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.
Found at least 20 result(s)
Regular Seminar Yoshinori Matsuo (Crete)
at: 14:00 room H503  abstract: Nonequilibrium black hole horizons are considered in scaling theories with generic Lifshitz invariance and an unbroken U(1) symmetry. There is also chargehyperscaling violation associated with a nontrivial conduction exponent. The boundary stress tensor is computed and renormalized and the associated hydrodynamic equations derived. Upon a nontrivial redefinition of boundary sources associated with the U(1) gauge field, the equations are mapped to the standard nonrelativistic hydrodynamics equations coupled to a mass current and an external Newton potential in accordance with the general theory of [arXiv:1502.00228]. The shear viscosity to entropy ratio is the same as in the relativistic case. 
Regular Seminar Saso Grozadanov (Leiden)
at: 14:00 room H503  abstract: Holography is a tool that can be most readily applied to studies of transport properties in gauge theories with infinitely strong interactions. Coupling constant corrections can then be incorporated through higherderivative (alphaprime) corrections to the supergravity action in the bulk. In the first part of this talk, I will discuss the dependence of higherorder hydrodynamic transport (beyond NavierStokes) and the higherfrequency (quasinormal) spectrum on the coupling constant in duals of Type IIB supergravity and curvaturesquared theories. In relation to the membrane paradigm, I will then present higherorder generalisations of the universal "eta over s" relation and universal anomalous conductivities at finite coupling. Recently, studies of holographic transport in the presence of broken translational symmetry and disorder have received much attention. In particular, it has been shown how thermoelectric conductivities can be computed by using the membrane paradigm. Through the power of the membrane paradigm and with a view towards future models of manybody localisation without hydrodynamic transport, in the second part of this talk, I will discuss the proofs of the lower bounds on thermal and electrical conductivities in a large family of holographic theories with arbitrarily strong disorder. 
Exceptional Seminar Cindy Keeler (NBI)
at: 14:00 room H503  abstract: After a review of the quasinormal mode method for partition function calculation developed by Denef, Hartnoll, and Sachdev, we study a scalar in AdS2. We find a series of zero modes with negative real values of the conformal dimension whose presence indicates a series of poles in the oneloop partition function. The contribution of these poles to the AdS partition function at physical mass values matches previous results. Additionally, extending our results to AdS in any even dimension 2n, we find a similar series of zero modes related to discrete series representations of SO(2n,1), and successfully calculate the oneloop determinant from these modes. Finally, we speculate on the physical meaning of these nonphysicalmass modes. 
Regular Seminar Iva Lovrekovic (Vienna)
at: 13:30 room H503  abstract: We compute the heat kernel for the Laplacians of symmetric transverse traceless fields of arbitrary spin on the AdS background in even number of dimensions using the group theoretic approach and apply it on the partition function of six dimensional conformal gravity. The obtained partition function consists of the Einstein gravity, conformal ghost, partially massless mode and massive mode. 
Triangular Seminar Nadav Drukker (KCL)
at: 15:00 room LT3 Level 1 Blackett  abstract: Matrix models are toy models for quantum field theories. They can be extremely complicated but can also be solved in a variety of ways. In my talk I will discuss general properties of matrix models and their solutions and focus on particular matrix models that arise in the study of 4d SUSY field theories. Those matrix models describe the index of the field theory, counting the number of states of the theory (with + sign for a boson and  for a fermion) and have been known for over 10 years. Though they look very complicated I will show how some simple tricks allow in certain cases to solve those matrix models exactly in terms of elementary functions. My talk will focus on the matrix model calculation and no specialized knowledge of SUSY field theories or indices would be required to follow it. 
Regular Seminar Massimiliano Rota (Durham)
at: 14:00 room H503  abstract: Entanglement entropy is a very important quantity in holography, nevertheless it is only a measure of the total amount of entanglement between two complementary subsystems in a global pure state. A more detailed knowledge about the pattern of entanglement is essential for a deeper understanding of the relation between bulk geometry and quantum information in the boundary theory. I will discuss how negativities and other measures can be used in this context focusing in particular on qubit systems for which a classification of possible entanglement structures is available. 
