytic formula for the distribution which
could easily be generalized to other heavy hadron decay.Comment: 13 pages, 4 figure
On the effect of the Delta(1232) in hypernuclear non-mesonic weak decay: a microscopic approach
The non-mesonic weak decay of -hypernuclei is studied within a
microscopic diagrammatic approach which includes, for the first time, the
effect or the -baryon resonance. We adopt a nuclear matter formalism
extended to finite nuclei via the local density approximation, a one-meson
exchange weak transition potential, a Bonn nucleon-nucleon strong potential and
a strong potential based on the Landau-Migdal theory. Ground
state correlations and final state interactions (FSI), at second order in the
baryon-baryon strong interaction, are introduced on the same footing for all
the isospin channels of one- and two-nucleon induced decays. Weak decay rates
and single and double-coincidence nucleon spectra are predicted for
C and compared with recent KEK and FINUDA data. The
introduces new FSI-induced decay mechanisms which lead to an
improvement when comparing the obtained nucleon spectra with data, while it
turns out to have a negligible effect on the decay rates. Discrepancies with
experiment remain only for emission spectra involving protons, but are mostly
restricted to double-nucleon correlations in the non-back-to-back kinematics.Comment: 11 pages, 5 figures. arXiv admin note: substantial text overlap with
arXiv:1103.227
Nuclear Multifragmentation Critical Exponents
We show that the critical exponents of nuclear multi-fragmentation have not
been determined conclusively yet.Comment: 3 pages, LaTeX, one postscript figure appended, sub. to
Phys.Rev.Lett. as a commen
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