The SEMPARIS seminar webserver hosts annoucements of all seminars taking place in Paris area, in all topics of physics, mathematics and computer science. It allows registered users to receive a selection of announcements by email on a daily or weekly basis, and offers the possibility to archive PDF or Powerpoint files, making it available to the scientific community. [ More information ]
Upcoming Seminars at LPTHE  
[ scheduler view ] 
Thursday 30 January 2020, 11:00 at LPTHE, bibliothèque du LPTHE, tour 1314, 4eme étage  SEMDARBOUX (Séminaire Darboux  physique théorique et mathématiques)  hepthmath.AG 



Abstract:  The K3 surfaces are complex algebraic surfaces with remarkable properties. A property that characterizes them, is the existence of a unique, up to scalar multiplication, global holomorphic two form which is never zero. In the last years their group of symmetry, the automorphisms of the K3 surfaces, aroused a lot of interest and it has been much studied. Depending on the action on the holomorphic two form, which can be trivial or not, an automorphism is called symplectic or nonsymplectic. After an introduction on the subject, the aim of the talk is to show recent results in the study of nonsymplectic automorphisms of 2power order. In particular in the case of the order 16, I give a full description of the families of K3 surfaces carrying such automorphisms. 
Friday 31 January 2020, 11:00 at LPTHE, Bibliothèque  SEMLPTHE (Séminaire du LPTHE)  condmat.statmech 



Abstract:  The perturbative expansions of many physical quantities are divergent, and defined only as asymptotic series. It is well known that this divergence reflects the existence of nonperturbative, exponentially damped contributions, such as instanton effects, which are not captured by a perturbative analysis. This connection between perturbative and nonperturbative contributions of a given physical observable can be systematically studied using the theory of resurgence, allowing us to construct a full nonperturbative solution from perturbative asymptotic data. In this talk I will start by reviewing the essential role of resurgence theory in the description of the analytic solution behind an asymptotic series, and its relation to the socalled Stokes phenomena and phase transitions. I will then exemplify how these techniques can be applied to to the LeeYang zeros in the context of matrix models, a subject of great interest in both mathematics and physics. 
Tuesday 4 February 2020, 11:00 at LPTHE, Library, tour 1314, 4th floor  P^3 (Particle Physics in Paris)  hepphhepth 



Abstract:  Effective Field Theories (EFTs) appear everywhere there is a mass scale. They serve to simplify complex multiscale problems (e.g. the theory of fermions below the electroweak scale), and they serve as general tools to parametrise the unknown or incalculable (e.g. the pion chiral Lagrangian, gravity, or physics beyond the standard model). In this sense, they are perhaps even too general (everything which is not forbidden is compulsory). In this talk I will present a tool to distinguish EFTs that can originate from microscopic unitary theories and I will show that this strongly limits the (classic and quantum) running of EFTs scattering amplitudes. In particular, Massive gravity, theories with isolated massive higherspin particles, and theories with very irrelevant interactions, cannot originate from unitary theories. 
Thursday 6 February 2020, 10:00 at LPTHE, LPTHE Library  RENCTHEO (Rencontres Théoriciennes)  hepth 



Abstract:  > This talk is dedicated to recent doublecopy constructions that unify massless treelevel amplitudes in a variety of perturbative string theories. All the polarization dependence in gauge and gravity amplitudes of typeI, typeII, bosonic and heterotic string theories is proposed to enter via fieldtheory building blocks with a known Lagrangian origin. The second doublecopy component of massless string amplitudes involves modulispace integrals over punctured sphere and disk worldsheets whose lowenergy expansion introduces multiple zeta values. At each order in the inverse string tension alpha’, the coefficients of highest transcendental weight turn out to be universal across the above perturbative string theories. These phenomena have not been explained by the known string dualities and are hoped to reflect a deeper principle in the theory of quantum gravity. 
Thursday 6 February 2020, 11:40 at LPTHE, LPTHE Library  RENCTHEO (Rencontres Théoriciennes)  hepth 


