22,281 research outputs found
Finite width induced modification to the electromagnetic form factors of spin-1 particles
The inclusion of the unstable features of a spin-1 particle, without breaking
the electromagnetic gauge invariance, can be properly accomplished by including
higher order contributions as done in the so-called fermion loop scheme (for
the W gauge boson), and the boson loop scheme (for vector mesons). This induces
a non trivial modification to the electromagnetic vertex of the particle, which
must be considered in addition to any other contribution computed as stable
particles. Considering the modified electromagnetic vertex, we obtain general
expressions for the corresponding corrections to the multipoles as a function
of the mass of the particles in the loop. For the W gauge boson no substantial
deviations from the stable case is observed. For the rho and K* mesons the mass
of the particles in the loop makes a significant effect, and can be comparable
with corrections of different nature .Comment: 11 pages, 1 figure. Extended discussion, main equations rewritten to
exhibit limiting behavior. Results for K* meson added. Accepted for
publication in PR
Classical resolution of black hole singularities via wormholes
In certain extensions of General Relativity, wormholes generated by
spherically symmetric electric fields can resolve black hole singularities
without necessarily removing curvature divergences. This is shown by studying
geodesic completeness, the behavior of time-like congruences going through the
divergent region, and by means of scattering of waves off the wormhole. This
provides an example of the logical independence between curvature divergences
and space-time singularities, concepts very often identified with each other in
the literature.ns of curvature divergences in the context of space-time
singularities.Comment: 6 pages, 4 figures; several improvements in main body and abstract;
final version to appear in Eur. Phys. J.
The INTEGRAL-OMC Scientific Archive
The Optical Monitoring Camera (OMC) on-board the INTEGRAL satellite has, as
one of its scientific goals, the observation of a large number of variable
sources previously selected. After almost 6 years of operations, OMC has
monitored more than 100 000 sources of scientific interest. In this
contribution we present the OMC Scientific Archive
(http://sdc.laeff.inta.es/omc/) which has been developed to provide the
astronomical community with a quick access to the light curves generated by
this instrument.We describe the main characteristics of this archive, as well
as important aspects for the users: object types, temporal sampling of light
curves and photometric accuracy.Comment: 4 pages, 5 figures. "Highlights of Spanish Astrophysics V"
Proceedings of the VIII Scientific Meeting of the Spanish Astronomical
Society (SEA) held in Santander, July 7-11, 200
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