## Directions

We are located on the Main Campus of City in Northampton Square (map)

Getting to the Strand Campus:

• #### By underground

Thea nearest tube stops are Farringdon, Angel, also nearby is Barbican

• #### By train

Farringdon (10 minutes walk) or King's Cross stations (20 minutes walk) have nearest main-line services

• #### By bus

Buses stopping outside the College: : 4, 19, 30, 38, 43, 55, 56, 63, 73, 153, 205, 214, 243, 274, 341, 394, 476.

## Seminars at City, University of London

Found at least 20 result(s)

### 01.02.2017 (Wednesday)

#### String Fluctuations in Non-Conformal Holography

Triangular Seminar Kostya Zarembo (NORDITA)

 at: 15:00 City U.room A130 abstract: Quantum fluctuations of the string worldsheet lead to important effects in gauge-string duality. One example is the Lüscher term is the QQ-bar potential in QCD, important for matching the lattice data. I will discuss non-conformal holography of the N=2* theory which provides a controllable setup where the effects of string fluctuations are explicitly calculable in field theory, using localization, even though the problem is intrinsically strongly-coupled. The results obtained by direct quantization of the dual string theory perfectly match the field-theory predictions, after subtle effects like dilaton coupling to the string worldsheet are properly taken into account.

### 01.02.2017 (Wednesday)

#### Probing the black hole interior in AdS/CFT

 at: 16:30 City U.room A130 abstract: I will review recent developments related to the holographic reconstruction of the black hole interior in AdS/CFT and I will discuss the implications for the black hole information paradox.

### 24.01.2017 (Tuesday)

#### Matrix models for the gauge-gravity correspondence

 at: 15:00 City U.room B103 abstract: The gauge-gravity correspondence identifies a field theory with a gravitational theory. The gravitational theory is weakly coupled when the field theory has large coupling and vice versa, which mostly prevents matching nontrivial results between the two descriptions. I will discuss cases when the field theory calculation can be reduced to a finite dimensional matrix integral, representing some counting problems. I will then evaluate the integral exactly and reexpand the exact result, which is valid for all coupling, at strong coupling. The resulting expression should match a weak coupling gravitational (or string theoretic) calculation and I’ll comment on what is known from that direction.

### 16.11.2016 (Wednesday)

#### Polygon Seminar: Boundaries, Modules and Symplectic Duality

Triangular Seminar Mathew Bullimore (Oxford)

 at: 15:00 City U.room B104 abstract: I will discuss connections between supersymmetric gauge theories in three dimensions and an exciting development in representation theory known as symplectic duality. I will focus on the simplest example of this phenomenon, which arises from a U(1) gauge theory with N hypermultiplets.

### 18.10.2016 (Tuesday)

#### Symmetry and String theory

 at: 13:00 City U.room C310 abstract: String theory in the tensionless limit is expected to have a large gauge symmetry. By recasting string theory on the AdS background as a generalization of Vasiliev's theory of massless higher-spin fields, it has become possible to understand the nature of this symmetry. In this talk, I will first give an overview of three-dimensional Vasiliev theory and its dual CFT. I will then discuss the current understanding of the symmetry algebra of string theory as well as open problems related to it.

### 18.10.2016 (Tuesday)

#### The Quantum Hall Zoo

Regular Seminar Carl Turner (DAMTP)

 at: 15:00 City U.room AG21 abstract: The Quantum Hall Effect is one of the richest phenomena in condensed matter (now featured in no fewer than three Nobel prizes!). I will introduce and explain it, insofar as we understand it. Towards the end, I will say a few words about work to try and rationalise and relate the many models of the effect.

### 11.10.2016 (Tuesday)

#### An operator for the zeros of the Riemann zeta function

Regular Seminar Dorje Brody (Brunel)

