arXiv subjects

L. Bonora

Publications and source records attributed to L. Bonora.

At least 37 records · Page 2Linked to original sources

arXiv2014

Generalized q-deformed Correlation Functions as Spectral Functions of Hyperbolic Geometry

We analyse the role of vertex operator algebra and 2d amplitudes from the point of view of the representation theory of infinite dimensional Lie algebras, MacMahon and Ruelle functions. A p-dimensional MacMahon function is the generating function of p-dimensional partitions of integers. These functions can be represented as amplitudes of a two-dimensional c=1 CFT. In this paper we show that p-dimensional MacMahon functions can be rewritten in terms of Ruelle spectral functions, whose spectrum is encoded in the Patterson-Selberg function of three dimensional hyperbolic geometry.

hep-th↗

arXiv2013

The energy of the analytic lump solution in SFT

In a previous paper a method was proposed to find exact analytic solutions of open string field theory describing lower dimensional lumps, by incorporating in string field theory an exact renormalization group flow generated by a relevant operator in a worldsheet CFT. In this paper we compute the energy of one such solution, which is expected to represent a D24 brane. We show, both numerically and analytically, that its value corresponds to the theoretically expected one.

hep-th↗

arXiv2013

Weyl transformations and trace anomalies in N=1, D=4 supergravities

We identify the supersymmetric extension of Weyl transformations in various types of supergravities, the minimal, nonminimal and new minimal N=1 SUGRA in 4D, formulated in terms of superfields. Based also on previous results we conclude that there are only two types of trace anomalies in nonminimal and new minimal supergravities, which correspond to the two nontrivial cocycles of the minimal supergravity and, when reduced to component form, to the well-known squared Weyl density and Euler density. There are nevertheless in new minimal supergravity other nontrivial cocycles which, however, are mapped to zero in the minimal supergravity.

hep-th↗

arXiv2012

Gravitational Chern-Simons terms and black hole entropy. Global aspects

We discuss the topological and global gauge properties of the formula for a black hole entropy due to a purely gravitational Chern-Simons term. We study under what topological and geometrical conditions this formula is well-defined. To this end we have to analyze the global properties of the Chern-Simons term itself and the quantization of its coupling. We show that in some cases the coupling quantization may interfere with the well-definiteness of the entropy formula.

hep-th↗

arXiv2012

Lump solutions in SFT. Complements

Recently a possible violation of the equation of motion for the recently proposed lump solutions in open SFT has been pointed out in the literature. In this paper we argue that, when the issue is considered in the appropriate mathematical setting of distribution theory, no violations to the equation of motion occur.

hep-th↗

arXiv2011

Relevant Deformations in Open String Field Theory: a Simple Solution for Lumps

We propose a remarkably simple solution of cubic open string field theory which describes inhomogeneous tachyon condensation. The solution is in one-to-one correspondence with the IR fixed point of the RG-flow generated in the two--dimensional world-sheet theory by integrating a relevant operator with mild enough OPE on the boundary. It is shown how the closed string overlap correctly captures the shift in the closed string one point function between the UV and the IR limits of the flow. Examples of lumps in non-compact and compact transverse directions are given.

hep-th↗

arXiv2011

Analytic solutions for Dp branes in SFT

This is the follow-up of a previous paper [ArXiv:1105.5926], where we calculated the energy of an analytic lump solution in SFT, representing a D24-brane. Here we describe an analytic solution for a Dp-brane, for any p, and compute its energy.

hep-th↗

arXiv2011

Partition Functions for Quantum Gravity, Black Holes, Elliptic Genera and Lie Algebra Homologies

There is a remarkable connection between quantum generating functions of field theory and formal power series associated with dimensions of chains and homologies of suitable Lie algebras. We discuss the homological aspects of this connection with its applications to partition functions of the minimal three-dimensional gravities in the space-time asymptotic to AdS3, which also describe the three-dimensional Euclidean black holes, the pure N = 1 supergravity, and a sigma model on N-fold generalized symmetric products. We also consider in the same context elliptic genera of some supersymmetric sigma models. These examples can be considered as a straightforward application of the machinery of modular forms and spectral functions (with values in the congruence subgroup of SL(2, Z)) to partition functions represented by means of formal power series that encode Lie algebra properties.

hep-th↗

arXiv2010

BRST, anti-BRST and their geometry

We continue the comparison between the field theoretical and geometrical approaches to the gauge field theories of various types, by deriving their Becchi-Rouet-Stora-Tyutin (BRST) and anti-BRST trasformation properties and comparing them with the geometrical properties of the bundles and gerbes. In particular, we provide the geometrical interpretation of the so--called Curci-Ferrari conditions that are invoked for the absolute anticommutativity of the BRST and anti-BRST symmetry transformations in the context of non-Abelian 1-form gauge theories as well as Abelian gauge theory that incorporates a 2-form gauge field. We also carry out the explicit construction of the 3-form gauge fields and compare it with the geometry of 2--gerbes.

hep-th↗

arXiv2009

Ghost story. II. The midpoint ghost vertex

We construct the ghost number 9 three strings vertex for OSFT in the natural normal ordering. We find two versions, one with a ghost insertion at z=i and a twist-conjugate one with insertion at z=-i. For this reason we call them midpoint vertices. We show that the relevant Neumann matrices commute among themselves and with the matrix $G$ representing the operator K1. We analyze the spectrum of the latter and find that beside a continuous spectrum there is a (so far ignored) discrete one. We are able to write spectral formulas for all the Neumann matrices involved and clarify the important role of the integration contour over the continuous spectrum. We then pass to examine the (ghost) wedge states. We compute the discrete and continuous eigenvalues of the corresponding Neumann matrices and show that they satisfy the appropriate recursion relations. Using these results we show that the formulas for our vertices correctly define the star product in that, starting from the data of two ghost number 0 wedge states, they allow us to reconstruct a ghost number 3 state which is the expected wedge state with the ghost insertion at the midpoint, according to the star recursion relation.

