# This week

### Tuesday

#### dS vs Quintessence: who sinks in the swampland?

Regular Seminar Michele Cicoli (Bologna University)

 at: 14:00 ICroom B1004 abstract: I will discuss different theoretical and phenomenological challenges of quintessence model building in string theory in order to be able to give an informed answer to the question in the title.

### Wednesday

#### Bootstrapping the Maldacena Wilson line at strong coupling

Regular Seminar Pietro Ferrero (Mathematical Institute, Oxford University)

 at: 13:45 KCLroom K0.20 abstract: The insertion of local operators along a straight Maldacena Wilson line in planar N=4 super Yang Mills defines a defect supersymmetric conformal field theory in one dimension. This is a simple but interesting setup where one can combine field theory techniques such as bootstrap, integrability and localization, aiming at a full solution of a non-trivial quantum mechanical system. I will adopt a bootstrap approach and study correlation functions of local operators for large t Hooft coupling, where the system is dual to an open superstring in $AdS_5 \times S^5$. I will present results for the four-point function of the displacement multiplet of the 1d defect CFT corresponding to three-loop diagrams in AdS, which are obtained using a suitable position-space ansatz and after considering a large system of mixed correlators. The problem is made particularly hard by the large degeneracy of operators at strong coupling, which we solve by taking into account four-point functions with external unprotected operators. The simple 1d kinematics is an ideal toy model for bootstrap techniques of interest for higher-dimensional cases as well. The seminar will be based on published as well as ongoing work with Carlo Meneghelli (see arxiv:2103.10440).

### Thursday

#### Factorization and global symmetries in holography

Journal Club Francesco Benini (SISSA)

 at: 16:00 QMULroom Zoom abstract: There exist low-dimensional models of holography in which the bulk gravitational theory is dual to an ensemble average of boundary quantum field theories (as opposed to a single theory). In the case of three-dimensional gravitational theories based on topological field theories, we draw a connection between the ensemble averaging (and the lack of factorization of the partition function) and the presence of global symmetries. Once the global symmetries are removed (by a suitable gauging procedure), the gravitational theory behaves as a unitary quantum system.; Part of London TQFT Journal Club; please register at https://www.london-tqft.co.uk;

#### Gravitational Edge Modes, Coadjoint Orbits, Hydrodynamics and matrix model

Regular Seminar Laurent Freidel (Perimeter)

 at: 14:00 QMULroom zoom abstract: In this talk I will present an overview of the local holography program which links the quantization of gravity with the representation theory of infinite dimensional symmetry groups attached to codimension 2 surfaces: the corners. I will present in detail the corner symmetry group for 4d gravity and show its connection with the symmetry algebra of perfect fluids. As a step towards quantization, I will recall the importance of the co-adjoint orbit method and I will derive a complete classification of the positive-area coadjoint orbits of this group for corners that are a 2-sphere. I will also show that a deformation of this symmetry group naturally involves matrix model as a quantum regulator. If time permits I will mention some connections these results have with celestial holography and the higher spin asymptotic symmetry group. [for zoom link please contact h(dot)jiang(at)qmul(dot)ac(dot)uk]