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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 | [Next 30 ] | |
| [ scheduler view ] | ||
| Tuesday 28 January 2020, 10:15 at IHES, Amphithéâtre Léon Motchane | MATH-IHES (TBA) | math |
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| Abstract: | In the talk I will present a mathematically challenging and difficult problem of the (non)existence of compact Clifford-Klein forms of homogeneous spaces G/H. These are quotients of such spaces by discrete subgroups of G acting freely, properly and co-compactly. I will formulate the challenging Toshiyuki Kobayashi conjecture and present several partial results supporting it. The results basically are negative in the sense that I will prove the non-existence of compact Clifford-Klein forms for large families of homogeneous spaces, and the non-existence of standard compact Clifford-Klein forms for all homogeneous spaces of exceptional simple real Lie groups. The methods are purely Lie-theoretical. The approach is quite computational: after expressing the problem as some conditions on Lie subalgebras, we develop algorithms checking known obstructions to the existence of compact Clifford-Klein forms. Algorithms are implemented in the computer algebra system GAP and use classifying algorithms of semisimple Lie subalgebras developed by Willem De Graaf. We use the works of Yosuke Morita and Nicolas Tholozan. The talk is based on my joint work with Maciej Bochenski and Piotr Jastrzebski. | |
| Tuesday 28 January 2020, 11:00 at CPHT, Salle Louis Michel | SEM-CPHT (Séminaire du CPHT) | hep-th |
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| Abstract: | I will discuss recent work on the normal charge density in quantum critical superfluids. The work is motivated by recent experiments on overdoped cuprate superconductors which indicate a non-zero density of uncondensed charge carriers at zero temperature. I will show this is consistent with translation invariant two-fluid hydrodynamics and is a consequence of an underlying quantum critical phase. I illustrate this with a holographic model of superfluidity which exhibits similar transport properties. Time permitting, I will discuss expectations for the normal charge density in critical phases with generic critical exponents. | |
| Tuesday 28 January 2020, 11:30 at LPTENS, LPENS Scherk library | STR-LPT-ENS-HE (Séminaire commun LPTENS/LPTHE) | hep-th |
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| Abstract: | We shall discuss entanglement in open finite free-Fermion chains associated with families of discrete orthogonal polynomials and present a simple construction for a tridiagonal matrix T that commutes with the hopping matrix for the entanglement Hamiltonian H. We shall rely on the notion of algebraic Heun operator attached to bispectral problems, and the parallel between entanglement studies and the theory of time and band limiting. As examples, we will examine Fermionic chains related to the Chebychev and Krawtchouk polynomials. For the former case, which corresponds to a homogeneous chain, the outcome of the construction coincides with recent results of Eisler and Peschel; the latter case yields commuting operators for a particular inhomogeneous chain. Since T is tridiagonal and non-degenerate, it can be readily diagonalized numerically, which in turn can be used to calculate the spectrum of H, and therefore the entanglement entropy. | |
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| Tuesday 28 January 2020, 11:30 at IHES, Amphithéâtre Léon Motchane | MATH-IHES (TBA) | math |
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| Abstract: | Let G be a real reductive Lie group and H a closed subgroup of G. According to the Benoist-Kobayashi criterion, the properness of an action on G/H is controlled by the Cartan projection of H. In this talk, we give some examples of closed subgroups that are not reductive in G but whose Cartan projection is computable (one example is an abelian horospherical subgroup of G). Applying these nonreductive subgroups, we show that some homogeneous spaces of reductive type do not have compact Clifford-Klein forms. | |
| Tuesday 28 January 2020, 14:00 at LPTHE, library | LPTHE-PPH (Particle Physics at LPTHE) | hep-ph |
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| Abstract: | Symmetry breaking in the Higgs field during cosmic inflaton can lead to condensation at a large vacuum expectation value (VEV). After inflation is over, the Higgs field must relax to the minimum of its effective potential, creating an era in which the CPT is effectively broken by the time-depended VEV. In this talk, I argue that the matter-antimatter asymmetry can be generated during this relaxation epoch. | |
| Tuesday 28 January 2020, 16:00 at IPHT, Salle Claude Itzykson, Bât. 774 | IPHT-HEP (Séminaire de physique des particules et de cosmologie) | hep-ph |
