1,721,095 research outputs found
Hawking radiation, W-infinity algebra and trace anomalies
No full textWe apply the “trace anomaly method” to the calculation of moments of the Hawking radiation of a Schwarzschild black hole. We show that they can be explained as the fluxes of chiral currents forming a W∞ algebra. Then we construct the covariant version of these currents and verify that up to order 6 they are not affected by any trace anomaly. Using cohomological methods we show that actually, for the fourth order current, no trace
anomalies can exist. The results reported here are strictly valid in two dimensions
KDV EQUATION ON RIEMANN SURFACES
No full textWe define a generalization of the KdV equation to Riemann surfaces, together with the corresponding hierarchy of equations and infinite set of charges in involution. We show that the second hamiltonian structure gives rise to a realization of the Krichever-Novikov algebra. Relying only on covariance, we define more general hamiltonian structures that give rise to generalizations to higher genus of some spin algebras
Non-simply laced Lie algebras via F theory strings
Full text linkIn order to describe the appearance in F theory of the non-simply-laced Lie
algebras, we use the representation of symmetry enhancements by means of string junctions.
After an introduction to the techniques used to describe symmetry enhancement, that is
algebraic geometry, BPS states analysis and string junctions, we concentrate on the latter.
We give an explicit description of the folding of D2n to Bn, of the folding of E6 to F4 and
that of D4 to G2 in terms of junctions and Jordan strings. We also discuss the case of Cn, but we are unable in this case to provide a string interpretation
A GLOBAL OPERATOR FORMALISM ON HIGHER GENUS RIEMANN SURFACES: B-C SYSTEMS
Full text linkWe explicitly construct bases for meromorphic λ-differentials over genus g Riemann surfaces. With the help of these bases we introduce a new operator formalism over Riemann surfaces which closely resembles the operator formalism on the sphere. As an application we calculate the propagators for b-c systems with arbitrary integer or half-integer λ (in the Ramond and Neveu-Schwarz sectors). We also give explicit expressions for the zero modes and for the Teichmüller deformations for a generic Riemann surface
Anomalies and locality in field theories and M-theory
No full textWe review some basic notions on anomalies in field theories and superstring theories, with particular emphasis on the concept of locality. The aim is to prepare the ground for a discussion on anomalies in theories with branes. In this light we review the problem of chiral anomaly cancellation in M-theory with a 5-brane
Dressed sliver solutions in vacuum string field theory
No full textWe consider a new class of solutions (dressed slivers) in Vacuum String Field
Theory, which represent D25-branes. For each dressed sliver we introduce a deformation parameter and define a family of states which are characterized by new abelian ¤-subalgebras.
We show that this deformation parameter can be used as a regulator: it allows us to define for each such solution a finite norm and energy density. Finally we show how to generalize
these results to parallel coincident and to lower dimensional branes
A note on consistent anomalies in noncommutative YM theories
No full textVia descent equations we derive formulas for consistent gauge anomalies in noncommutative Yang-Mills theorie
BASES OF MEROMORPHIC DIFFERENTIALS ON GENUS G RIEMANN SURFACES AND APPLICATIONS
No full textElsevier Science Publishers B.V. (North-Holland), 198
Revisiting pinors and orientability
No full textWe study the relations between pin structures on a non-orientable even-dimensional manifold, with or without boundary, and pin structures on its orientable double cover, requiring the latter to be invariant under sheet-exchange. We show that there is not a simple bijection, but that the natural map induced by pull-back is neither injective nor surjective: we thus find the conditions to recover a full correspondence. We also show how to describe such a correspondence using spinors instead of pinors on the double cover: This is in a certain sense possible, but in a way that contains anyhow an explicit reference to pinors. We then consider the example of surfaces, with detailed computations for the real projective plane, the Klein bottle and the Moebius strip
RELATION BETWEEN REPRESENTATIONS OF K-N AND VIRASORO ALGEBRAS
No full textSome aspects of conformal field theory over Riemann surfaces are examined. We study, in particular, on simple systems (b-c systems) the relation between representations of the Virasoro and the KN algebras. KN algebra representations decompose into an infinite sum of the Virasoro algebra representations. We argue that the KN algebra representations are the right tool in order to classify conformal field theories over higher genus Riemann surfaces
- …
