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 ]
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Friday 12 October 2018, 14:00 at LPTHE, Library  LPTHEPPH (Particle Physics at LPTHE)  hepph 



Abstract:  The existence of physics beyond the Standard Model (BSM) is well motivated from both an experimental and theoretical point of view. However, data from the 7/8 TeV LHC (Run I) have ruled out new, electroweakscale states that couple strongly to the Standard Model. This suggests that new physics, if it is indeed accessible at the LHC, is either light and very weakly coupled or very heavy with sizable couplings. Interestingly, such mass scales correspond to regions of phase space for BSM collider processes where QCD corrections can be large, making necessary their resummation. In this seminar, examples of how QCD resummation can quantitatively and qualitatively change BSM phenomenology at the 13 TeV LHC (and prospective 100 TeV VLHC) are presented. 
Tuesday 16 October 2018, 14:00 at APC, 646 A  Mondrian  APCTH (Seminar of the theory group of APC)  hepth 


Thursday 18 October 2018, 11:00 at CPHT, Salle de Conférence Jean Lascoux (aile 0)  SEMCPHT (Séminaire du CPHT)  hepth 



Abstract:  BirmanMurakamiWenzl (BMW) algebra was introduced in connection with knot theory. We treat here interaction round the face solvable (IRF) lattice models. We assume that the face transfer matrix obeys a cubic polynomial equation, which is called the three block case. We prove that the three block theories all obey the BMW algebra. This result is important to the solution of IRF lattice models and the development of new models, as well as to knot theory. (based on 1807.05603 ) 
Thursday 18 October 2018, 14:00 at IPHT, Amphi Claude Bloch, Bât. 774  SOUTENTH (Soutenance de thèse)  physics 


Friday 19 October 2018, 10:00 at
IPHT,
Salle Claude Itzykson, Bât. 774 ( https://courses.ipht.cnrs.fr/?q=en/node/220 )  COURS (Cours)  astrophgrqc 



Abstract:  The recent observation of gravitational wave signals from inspiralling and coalescing binary black holes has been significantly helped, from the theoretical side, by the availability of analytical results on the motion and gravitational radiation of binary systems. \par The course will deal with the Effective OneBody (EOB) theory of the motion and radiation of binary systems, and explain the links between this formalism and various classical and quantum approaches to gravitationally interacting twobody systems, from traditional postNewtonian computations of the effective twobody action to quantum gravitational scattering amplitudes. \par The following analytical techniques will be reviewed ab initio: \\ 1  Matched Asymptotic Expansions approach to the motion of black holes and neutron stars; \\ 2  postNewtonian theory of the motion of point particles; \\ 3  Multipolar postMinkowskian theory of the gravitational radiation of general sources; \\ 4  Effective OneBody (EOB) theory of the motion and radiation of binary systems. \par The EOB formalism was initially based on a resummation of postNewtonianexpanded results. The postNewtonian approach assumes small gravitational potentials and small velocities, and loses its validity during the last orbits before the merger of black holes. The resummed EOB approach was able to extend the validity of the postNewtonian description of the motion and radiation of binary black holes to the strongfield, highvelocity regime reached during the last orbits, and the merger. EOB theory initially used a dictionary to translate postNewtonianexpanded results on (slowmotion) bound states of gravitationally interacting binary systems into the (resummed) Hamiltonian of a particle moving in an effective external gravitational field. \par The second part of the course will present the recent extension of EOB theory to the description of (classical) scattering states within the postMinkowskian approach which does not assume that velocities are small. This led to new insights in the highenergy limit of gravitational scattering and opened the way to transcribe quantum gravitational scattering amplitudes into their EOB Hamiltonian description. For instance, some twoloop ultra highenergy quantum scattering results of Amati, Ciafaloni and Veneziano could be transcribed into an improved knowledge of the highenergy limit of the classical gravitational interaction of two black holes. This leads also to interesting predictions about a linearReggetrajectory behavior of highangularmomenta, highenergy circular orbits.  
Attachments: 
Friday 19 October 2018, 11:00 at LPTHE, Bibliothèque  SEMLPTHE (Séminaire du LPTHE)  condmat.statmech 



