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)

13.03.2013 (Wednesday)

The Quest for the Higgs Boson at the LHC

Exceptional Seminar Jim Virdee (Imperial)

at:
15:30 IC
room Lecture Theatre 1, Blackett Lab
abstract:

In July 2012 ATLAS and CMS experiments reported the discovery of a Higgs-like boson, most likely confirming the mechanism for generation of mass of fundamental particles put forward by Higgs, Kibble and others in the 1960’s. An outline of the challenges faced during the construction of both the LHC and the experiments will be presented as well as an overview of the current operation and performance. Selected physics results and future aims, in particular those relating to the discovery of the Higgs-like boson, will be discussed. [Symmetry and Fundamental Physics - Tom Kibble at 80]

13.03.2013 (Wednesday)

Tom Kibble: breaking symmetries, breaking ground and the new boson

Colloquium Steven Weinberg (Univ. of Texas at Austin)

at:
18:00 IC
room Great Hall, Sherfield building
abstract:

The talk will describe my first interaction with Tom Kibble, when I visited Imperial College in 1961-2; Tom's ground-breaking work on broken symmetry and the Higgs boson; and how a 1967 paper by Tom laid the foundation for understanding the photon. [Symmetry and Fundamental Physics - Tom Kibble at 80]

27.02.2013 (Wednesday)

Non-Abelian T-duality in sypergravity and the AdS/CFT correspondence

Regular Seminar Konstadinos Sfetsos (Surrey)

at:
14:00 IC
room H503
abstract:

We will explain the notion of T-duality in supergravity backgrounds with non-Abelian isometries and non-vanishing RR fluxes. We will then focus on type-II backgrounds on which the duality action preserves supersymmetry. For the case of D3-branes at the tip of the conifold dualising along an SU(2) isometry provides a type-IIA background with M-theory lift is of the type describing duals to certain N=1 SCFT quivers produced by M5-branes wrapping a Riemann surface. In the non-conformal cases we find smooth duals in massive IIA supergravity with a Romans mass naturally quantised. We initiate the interpretation of these geometries in the context of the AdS/CFT correspondence and discuss the fate of various charges under dualisation. The backgrounds suggest a form of Seiberg duality in the dual field theories which also exhibit domain walls and confinement in the infrared.

21.02.2013 (Thursday)

Exact Results in 2d SUSY Theories and Applications

Regular Seminar Sungjay Lee (DAMTP, Cambridge)

at:
14:00 IC
room B741
abstract:

I will present the exact computation of the two-dimensional supersymmetric theories on two-sphere using the localization techniques. I will then apply these new results to study type II string compactifications (with emphasis on the exact Kaehler potential of quantum Kaehler moduli of Calabi-Yau geometry and mirror symmetry) and non-rational CFTs.

13.02.2013 (Wednesday)

Supersymmetry invariants and UV divergences in N=4 supergravity

Regular Seminar Guillaume Bossard (CPHT, Ecole Polytechnique)

at:
14:00 IC
room H503
abstract:

I shall discuss the structure of supersymmetry invariants in N=4 supergravity coupled to n vector multiplets, and in particular their transformation properties with respect to duality symmetry. This will permit to discuss the anomalous Ward identities for the duality symmetry, and their consequences on the logarithmic divergences of the theory.

06.02.2013 (Wednesday)

Supersymmetric Field Theories on Three-Manifolds and Applications

Regular Seminar Cyril Closset (Weizmann)

at:
14:00 IC
room H503
abstract:

In the first part of my talk, I will present a general classification of Riemannian three-manifolds on which one can put 3d N=2 supersymmetric field theories while preserving some amount of supersymmetry. This formalism clarifies the relationship between the extra couplings necessary to preserve supersymmetry in curved space, on the one hand, and various operators of the flat space theory, on the other hand. In the second part of the talk I will present some simple applications of this formalism. In particular I will present exact results for various two-point functions of N=2 SCFTs which were hitherto out of reach.

04.02.2013 (Monday)

Classical and Quantum N=8 Supergravity

Exceptional Seminar Gianguido Dall'Agata (Padova)

at:
14:00 IC
room H503
abstract:

I will present a series of new results on classical and quantum properties of maximal supergravity in 4 dimensions, emphasizing the role of the recently discovered "new SO(8) theories". I will explain how this changes our understanding of some general properties of supergravity theories and comment on the impact of these results on the gauge/gravity correspondence.

