1,985 research outputs found
Gluon Regge trajectory at two loops from Lipatov's high energy effective action
We present the derivation of the two-loop gluon Regge trajectory using
Lipatov's high energy effective action and a direct evaluation of Feynman
diagrams. Using a gauge invariant regularization of high energy divergences by
deforming the light-cone vectors of the effective action, we determine the
two-loop self-energy of the reggeized gluon, after computing the master
integrals involved using the Mellin-Barnes representations technique. The
self-energy is further matched to QCD through a recently proposed subtraction
prescription. The Regge trajectory of the gluon is then defined through
renormalization of the reggeized gluon propagator with respect to high energy
divergences. Our result is in agreement with previous computations in the
literature, providing a non-trivial test of the effective action and the
proposed subtraction and renormalization framework.Comment: 22 page
The quark induced Mueller-Tang jet impact factor at next-to-leading order
We present the NLO corrections for the quark induced forward production of a
jet with an associated rapidity gap. We make use of Lipatov's QCD high energy
effective action to calculate the real emission contributions to the so-called
Mueller-Tang impact factor. We combine them with the previously calculated
virtual corrections and verify ultraviolet and collinear finiteness of the
final result.Comment: 29 pages, many figure
Dijet Production at Large Rapidity Separation in N=4 SYM
Ratios of azimuthal angle correlations between two jets produced at large
rapidity separation are studied in the N=4 super Yang-Mills theory (MSYM). It
is shown that these observables, which directly prove the SL(2,C) symmetry
present in gauge theories in the Regge limit, exhibit an excellent perturbative
convergence. They are compared to those calculated in QCD for different
renormalization schemes concluding that the momentum-substraction (MOM) scheme
with the Brodsky-Lepage-Mackenzie (BLM) scale-fixing procedure captures the
bulk of the MSYM results.Comment: 13 pages, 7 figure
The next-to-leading order vertex for a forward jet plus a rapidity gap at high energies
We present the results for the calculation of the forward jet vertex
associated to a rapidity gap (coupling of a hard pomeron to the jet) in the
Balitsky-Fadin-Kuraev-Lipatov (BFKL) formalism at next-to-leading order (NLO).
We handle the real emission contributions making use of the high energy
effective action proposed by Lipatov, valid for multi-Regge and
quasi-multi-Regge kinematics. This result is important since it allows,
together with the NLO non-forward gluon Green function, to perform NLO studies
of jet production in diffractive events (Mueller-Tang dijets, as a well-known
example).Comment: 12 pages, some figure
Dynamical Mass Generation and Confinement in Maxwell-Chern-Simons Planar Quantum Electrodynamics
We study the non-perturbative phenomena of Dynamical Mass Generation and
Confinement by truncating at the non-perturbative level the Schwinger-Dyson
equations in Maxwell-Chern-Simons planar quantum electrodynamics. We obtain
numerical solutions for the fermion propagator in Landau gauge within the
so-called rainbow approximation. A comparison with the ordinary theory without
the Chern-Simons term is presented.Comment: 9 pages, 9 figures; prepared for the XIV Mexican School of Particles
and Fields, 4-12 November 2010, Morelia, Michoacan, Mexic
Resumming large higher-order corrections in non-linear QCD evolution
Linear and non-linear QCD evolutions at high energy suffer from severe issues
related to convergence, due to higher order corrections enhanced by large
double and single transverse logarithms. We resum double logarithms to all
orders by taking into account successive soft gluon emissions strongly ordered
in lifetime. We further resum single logarithms generated by the first
non-singular part of the splitting functions and by the one-loop running of the
coupling. The resulting collinearly improved BK equation admits stable
solutions, which are used to successfully fit the HERA data at small-x for
physically acceptable initial conditions and reasonable values of the fit
parameters.Comment: 4 pages, 4 figures, based on talk given at Hard Probes 2015, 29 June
- 3 July 2015, Montreal, Canad
Resummation of Large Logarithms in the Rapidity Evolution of Color Dipoles
Perturbative corrections beyond leading-log accuracy to BFKL and BK
equations, describing the rapidity evolution of QCD scattering amplitudes at
high energy, exhibit strong convergence problems due to radiative corrections
enhanced by large single and double transverse logs. We identify explicitly the
physical origin of double transverse logs and resum them directly in coordinate
space as appropriate for BK equation, in terms of an improved local-in-rapidity
evolution kernel. Numerical results show the crucial role of double-logarithmic
resummation for BK evolution, which is stabilized and slowed down by roughly a
factor of two.Comment: 6 pages, 4 figures; Proceedings of the XXIII International Workshop
on Deep-Inelastic Scattering (27 April-May 1 2015, Dallas (USA)
Health in my community: Conducting and evaluating photovoice as a tool to promote environmental health and leadership among Latino/a youth
BackgroundThe PhotoVoice method has shown substantial promise for work with youth in metropolitan areas, yet its potential for use with Latino youth from agricultural areas has not been well documented.ObjectivesThis project was designed to teach environmental health to 15 high school youth while building their individual and community capacity for studying and addressing shared environmental concerns. The project also aimed to test the utility of PhotoVoice with Latino agricultural youth.MethodsFifteen members of the Youth Community Council (YCC), part of a 15-year project with farmworker families in Salinas, CA, took part in a 12-week PhotoVoice project. Their pictures captured the assets and strengths of their community related to environmental health, and were then analyzed by participants. A multi-pronged evaluation was conducted.ResultsYCC members identified concerns such as poor access to affordable, healthy foods and lack of safe physical spaces in which to play, as well as assets, including caring adults and organizations, and open spaces in surrounding areas. Participants presented their findings on radio, television, at local community events, and to key policy makers. The youth also developed two action plans, a successful 5K run/walk and a school recycling project, still in progress. Evaluation results included significant changes in such areas as perceived ability to make presentations, leadership, and self-confidence, as well as challenges including transportation, group dynamics, and gaining access to people in power.ConclusionThe PhotoVoice method shows promise for environmental health education and youth development in farmworker communities
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