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| Abstract: | We consider the question of whether the scalar sector of the Standard Model, and possible deviations from its predicted interactions, are best parametrised by "SMEFT" or "HEFT". Here "SMEFT" means an effective field theory built out of a Higgs doublet, whose components transform linearly under electroweak symmetries; "HEFT" is built out of a singlet Higgs field and three Goldstones upon which symmetry transformations are non-linearly realised. Ultimately, they are just different coordinate choices for a scalar field space manifold. Drawing heavily on the recent literature, we formulate field redefinition invariant (i.e. geometric) criteria on the analyticity and convergence of the lagrangian, to understand when one must and should use a "HEFT" to parametrise the effects of new physics. | |
| Tuesday 28 January 2020, 16:45 at IHES, Amphithéâtre Léon Motchane | PT-IHES (Séminaire de physique théorique de l'IHES) | hep-th |
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| Abstract: | We study the one-loop corrections to correlation functions in quantum field theories in the Anti de Sitter space-time. Our calculation shows the existence of non-local counterterms which however respect the AdS isometry. Our arguments are general and applicable to general non-conformal AdS field theories. We also explain why calculations in Euclidean and Lorentzian signatures should differ even at the leading order in non globaly hyperbolic manifolds. | |
| Wednesday 29 January 2020, 11:30 at IJCLAB, 015 | NUC-THEO (Séminaire de physique nucléaire théorique) | nucl-th |
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| Abstract: | The extension of nuclear physics to the strange sector is a difficult challenge due to the shortage of experimental data, and the difficulty in solving QCD at low energies. With the forthcoming new facilities and new experiments dedicated to the study of single- and double-lambda hypernuclei we prospect new and important developments in this field in the very near future. Reliable theories are essential to support and analyze these experimental campaigns. In this talk, we present the first comprehensive application of pionless effective field theory to single and double $\Lambda$ hypernuclei composed of up to 6 baryons. The theory, fitted to reproduce available experimental data, solves the longstanding overbinding problem of the $^5_\Lambda$He hypernucleus and predicts the existence of a five-body double-$\Lambda$ Hypernuclear bound state yet to be found. Pionless effective field theory is revealed to be a very successful approach to hypernuclei due to the small number of free parameters, and the good theoretical accuracy, enhanced by the large breaking scale and the small momentum of the lambda particles. | |
| Wednesday 29 January 2020, 16:00 at LPENS, Conf IV | LPENS-ACE (Astronomy and Cosmology at ENS) | astro-ph |
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| Abstract: | Do all spiral galaxies exhibit coherent magnetic fields? How are galactic magnetic fields amplified and maintained? What is the distribution of field strengths? How did this change with time? In this talk, I address these questions using a model which computes the magnetic properties of a statistical sample of evolving galaxies. It employs a semi-analytic model of galaxy formation to produce realistic time-varying galactic properties and numerically solves the dynamo equations from the early universe until the present. I will also discuss what are the prospects for observationally constraining this and similar models using a range of tracers. | |
| Wednesday 29 January 2020, 17:00 at LPENS, Conf IV | LPENS-ACE (Astronomy and Cosmology at ENS) | astro-ph |
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| Abstract: | About half of the energy emitted by stars in galaxies was absorbed by dust and re-emitted in the far-infrared. This phenomenon is particularly dramatic for the UV radiation from young stars tracing the star formation. Estimating this intrinsic UV emission is key to understand the star formation across cosmic times. We thus need to know both the amount of UV and far-infrared emitted by the galaxies. During the last decade, Herschel and ALMA have pushed our knowledge of the dusty Universe up to the end of the reionization. It is now clear that very dusty objects exist very early in the Universe and a large fraction of the star formation budget at very high redshift (z~6) is still hidden by dust. I will review the main results from the last years and discuss the consequence on our understanding of galaxy formation. Finally, I will discuss how the SPICA mission can improve our knowledge of this dusty Universe. In particular, the B-BOP instrument will offer us the first opportunity to detect the polarized signal from high-redshift dusty galaxies. | |
