Seminars



Monday, 25 June, 2018 - 14:30 - 15:30
Aula Grassano

Dr. Marco Garofalo (Edinburgh University)

Titolo: Investigation of Hybrid Monte Carlo in Numerical Stochastic Perturbation Theory




Monday, 2 July, 2018 - 14:30 - 15:30
Aula Grassano

Prof. Maxim Khlopov (APC - Paris)

Title: "Probes for composite dark matter"

 




Wednesday, 24 October, 2018 - 14:30 - 15:30
Aula Grassano

Prof. Paolo Di Vecchia (NORDITA, Stoccolma)

Title: Multiloop soft theorems for gravitons and dilatons in the bosonic string




Wednesday, 7 November, 2018 - 14:00 - 16:00
Aula Paoluzi

Discussion Leaders: Massimo Bianchi, Giancarlo Rossi, Alberto Salvio

Title: Axions from P-Q to S-R and in between




Monday, 12 November, 2018 - 11:30 - 12:30
Aula Grassano

Dr. Eran Palti (Max-Planck-Institute for Physics - Munich)

Title: Distance and de Sitter Conjectures on the Swampland

Abstract:

The string theory Swampland programme aims at distinguishing quantum field theories which can be completed into quantum gravity in the ultraviolet from those which cannot. I will outline relations between different conjectural properties of the Swampland, showing how a coherent picture is emerging, and discuss a proposal for the microscopic physics underlying them. I will focus in particular on the Swampland Distance Conjecture which is concerned with large variations of scalar field expectation values. I will then discuss a proposed connection between this conjecture and the Swampland de Sitter conjecture. The latter gives a lower bound on the gradient of positive potentials, in particular implying that there are no (meta-)stable de Sitter vacua in string theory.




Monday, 12 November, 2018 - 14:00 - 15:00
Aula Grassano

Dr. Nicolò Piazzalunga (Simons Center for Geometry and Physics - Stony Brook)

Title: Magnificent Four with colors




Monday, 12 November, 2018 - 15:00 - 16:00
Aula Grassano

Dr. Lucrezia Ravera (Università di Milano & INFN Sez. Milano)

Title: Hidden Symmetries of the Supersymmetric Free Differential Algebra of D=11 Supergravity

Abstract: I will present an investigation of the hidden symmetries of the supersymmetric Free Differential Algebra of D=11 supergravity, focusing on the physical role of the nilpotent fermionic generator naturally appearing in the hidden superalgebra underlying the theory. I will also discuss the relation between this superalgebra and osp(1|32).




Monday, 19 November, 2018 - 14:30 - 15:30
Aula Grassano

Prof. Timo Weigand (CERN & Università di Heidelberg)

Title: A Stringy Test of the Weak Gravity Conjecture

Abstract: Various swampland conjectures have been put forward in the recent literature to characterize general properties of an effective field theory which can be consistently coupled to quantum gravity. String theory as a framework for quantum gravity allows us to put these conjectures to a quantitative test. Among the earliest of these conjectures is the Weak Gravity Conjecture: It postulates the existence of a set of particles in any quantum gauge theory coupled to gravity whose charge-to-mass ratio must exceed that of an extremal black hole. In this talk we will verify this and further swampland conjectures in string theory, focussing for simplicity on string compactifications to six dimensions with 8 supercharges, in the vicinity of the weak coupling point of the gauge theory. Our proof of the Weak Gravity Conjecture near the weak coupling point combines various aspects of the Kahler geometry of complex surfaces, arithmetic properties of weak Jacobi forms and BPS invariants on Calabi-Yau threefolds. Along the way we elucidate the modification of the Weak Gravity Conjecture due to massless scalar fields. We find perfect agreement between the predictions of the modified conjecture and the charge-to-mass ratio of a set of physical stringy non-BPS states in the theory. Their charges span a sublattice of the full charge lattice, whose index we determine geometrically.




Wednesday, 21 November, 2018 - 14:30 - 15:30
Aula Paoluzi

Dr Dimitri SKLIROS (Max-Planck Institute, Munich, Germany)

Title: Coherent states of strings




Monday, 26 November, 2018 - 14:30 - 15:30
Aula Paoluzi

Dr. Yago Bea (University of Barcelona)

Title: Holographic collisions across a phase transition

Abstract: We use holography to mimic heavy ion collisions and obtain new qualitative insights possibly relevant for QCD. Our studies are motivated by the extensive experimental efforts devoted to the search of the conjectured critical point in the QCD phase diagram. Holographically, we perform collisions in strongly-coupled gauge theories with thermal phase transitions. We find that near a second order phase transition almost all the energy of the projectiles is deposited into a long-lived, quasi-static blob of energy. Moreover, hydrodynamics describes this blob only if we consider a formulation different from the Muller-Israel-Stewart formulation that is almost universally used in the numerical codes describing the quark-gluon plasma formed at RHIC and LHC.