31.01.2013 (Thursday)

Deformed Seiberg-Witten curves for ADE quivers

Exceptional Seminar Daniel Ricci Pacifici (Padova)

at:
14:00 IC
room B741
abstract:

We study N=2 ADE quiver gauge theories in presence of a non-trivial Omega background along a two dimensional plane. In particular we perform a saddle point analysis to the partition function and derive an epsilon-deformed version of Seiberg-Witten like equations. The result can be interpreted as a non-commutative version of the standard Seiberg-Witten curves associated to the quiver theories.

30.01.2013 (Wednesday)

Holographic d-wave superconductors

Regular Seminar Marika Taylor (Southampton)

at:
14:00 IC
room H503
abstract:

In recent years there has ben considerable interest in using holographic methods to model strongly interacting condensed matter systems, including unconventional superconductors. However, many high Tc superconductors exhibit d-wave pairing and a satisfactory holographic realization of d-wave superconductors has been elusive. In this talk we will present a top down model for d-wave superconductors and discuss its phenomenology.

16.01.2013 (Wednesday)

Takiff superalgebras and related CFT

Regular Seminar Andrei Babichenko (Weizmann)

at:
13:30 IC
room B630
abstract:

A class of non-semisimple extensions of Lie superalgebras is studied. They are obtained by adjoining to the superalgebra its adjoint representation as an abelian ideal. When the superalgebra is of affine Kac-Moody type, a generalisation of Sugawara’s construction is shown to give rise to a copy of the Virasoro algebra and so, presumably, to a conformal field theory. Evidence for this is detailed for the extension of the affinisation of the superalgebra gl (1|1): Its highest weight irreducible modules are classified using spectral flow, the irreducible supercharacters are computed and a continuum version of the Verlinde formula is verified to give non-negative integer structure coefficients. Interpreting these coefficients as those of the Grothendieck ring of fusion, partial results on the true fusion ring and its indecomposable structures are deduced.

09.01.2013 (Wednesday)

Yet another duality: Nichols algebras and logarithmic two-dimensional CFT models

Regular Seminar Alexei M. Semikhatov (Lebedev Physical Institute)

at:
14:00 IC
room H503
abstract:

The task of classifying logarithmic conformal field theories, traditionally considered beyond reach, has become feasible by identifying an algebraic object that largely captures this classification. In some sense, the relevant algebraic tool is a braided analogue of the Howe/Schur--Weyl duality.

12.12.2012 (Wednesday)

Quantum gravity at one-loop and AdS/CFT

Regular Seminar Marcos Marino (Geneva U.)

at:
14:00 IC
room H503
abstract:

In the AdS/CFT correspondence, gauge theory calculations beyond the planar approximation correspond to quantum corrections in gravity or in string theory. Recently, the partition function on the three-sphere of Chern-Simons-matter theories has been computed at all orders in the 1/N expansion, and this leads to predictions for quantum corrections in M-theory/string theory. Using the ideas of effective field theory, we show that some of these corrections can be calculated reliably by doing one-loop calculations in supergravity. A similar reasoning has been used recently to calculate logarithmic corrections to black hole entropy, and we use it here to perform a successful test of AdS_4/CFT_3 beyond the leading, planar approximation.

05.12.2012 (Wednesday)

Curved geometries for rigid supersymmetry

Regular Seminar Davide Cassani (King's College)

at:
14:00 IC
room H503
abstract:

Supersymmetry on curved spaces has recently attracted much attention, mainly as a tool towards the exact computation of quantum field theory observables via localization. Taking a holographic perspective, I will discuss how the conditions for rigid supersymmetry to be preserved on a curved boundary arise from the bulk supergravity Killing spinor equations. In particular, I will show that a four-dimensional superconformal field theory can be put on a curved, Lorentzian spacetime if and only if this admits a null conformal Killing vector. For a supersymmetric field theory with an R-symmetry, not necessarily conformal, the vector is further restricted to be Killing. After having presented some illustrative examples, I will conclude comparing with the Euclidean case.

03.12.2012 (Monday)

Higher-spin cubic interactions and holography

Exceptional Seminar Euihun Joung (SNS, Pisa)

at:
14:00 IC
room B741
abstract:

Some issues of higher-spin (HS) gauge theory (in d+1>3) related to its cubic interactions and holography are discussed. After providing a very brief overview on the topic, I show how to construct all gauge consistent cubic interactions using the ambient-space formulation. Its number matches that of all possible 3pt functions, recently derived by other groups. However only one vertex corresponds to the free scalar CFT on the boundary, hence the metric-like version of the vertex encoded in Vasiliev's equation.