Regular Seminar Blaise Gouteraux (Stanford)
at: 14:00 room H503  abstract: In this talk, I will summarize recent progress in the description of thermoelectric transport using gauge/gravity duality. I will first review thermoelectric transport in hydrodynamics, where momentum conservation implies infinite zerofrequency conductivities. By a change of basis of the conserved currents, a universal, finite conductivity can be extracted. It can be computed holographically. I will discuss its lowtemperature scaling in terms of critical exponents characterizing time and space anisotropy and anomalous dimensions for the free energy and conserved current. When momentum is almost conserved, the zerofrequency delta functions broaden into Drudelike peaks. A holographic computation precisely identifies the redistribution of the lowfrequency spectral weight between two contributions originating from the nonconservation of momentum and intrinsic dissipation respectively. It also sheds some light on how to construct effective theories of thermoelectric transport when momentum is not conserved. 
Regular Seminar Andrea Amoretti (Cambridge)
at: 14:00 room H503  abstract: Gauge/gravity duality can be used to study the transport properties of strongly interacting systems with no quasiparticles. I will give an overview of some holographic toy models of states like this, in which momentum is not conserved and thus the transport of energy and charge is nontrivial. Specifically I will discuss the thermoelectric transport properties of these toy models and their possible relations to the phenomenology of the strange metals. 
Regular Seminar Peter Goddard (IAS)
at: 14:00 room H503  abstract: Describing work in collaboration with Louise Dolan, I will discuss the scattering equations, originally introduced in 1972 by Fairlie and Roberts searching for new dual models, rediscovered by Gross and Mende in 1988, discussing the high energy behaviour of string theory, and more recently shown by Cachazo, He and Yuan to provide a kinematic basis for describing remarkable formulae for tree amplitudes for massless particles in arbitrary spacetime dimension (including scalars, gauge bosons and gravitons). We reformulate the scattering equations for N particles as a system of N 3 homogeneous polynomial equations in N  2 complex variables, which are linear in each variable separately. The linearity of the equations enables their explicit solution in terms of the roots of a singlevariable polynomial of degree (N3)!, which can itself be explicitly constructed in terms of the Mandelstam variables formed from the momenta. The possible extension to one loop and the special case of fourdimensional spacetime will also be briefly discussed. 
Regular Seminar Julian Sonner (University of Geneva)
at: 14:30 room H503  abstract: The recent focus on entanglement entropy in holography has many motivations, ranging from the applied (e.g. AdS/CMT) to the foundational (emergence of gravity). For all of these programs It is important to find examples, where the quantities of interest can be directly calculated in stronglycoupled field theories and, moreover, the dual geometry constructed at strong coupling. In this talk I will describe joint work with Crossley and Dyer on using localization methods to obtain entanglement and (super) Renyi entropies of the N=4 SYM theory with gauge group SU(N) in 4D at all values of the ’t Hooft coupling \lambda and number of colors N. Since obtaining quantities like entanglement and Renyi entropies involves working on singular spaces, which typically break the supersymmetry, we focus on a supersymmetric generalization, the socalled superRenyi entropy where the supersymmetry breaking effects of the singularities are suitably compensated. I will also discuss dual gravity solutions as fivedimensional BPS black holes with hyperbolic horizon. I will conclude with a description of Wilson loops, that is the contribution to the entanglement and Renyi entropies due to adding fundamental matter to the theory. 
Triangular Seminar Jan de Boer (Amsterdam U.)
at: 15:00 room LT1  abstract: While a lot of work has been done on understanding thermalization in 2d CFTs, several confusing aspects remain, in particular regarding integrable aspects of 2d CFTs. In this talk I will try to summarize some of these confusions and how these connect to AdS/CFT and black hole formation. There appears to be a significant difference between thermalization in low c CFTs versus thermalization in large c CFTs with gravitational duals. 
