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Upcoming Seminars at LPTHE
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Thursday 29 February 2024, 10:00 at IHP, 314 (Grisvard) RENC-THEO (Rencontres Théoriciennes) hep-th
Sakura Schafer-Nameki ( Oxford ) Categorical Symmetries and Phases
Abstract: Global symmetries can highly constrain the IR or QFTs. With the advent of non- invertible or categorical symmetries, a natural question is how these can characterize the IR phases -- both gapped and gapless. I will survey the so- called Symmetry Topological Field Theory (SymTFT) approach to answering this question. The proposal is applicable in general dimension, it provides a systematic classification of the gapped phases, as well as the order parameters -- thus generalizing the standard Landau paradigm. I will illustrate this approach in 1+1d theories with fusion category symmetries, describing all gapped phases with categorical symmetries and phase transitions between them.

Thursday 29 February 2024, 11:45 at IHP, 314 (Grisvard) RENC-THEO (Rencontres Théoriciennes) hep-th
Thomas Grimm ( Utrecht ) Tameness and Complexity of the Flux Landscape
Abstract: Flux compactifications provide an opportunity to sharpen our understanding of the properties of effective theories arising from string theory. Many of their features are mathematically captured by Hodge theory, a field that has recently seen a number of mathematical breakthroughs in connection with tame geometry. In this talk, I suggest a novel perspective on the locus of flux vacua that will allow us to revise some of the old claims about the number of such vacua, their properties, and their geometric complexity. A key point will be to use the dichotomy of the transcendentality of the arising scalar potentials and the existence of symmetries.

Tuesday 5 March 2024, 14:00 at LPENS, Conf IV-E244, 24 Rue Lhomond LPTENS-HE (Séminaire commun LPTENS-LPTHE) hep-th
Alexey Milekhin ( California Institute of Technology ) Sachdev-Ye-Kitaev model: from statistical mechanics to anti-de Sitter and de Sitter holographies
Abstract: I give an overview of the Sachdev-Ye-Kitaev model. Despite the simplicity of its Hamiltonian, it displays very rich physics with applications in both statistical mechanics and quantum gravity. And the end of my talk I will argue that a variant of this model also shares a lot of properties with de Sitter spacetime.

Tuesday 5 March 2024, 14:00 at LPTHE, Library and Zoom (link in the comments) LPTHE-PPH (Particle Physics at LPTHE) hep-ph
Johannes Braathen ( DESY ) Cornering New Physics with precision calculations of Higgs-boson properties
Abstract: Thanks to the Higgs boson's close connection with many unsolved problems of Particle Physics, precision studies of Higgs properties constitute a crucial probe of Beyond-the-Standard Model (BSM) Physics. Among these properties, the trilinear Higgs coupling provides a unique opportunity to access the structure of the Higgs sector, investigate the nature of the electroweak phase transition and the origin of the baryon asymmetry of the Universe, and search for indirect signs of BSM Physics. I will show that the trilinear Higgs coupling can, in models with extended scalar sectors, be significantly enhanced with respect to its SM prediction. Consequently, the current experimental bounds on this coupling are already sufficient to rule out significant parts of the BSM parameter space that would otherwise be unconstrained by state-of-the-art theoretical and experimental constraints. Next, I will present the new public tool anyH3, which provides complete one-loop predictions for the trilinear Higgs coupling in arbitrary renormalisable theories. I will review the main features of anyH3 and present examples of new results obtained with it, as well as ongoing developments.

Thursday 7 March 2024, 11:00 at LPTHE, bibliothèque du LPTHE, tour 13-14, 4eme étage SEM-DARBOUX (Séminaire Darboux - physique théorique et mathématiques) hep-th|math.AG
Tudor Padurariu ( Laboratoire de Mathématiques d'Orsay, Université Paris-Saclay ) Quasi-BPS categories for K3 surfaces
Abstract: BPS invariants and cohomology are central objects in the study of (Kontsevich- Soibelman) Hall algebras or in enumerative geometry of Calabi-Yau 3-folds. In joint work with Yukinobu Toda, we introduce a categorical version of BPS cohomology for local K3 surfaces, called quasi-BPS categories. When the weight and the Mukai vector are coprime, the quasi-BPS category is smooth, proper, and with trivial Serre functor etale locally on the good moduli space. Thus quasi-BPS categories provide (twisted) categorical (etale locally) crepant resolutions of the moduli space of semistable sheaves on a K3 surface for generic stability condition and a general Mukai vector. Time permitting, I will also discuss a categorical version of the \chi-independence phenomenon for BPS invariants.

Friday 8 March 2024, 14:00 at LPTHE, library LPTHE-PPH (Particle Physics at LPTHE) hep-ph
Mathieu Pellen ( Freiburg U. ) Theory input for the measurement of W+c production at the LHC
Abstract: The production of W+c at the LHC features very interesting physics but also poses several problems. With the current experimental precision, precise theoretical predictions are therefore crucial to fully explore the physics content of the process. In this presentation, I will present state-of-the-art theoretical predictions and discuss theoretical aspects relevant for the precise measurement of the process.

Friday 15 March 2024, 14:00 at LPTHE, library LPTHE-PPH (Particle Physics at LPTHE) hep-ph
Saad Nabeebaccus ( IJCLab Orsay ) Using the exclusive photoproduction of a photon-meson pair in collinear factorisation to extract generalised parton distributions
Abstract: Various 2 to 3 exclusive processes in the collinear factorisation framework have been studied. Such processes give access to enhanced x-dependence of generalised parton distributions (GPDs), beyond the moment-type information that is accessed in well-studied 2 to 2 exclusive processes such as Deeply Virtual Compton Scattering. It was recently proved that a wide range of 2 to 3 exclusive processes factorise. Moreover, through the exclusive photoproduction of a photon-meson pair with large invariant mass, which falls in the latter category and which will be the focus of my talk, chiral-odd GPDs can be probed at the leading twist. The first part of my talk will be dedicated to our results from 2212.00655 and 2302.12026 on the subject, performed at leading order and leading twist, for a charged pion and rho meson of any charge and polarisation. Our results indicate that the statistics are very promising for performing an experimental study at various experiments, such as COMPASS, future EIC, LHC in ultraperipheral collisions, and especially at JLab. For the second part, I will discuss our recent results from 2311.09146, on an unexpected case of the breakdown of collinear factorisation in the exclusive photoproduction of a photon-pi0 pair, that is, when the outgoing meson is a neutral pion. This is due to the existence of the so-called Glauber pinch in this process, which happens due to the presence of the gluon GPD channel here. I stress that such factorisation breaking effects are absent for the processes that we have previously considered, where the outgoing meson is a charged pion or a rho meson, since they are sensitive to quark GPDs only.

Thursday 23 May 2024, 11:00 at LPTHE, bibliothèque du LPTHE, tour 13-14, 4eme étage SEM-DARBOUX (Séminaire Darboux - physique théorique et mathématiques) hep-th|math.DG
Eleanora Di Nezza ( IMJ ) TBA

seminars from series at institute
in subject with field matching

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