SEMPS Schedule

Arrival & Coffee 10:00 - 11:00

Everything homotopy algebras: supergravity and U-duality

Leron Borsten (University of Hertfordshire)

Abstract: Higher notions of symmetry are increasing prevalent in varied facets of physics, from condensed matter to M-theory. I will review higher symmetries in physics and mathematics from various perspectives. I will then introduce the fundamental relationship between Lagrangian quantum field theories and homotopy Lie, or L-infinity, algebras. While powerful, L-infinity algebras alone are insufficient in certain physical contexts. Interestingly, such shortcomings may often be alleviated by generalising further to “everything homotopy Lie”, or EL-infinity, algebras, which represent a complete categorification of Lie algebras. This will be illustrated in the contexts of gauged supergravity and the U-dualities of M-theory.

Integrable deformations of superstrings: focus on AdS3xS3xT4

Fiona Seibold (Imperial College)

Abstract: I will give an overview of certain types of deformations of superstring backgrounds that have the property of preserving exact solvability of the resulting string non-linear sigma model -- usually at the expense of breaking all supersymmetries. In the case of AdS3xS3xT4 however, the special algebraic structure leads to a rich space of deformed models, some of which preserve half the supersymmetries of the original AdS3 background. Based on work in progress with Arkady Tseytlin and Ben Hoare.

Lunch 12:40 - 14:00

Colour-kinematics duality, Batalin-Vilkovisky algebras, operadic Koszul duality and Hopf algebras

Hyungrok Kim (Heriot-Watt University)

Abstract: Did you think that the series of buzzwords in the title were related? Neither did the speaker until he worked on this project. Colour-kinematics duality is a hidden symmetry of a wide class of quantum field theories. I will describe how this symmetry can be captured by a certain homotopy-algebraic structure (using the rest of the buzzwords), which has been christened a BV^◻_∞-algebra (following the long tradition of ungoogleable names of such algebras), and give examples including Chern-Simons theory and supersymmetric Yang-Mills theory.

The concatenation of terms (besides betraying a lack of creativity) is meant to be disjunctive, not conjunctive: anyone interested in at least one (or none!) of the topics is welcome; no prior knowledge will be assumed (to the best of the speaker's ability).

Generalised Hydrodynamics of Particle Creation and Decay

Cecilia De Fazio (Univeristy of Nottingham)

Abstract: In this talk we study the out-of-equilibrium dynamics of an integrable quantum field theory possessing an unstable excitation in its spectrum. In the standard scattering picture, unstable particles result from complex poles of the twoparticle scattering matrix located in the unphysical sheet of rapidity space. Since they are not part of the asymptotic spectrum, their presence is only felt through the effect they have on physical quantities associated to the stable constituent particles (i.e. energy/particle density). A good way to study those quantities is to adopt the generalised hydrodynamic approach and to consider the effective velocities and particle densities of the stable particles in the theory. We will see that, for an initial state given by a spacial Gaussian profile of temperatures peaked at the origin, time evolution gives rise to particle and spectral particle densities that exhibit hallmarks of the creation and decay of unstable particles. These signatures of instability can be used to provide a better understanding of the dynamics of the unstable excitations that goes beyond the pole structure of the scattering matrix.

Tea 15:40 - 16:10