Triangular Seminar Aristomenis Donos (Durham U.)
at: 16:30 room LT1  abstract: Certain materials, such as the cuprate superconductors and heavy fermion materials exhibit fascinating, yet hard to explain transport properties. Holography provides a consistent framework to examine linear response and in particular transport of strongly coupled matter. I will discuss momentum dissipation in holography and show that DC transport is fixed via a Stokes flow of an "auxiliary fluid" residing on the horizon of black holes. 
Regular Seminar Masahito Yamazaki (Kavli IPMU)
at: 14:00 room H503  abstract: I will discuss knotlike defects in CS theory with complex gauge group SL(N), in the context of its connection with 3d N=2 theory (the socalled 3d3d correspondence). I am hoping to discuss this problem from a number of different perspectives, including cluster algebras, stateintegral models, 3d N=2 nonAbelian gauge theories, 5d N=2 SYM, and holographic dual, and discuss the consistency checks as well as new predictions/implications. This talk is mostly based on my recent papers with D. Gang, N. Kim and M. Romo. 
Exceptional Seminar Antonio Pittelli (Surrey University)
at: 13:30 room H503  abstract: Dual superconformal symmetry is a remarkable, hidden feature of N=4 SYM in 4 dimensions. Via AdS/CFT, such a symmetry corresponds to the invariance of the AdS(5) x S(5) superstring under specific combinations of bosonic and fermionic Tdualities. We show that AdS(d) x S(d) x S(d) superstrings with D(2,1;\alpha) isometry supergroup are Tselfdual if additional Tdualities along complexified S(d) directions are performed. This implies that CFTs dual to AdS(d) x S(d) x S(d) x T(103d) superstrings enjoy a new type of dual superconformal symmetry. 
Exceptional Seminar Massimo Taronna (AEI)
at: 13:30 room H503  abstract: The aim of this talk is to extract the quadratic corrections to Fronsdal equations from Vasiliev's equations, and discuss their structure. The issue of locality in higherspin theories will be addressed. Implications of this analysis in relation to GiombiYin checks of higherspin/vector model duality will be discussed. Some of the previous puzzles will be resolved, while others will be elucidated. 
Regular Seminar Ehsan Hatefi (Queen Mary)
at: 14:00 room H503  abstract: We would like to talk about all kinds of supersymmetric and nonsupersymmetric scattering amplitudes of type IIA,IIB superstring theory as well as their corrections. In fact we want to address how to get to a universal conjecture for DBI, ChernSimons and more importantly new Wess Zumino actions with their all order $\alpha'$ corrections. Indeed we try to provide a comprehensive explanation even for D braneanti Dbrane systems, where various new techniques will be also introduced. If time allows , we then mention several issues related to those effective actions and eventually highlight some comments about higher point functions of the Mixed closed string RR , scalar fields in different pictures of the string theory amplitude. 
Regular Seminar Jose FernandezMelgarejo (Harvard)
at: 13:30 room H503  abstract: We study the general formulation of gauged supergravity in seven dimensions with sixteen supercharges keeping duality covariance by means of the embedding tensor formalism. We first classify all inequivalent duality orbits of consistent deformations. Secondly, we analyse the complete set of critical points in a systematic way. Interestingly, we find the first examples of stable de Sitter solutions within a theory with such a large amount of supersymmetry. 
Regular Seminar Branislav Jurco (Charles University/MPIM)
at: 14:00 room H503  abstract: We introduce connection, torsion and curvature for Courant algebroids. We discuss in detail torsionless connections compatible with a generalized metric and the related EinsteinHilbert actions. 
Regular Seminar Kazutoshi Ohta (Meiji Gakuin University)
at: 13:00 room H503  abstract: We derive the localization formula for N=4 supersymmetric quiver quantum mechanics in the Higgs and Coulomb branch. The partition function (index) is exactly evaluated and it is shown that the path integral is localized at fixed points, which are given by solutions to the BRST equations combined with Dterm and Fterm conditions. We give various examples of the quiver theory and classifications of their fixed points. The indexes completely agree with the mathematical wall crossing formulae for the quiver moduli spaces. We also discuss a gravitational picture of the localization in the Coulomb branch. 
Regular Seminar Peter Koroteev (PI)
at: 14:00 room H503  abstract:
