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)

08.12.2021 (Wednesday)

TBA

Regular Seminar Andreas Schachner ()

at:
14:00 IC
room H503
abstract:

01.12.2021 (Wednesday)

tba

Regular Seminar Hongliang Jiang ()

at:
14:00 IC
room H503
abstract:

30.11.2021 (Tuesday)

Quasi-Normal Modes of Black-Holes and Branes from Quantum Seiberg-Witten Curves

Regular Seminar Massimo Bianchi (Universita degli studi di Roma Tor Vergata)

at:
14:00 IC
room Online and H342
abstract:

After reviewing the role Quasi-Normal Modes (QNMs) play in the Gravitational Wave (GW) signals emitted in the ring-down phase of Black-Hole (BH) mergers, we present a novel efficient approach to compute QNMs of BHs, D-branes and fuzz-balls, based on quantum Seiberg-Witten (SW) curves for N=2 supersymmetric Yang-Mills (SYM) theories. We find remarkable agreement with numerical results obtained by means of Leaver's method of continuous fractions and with `semi-classical' results obtained in the eikonal approximation, based on geodetic motion. Finally we discuss the extension to D3-branes and their bound states of Couch-Torrence (CT) conformal inversions, that exchange horizon and infinity, and show that they keep the photon-sphere (or photon-halo) fixed.

24.11.2021 (Wednesday)

tba

Regular Seminar Emanuel Malek ()

at:
14:00 IC
room zoom
abstract:

23.11.2021 (Tuesday)

The Higgs mass, UV/IR mixing and the effective field theory from a string perspective.

Regular Seminar Steve Abel (Durham)

at:
14:00 IC
room H324
abstract:

Almost all existing calculations that concern the Higgs mass are performed within the framework of an effective field theory. While sufficient for certain purposes, such calculations throw up problems to do with fine-tuning and naturalness in particular the famous hierarchy problem. This makes most attempts within field theory to understand the Higgs mass pretty much futile. Even most phenomenology done within string theory does not respect the full string symmetries that are responsible for many of the remarkable finiteness properties for which string theory is famous. Chief among these symmetries is worldsheet modular invariance, which is an exact symmetry of all perturtubative closed-string vacua. And yet if the UV is tamed by this symmetry then it should be exact even today! In this talk I will discuss the many things one can learn from this fact. For example that a gravitational modular anomaly generically relates the Higgs mass to the one-loop cosmological constant, yielding a string-theoretic connection between the two fundamental quantities which are known to suffer from hierarchy problems in the absence of spacetime supersymmetry. In addition one learns about the use and interpretation of modular invariant regulators in string theory, which in turn dictates how string theory arranges its UV/IR-mixing to make itself finite. Finally, I discuss how the effective field theory emerges showing that ultimately the Higgs mass can be understood as arising from an infinite “stringy” sum of Coleman-Weinberg effective potentials in such theories. The results can therefore serve as the launching point for a rigorous investigation of hierarchy problems in a UV complete theory.

17.11.2021 (Wednesday)

Superspin chains from superstring theory

Regular Seminar Faroogh Moosavian ()

at:
14:00 IC
room zoom
abstract:

The Bethe-Gauge Correspondence (BGC) of Nekrasov and Shatashvili, which relates 1d quantum integrable spin chains to two-dimensional supersymmetric gauge theories with \mathcal{N}=2 supersymmetry, is one of the instances of the deep connection between supersymmetric gauge theories and integrable models. The question that will be the main content of the talk is the origin of this correspondence. I will explain how the BGC could be naturally realized within superstring theory. Toward this aim, I will first explain The Bethe Side (noncompact rational integrable \mathfrak{gl}(m|n) superspin chains) and the corresponding Gauge Side of the BGC. I will then discuss the brane setup for the realization of The Gauge Side. Using string dualities, this brane setup will be mapped to another setup, which realizes The Bethe Side of the correspondence. An important role in this duality frame is played by the 4d Chern-Simons Theory of Costello which explains the integrability of The Bethe Side. If time permits, I will also explain the story for the compact rational integrable \mathfrak{gl}(m|n) superspin chains. This talk is based on the joint work (arXiv:2110.15112) with Nafiz Ishtiaque, Surya Raghavendran, and Junya Yagi.