Abstract:  Many classes of complex computational problems admit no efficient solution or even approximation, yet have a vast reach in applications across science and industry. From a physics perspective, computational complexity originates from correlations between bits of information. It is reasonable to ask whether computational approaches to quantum manybody problems can be practically useful in this context. In this talk, I will present newly found cases where the answer is affirmative. I will introduce constraint satisfaction problems (CSPs) and reformulate them as interacting models whose ground states represent the solution manifold. A procedure that reaches the ground states of these models implements a protocol of computation. In some protocols, the complexity that arises during computation can be viewed as quantum entanglement, and efficiency is achieved by controlling its growth. Using this reasoning, I will introduce practical methods for solving CSPs based on tensor network contraction and demonstrate that they outperform stateoftheart solvers for some of these problems by a significant margin. I will conclude with an outline of ongoing work on extensions and applications to problems of current interest, such as the simulation of existing and nearterm quantum circuits. 
Friday 19 October 2018, 14:15 at
IPHT,
Salle Claude Itzykson, Bât. 774 ( https://courses.ipht.cnrs.fr/?q=en/node/220 )  COURS (Cours)  astrophgrqc 



Abstract:  The recent observation of gravitational wave signals from inspiralling and coalescing binary black holes has been significantly helped, from the theoretical side, by the availability of analytical results on the motion and gravitational radiation of binary systems. \par The course will deal with the Effective OneBody (EOB) theory of the motion and radiation of binary systems, and explain the links between this formalism and various classical and quantum approaches to gravitationally interacting twobody systems, from traditional postNewtonian computations of the effective twobody action to quantum gravitational scattering amplitudes. \par The following analytical techniques will be reviewed ab initio: \\ 1  Matched Asymptotic Expansions approach to the motion of black holes and neutron stars; \\ 2  postNewtonian theory of the motion of point particles; \\ 3  Multipolar postMinkowskian theory of the gravitational radiation of general sources; \\ 4  Effective OneBody (EOB) theory of the motion and radiation of binary systems. \par The EOB formalism was initially based on a resummation of postNewtonianexpanded results. The postNewtonian approach assumes small gravitational potentials and small velocities, and loses its validity during the last orbits before the merger of black holes. The resummed EOB approach was able to extend the validity of the postNewtonian description of the motion and radiation of binary black holes to the strongfield, highvelocity regime reached during the last orbits, and the merger. EOB theory initially used a dictionary to translate postNewtonianexpanded results on (slowmotion) bound states of gravitationally interacting binary systems into the (resummed) Hamiltonian of a particle moving in an effective external gravitational field. \par The second part of the course will present the recent extension of EOB theory to the description of (classical) scattering states within the postMinkowskian approach which does not assume that velocities are small. This led to new insights in the highenergy limit of gravitational scattering and opened the way to transcribe quantum gravitational scattering amplitudes into their EOB Hamiltonian description. For instance, some twoloop ultra highenergy quantum scattering results of Amati, Ciafaloni and Veneziano could be transcribed into an improved knowledge of the highenergy limit of the classical gravitational interaction of two black holes. This leads also to interesting predictions about a linearReggetrajectory behavior of highangularmomenta, highenergy circular orbits.  
Attachments: 
Tuesday 23 October 2018, 14:00 at APC, 646 A  Mondrian  APCTH (Seminar of the theory group of APC)  hepth 



Abstract:  In this talk I will demonstrate how, by introducing additional scalar degrees of freedom, one can measure properties of the inflationary era which may be otherwise inaccessible. Using two explicit examples (the curvaton and a feebly interacting model of dark matter), which introduce new informative priors into the post inflationary phenomenology, we are able to constrain either the total duration that inflation takes place or its energy scale independently of the tensortoscalar ratio. Measurements of this kind may prove crucial in advancing the study of inflation if the future observational data were to yield a limited amount of new information. 
Tuesday 23 October 2018, 16:30 at UPMC, Amphi 24  Campus Pierre et Marie Curie  CPMC (Colloquium Pierre et Marie Curie)  nlin 



Abstract:  Water waves involve fluxes of momentum and energy that transport sediment along the shore. The flux toward shore of alongshore momentum depends on coastline orientation (relative to the wave propagation direction). Spatial variations in coastline orientation, therefore, are associated with gradients in alongshore sediment flux. Divergences in alongshore sediment flux cause coastline erosion, and convergences cause accretion. i.e., coastline shape determines the pattern of sediment fluxes that in turn change coastline shape. This ‘morphodynamic’ feedback can produce instabilities leading to the growth of largescale coastline features. In numerical experiments, finiteamplitude interactions then lead to a variety of coastline shapes, which are functions of wave climate (angular distribution). Changes in wave climate arising from changes in storm climate tend to reshape coastlines. In a case study, hindcasts of associated changes in shoreline erosion patterns are consistent with historical observations, opening up the possibility to forecast future coastal erosion ‘hot spots.’ However, on developed coastlines, couplings between human dynamics and coastline dynamics must be considered.  
Attachments: 
Wednesday 24 October 2018, 14:15 at IPHT, Salle Claude Itzykson, Bât. 774  IPHTMAT (Séminaire de matrices, cordes et géométries aléatoires)  hepth 


Friday 26 October 2018, 14:15 at IPHT, Salle Claude Itzykson, Bât. 774  IPHTMAT (Séminaire de matrices, cordes et géométries aléatoires)  hepth 



Abstract:  (TBA) 
Monday 12 November 2018, 11:00 at IPHT, Salle Claude Itzykson, Bât. 774  IPHTPHM (Séminaire de physique mathématique)  mathph 



Abstract:  CFT has been extremely successful in describing universal effects in critical onedimensional (1D) systems, in situations in which the bulk is uniform. However, in many experimental contexts, such as quantum gases in trapping potentials and in several outofequilibrium situations, systems are strongly inhomogeneous. Recently it was shown that the CFT methods can be extended to deal with such 1D situations: the systemâ€™s inhomogeneity gets reabsorbed in the parameters of the theory, such as the metric, resulting in a CFT in curved space. Here in particular we make use of CFT in curved spacetime to deal with the outofequilibrium situation generated by a frequency quench in a TonksGirardeau gas in a harmonic trap. We show compatibility with known exact result and use this new method to compute new quantities, not explicitly known by means of other methods, such as the dynamical fermionic propagator and the one particle density matrix at different times. 
Tuesday 13 November 2018, 11:00 at LPTMS, LPTMS, salle 201, 2ème étage, Bât 100, Campus d'Orsay  LPTMS (Séminaire du Laboratoire de Physique Théorique et Modèles Statistiques (Orsay))  physics 


Wednesday 14 November 2018, 14:15 at IPHT, Salle Claude Itzykson, Bât. 774  IPHTMAT (Séminaire de matrices, cordes et géométries aléatoires)  hepth 



Abstract:  (TBA) 
Tuesday 20 November 2018, 16:00 at IPHT, Salle Claude Itzykson, Bât. 774  IPHTHEP (Séminaire de physique des particules et de cosmologie)  hepph 



Abstract:  Bosonic ultralight dark matter (ULDM) would form cored density distributions at the centre of galaxies. Numerical simulations suggest a scaling relation between the core and the virialised host halo. This prediction lends itself to observational tests, because it implies that the peak circular velocity, measured for the host halo in the outskirts of the galaxy, should approximately repeat itself in the central region. Contrasting this prediction to the measured rotation curves of dozens of wellresolved galaxies, we show that ULDM in the mass range $m\sim (10^{22}\div 10^{21})$~eV, which has been invoked as a possible solution to the smallscale puzzles of $\Lambda$CDM, is in tension with the data. Analysis of the Milky Way inner gravitational potential could probe ULDM up to $m< \sim 10^{19}$~eV. 
Tuesday 4 December 2018, 11:00 at LPTMS, LPTMS, salle 201, 2ème étage, Bât 100, Campus d'Orsay  LPTMS (Séminaire du Laboratoire de Physique Théorique et Modèles Statistiques (Orsay))  physics 



Abstract:  We will discuss the properties of a family of integrals involving the cardinal sine fuction, first studied by Borwein & Borwein. The aim is to provide a physicist’s perspective onto a curious change of behaviour occurring within this family, noticed when benchmarking computer algebra packages, and initially attributed to a bug. A number of nontrivial generalizations will be obtained. 
Friday 7 December 2018, 11:00 at APC, TBA  APCCOLLOQUIUM (Colloquium de l'APC)  astroph 


Friday 28 December 2018, 16:00 at LPT, 114  LPTPTH (Particle Theory Seminar of LPT Orsay)  hepph 



Abstract:  Weakly Interacting Massive Particles (WIMPs) are among the best motivated dark matter candidates. However, in light of non conclusive detection signals and strong constraints from collider, direct and indirect detection experiments, I will start by giving an overview of the WIMP paradigm in the context of simplified dark matter models. I will then discuss models considering extended gauge structures such as constructions involving generalized Chern Simons couplings and a specific WIMP scenario motivated by flavor anomalies. In a second part, I will discuss an alternative dark matter thermal production mechanism by showing an explicit realization of the Strongly Interacting Massive Particles (SIMPs) paradigm in the context of a nonabelian hidden gauge structure. In a last part I will discuss the strong impact of the reheating stage of the universe on the dark matter density production in the context of nonthermal scenarios. 

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