| Thursday 30 January 2020, 11:00 at LPTHE, bibliothèque du LPTHE, tour 13-14, 4eme étage | SEM-DARBOUX (Séminaire Darboux - physique théorique et mathématiques) | hep-th|math.AG |
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| 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 non-symplectic. After an introduction on the subject, the aim of the talk is to show recent results in the study of non-symplectic automorphisms of 2-power 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, 10:00 at
IPHT,
Salle Claude Itzykson, Bât. 774 ( https://courses.ipht.cnrs.fr/?q=en/node/246 ) | COURS (Cours) | hep-ph|hep-th |
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| Abstract: | This series of lectures is primarily associated with collider physics where one seeks to learn about fundamental interactions by colliding particles at high energy and by studying the products of these collisions. In this sense, talking about jets is essentially talking about the highly-energetic quarks and gluons produced in these collisions and their dynamics governed by the strong interaction. This is ubiquitous in all recent colliders and jets are (to varying degrees) present in almost all aspects of collider phenomenology. This set of lectures is mostly two-folded: on one side it will try to give a taste of the broad range of aspects and applications of jet physics, on the other side it will show how it is rooted in (perturbative) Quantum Chromodynamics (QCD). Lectures 4-5/5 - Jet substructure in QCD:I will cover several aspects of QCD calculations in the context of jet substructure with a specific focus on their conceptual interpretation. This will cover applications to quark/gluon separation, heavy-boson (W/Z/Higgs) tagging as well as a few curiosities that arise in the process of understanding jet substructure from first principles in perturbative QCD. Remarks:In terms of reference material, most of material covered in the lectures can be found in the set of Springer Lecture Notes "Looking Inside Jets: an introduction to jet substructure and boosted-object phenomenology" (arXiv:1901.10342).Some of the material covered in the first lecture can also be found in the review "Towards Jetography" (arXiv:0906.1833) as well as in standard QCD textbooks (e.g. "QCD and collider physics" by Keith Ellis, James Stirling and Brian Webber). The first and third lectures will be oriented towards concepts and phenomenological aspects. While keeping physics consequences as a target, lectures 2, 4 and 5 will focus more on calculations in the context of perturbative QCD. Note however that this is a tentative plan: I am happy to make adjustments if, in the course of the lectures, it appears that some aspects are worth exploring in more details or some different directions worth being introduced. | |
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| Friday 31 January 2020, 11:00 at LPTHE, Bibliothèque | SEM-LPTHE (Séminaire du LPTHE) | cond-mat.stat-mech |
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| 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 non-perturbative contributions of a given physical observable can be systematically studied using the theory of resurgence, allowing us to construct a full non-perturbative 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 so-called Stokes phenomena and phase transitions. I will then exemplify how these techniques can be applied to to the Lee-Yang zeros in the context of matrix models, a subject of great interest in both mathematics and physics. | |
| Friday 31 January 2020, 11:00 at APC, 454A | APC-COLLOQUIUM (Colloquium de l'APC) | astro-ph |
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| Abstract: | With the advent of ground-based gravitational waves detectors, such as Advanced Ligo and Advanced Virgo, the era of multimessenger astrophysics from compact binary merger has started. Such a kind of events represent bright sources of gravitational waves and electromagnetic radiation, as well as neutrinos and heavy nuclei. The detection and interpretation of multimessenger signals from the collision of two compact objects requires a fruitful interplay between the observational efforts and the theoretical modeling. The pivotal role of all fundamental interactions, as well as the multiscale, multiphysics nature of the process, represents a great challenge in the path towards a deeper understanding of the coalescence process and of its rich phenomenology. In this talk, I will review our present understanding of the major processes involved in the merger of two neutron stars and on their impact on some of the many observable we can presently detect. A special emphasis will be given to the role of neutrinos and weak interactions. | |
| Monday 3 February 2020, 10:45 at LPTMC, Jussieu tower 13-12 5th floor room 5-23 | SEM-LPTMC (Séminaire du Laboratoire de Physique Théorique de la Matière Condensée) | cond-mat.mes-hall |