 at: 15:00 City U.room B103 abstract: The Riemann hypothesis asserts that the nontrivial zeros of the Riemann zeta function should be of the form 1/2 + i E_n, where the set of numbers {E_n} are real. The so-called Hilbert-Pólya conjecture assumes that {E_n} should correspond to the eigenvalues of an operator that is Hermitian. The discovery of such an operator, if it exists, thus amounts to providing a proof of the Riemann hypothesis. In 1999 Berry and Keating conjectured that such an operator should correspond to a quantisation of the classical Hamiltonian H = xp. Since then, the Berry-Keating conjecture has been investigated intensely in the literature, but its validity has remained elusive up to now. In this talk I will derive a “Hamiltonian” (a differential operator), whose classical counterpart is H = xp, having the property that with a suitable boundary condition on its eigenstates, the eigenvalues {E_n} correspond to the nontrivial zeros of the Riemann zeta function. This Hamiltonian is not Hermitian, but is symmetric under space-time reflection (PT symmetric) in a special way. A formal argument will be given for the construction of the metric operator to define an inner-product space for the eigenstates, and the formally “Hermitian" counterpart Hamiltonian. The talk is based on the work carried out in collaboration with Carl M. Bender (Washington University) and Markus P. Müller (University of Western Ontario).

### 04.10.2016 (Tuesday)

#### String Theory as a Spin Chain

Regular Seminar Alessandro Torrielli (Surrey)

 at: 15:00 City U.room B103 abstract: In recent years, the discovery of integrable sectors of string theory has expanded the range of models which are solvable by the techniques of the Bethe ansatz and by the general theory of quantum groups. In this talk, we will give an overview of the S-matrix theory involved in the solution of these models, with mention to the problem of massless particles emerging in a particular instance of the AdS/CFT correspondence.

### 16.02.2016 (Tuesday)

#### Yang-Mills Theory and the ABC Conjecture

Regular Seminar Yang-Hui He (City)

 at: 15:00 City U.room B103 abstract: We establish a precise correspondence between the ABC Conjecture and N=4 super-Yang-Mills theory. This is achieved by combining three ingredients: (i) Elkies' method of mapping ABC-triples to elliptic curves in his demonstration that ABC implies Mordell/Faltings; (ii) an explicit pair of elliptic curve and associated Belyi map given by Khadjavi-Scharaschkin; and (iii) the fact that the bipartite brane-tiling/dimer model for a gauge theory with toric moduli space is a particular dessin d'enfant in the sense of Grothendieck. We explore this correspondence for the highest quality ABC-triples as well as large samples of random triples. The Conjecture itself is mapped to a statement about the fundamental domain of the toroidal compactification of the string realization of N=4 SYM.

### 09.02.2016 (Tuesday)

#### Modelling sleep-wake regulation

Regular Seminar Anne Skeldon (Surrey)

 at: 15:00 City U.room B103 abstract: Sleep is core to our ability to function and there is increasing evidence that poor or mis-timed sleep increases our risk of cardio vascular disease, type II diabetes, obesity and cognitive decline. In this talk I will discuss the mechanisms that are believed to underlie sleep wake regulation and review some recent mathematical models. In particular, I will focus on age-related changes to sleep and explain how the mathematical models can be used to bring insight into the possible mechanisms that could cause these changes.

### 03.02.2016 (Wednesday)

#### Holographic cosmology and Planck data

Triangular Seminar Kostas Skenderis (Southampton)

 at: 16:00 City U.room AG07b abstract: I will present holographic models for the very early Universe, the period usually associated with inflation, and compare the predictions of these models against Planck 2015 data. Within the holographic framework the early Universe is described by a three dimensional QFT. Conventional inflation is included in this framework as strong coupled QFT while qualitatively new models arise when the QFT has weak or intermediate coupling. The weakly coupled models describe a very quantum early Universe and it turns out that these models fit the Planck data remarkably well, providing an alternative to LambdaCDM. New models based on QFT at intermediate coupling may be constructed using Lattice methods and I will also describe on-going work in this direction.

### 02.02.2016 (Tuesday)

#### Supersymmetric gauge theories, localization and holography

Regular Seminar Dario Martelli (King's)

 at: 15:00 City U.room B103 abstract: I will discuss some exact results in supersymmetric field theories, focussing on the localization technique in supersymmetric gauge theories and its interplay with holography.

### 26.01.2016 (Tuesday)

#### Eigenstate Phase Transitions for Strong Zero Modes

Regular Seminar Paul Fendley (Oxford)

 at: 15:00 City U.room B103 abstract: Traditionally, most studies of quantum many-body systems have been mainly concerned with properties of the states of low-lying energy. Recently, however, fascinating features of the full energy spectrum have been uncovered. Among these are eigenstate phase transitions, where sharp transitions occur not only in the ground state, but in all the states. I describe a simple example of such, a transition for a strong zero mode in the XYZ spin chain. The strong zero mode is an operator that pairs states in different symmetry sectors, resulting in identical spectra up to exponentially small finite-size corrections. Such pairing occurs in the Ising/Majorana fermion chain and possibly in parafermionic systems and strongly disordered many-body localized phases. My proof here shows that the strong zero mode occurs in a clean interacting system, and that it possesses some remarkable structure despite being a rather elaborate operator, it squares to the identity.

