Found 16 result(s)

09.03.2007 (Friday)

Quantum Mechanics of the Doubled Torus

Regular Seminar Emily Hackett-Jones (Edinburgh)

at:
12:00 QMW
room 112
abstract:

08.03.2007 (Thursday)

The wave function behavior of the open topological string

Regular Seminar Amir-Kian Kashani-Poor (University of Amsterdam)

at:
13:30 IC
room Huxley 503
abstract:

Suppose we could calculate the string partition function to all genera using worldsheet methods. What could we learn from this expression about a potentially underlying (non-perturbative) target space description of the theory? We address this question in the context of the open topological A-model.

16.11.2006 (Thursday)

Magnon Boundstates in Gauge/String Duality

Regular Seminar Heng-Yu Chen (DAMTP, Cambridge)

at:
13:30 IC
room Huxley 503
abstract:

I will begin with basic review on the integrabilities in AdS/CFT correspondence, and move on discussing the role of scattering matrices in gauge and string thoeries. I will then explain the formation of magnon boundststates in gauge theory and their corresponding classical string solution. The scattering of magnon boundstates and their classifications will also be discussed in this seminar. I will also mention some work in progress.

03.10.2006 (Tuesday)

Twistor Strings and Gravity

Regular Seminar Mohab Abou-Zeid (Vrije U., Brussels and Intl. Solvay Inst., Brussels)

at:
14:00 IC
room 503 Huxley
abstract:

I will present a modification of the Berkovits twistor string model which gives Einstein supergravity coupled to Yang-Mills, and has a limit in which the gravity modes can be decoupled to give pure gauge theory amplitudes. I will start by reviewing a number of relevant aspects of twistor theory, including special features associated with different space-time signatures, supertwistor space, the Penrose transform, the infinity twistor and Penrose's non-linear graviton construction. I will then review the Witten and Berkovits twistor strings, with emphasis on the latter. The world-sheet formulation of the Berkovits model involves so-called beta-gamma systems, I will describe the symmetries of such systems and their gauging, and explain how the analysis can be applied to the construction of a family of new gauged Berkovits twistor strings which are free from world-sheet anomalies. I will also describe the corresponding spectra in space-time, and show that they give Einstein supergravities instead of the higher derivative conformal supergravities arising in the original twistor string models. The new theories include one with the spectrum of N = 8 supergravity, two theories with the spectrum of N = 4 supergravity coupled to N = 4 Yang-Mills, a family of N greater than 0 models with the spectra of self-dual supergravity coupled to self-dual super-Yang-Mills, and a non-supersymmetric string with the spectrum of self-dual gravity coupled to self-dual Yang-Mills and a scalar. Time permitting, I will discuss what is known about the interactions.

01.06.2006 (Thursday)

Time Dependent AdS/CFT Proposal and Spacetime Singularities

Regular Seminar Chong-Sun Chu (Durham)

at:
14:00 QMW
room 112
abstract:

06.03.2006 (Monday)

Heterotic MSSM

Regular Seminar Yang-Hui He (Oxford)

at:
13:30 IC
room Ballroom, 58 Princes Gate
abstract:

We show the existence of an N=1 supersymmetric vacuum in string theory whose observable sector has exactly the matter content of the MSSM without exotic particles and vector-like pairs of any type. This is done so by compactifying the E_8 x E_8 heterotic string on a Calabi-Yau threefold endowed with an SU(4) vector bundle which has been constructed after extensive search. In addition, we discuss the Yukawa couplings and Higgs mu-terms in this model.

23.02.2006 (Thursday)

On T-folds and Supersymmetry

Regular Seminar Emily Hackett-Jones (Edinburgh)

at:
14:00 QMW
room 112
abstract:

19.01.2006 (Thursday)

Matrix Representation of the Combinatorics of Renormalization in Perturbative QFT

Regular Seminar Kurusch Ebrahimi-Fard (IHES)

at:
14:00 QMW
room 112
abstract:

Kreimer discovered a Hopf algebra structure underlying the combinatorics of renormalization in perturbative quantum field theory. Later, Connes and Kreimer explored the link to non-commutative geometry via a Hopf algebra of rooted trees and described a Hopf algebra of Feynman graphs. After reviewing these developments in some detail we show in this talk how to organize the combinatorics of renormalization in terms of unipotent triangular matrix representations. A simple decomposition of such matrices is used to characterize the process of renormalization. We thereby recover a matrix (anti-)representation of the Birkhoff decomposition of Connes and Kreimer.

06.10.2005 (Thursday)

Twistors, Amplitudes and Unitarity Methods

Regular Seminar Emil Bjerrum-Bohr (Swansea)

at:
14:00 QMW
room 112
abstract:

05.10.2005 (Wednesday)

Gauged sigma models and generalised geometry

Triangular Seminar Jose Figueroa-O'Farrill (Edinburgh)

at:
15:00 QMW
room 410
abstract:

05.10.2005 (Wednesday)

Quantum corrections to spinning strings

Triangular Seminar Sakura Schafer-Nameki (Hamburg)

at:
16:30 QMW
room 410
abstract:

09.06.2005 (Thursday)

Noncentral extension of AdS superalgebra

Regular Seminar Jeong-Hyuck Park (IHES-Paris)

at:
16:00 IC
room H503
abstract:

Four dimensional N=4 super Yang-Mills theory contains a bigger superalgebra than AdS or superconformal algebra, su(2,2/4). It corresponds to a noncentral extension of the latter. The talk is for both physicsts and mathematicans interested in a novel way of obtaining noncentral extensions of Lie algebras.

19.05.2005 (Thursday)

Causality and locality in string and field theory

Regular Seminar Chong-Sun Chu (Durham)

at:
14:00 QMW
room 112
abstract:

10.11.2004 (Wednesday)

GUT spectrum from Heterotic Compactification

Regular Seminar Yang-Hui He (University of Pennsylvania)

at:
13:15 KCL
room 423
abstract:

25.10.2004 (Monday)

Correlation functions from spin chains with impurities

Triangular Seminar Olalla Castro-Alvaredo (Ecole Normale Superieure de Lyon)

at:
15:00 City U.
room Geary Room CM524
abstract:

In this talk I will present a short review on the algebraic Bethe ansatz technique and on the recently found solution of the so-called inverse problem. I will show how this solution provides a means for the explicit and exact computation of correlation functions in spin chains and summarize some of the many results obtained in this direction by members of the theory group at the ENS-Lyon in the last years. Finally I will present some work still in progress which intends the generalization of these techniques to the case of spin chains in the presence of impurities.

21.10.2004 (Thursday)

Symmetry and supersymmetry in M-theory backgrounds

Regular Seminar Jose' Figueroa-O' Farrill (Edinburgh)

at:
14:00 QMW
room 112
abstract: