## Directions

Imperial College has its own detailed information on general directions and on getting to the theoretical physics group. The College is located on Prince Consort Road, south of Hyde Park (map). The most convenient access is via tube (South Kensington, Gloucester Road) or buses. The Theoretical Physics group resides on the 5th floor of the Huxley Building. The group also possesses its own description.

## Seminars at Imperial College

Found at least 20 result(s)

### 11.11.2014 (Tuesday)

#### String Compactifications, Dark Radiation and a 0.1-1 keV Cosmic Axion Background

Regular Seminar Joseph Conlon (Oxford U., Theor. Phys.)

 at: 13:30 ICroom H503 abstract:

### 05.11.2014 (Wednesday)

#### Gerbes on the Lattice

Regular Seminar Ron Reid-Edwards (Hull)

 at: 14:00 ICroom H503 abstract: Abelian gerbes play a ubiquitous role in string and supergravity theories. It is conjectured that non-abelian gerbe theories exist, but a satisfactory explicit construction of such a theory has not yet been achieved. Inspired by the possibility that a non-abelian theory of gerbes may be possible on non-conventional spacetimes, I will consider a toy model on a lattice that allows one to make some progress in this problem. In this talk, I will show how abelian gerbe theories may be described naturally on the lattice. I will outline a non-abelian generalisation and show how, under dimensional reduction, such theories give rise to lattice Yang-Mills.

### 29.10.2014 (Wednesday)

#### From higher spins to strings: a constructive approach

Regular Seminar Massimo Taronna (Potsdam)

 at: 14:00 ICroom H503 abstract: Starting from some examples, I will review various implications of classical consistency that have played a key role in the context of higher-spin theories (Vasiliev's equations) and holography. I will then review the current understanding higher-spin interactions involving totally-symmetric higher-spin fields and the associated classification of higher-spin algebras generalizing Coleman-Mandula theorem in the context of AdS/CFT. Finally, I will discuss the extension of this analysis to massive higher spins, towards a new understanding of string theory.

### 22.10.2014 (Wednesday)

#### Anatomy of the amplituhedron

Regular Seminar Daniele Galloni (Durham)

 at: 14:00 ICroom H503 abstract: I will present this very recently proposed geometric object, conjectured to give the N=4 SYM scattering amplitudes at all orders, and illustrate the techniques used to fully explore its structure. In so doing I will give firm nontrivial evidence to the amplituhedron conjecture.

### 22.10.2014 (Wednesday)

#### Aspects of Higher Spin Symmetries in Various Dimensions

Regular Seminar Karan Govil (U. Penn)

 at: 14:30 ICroom H503 abstract: The algebras of higher spin symmetries in conformal field theories in four and six dimensions are not unique and have a richer structure due to the existence of infinite short multiplets besides the usual scalar and spinor. We will focus on recent results that show there exists a one parameter family (continuous of d=4 and discrete for d=6) of higher spin algebras and superalgebras, and give an explicit unitary representation for these algebras using quasiconformal methods. We will also discuss the implications of these results for the AdS5/CFT4 and AdS7/CFT6 higher spin holography.

### 15.10.2014 (Wednesday)

#### A universal correction to higher spin entanglement entropy

Regular Seminar Michael Ferlaino (Swansea)

 at: 14:00 ICroom H503 abstract: Within the context of the duality between higher spin gravitational theories and a semi- classical limit of W_N minimal models, we consider 2D CFTs with W_∞ symmetry at finite temperature, deformed by the presence of a chemical potential for the spin–three current. As a perturbative expansion in the chemical potential, we compute the Renyi and entanglement entropies for a single interval. The leading correction is universal and matches the holographic result, based on Wilson line functionals, obtained from the higher spin gravitational dual.

### 15.10.2014 (Wednesday)

#### 3d and 5d gauge theory partition functions as q-deformed CFT correlators

Regular Seminar Fabrizio Nieri (Surrey)

 at: 14:30 ICroom H503 abstract: In recent years, due to the method of supersymmetric localization, many exact results have been achieved in the study of supersymmetric gauge theories on compact spaces of various dimension and topology, leading to the discovery of surpraising structures. An important example is provided by the correspondence introduced by Alday, Gaiotto and Tachikawa, relating the partition functions of a large class of supersymmetric gauge theories on S4 and S2 to correlators in Liouville CFT. In this talk, I will explain how this picture can be lifted to higher dimensional gauge theories via the correspondence of partition functions on S5, S4xS1, S3 and S2xS1 to correlators in theories whose underlying symmetry is given by a quantum deformation of the Virasoro algebra. In particular, I will discuss how 3-point functions can be derived by the bootstrap approach and used to define this novel class of q-deformed CFTs. I will also discuss some aspects related to integrable structures in these models, such as reflection coefficients, as well as possible generalisation.

### 14.10.2014 (Tuesday)

#### Superalgebras and supersymmetry in low dimensional lattice systems

Regular Seminar Sarben Sarkar (King's College London)

 at: 13:30 ICroom H503 abstract: It will be shown how supersymmetry and superalgebras arise in lattice models both in one and higher dimensions. Examples using correlated fermions and bosons will be primarily used. Some of the examples will have associated superalgebras and others will have supersymmetry more commonly used in field theory. Some aspects of continuum limits will also be touched upon.

### 13.10.2014 (Monday)

Exceptional Seminar Sonnenschein Jacob (Tel Aviv)

 at: 14:00 ICroom H503 abstract: I will show that the non-stringy holographic description of hadrons, namely the one based on fields that reside on the bulk and flavor branes, fails to reproduce the hadronic spectra. I will briefly review the stringy duals of Wilson loops and determine the sufficient conditions of confining backgrounds. I will show that the latter are also the requirements for holographic stringy mesons to admit a Regge-like spectrum. I will determine a map between holographic stringy mesons and strings with massive endpoints in 4d flat space-time. Models of classical rotating strings with massive endpoints will be written down. I will discuss the (still unsolved) quantization of such systems. Fits of the models to mesonic data will be presented. A universal model that describes mesons of u,d,s,c quarks will be developed. Mesons with b quarks will also be fitted. I will describe the construction of stringy baryons in holography. I will show that the best description of baryons is in terms of a single string with a quark and a di-quark on its ends. I will present fits of such a model to the baryonic data. Finally I will describe the stringy decays of holographic hadrons.

### 08.10.2014 (Wednesday)

#### Short-range entangled phases and topology

Triangular Seminar Anton Kapustin (SCGP)

 at: 15:00 ICroom Lecture Theatre 3, Blackett abstract:

### 01.10.2014 (Wednesday)

#### Regge theory for correlation functions in CFTs

Regular Seminar Vasco Goncalves (U. do Porto)

 at: 14:00 ICroom H503 abstract: In this talk we will try to motivate why the study of the Regge limit in a correlation function of a conformal field theory is interesting. We will review the results obtained in the past few years and present some on going work in phi^3 theory using skeleton expansion.

### 29.09.2014 (Monday)

#### Twistor Origin of the Superstring

Exceptional Seminar Nathan Berkovits (Sao Paulo)

 at: 14:00 ICroom H503 abstract:

### 18.06.2014 (Wednesday)

#### Scattering amplitudes in certain gauged supergravity theories

Regular Seminar Radu Roiban (Penn State)

 at: 14:00 ICroom H503 abstract:

### 11.06.2014 (Wednesday)

#### Heterotic NS5-branes from closed string tachyon condensation

Regular Seminar Inaki Garcia Etxebarria (MPI, Munich)

 at: 14:00 ICroom H503 abstract: I will show how to construct the familiar heterotic NS5 brane as a topological soliton in a supercritical version of heterotic string theory. Closed string tachyon condensation removes the extra dimensions, leaving the NS5 in 10d, in a process highly reminiscent of the K-theoretical description of type II D-branes, but linking non-trivial gauge bundles and geometry. The construction requires a modification of the anomalous Bianchi identity for H_3 in supercritical heterotic string theory. I will give various proofs for the existence of this modification.

### 04.06.2014 (Wednesday)

#### N = (0, 2) Heterotic Sigma Models: Geometric Structure, Holomorphic Anomaly and Exact Beta Functions

Regular Seminar Xiaoyi Cui (MPI, Bonn)

 at: 14:00 ICroom H503 abstract: We study geometric aspects and holomorphic properties of N = (0, 2) Heterotic Sigma Models over symmetric spaces, and derive a number of exact relations for the β functions in terms of the analogy to the NSVZ β function in four-dimensional Yang-Mills. We will show that in spite of the heterotic nature, the isometries are preserved at the quantum level. We will also discuss the N = (0, 2) supercurrent multiplet (the so-called hypercurrent) and its anomalies, as well as the “Konishi anomaly.” This gives us another method for ﬁnding two-loop β functions. The talk is based on joint work with J. Chen, M. Shifman and A. Vainshtein.

### 28.05.2014 (Wednesday)

#### Geometric Constraints in Heterotic/F-theory Duality

Regular Seminar Lara Anderson (Virginia Tech)

 at: 14:00 ICroom H503 abstract: We systematically analyze a broad class of dual heterotic and F-theory models that give four-dimensional supergravity theories, and compare the geometric constraints on the two sides of the duality. In this talk I will show that F-theory gives new insight into the conditions under which heterotic vector bundles can be constructed. We show that in many cases the F-theory geometry imposes a constraint on the extent to which the gauge group can be enhanced, corresponding to limits on the way in which the heterotic bundle can decompose. We explicitly construct all dual F-theory/heterotic pairs in the class under consideration where the common twofold base surface is toric, and give both toric and non-toric examples of the general results. Finally, we provide evidence for important new aspects of G-flux in four-dimensional compactifications.

### 27.05.2014 (Tuesday)

#### (Non)-Integrability of Geodesics in D-brane Backgrounds

Exceptional Seminar Oleg Lunin (Unveristy of Albany)

 at: 13:30 ICroom H503 abstract: Motivated by the search for new backgrounds with solvable string theories, the talk classifies the D-brane geometries leading to integrable geodesics. This analysis gives severe restrictions on the potential candidates for integrable string theories. It is demonstrated that the Hamilton-Jacobi equation for massless geodesics can only separate in elliptic or spherical coordinates, all known integrable backgrounds are covered by this separation, and new examples are constructed. The Killing and Killing-Yano tensors associated with such separation and their transformations under string dualities are also discussed.

### 14.05.2014 (Wednesday)

#### Generalized entropy and higher derivative Gravity

Regular Seminar Joan Camps (DAMTP Cambridge)

 at: 14:00 ICroom B1004 abstract: I will discuss the Maldacena-Lewkowycz derivation of the Ryu-Takayangi prescrition for holographic entanglement entropy, and extend it to a more general class of theories of gravity in the bulk. This analysis results in a new euclidean entropy functional, that generalises Wald's entropy. In lorentzian signature, this functional is a natural extension of Wald's black hole entropy to time dependent situations.

### 09.05.2014 (Friday)

#### On M5 branes

Exceptional Seminar Kimyeong Lee (KIAS)

 at: 13:30 ICroom B539 abstract:

### 08.05.2014 (Thursday)

#### New results on AdS black holes

Regular Seminar Dietmar Klemm (Milano 1)

 at: 14:00 ICroom H503 abstract: We give a survey on recent results on the physics of black holes in four-dimensional anti-de Sitter space. In particular, we present a general recipe for constructing rotating black holes in N=2 matter-coupled gauged supergravity. Several physical aspects of these solutions are discussed, like their thermodynamics and dual hydrodynamical interpretation. It turns out that there exist new exotic black holes whose horizon is a noncompact manifold with finite volume. Finally, we show how to construct multi-centered black hole solutions in anti-de Sitter space.