Friday 7 February 2020, 11:00 at LPTHE, Bibliothèque  SEMLPTHE (Séminaire du LPTHE)  condmat.statmechhepthmathph 



Abstract:  The study of irrelevant perturbations has profound implications on our understanding of the space of QFTs and possesses important applications in Statistical and Condensed Matter Physics  e.g. the control on subleading corrections to the scaling limits of lattice models. In 1+1 D a partial map of the above mentioned space can be traced out thanks to the existence of integrable systems, which grant us a high degree of control on certain renormalization flows trajectories. In this talk I will present some results from a recent work concerning a large class of irrelevant perturbations that, in the framework of factorized scattering, can be described by generic deformations of the Smatrix by a CDD factor. I will show how these deformations can be described as certain fielddependent twists in the boundary conditions of the fields  a natural generalization of the geometric interpretation of the $T\bar{T}$ deformation  and that there exists a relation amongst CDD deformations and the thermodynamics of the Generalized Gibbs Ensemble. Exploiting the integrability of the models, I will derive a general flow equation for the finite size spectrum and, for the particular case of the sinhGordon model, will present a connection with the fermionic basis description of finitesize onepoint functions. 
Thursday 27 February 2020, 10:00 at IHP, 314  RENCTHEO (Rencontres Théoriciennes)  hepth 



Abstract:  TBA 
Thursday 5 March 2020, 11:00 at LPTHE, bibliothèque du LPTHE, tour 1314, 4eme étage  SEMDARBOUX (Séminaire Darboux  physique théorique et mathématiques)  math.AG 



Abstract:  The theory of Bridgeland stability conditions has seen important developments in the past few years. Emerging from the mathematical physics literature, in particular in Douglas' work, it now connects to different branches in mathematics including symplectic geometry and representation theory. In this talk we will give a quick introduction to the basic theory of stability conditions for the derived category of coherent sheaves on a smooth projective variety, focusing on the recent advances in the threefold case; in particular, on the existence result for the quintic CalabiYau threefold. 
Tuesday 10 March 2020, 11:00 at IHP, Salle 314  P^3 (Particle Physics in Paris)  hepphhepth 


Thursday 12 March 2020, 10:00 at IHP, 314  RENCTHEO (Rencontres Théoriciennes)  hepth 


Friday 13 March 2020, 14:00 at LPTHE, library  LPTHEPPH (Particle Physics at LPTHE)  hepph 


Tuesday 17 March 2020, 11:00 at LPTHE, LPTHE library  STRLPTENSHE (Séminaire commun LPTENS/LPTHE)  hepth 


Thursday 26 March 2020, 11:40 at IHP, 201  RENCTHEO (Rencontres Théoriciennes)  hepth 


Thursday 23 April 2020, 10:00 at IHP, 314  RENCTHEO (Rencontres Théoriciennes)  hepth 


Thursday 7 May 2020, 11:00 at LPTHE, bibliothèque du LPTHE, tour 1314, 4eme étage  SEMDARBOUX (Séminaire Darboux  physique théorique et mathématiques)  hepth 


Tuesday 12 May 2020, 11:00 at IHP, Salle 314  P^3 (Particle Physics in Paris)  astrophhepphhepth 


Thursday 14 May 2020, 10:00 at IHP, 314  RENCTHEO (Rencontres Théoriciennes)  hepth 


Thursday 28 May 2020, 11:00 at LPTHE, bibliothèque du LPTHE, tour 1314, 4eme étage  SEMDARBOUX (Séminaire Darboux  physique théorique et mathématiques)  hepthmath.MP 


Friday 5 June 2020, 14:00 at LPTHE, library  LPTHEPPH (Particle Physics at LPTHE)  hepph 


Thursday 18 June 2020, 10:00 at IHP, 201  RENCTHEO (Rencontres Théoriciennes)  hepth 



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