504 research outputs found
Two observers calculate the trace anomaly
We adapt a calculation due to Massacand and Schmid to the coordinate
independent definition of time and vacuum given by Capri and Roy in order to
compute the trace anomaly for a massless scalar field in a curved spacetime in
1+1 dimensions. The computation which requires only a simple regulator and
normal ordering yields the well-known result in a
straightforward manner.Comment: RevTeX, 13 pages, some typos corrected and an appendix added, this is
the version to appear in Class. and Quantum Gavit
Massive particle creation in a static 1+1 dimensional spacetime
We show explicitly that there is particle creation in a static spacetime.
This is done by studying the field in a coordinate system based on a physical
principle which has recently been proposed. There the field is quantized by
decomposing it into positive and negative frequency modes on a particular
spacelike surface. This decomposition depends explicitly on the surface where
the decomposition is performed, so that an observer who travels from one
surface to another will observe particle production due to the different vacuum
state.Comment: 17 pages, RevTeX, no figure
A study of the Higgs and confining phases in Euclidean SU(2) Yang-Mills theories in 3d by taking into account the Gribov horizon
We study SU(2) three-dimensional Yang-Mills theories in presence of Higgs
fields in the light of the Gribov phenomenon. By restricting the domain of
integration in the functional integral to the first Gribov horizon, we are able
to discuss a kind of transition between the Higgs and the confining phase in a
semi-classical approximation. Both adjoint and fundamental representation for
the Higgs field are considered, leading to a different phase structure.Comment: 12 pages. Version accepted for publication in the EPJ
A remark on the BRST symmetry in the Gribov-Zwanziger theory
We show that the soft breaking of the BRST symmetry arising in the
Gribov-Zwanziger theory can be converted into a linear breaking upon
introduction of a set of BRST quartets of auxiliary fields. Due to its
compatibility with the Quantum Action Principle, the linearly broken BRST
symmetry can be directly converted into a suitable set of useful Slavnov-Taylor
identities. As a consequence, it turns out that the renormalization aspects of
the Gribov-Zwanziger theory can be addressed by means of the cohomology of a
nilpotent local operatorComment: 11 pages, final version to appear in Phys. Rev.
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