23 research outputs found
Semi-transparent Boundary Conditions in the Worldline Formalism
The interaction of a quantum field with a background containing a Dirac delta
function with support on a surface of codimension 1 represents a particular
kind of matching conditions on that surface for the field. In this article we
show that the worldline formalism can be applied to this model. We obtain the
asymptotic expansion of the heat-kernel corresponding to a scalar field on
in the presence of an arbitrary regular potential and
subject to this kind of matching conditions on a flat surface. We also consider
two such surfaces and compute their Casimir attraction due to the vacuum
fluctuations of a massive scalar field weakly coupled to the corresponding
Dirac deltas.Comment: 12 page
Casimir effect in Snyder Space
We show that two indistinguishable aspects of the divergences occurring in
the Casimir effect, namely the divergence of the energy of the higher modes and
the non-com\-pact\-ness of the momentum space, get disentangled in a given
noncommutative setup. To this end, we consider a scalar field between two
parallel plates in an anti-Snyder space. Additionally, the large mass decay in
this noncommutative setup is not necessarily exponential.Comment: 15 pages, discussion regarding the large-mass asymptotics added,
typos corrected, missing factor in eq. (1) correcte
Boundaries in the Moyal plane
We study the oscillations of a scalar field on a noncommutative disc
implementing the boundary as the limit case of an interaction with an
appropriately chosen confining background. The space of quantum fluctuations of
the field is finite dimensional and displays the rotational and parity symmetry
of the disc. We perform a numerical evaluation of the (finite) Casimir energy
and obtain similar results as for the fuzzy sphere and torus.Comment: 19 pages, 6 figures. Replaced by published versio
Trace anomalies for Weyl fermions: too odd to be true?
We review recent discussions regarding the parity-odd contribution to the
trace anomaly of a chiral fermion. We pay special attention to the perturbative
approach in terms of Feynman diagrams, comparing in detail the results obtained
using dimensional regularization and the Breitenlohner--Maison prescription
with other approaches.Comment: 19 pages, 2 figures. Contribution to "Avenues of Quantum Field Theory
in Curved Spacetime", Genoa, 2022. Partially based on 2101.11382 [hep-th
Trace anomaly for Weyl fermions using the Breitenlohner-Maison scheme for γ *
We revisit the computation of the trace anomaly for Weyl fermions using dimensional regularization. For a consistent treatment of the chiral gamma matrix γ* in dimensional regularization, we work in n dimensions from the very beginning and use the Breitenlohner-Maison scheme to define γ*. We show that the parity-odd contribution to the trace anomaly vanishes (for which the use of dimension-dependent identities is crucial), and that the parity-even contribution is half the one of a Dirac fermion. To arrive at this result, we compute the full renormalized expectation value of the fermion stress tensor to second order in perturbations around Minkowski spacetime, and also show that it is conserved.Facultad de Ciencias Exacta