hep-th↗

arXiv2009

Ghost story. III. Back to ghost number zero

After having defined a 3-strings midpoint-inserted vertex for the bc system, we analyze the relation between gh=0 states (wedge states) and gh=3 midpoint duals. We find explicit and regular relations connecting the two objects. In the case of wedge states this allows us to write down a spectral decomposition for the gh=0 Neumann matrices, despite the fact that they are not commuting with the matrix representation of K1. We thus trace back the origin of this noncommutativity to be a consequence of the imaginary poles of the wedge eigenvalues in the complex k-plane. With explicit reconstruction formulas at hand for both gh=0 and gh=3, we can finally show how the midpoint vertex avoids this intrinsic noncommutativity at gh=0, making everything as simple as the zero momentum matter sector.

hep-th↗

arXiv2009

Hawking fluxes, Fermionic currents, W(1+infinity) algebra and anomalies

We complete the analysis carried out in previous papers by studying the Hawking radiation for a Kerr black-hole carried to infinity by fermionic currents of any spin. We find agreement with thermal spectrum of the Hawking radiation for fermionic degrees of freedom. We start by showing that the near-horizon physics for a Kerr black-hole is approximated by an effective two-dimensional field theory of fermionic fields. Then, starting from 2d currents of any spin that form a W(1+infinity) algebra, we construct an infinite set of covariant currents, each of which carry the corresponding moment of the Hawking radiation. All together they agree with the thermal spectrum of the latter. We show that the predictive power of this method is not based on the anomalies of the higher spin currents (which are trivial), but on the underlying W(1+infinity) structure. Our results point toward the existence in the near-horizon geometry of a symmetry larger than the Virasoro algebra, which very likely takes the form of a W(infinity) algebra.

hep-th↗

arXiv2009

BRST, anti-BRST and gerbes

We discuss BRST and anti--BRST transformations for an Abelian antisymmetric gauge field in 4D and find that, in order for them to anticommute, we have to impose a condition on the auxiliary fields. This condition is similar to the Curci-Ferrari condition for the 4D non--Abelian 1-form gauge theories and represents a consistency requirement. We interpret it as a signal that our Abelian 2-form gauge field theory is based on gerbes. To support this interpretation we discuss, in particular, the case of the 1-gerbe for our present field theory and write the relevant equations and symmetry transformations for 2-gerbes.

hep-th↗

arXiv2008

Hawking Fluxes, $W_\infty$ Algebra and Anomalies

We complete the analysis started in [arXiv:0804.0198] of the Hawking radiation calculated by means of anomaly techniques. We concentrate on a static radially symmetric BH, reduced to two dimensions. We compare the two methods used to derive the integrated Hawking radiation, based on the trace and diffeomorphism anomaly, respectively, and show that they can be reduced to the same basic elements. We then concentrate on higher moments of the Hawking radiation and on higher spin currents, and show that, similarly to trace anomalies, also diffeomorphism anomalies are absent from the conservation laws of higher spin currents. We show that the predictivity of the method is due to the $W_\infty$ current algebra underlying the effective model that describes matter around the black hole.

hep-th↗

arXiv2008

Hawking radiation, W-infinity algebra and trace anomalies

We 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-infinity 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.

hep-th↗

arXiv2008

Spectral properties of ghost Neumann matrices

We continue the analysis of the ghost wedge states in the oscillator formalism by studying the spectral properties of the ghost matrices of Neumann coefficients. We show that the traditional spectral representation is not valid for these matrices and propose a new heuristic formula that allows one to reconstruct them from the knowledge of their eigenvalues and eigenvectors. It turns out that additional data, which we call boundary data, are needed in order to actually implement the reconstruction. In particular our result lends support to the conjecture that there exists a ghost three strings vertex with properties parallel to those of the matter three strings vertex.

hep-th↗

arXiv2007

Ghost story. I. Wedge states in the oscillator formalism

This paper is primarily devoted to the ghost wedge states in string field theory formulated with the oscillator formalism. Our aim is to prove, using such formalism, that the wedge states can be expressed as |n> = exp[{2-n}/2 ({\cal L}_0+{\cal L}_0^\daggert)]|0>, separately in the matter and ghost sector. This relation is crucial for instance in the proof of Schnabl's solution. We start from the exponentials in the rhs and wish to prove that they take precisely the form of wedge states. As a guideline we first re-demonstrate this relation for the matter part. Then we turn to the ghosts. On the way we face the problem of `diagonalizing' infinite rectangular matrices. We manage to give a meaning to such an operation and to prove that the eigenvalues we obtain satisfy the recursion relations of the wedge states.

hep-th↗

arXiv2006

Towards open-closed string duality: Closed Strings as Open String Fields

We establish a translation dictionary between open and closed strings, starting from open string field theory. Under this correspondence, (off-shell) level-matched closed string states are represented by star algebra projectors in open string field theory. Particular attention is paid to the zero mode sector, which is indispensable in order to generate closed string states with momentum. As an outcome of our identification, we show that boundary states, which in closed string theory represent D-branes, correspond to the identity string field in the open string side. It is to be remarked that closed string theory D-branes are thus given by an infinite superposition of star algebra projectors.

hep-th↗