# The 21st Nordic Network Meeting on "Strings, Fields and Branes"

Feb 15 – 17, 2007
The AlbaNova University Center, Stockholm
Europe/Stockholm timezone

## Talk Titles&Abstracts

List of talk titles and abstracts (where provided) in no particular order:

 Name City Title of talk : Abstract : PIDOKRAJT, Narit Stockholm Thermodynamic Geometry of Dilaton Black Holes (not provided) LARFORS, Magdalena Uppsala The world next door - Results in landscape topography There are increasing evidence for the existence of a string landscape describing a huge number of different vacua. Possibly, our universe is given by one of these vacua and it is interesting to ask in what effects the presence of these other vacua gives rise to. To understand this issue, it is important to map out the topographic properties of the string landscape. This talk deals with the topography of the part of the string landscape corresponding to complex structure moduli of flux compactified type IIB string theory. We find evidence for series of continuously connected minima and describe their properties. MåNSSON, Teresia Potsdam The Leigh-Strassler deformation and the Quest of Integrability In this talk we study the dilatation operator of the full scalar field sector of Leigh-Strassler deformed N=4 SYM theory. In particular, we map it onto a spin chain and employ the Reshetikhin criteria to study integrability. In addition, different integrable subsectors of the full theory are presented. HARTONG, Jelle Groningen New seven--branes and instantons in IIB supergravity Recent studies of 7-branes and supersymmetry as well as the dual 8-from formulation of the IIB coset SL(2,R)/SO(2) have shown existence of 1/2 BPS 7-branes and instantons which are in no relation to the standard D7-brane and D-instanton by a duality rotation. GREEN, Michael Cambridge M-theory Duality and Nonrenormalization Conditions The duality between eleven-dimensional supergravity compacified on a circle and type II string theories in nine dimensions is exploited to obtain exact properties of the low energy expansion of the four-graviton amplitude. This leads to some powerful nonrenormalization conditions. ROENNE, Peter Browne Copenhagen Factorization of Seiberg-Witten Curves The vacuum moduli space for N=2 supersymmetric U(N_c) gauge theory was shown by Seiberg and Witten to be described via a hyperelliptic curve. This Seiberg-Witten curve factorizes when we softly break the N=2 supersymmetry to N=1 with a superpotential. In this talk I will give the exact solution of the factorization problem for an elliptic curve when we include fundamental matter in the theory. PERSSON, Jonas Uppsala Extended supersymmetry and T-duality We review the recent progress in the relation between Generalized Complex Geometry and extended supersymmetry. After a brief introduction to Generalized Complex Geometry we will introduce the phase space of the string and discuss extended supersymmetry in this setting. We will also mention how generalized Kähler geometry and generalized hyperKähler geometry arise from the N=(1,1) sigma model with extended supersymmetry. Further, we discuss T-dulality in the phase space and discuss under which conditions the extended supersymmetry is realized in the T-dual model. ARGURIO, Riccardo Brussels Dynamical Supersymmetry Breaking (not provided) BERGSHOEFF, Eric Groningen D=11 Supergravity and $E_{11}$ We will discuss an explicit realization of the very-extended Kac-Moody algebra $E_{11}$ in terms of the fields of D=11 supergravity and their dual representations. JOKELA, Niko Helsinki A Thermodynamic Interpretation of Time for Rolling Tachyons We show that the open string worldsheet description of brane decay (discussing a specific example of a rolling tachyon background) can be related to a sequence of points of thermodynamic equilibrium of a grand canonical ensemble of point charges on a circle, the Dyson gas. Subsequent instants of time are related to neighboring values of the chemical potential or the average particle number . The free energy of the system decreases in the direction of larger or later times, thus defining a thermodynamic arrow of time. Time evolution equations are mapped to differential equations relating thermal expectation values of certain observables at different points of thermal equilibrium. This suggests some lessons concerning emergence of time from an underlying microscopic structure in which the concept of time is absent. GRAN, Ulf Göteborg 31 Implies 32 - A Study of Near Maximal Supersymmetry By adapting the method of spinorial geometry to backgrounds with near maximal supersymmetry we show that, for both 11D and IIB supergravity, backgrounds with thirty one supersymmetries are actually maximally supersymmetric. This rules out the existence of (simply connected) supergravity preons. KOSOWER, David Paris, Zurich Amplitudes in Gauge Theories The three talks will discuss the following topics: 1)New Techniques for Trees, 2)The Unitarity-Bootstrap for Loops 3) The Higher-Loop Cusp Anomalous Dimension Di VECCHIA , Paolo Nordita An Introduction to String Theory and its use in Particle Phenomenology Canceled WALDRAM, Daniel London Generalized Geometry and fluxes (not provided) SEMENOFF , Gordon Vancouver Gauge invariant finite size spectrum of the giant magnon The problem of computing finite size corrections to the spectrum of the giant magnon solution of classical string theory is revisited. It is shown that gauge dependence of previous results found using the uniform light-cone gauge cancels from physical quantities. The resulting finite size effects are physically meaningful and are exponentially small in the R-charge and the exponent (but not the prefactor) agrees with gauge theory computations of the same quantity using the integrable Hubbard model Ansatz.