1,299 research outputs found
Schwinger pair production in AdS2
We analyze the pair production of charged particles in two-dimensional
Anti-de Sitter space (AdS_2) with a constant, uniform electric field. We
compute the production rate both at a semi-classical level, viewing Schwinger
pair production as a tunneling event, and at the full quantum level, by
extracting the imaginary part of the one-loop amplitude. In contrast to the
usual Schwinger pair production in flat space, pair production in AdS_2
requires a sufficiently large electric field E^2> M^2+1/4 in order to overcome
the confining effect of the AdS geometry -- put in another way, the presence of
an electric field E raises the Breitenlohner-Freedman bound to M^2 > -1/4 +
E^2. For E greater than this threshold, the vacuum is unstable to production of
charged pairs in the bulk. We expect our results to be helpful in constructing
supersymmetric AdS_2 X S^2 perturbative string vacua, which enter in the
near-horizon limit of extremal charged black holes. Although the generalized
Breitenlohner-Freedman bound is obeyed in these cases, production of BPS
particles at threshold is possible and relevant for AdS_2 fragmentation.Comment: 23 pages, 4 figures, v2:important revision, discussion of one-loop
amplitude extended, several references adde
Models for Modules
We recall the structure of the indecomposable sl(2) modules in the
Bernstein-Gelfand-Gelfand category O. We show that all these modules can arise
as quantized phase spaces of physical models. In particular, we demonstrate in
a path integral discretization how a redefined action of the sl(2) algebra over
the complex numbers can glue finite dimensional and infinite dimensional
highest weight representations into indecomposable wholes. Furthermore, we
discuss how projective cover representations arise in the tensor product of
finite dimensional and Verma modules and give explicit tensor product
decomposition rules. The tensor product spaces can be realized in terms of
product path integrals. Finally, we discuss relations of our results to brane
quantization and cohomological calculations in string theory.Comment: 18 pages, 6 figure
Pompoenen - biologische teelt : de teelt van A tot Z
In deze teelthandleiding wordt de teelt en de afzet van de biologische pompoen besproken. Deze teelthandleiding is tot stand gekomen als onderdeel van het project Leren met Toekomst. De auteurs, studenten aan de Christelijke Agrarische Hogeschool ,hebben deze teelthandleiding geschreven voor de biologische pompoenenteler
Notes on the Verlinde formula in non-rational conformal field theories
We review and extend evidence for the validity of a generalized Verlinde
formula in particular non-rational conformal field theories. We identify a
subset of representations of the chiral algebra in non-rational conformal field
theories that give rise to an analogue of the relation between modular
S-matrices and fusion coefficients in rational conformal field theories. To
that end we review and extend the Cardy-type brane calculations in bosonic and
supersymmetric Liouville theory (and its duals) as well as in the hyperbolic
three-plane H3+. We analyze the three-point functions of Liouville theory and
of H3+ in detail to directly identify the fusion coefficients from the operator
product expansion.Comment: 29 pages, 6 figures, v2: minor corrections, PRD versio
Batalin-Vilkovisky gauge-fixing of a chiral two-form in six dimensions
We perform the gauge-fixing of the theory of a chiral two-form boson in six
dimensions starting from the action given by Pasti, Sorokin and Tonin. We use
the Batalin-Vilkovisky formalism, introducing antifields and writing down an
extended action satisfying the classical master equation. Then we gauge-fix the
three local symmetries of the extended action in two different ways.Comment: 15 pages, latex, no figures, version accepted by Class. Quant. Gra
A Superspace Formulation for the Master Equation
It is shown that the quantum master equation of the Field Antifield
quantization method at one loop order can be translated into the requirement of
a superfield structure for the action. The Pauli Villars regularization is
implemented in this BRST superspace and the case of anomalous gauge theories is
investigated. The quantum action, including Wess Zumino terms, shows up as one
of the components of a superfield that includes the BRST anomalies in the other
component. The example of W2 quantum gravity is also discussed.Comment: The constrained nature of standard BRST superfields and the
importance of using Alfaro and Damgaard's collective fields in the superspace
approach to avoid undefined superfield derivatives was emphasized. To appear
in Phys. Rev. D. Latex file, 20 page
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