02.12.2012 (Sunday)

Quantum mechanical models, cellular automata and a discrete action principle

Regular Seminar Thomas Elze (Pisa University)

at:
13:30 IC
room H503
abstract:

It will be shown that the dynamics of discrete (integer-valued) Hamiltonian cellular automata can only be consistently defined, if it is linear in the same sense that unitary evolution in quantum mechanics is linear. This suggests us to look for an invertible map between such automata and continuous quantum mechanical models. Based on sampling theory, such a map can indeed be constructed and leads to quantum mechanical models which incorporate a fundamental scale. The admissible observables, the one-to-one correspondence of the respective conservation laws, and the existence of solutions of the modified dispersion relation for stationary states are discussed. References: H.-T. Elze, Action principle for cellular automata and the linearity of quantum mechanics, Phys. Rev. A 89, 012111 (2014) [arXiv:1312.1615]; do., Journal of Physics: Conference Series 504 (2014) 012004 [arXiv:1403.2646].

20.11.2012 (Tuesday)

WZW term in Permutation Cosets

Regular Seminar Alessandra Cagnazzo (Nordita)

at:
13:30 IC
room H503
abstract:

The study of Superstring Theories on AdS backgrounds is important in the context of Gauge/Gravity correspondence. These theories can be reduced, under certain assumptions, to Sigma Models on semi-symmetric super-cosets. For a peculiar class of these cosets one can also introduce a WZW term. This correspond to study a Superstring Theory on a background supported by a mixture of RR and NSNS fluxes, as can happen for theories on $AdS_3\times S^3 \times M_4$. I will show the effect of this term on Integrability, Kappa symmetry and conformality of the theory, computing also the BMN spectrum in some relevant case for $AdS_3/CFT_2$ correspondence.

14.11.2012 (Wednesday)

Wall-crossing, multi-centered black holes and quivers

Regular Seminar Boris Pioline (LPTHE Jussieu and CERN)

at:
14:00 IC
room H503
abstract:

BPS states in N=2 gauge theories or string vacua are generically stable but liable to decay across certain codimension-one loci in moduli space. This process is easily understood by viewing BPS states as a bound state of more elementary BPS constituents, described classically by multi-centered solutions of the low energy effective action. The semi-classical quantization of the space of such solutions agrees with the wall-crossing formulae derived in the mathematical literature on BPS invariants, providing a physically elementary justification of the latter. Using this intuition, it is possible to express the BPS index, at any point in moduli space, in terms of indices associated to elementary (or single-centered) constituents. If time permits, I will present evidence for this idea in the case of BPS states described by quiver representations.

07.11.2012 (Wednesday)

The AdS5xS5 string spectrum, Pohlmeyer reduction and quantum deformations

Regular Seminar Stijn van Tongeren (ITP and Spinoza Inst., Utrecht)

at:
14:00 IC
room H503
abstract:

In the setting of integrability in AdS/CFT, in the typical approach to the AdS_5 x S^5 string a light-cone gauge is fixed, breaking Lorentz invariance on the worldsheet. One attempt to avoid the need for this goes under the name of Pohlmeyer reduction. Recently an S-matrix was conjectured to describe the scattering of solitons in this theory. Now as I will explain in my talk, the S-matrix of an integrable quantum field theory together with its dispersion relation are enough to find its finite volume spectrum exactly, through the so-called thermodynamic Bethe ansatz. I will work this out for an S-matrix and dispersion that interpolate between the standard light-cone gauge fixed superstring and this conjectured Pohlmeyer S-matrix, by analogy to a simpler model. Viewed as a deformation of the light-cone gauge fixed superstring TBA, this story is very similar to deforming the XXX spin chain to the XXZ one, which I will concretely discuss. I will finish by emphasizing important differences to this simple toy model, and discuss surprises in the so-called Y-system associated to the TBA equations.

31.10.2012 (Wednesday)

Anomalous Transport from Kubo Formulae

Regular Seminar Karl Landsteiner (IFT, UAM)

at:
14:00 IC
room H503
abstract:

Chiral anomalies have profound impact on the transport properties of relativistic fluids. They are closely related to the creation of currents by magnetic fields or vortices in the fluid via the so called Chiral Magnetic Conductivity and the Chiral Vortical Conductivity. Both can be computed by Kubo type formulae from special kinematic limits of two point functions of currents. I will review the calculation of these conductivites in a gas of free Weyl fermions and at strong coupling via a holographic model. A special and somewhat mysterious role is played by the mixed gauge-gravitational anomaly.

24.10.2012 (Wednesday)

Towards a taxonomy of extremal black brane geometries

Triangular Seminar Shamit Kachru (Stanford and SLAC)

at:
15:00 IC
room Blackett, Lecture Theatre 2
abstract: