Pantheon SEMPARIS Le serveur des séminaires parisiens Paris

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
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Tuesday 23 July 2019, 14:00 at LPTHE, library LPTHE-PPH (Particle Physics at LPTHE) hep-ph
Cen Zhang ( IHEP Beijing ) Positivity bounds on vector boson scattering
Abstract: Searching for deviations in quartic gauge boson couplings (QGCs) is one of the main goals of the electroweak program at the LHC. We consider positivity bounds adapted to the Standard Model EFT, and show that a set of positivity constraints on 18 anomalous QGC couplings can be derived, by requiring that the vector boson scattering amplitudes satisfy the fundamental principles of quantum field theory. We solve the positivity inequalities and find that the allowed parameter space is carved out by the intersection of pyramids, prisms, and cones. Altogether, the allowed parameter space is reduced to ~2% of total. These bounds provide guidance to future BSM searches and could affect the limits on couplings by modifying the prior.

Thursday 25 July 2019, 11:00 at IPN, Salle A015 IPN-X (Séminaire commun de physique théorique des particules IPN-CPHT-X) hep-ph
Daniel Kikola ( Warsaw University of Technology ) A fixed-target program at the LHC for heavy-ion, hadron, spin and astroparticle physics: recent progress and current status
Abstract: Thanks to its multi-TeV LHC proton and lead beams, the LHC complex allows one to perform the most energetic fixed-target experiments ever and to study with high precision pp and pA collisions at \sqrt(sNN) = 115 GeV and Pbp and PbA collisions at \sqrt(sNN) = 72 GeV. Such an experiment will facilitate a broad physics program, covering the large-x frontier for particle and astroparticle physics, spin and heavy-ion physics. We will present performance studies for measurements of the production of Drell-Yan pairs, quarkonia, open heavy-flavor mesons as well as light-flavor hadrons in pp, pA and PbA collisions using the LHCb and ALICE detectors in a fixed-target mode. Recent progress on the implementation of the fixed target program at the LHC and its perspectives will be also discussed.

Friday 26 July 2019, 14:00 at LPTHE, library LPTHE-PPH (Particle Physics at LPTHE) hep-ph
Florian Domingo ( Bonn U. ) Electroweak corrections to the fermionic decays of heavy Higgs states
Abstract: Extensions of the Standard Model often come with additional, possibly electroweakly charged Higgs states, the prototypal example being the Two-Higgs-Doublet Model. While collider phenomenology does not exclude the possibility for some of these new scalar fields to be light, it is relatively natural to consider masses in the multi-TeV range, where decoupling of the SM-like boson is almost guaranteed. The appearance of a hierarchy between the new-physics states and the electroweak scale then leads to sizable electroweak corrections in e.g. the decays of the heavy Higgs, which are dominated by effects of infrared type, namely Sudakov logarithms. Such radiative contributions obviously affect the two-body decays, but should also be paired with the radiation of electroweak (or lighter Higgs) bosons for a consistent picture at the one-loop order. Resummation of the leading terms is also relatively easy to achieve. We re-visit these questions in the specific case of the fermionic decays of heavy Higgs particles in the Next-to-Minimal Supersymmetric Standard Model, in particular pointing out the consequences of the three-body final states for the branching ratios of the heavy scalars.

Tuesday 3 September 2019, 11:00 at IPHT, Salle Claude Itzykson, Bât. 774 IPHT-GEN (Séminaire général du SPhT) physics
Alexander Turbiner ( ICN-UNAM, Mexico and Stony Brook University, USA ) Choreography in Physics (living in motion, moving polymers, superintegrability etc)
Abstract: By definition the choreography (dancing curve) is a closed trajectory on which $n$ classical bodies move chasing each other without collisions. The first choreography (the Remarkable Figure Eight) at zero angular momentum was discovered unexpectedly by C Moore (Santa Fe Institute) at 1993 for 3 equal masses in $R^3$ Newtonian gravity numerically. At the moment about 6,000 choreographies in $R^3$ Newtonian gravity are found, all numerically for different $n > 2$. A number of 3-body choreographies is known in $R^2$ Newtonian gravity, for Lennard-Jones potential (hence, relevant for molecular physics), and for some other potentials, again numerically; it might be proved their existence for quarkonia potential. \par Does exist (non)-Newtonian gravity for which dancing curve is known analytically? - Yes, a single example is known - it is algebraic lemniscate by Jacob Bernoulli (1694) - and it will be a concrete example of the talk. Astonishingly, $R^3$ Newtonian Figure Eight coincides with algebraic lemniscate with $\chi^2$ deviation $\sim 10^{-7}$. Both choreographies admit any odd numbers of bodies on them. Both 3-body choreographies define maximally superintegrable trajectory with 7 constants of motion. \par Talk will be accompanied by numerous animations.

Monday 16 September 2019, 10:45 at LPTMC, Jussieu, tower 13-12, room 5-23 SEM-LPTMC (Séminaire du Laboratoire de Physique Théorique de la Matière Condensée) cond-mat.mes-hall
Ivan Dornic ( SPEC Saclay & LPTMC ) A tale of Pfaffian persistence tails told by a Painlevé VI transcendent
Abstract: We identify the persistence probability for the spin located at the origin of a half-space magnetized Glauber-Ising chain as a Fredholm Pfaffian gap probability generating function with a sech-kernel. This is then recast as a tau-function for a certain Painlevé VI transcendent --- a sort of exact Kramers' formula for the associated explicitely time-dependent Hamiltonian --- where the persistence exponent emerges as an asymptotic decay rate. By a known yet remarkable correspondence that relates Painlevé equations to Bonnet surfaces, the persistence probability has also a geometric meaning à la Gauss-Bonnet in terms of the intrinsic curvature of the underlying surface. Since the same sech-kernel with an underlying Pfaffian structure shows up in a variety of Gaussian first-passage problems, our Painlevé VI characterization appears as a universal probability distribution akin to the famous Painlevé II Tracy-Widom laws. Its tail behavior in the magnetization-symmetric case allows in particular to recover the exact value 3/16 for the persistence exponent of a 2d diffusing random field, as found very recently by Poplavskyi and Schehr (arXiv:1806.11275). Due to its topological origin, this value should constitute the super-universal persistence exponent for the coarsening of a non-conserved scalar order parameter in two space dimensions.

Monday 16 September 2019, 14:00 at LPNHE, Amphi Charpak LPNHE (Séminaires du LPNHE) hep-ex
Loïc Valery ( LPC Clermont Ferrand ) TBA

Monday 23 September 2019, 10:45 at LPTMC, Jussieu, tower 13-12, room 5-23 SEM-LPTMC (Séminaire du Laboratoire de Physique Théorique de la Matière Condensée) cond-mat.mes-hall
Juliette Mignot ( IPSL-LOCEAN Jussieu ) Changement climatique et mesures concrètes prises par des labos (provisoire)

Monday 30 September 2019, 10:45 at LPTMC, Jussieu, tower 13-12, room 5-23 SEM-LPTMC (Séminaire du Laboratoire de Physique Théorique de la Matière Condensée) cond-mat.mes-hall
Claude Loverdo ( Laboratoire Jean Perrin, Paris ) Biophysique (provisoire)

Wednesday 2 October 2019, 14:15 at IPHT, Salle Claude Itzykson, Bât. 774 IPHT-MAT (Séminaire de matrices, cordes et géométries aléatoires) hep-th
Elias Kiritsis ( APC ) (TBA)

Tuesday 22 October 2019, 11:30 at LPTENS, LPTENS library STR-LPT-ENS-HE (Séminaire commun LPTENS/LPTHE) hep-th
Ida Zadeh ( ICTP ) TBA

Monday 25 November 2019, 10:45 at LPTMC, Jussieu, tower 13-12, room 5-23 SEM-LPTMC (Séminaire du Laboratoire de Physique Théorique de la Matière Condensée) cond-mat.mes-hall
Janos Asboth ( Budapest ) Marche quantique sous champ magnétique (provisoire)

Monday 9 December 2019, 10:45 at LPTMC, Jussieu, tower 13-12, room 5-23 SEM-LPTMC (Séminaire du Laboratoire de Physique Théorique de la Matière Condensée) cond-mat.mes-hall
Cesare Nardini ( CEA SPEC Saclay ) Matière active (provisoire)

seminars from series at institute
in subject with field matching

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