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| Abstract: | We present an N=2-supersymmetric extension [1] of Jackiw-Pi´s chiral gauge theory (CGT) [2] originally designed to describe Dirac electrons in graphene. The augmented framework allows for the identification of non-perturbative solutions, as vortex-like configurations that saturate a topologically non-trivial (BPS- )bound are proven to be. Remarkably, that regime reveals to be free from extra scalar degrees of freedom brought about to the model as needed partners to fermions in such a linear realisation of supersymmetry, but lacking a phenomenological interpretation. Furthermore, inherent R-Parity provides the room for incorporating a global phase-fermion number symmetry already manifest in the CGT, but now regarded as an external (superspace) invariance. Comments on the fermionic mass-matrix and perspectives shall compose our conclusions. [1] E.M.C. Abreu, M.A. De Andrade, L.P.G. De Assis, J.A. Helayël-Neto, A.L.M.A. Nogueira, R.C. Paschoal, Annals of Physics 354 (2015) 618–636. [2] R. Jackiw, S.-Y. Pi, Phys. Rev. Lett. 98 (2007) 266402. | |
| Monday 3 February 2020, 13:30 at LPENS, Conf IV | LPENS-MDQ (Séminaire Matériaux et Dispositifs Quantiques du LPENS) | cond-mat |
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| Abstract: | While the integration of nanocrystals for display application has demonstrated the viability of these nanomaterials for a mass market, their use for infrared sensing appears also quite promising. When infrared wavelengthes are considered, I will show that HgTe nanocrystals offer a unique combination of broadly tunable optical absorption in the infrared from 1 to 100 µm [1 and top part of figure] and photoconductive properties. However, the maturity of the current device remains far weaker what have been achieve for solar cell using PbS nanocrystals. Current limitations are the result of limited material development and poor understanding of the electronic structure of the material under colloidal form. In this talk, I will discuss some of the recent developments relative to HgTe nanocrystal integration into photodiodes operating in the short wave and mid wave infrared. I will present how the concepts of unipolar barrier has been transferred from III-V semiconductor to colloidal HgTe nanocrystal film [2]. Another important limitation to address is tradeoff between the absorption depth (> 1 µm) and the carrier diffusion length (< 100 nm) which make that most current devices have a weak light absorption (10 % of the incident light typically). This issue can be addressed by two strategies which are the development of ink to achieve thick high mobility film [3] and by enhancing the light matter coupling thanks to the introduction of plasmonic resonator (bottom left part of figure). I will briefly also report about recent development relative to the integration into focal plane array to conduct imaging (bottom right part of figure). Finally, I will discuss about how it is possible to take advantage of intraband transitions in self doped nanocrystal to design mid wave infrared detector [4-5]. I will in particular discuss how early limitations of the doped nanocrystals (large dark current in particular) can be overcome by carefully engineering the energy landscape of the nanocrystal film. To reach this goal design inspired from II-V semiconductor has been used. References [1] Terahertz HgTe nanocrystals: beyond confinement, N. Goubet, A. Jagtap, C. Livache, B. Martinez, H. Portales, X. Zhen Xu, R.P.S.M. Lobo, B. Dubertret, E. Lhuillier, J. Am. Chem. Soc. 140, 5053 (2018). [2] Design of Unipolar Barrier for Nanocrystal Based Short Wave Infrared Photodiode, A.Jagtap, B. Martinez, N. Goubet, A. Chu, C. Livache, C. Greboval, J. Ramade, D. Amelot, P. trousset, A. triboulin, S. Ithurria, M. G. Silly, B. Dubertret, E. Lhuillier, ACS Phot. 5, 4569 (2018) [3] HgTe Nanocrystal Inks for Extended Short Wave Infrared Detection, B. Martinez, J. Ramade, C. Livache, N. Goubet, A. Chu, C. Gréboval, J. Qu, W. L. Watkins L. Becerra, E. Dandeu, J.-L. Fave, C. Méthivier, E. Lacaze, E. Lhuillier, Adv Opt Mat 1900348 (2019). [4] Infrared photo-detection based on colloidal quantum-dot films with high mobility and optical absorption up to the THz, E. Lhuillier, M. Scarafagio, P. Hease, B. Nadal, H. Aubin, X. Z. Xu, N. Lequeux, G. Patriache, S. Ithurria, B. Dubertret, Nano Lett 16, 1282 (2016) [5] A Colloidal Quantum Dot Infrared Photodetector and its use for Intraband Detection, C. Livache, B. Martinez, N. Goubet, C. Greboval, J. Qu, A. Chu, S. Royer, S. Ithurria, M. G. Silly, B. Dubertret, E. Lhuillier, Nature Comm 10, 2125 (2019) | |
| Monday 3 February 2020, 14:30 at
IHES,
Amphithéâtre Léon Motchane ( Séminaire Géométrie et groupes discrets ) | MATH-IHES (TBA) | hep-th |
