792 research outputs found
Classical ultrarelativistic bremsstrahlung in extra dimensions
The emitted energy and the cross-section of classical scalar bremsstrahlung
in massive particle collisions in D=4+d dimensional Minkowski space M_D as well
as in the brane world M_4 \times T^d is computed to leading ultra-relativistic
order. The particles are taken to interact in the first case via the exchange
of a bulk massless scalar field \Phi and in the second with an additional
massless scalar \phi confined together with the particles on the brane. Energy
is emitted as \Phi radiation in the bulk and/or \phi radiation on the brane. In
contrast to the quantum Born approximation, the classical result is unambiguous
and valid in a kinematical region which is also specified. For D=4 the results
are in agreement with corresponding expressions in classical electrodynamics.Comment: Preprint number adde
Casimir interaction of finite-width strings
Within the trln-formalism we investigate the vacuum interaction of cosmic
strings and the influence of strings width on this effect. For the massless
real scalar field we compute the Casimir contribution into the total vacuum
energy. The dimensional-regularization technique is used. It is shown that the
regularized Casimir term contains neither the UV-divergences, nor the
divergences related with the non-integrability of the renormalized vacuum mean
of the energy-momentum tensor.Comment: 3 figure
- …