16.11.2021 (Tuesday)

Aspects of Rotating Black Holes in Dynamical Chern-Simons Gravity

Regular Seminar Leah Jenks (Brown University)

at:
14:00 IC
room H342
abstract:

In this talk I will give an overview of recent and ongoing work regarding rotating black holes in dynamical Chern-Simons (dCS) gravity. dCS gravity is a well motivated modified theory of gravity which has been extensively studied in gravitational and cosmological contexts. I will first discuss unique geometric structures, `the Chern-Simons caps,' which slowly rotating black holes in dCS gravity were recently found to possess. Motivated by the dCS caps, I will then discuss superradiance in the context of slowly rotating dCS black holes and show that there are corrections to the usual solution for a Kerr black hole. Lastly, I will comment on the observable implications for these corrections and point towards avenues for future work.

10.11.2021 (Wednesday)

Defect Central Charges

Regular Seminar Adam Chalabi (Southampton)

at:
14:00 IC
room 503
abstract:

Conformal defects can be characterised by their contributions to the Weyl anomaly. The coefficients of these terms, often called defect central charges, depend on the particular defect insertion in a given conformal field theory. I will review what is currently known about defect central charges across dimensions, and present novel results. I will discuss many examples where they can be computed exactly without requiring any approximations or limits. These include defects in free theories, and recently developed tools for defects in superconformal field theories.

09.11.2021 (Tuesday)

Black holes, information and wormholes

Regular Seminar Geoff Penington (UC Berkeley and IAS)

at:
15:00 IC
room Online
abstract:

Hawking famously argued, based on semiclassical calculations, that the radiation from evaporating black holes is contains no information about the matter that fell in. This would be inconsistent with the unitarity of quantum mechanics. In this talk, I will show that, in more careful ‘replica trick’ calculations, the gravitational path integral becomes dominated at late times by saddles containing spacetime wormholes. These wormholes cause the entropy to decrease after the Page time, consistent with unitarity, and allow information to escape from the interior of the black hole.

03.11.2021 (Wednesday)

Geometric Engineering and Correspondences

Regular Seminar Michele Del Zotto (Uppsala)

at:
14:00 IC
room zoom
abstract:

Over the past decade we have witnessed the emergence of a plethora of correspondences between QFTs in various dimensions arising from higher dimensional SCFTs. In this talk I will overview another strategy to produce correspondences building upon geometric engineering techniques. As applications I will touch upon higher DT theory for Calabi-Yau 3-folds, the algebra of G(2) instantons, and generalizations of level/rank dualities.

02.11.2021 (Tuesday)

Spinning Black Holes Made Simple

Regular Seminar Alfredo Guevara (Harvard University)

at:
14:00 IC
room Huxley 342
abstract:

I will cover some of the most recent developments on classical spinning black holes and their perturbations. The reinterpretation of them in terms of a classical limit of QFT three-point amplitudes, where the black hole is modeled as a massive spinning particle, sheds light on many fundamental properties such as integrability, the Newman-Janis construction, and the so-called classical double copy relating the solution to gauge theory.

27.10.2021 (Wednesday)

Supersymmetric Yang--Mills theories on the lattice

Regular Seminar David Schaich (Liverpool)

at:
14:00 IC
room H503
abstract:

Lattice field theory provides a non-perturbative regularization suitable for strongly interacting systems, which has proven crucial to the study of quantum chromodynamics among many other theories. Lattice investigations of supersymmetric field theories have a long history but often struggle due to the interplay of supersymmetry with the lattice discretization of space-time. I will discuss a way around these difficulties for d-dimensional supersymmetric Yang--Mills theories with at least 2^d supercharges. After informally reviewing some highlights of the lattice formulation, I will survey a selection of results from recent and ongoing numerical studies, including tests of holographic dualities.

26.10.2021 (Tuesday)

Black hole microstates from the worldsheet

Regular Seminar David Turton (Southampton)

at:
14:00 IC
room Huxley 342
abstract:

I will describe recent studies of bound states of NS5 branes carrying momentum and/or fundamental string charge, in the decoupling limits leading to little string theory and to AdS3/CFT2 duality. This work involves a class of exactly solvable worldsheet models that describe families of BPS and non-BPS black hole microstates. These models have enabled studies of string and D-brane probes of these microstates, yielding insight into their stringy structure in the gravitational bulk description.

19.10.2021 (Tuesday)

New postdoc introduction

Regular Seminar David Tennyson and Morteza Hosseini (Imperial)

at:
1:30 IC
room B630
abstract:

Morteza Hosseini: "Microstates of AdS black holes in string theory." I’ll review recent advances of counting black holes microstates in AdS spacetimes. David Tennyson: "Supersymmetric flux backgrounds of string theory." I will review my work on the geometry of supersymmetric flux backgrounds of string theory through generalised geometry. In particular, I will introduce the exceptional complex structure and discuss some applications.

12.10.2021 (Tuesday)

Quantum algebras in supersymmetric gauge theories: interfaces and stable envelopes

Regular Seminar Nikita Nekrasov (SCGP, Stony Brook and Center for Advanced Studies, Skoltech, Moscow)

at:
13:20 IC
room B630
abstract:

I will give an overview of a three decade long project of novel symmetries in quantum field theory, with the emphasis on the most recent development concerning the realisation of stable envelopes (proposed by A. Okounkov and collaborators) and R-matrices via supersymmetric interfaces in 1-2-3 dimensional supersymmetric gauge theories. Based on the recent paper arXiv:2109.10941 with Mykola Dedushenko.

05.10.2021 (Tuesday)

Aspects of the black hole/string transition

Regular Seminar Yiming Chen (Princeton University)

at:
13:30 IC
room NA
abstract:

Abstract: It has long been speculated that a black hole in string theory turns into highly excited strings close to the Hagedorn temperature. Gravitational attraction pulls different parts of the string together, forming a star-like configuration. In this talk, I will review the properties of a concrete solution of this kind, first discovered by Horowitz and Polchinski. I will discuss whether the Horowitz-Polchinski solution can be smoothly connected with the black hole as worldsheet CFTs. I will also discuss how the story can be generalized to charged cases, as well as its implication on the near extremal limit.

29.06.2021 (Tuesday)

The classical interior of black holes in holography

Regular Seminar Sean Hartnoll (ITP Stanford University)

at:
13:30 IC
room zoom 871 9223 5980
abstract:

The exterior dynamics of black holes has played a major role in holographic duality, describing the approach to thermal equilibrium of strongly coupled media. The interior dynamics of black holes in a holographic setting has, in contrast, been largely unexplored. I will describe recent work investigating the classical interior dynamics of various holographic black holes. I will discuss the nature of the singularity, the absence of Cauchy horizons and a new kind of chaotic behavior that emerges in the presence of charged scalar fields. [please email a.held@imperial.ac.uk for zoom link or password]

22.06.2021 (Tuesday)

On Vacuum Transitions and the String Lanscape

Regular Seminar Senarath de Alwis (University of Colorado)

at:
15:30 IC
room zoom 871 9223 5980
abstract:

I discuss from a Hamiltonian (Lorentzian) perspective the calculations of vacuum transitions in flat space field theory and in gravitational backgrounds without the use of problematic Euclidean arguments. Some implications for the string theory landscape are highlighted. [please note the unusual time] [please email a.held@imperial.ac.uk for zoom link or password]

15.06.2021 (Tuesday)

Discovering Lepton Flavour Universality Violating New Physics

Regular Seminar Andreas Crivellin (CERN, Zurich University, PSI Villigen)

at:
13:30 IC
room zoom 871 9223 5980
abstract:

While the LHC has not discovered any new particles directly yet, hints for the violation of lepton flavour universality (satisfied within the SM) accumulated in recent years. In particular, deviations from the SM predictions were observed in semi-leptonic B decays (b->sll and b->ctau), in the anomalous magnetic moment of the muon (g-2), in leptonic tau decays and di-electron searches. Furthermore, also the deficit in first row CKM unitarity, known as the Cabibbo Angle Anomaly, can be interpreted as a sign of lepton flavour universality violation. In this talk I review the status of these anomalies and give an overview of the possible interpretations in terms of new physics models. [please email a.held@imperial.ac.uk for zoom link or password]

08.06.2021 (Tuesday)

Towards the path integral for gravity

Regular Seminar Neil Turok (Perimeter Institute and University of Edinburgh)

at:
13:30 IC
room zoom 871 9223 5980
abstract:

We show how Feynman's path integral for quantum mechanics may be defined without a Wick rotation to imaginary time. Instead, we employ analytic continuation (and Cauchy's theorem) in the complexified space of paths being integrated over. We outline an existence proof and describe applications to both nonrelativistic quantum mechanics and to interference patterns due to gravitational microlensing in radio astronomy. [please email a.held@imperial.ac.uk for zoom link or password]