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| Abstract: | In low dimension, it is expected that topological properties determine a natural geometry. In this spirit, several characterizations are conjectured for Kleinian groups, i.e. discrete subgroups of PSL(2,C). We will survey different methods that lead to their topological and dynamical characterizations, and point out their limits and the difficulties encountered in obtaining a complete answer. | |
| Monday 3 February 2020, 16:30 at
IHES,
Amphithéâtre Léon Motchane ( Séminaire Géométrie et groupes discrets ) | MATH-IHES (TBA) | hep-th |
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| Abstract: | Let W be a Coxeter group. We provide a precise description of the conjugacy classes in W, yielding an analogue of Matsumoto's theorem for the conjugacy problem in arbitrary Coxeter groups. This extends to all Coxeter groups an important result on finite Coxeter groups by M. Geck and G. Pfeiffer from 1993. In particular, we describe the cyclically reduced elements of W, thereby proving a conjecture of A. Cohen from 1994. | |
| Tuesday 4 February 2020, 11:00 at LPTHE, Library, tour 13-14, 4th floor | P^3 (Particle Physics in Paris) | hep-ph|hep-th |
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| 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 higher-spin particles, and theories with very irrelevant interactions, cannot originate from unitary theories. | |
| Tuesday 4 February 2020, 11:00 at IPHT, Amphi Hermite | IPHT-HEP (Séminaire de physique des particules et de cosmologie) | hep-ph |
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| 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 higher-spin particles, and theories with very irrelevant interactions, cannot originate from unitary theories.  | |
| Tuesday 4 February 2020, 17:15 at DPT-PHYS-ENS, Conf IV (E244) - Département de Physique de l'ENS 24 rue Lhomond 75005 PARIS | COLLOQUIUM-ENS (Colloquium of the Physics Department of ENS) | physics |
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| Abstract: | The organization of fluid systems into a turbulent layer adjacent to a stably stratified one is common both in Nature (atmospheres, stellar interiors, ...) and in the industry (e.g. nuclear power plant in accidental configurations). Understanding the exchanges of mass and momentum at the interface and the coupled dynamics of such systems is challenging, because of the large range of involved time- and length-scales, from the rapid small-scale turbulence associated to the excitation of propagating waves, to their longterm non-linear interactions associated to large-scale circulations. I will present the results of various experimental investigations of idealised configurations, complemented by numerical simulations: a turbulent jet impinging a density interface, the convection in water around 4 degree Celsius, etc. Applications in meteorology, stellar evolution, and nuclear safety, will be addressed. | |
| Wednesday 5 February 2020, 12:00 at LPENS, Conf. IV | FORUM-ENS (Forum de Physique Statistique @ ENS) | cond-mat.stat-mech |
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| Abstract: | Abstract: I will consider the non-equilibrium dynamics of a recently introduced class of "statistically solvable” many-body quantum systems: the dual-unitary circuits. These systems furnish a minimal modelling of generic locally interacting many-body quantum systems: they are generically non-integrable and include a quantum chaotic subclass. I will first discuss the dynamics of initial-state dependent quantities, such as the entanglement entropies and local correlators, showing that it is possible to find (and classify) a family of initial states in MPS form that allow for an exact solution of the dynamics (also in the presence of quantum chaos). Then I will discuss the dynamics of an initial-state independent quantity, the so called “operator entanglement”, that measures the growth of entanglement that the Heisenberg evolution induces in operator space. I will show that one can identify different subclasses of dual- unitary circuits. In particular I will describe a “maximally chaotic” subclass, where the entanglement of local operators grows linearly, and a “dynamically constrained” one, where the entanglement of local operators is bounded. | |
| Wednesday 5 February 2020, 14:15 at IPHT, Salle Claude Itzykson, Bât. 774 | IPHT-MAT (Séminaire de matrices, cordes et géométries aléatoires) | hep-th |
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| Thursday 6 February 2020, 10:00 at LPTHE, LPTHE Library | RENC-THEO (Rencontres Théoriciennes) | hep-th |
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| Abstract: | > This talk is dedicated to recent double-copy constructions that unify massless tree-level amplitudes in a variety of perturbative string theories. All the polarization dependence in gauge- and gravity amplitudes of type-I, type-II, bosonic and heterotic string theories is proposed to enter via field-theory building blocks with a known Lagrangian origin. The second double-copy component of massless string amplitudes involves moduli-space integrals over punctured sphere and disk worldsheets whose low-energy 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 | RENC-THEO (Rencontres Théoriciennes) | hep-th |