### 14.12.2015 (Monday)

#### Mechanics of a Volvox Embryo Turning Itself Inside Out

Regular Seminar Pierre Haas (DAMTP)

 at: 14:30 City U.room ELG03 abstract: Deformations of cell sheets are ubiquitous in early animal development, yet they arise from an intricate interplay of cell shape changes, cell migration, cell intercalation, and cell division. We combine theory and experiment to explore what is perhaps the simplest instance of cell sheet folding, the "inversion" process in the green alga Volvox: at the end of cell division, a Volvox embryo consists of several thousand cells arrayed to form a thin spherical sheet, but those cell poles whence will emanate the flagella point into the sphere. In a process hypothesised to arise from cell shape changes alone, the embryos therefore turn themselves inside out to acquire the ability to swim. We have recently acquired the first three-dimensional time-lapse visualisations of this inversion, using light sheet microscopy to reveal the intriguing dynamics of the process. A theoretical model, in which cell shape changes correspond to local variations of intrinsic curvature and stretches of an elastic shell, sheds light on the underlying mechanics of inversion and reproduces the shapes and dynamics of inversion qualitatively. This is joint work with Stephanie Hhn, Aurelia Honerkamp-Smith, Philipp Khuc Trong and Ray Goldstein.

### 14.12.2015 (Monday)

#### Can Molecular Simulations Help us Understand how Nerve Cells in the Brain Communicate?

Regular Seminar Carla Molteni (King's)

 at: 15:30 City U.room ELG03 abstract: Neurotransmitter-gated ion channels are complex neuroreceptors located in the membrane of nerve cells that control the rapid transmission of nerve impulses. Their malfunction is linked to serious neurological disorders, including Alzheimers disease, and they are major therapeutic targets; in invertebrates they are involved in insecticide resistance. However, we have little idea of how they function at the molecular level due to their complexity and limited experimental information. In particular it is not clear how the binding of a small molecule (the neurotransmitter) triggers a series of events culminating into the opening (gating) of the transmembrane channel: ions can then flood across the cell membrane modifying the cell activity. State-of-the-art and novel computational techniques are therefore crucial to build an accurate picture at the atomic level of the mechanisms that drive the activation of these ion channels, complementing the available experimental data. We have used a range of simulation techniques, including metadynamics (a method for accelerating rare events and sample free energy landscapes), to explore the mechanisms of neurotransmitter binding and a potential molecular switch for channel gating. As prototypical examples, we have focussed on the insect GABA-activated RDL receptor and on the serotonin-activated 5-HT3 receptor.

### 14.12.2015 (Monday)

#### TBA

 at: 17:00 City U.room ELG03 abstract:

### 08.12.2015 (Tuesday)

#### tba

Regular Seminar Nicola Perra (Greenwich)

 at: 16:00 City U.room B104 abstract:

### 01.12.2015 (Tuesday)

#### What is computational algebraic geometry in systems biology?

Regular Seminar Heather Harrington (Oxford)

 at: 16:00 City U.room B104 abstract: Systems biology aims to understand the molecular interactions that turn genes on/off, ultimately regulating cellular decisions. These interactions may be described by a mathematical model that is a polynomial dynamical system. Generally these interactions are unknown, leading to multiple models; therefore it is desirable to compare models with experimental data (e.g., steady-state concentrations of proteins). Often model parameter values are unknown, and data is limited (subset of measurable variables, often with noise). An emerging field, `algebraic systems biology', offers algebraic approaches to study problems systems biology. We present an algebro-geometric method for ruling out models with limited information and apply it to a biological system known to dysfunction in many colorectal cancers. We are currently extending the framework to include dynamics (i.e. time course data) using differential algebra elimination and will present preliminary results.

### 24.11.2015 (Tuesday)

#### tba

Regular Seminar Tom Leinster (Edinburgh)

 at: 16:00 City U.room B104 abstract:

### 17.11.2015 (Tuesday)

#### On the origins of the viscous instability mechanism

Regular Seminar Jonathan Healey (Keele)

 at: 16:00 City U.room B104 abstract: