2,855 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
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
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
All-carbon multi-electrode array for real-time in vitro measurements of oxidizable neurotransmitters
We report on the ion beam fabrication of all-carbon multi electrode arrays
(MEAs) based on 16 graphitic micro-channels embedded in single-crystal diamond
(SCD) substrates. The fabricated SCD-MEAs are systematically employed for the
in vitro simultaneous amperometric detection of the secretory activity from
populations of chromaffin cells, demonstrating a new sensing approach with
respect to standard techniques. The biochemical stability and biocompatibility
of the SCD-based device combined with the parallel recording of
multi-electrodes array allow: i) a significant time saving in data collection
during drug screening and/or pharmacological tests over a large number of
cells, ii) the possibility of comparing altered cell functionality among cell
populations, and iii) the repeatition of acquisition runs over many cycles with
a fully non-toxic and chemically robust bio-sensitive substrate.Comment: 24 pages, 5 figure
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
- …