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| Thursday 6 February 2020, 14:00 at LPTM, 4.13 St Martin II | SEM-LPTM-UCP (Seminaires du LPTM , Universite de Cergy Pontoise) | math-ph |
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| Abstract: | Classical chaos refers to exponential sensitivity of phase-space trajectories to small changes in initial conditions. It is not straightforward to extend this notion to quantum systems, which undergo linear evolution and moreover do not exhibit precise phase space trajectories. One possible way to define quantum chaos is via statistical properties of energy levels, which have been related to those of random matrices. Recently, motivated by studies of black holes, exponential growth of out-of-time-order correlators has received a lot of attention as another possible diagnostic of quantum chaos, and an upper bound on the corresponding “Lyapunov exponent” has been obtained. Chaos is closely related to the thermalization of isolated quantum systems. Via holography, quantum chaos is reflected in the physics of black holes, which are dual to thermal states. In the same way, the study of black hole formation has given a new handle on the thermalization of strongly correlated systems. This talk contains a review of these ideas as well as brief discussions of some recent projects in our group. | |
| Friday 7 February 2020, 10:00 at
IPHT,
Salle Claude Itzykson, Bât. 774 ( https://courses.ipht.cnrs.fr/?q=en/node/246 ) | COURS (Cours) | hep-ph|hep-th |
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| Abstract: | This series of lectures is primarily associated with collider physics where one seeks to learn about fundamental interactions by colliding particles at high energy and by studying the products of these collisions. In this sense, talking about jets is essentially talking about the highly-energetic quarks and gluons produced in these collisions and their dynamics governed by the strong interaction. This is ubiquitous in all recent colliders and jets are (to varying degrees) present in almost all aspects of collider phenomenology. This set of lectures is mostly two-folded: on one side it will try to give a taste of the broad range of aspects and applications of jet physics, on the other side it will show how it is rooted in (perturbative) Quantum Chromodynamics (QCD). Lectures 4-5/5 - Jet substructure in QCD:I will cover several aspects of QCD calculations in the context of jet substructure with a specific focus on their conceptual interpretation. This will cover applications to quark/gluon separation, heavy-boson (W/Z/Higgs) tagging as well as a few curiosities that arise in the process of understanding jet substructure from first principles in perturbative QCD. Remarks:In terms of reference material, most of material covered in the lectures can be found in the set of Springer Lecture Notes "Looking Inside Jets: an introduction to jet substructure and boosted-object phenomenology" (arXiv:1901.10342). Some of the material covered in the first lecture can also be found in the review "Towards Jetography" (arXiv:0906.1833) as well as in standard QCD textbooks (e.g. "QCD and collider physics" by Keith Ellis, James Stirling and Brian Webber). The first and third lectures will be oriented towards concepts and phenomenological aspects. While keeping physics consequences as a target, lectures 2, 4 and 5 will focus more on calculations in the context of perturbative QCD. Note however that this is a tentative plan: I am happy to make adjustments if, in the course of the lectures, it appears that some aspects are worth exploring in more details or some different directions worth being introduced. | |
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| Friday 7 February 2020, 11:00 at LPTHE, Bibliothèque | SEM-LPTHE (Séminaire du LPTHE) | cond-mat.stat-mech|hep-th|math-ph |
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| 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 sub-leading 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 S-matrix by a CDD factor. I will show how these deformations can be described as certain field-dependent 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 sinh-Gordon model, will present a connection with the fermionic basis description of finite-size one-point functions. | |
| Friday 7 February 2020, 11:00 at APC, Amphithéatre Pierre Gilles de Gennes | APC-COLLOQUIUM (Colloquium de l'APC) | astro-ph |
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| Friday 7 February 2020, 14:15 at IPHT, Salle Claude Itzykson, Bât. 774 | IPHT-MAT (Séminaire de matrices, cordes et géométries aléatoires) | hep-th |
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