Mini workshop on the S-matrix bootstrap

vendredi 20 sept. 2024, 09:00 → 22:00 Europe/Paris

LAPTh

Piotr TOURKINE (LAPTh, CNRS, Annecy)

One-day workshop on S-matrix bootstrap in Annecy, targeting the local community of Paris and Lemanic area. This is the continuation of similar events that took place in Paris last year.

There will be a few seminars, a gong show and ample time for discussions in a relaxed athmosphere.

Last updated on Sept. 14th

Gong-show

• A gong show will take place after lunch, everyone is encouraged to participate! Tell a story in 3-5 minutes (depending on final number of participants) about what you work on at the moment, an idea you find interesting, a nice method, a problem you have, anything you would like to share. Register here https://indico.in2p3.fr/event/33034/registrations/4173/

 

Accomodation:

• If you requested a room, you have received up-to-date information from Indico on Sept. 13th (check your spams). Your hotel is the Centre Jean XXIII, a short walk away from the conference.

 

Transportation:

• From Paris, the easiest is to come by TGV. Public buses in Annecy will take you to the LAPTh: take line 1 direction "Parc des Glaisins" and stop at Campus, then there is a 2 minutes walk to the lab.
• For those travelling by car, there is free parking in front of the lab. The barrier on the driveway opens automatically.  

 

Information_Notices_Colloques20ENG-1.pdf

Mentions_information_Colloque2020FR-1.pdf

09:00 → 10:00 Welcom coffee and discussions

10:00 → 10:35 The Hybrid Bootstrap

In recent years, great focus has been given to analytical functionals to bootstrap extremal solutions to crossing. Current bootstrap methods mainly focus on determining the CFT data associated to the lowest lying operators. We will attempt to open a path towards approximating the full spectrum of extremal solutions in 1d by employing the powerful extremal functionals. Knowing the asymptotic behavior of both solutions and functionals, we rewrite crossing as an integral equation in the large Δ limit. This leads to the construction of a hybrid bootstrap : analytical solution of crossing in the UV, and standard numerical methods in the IR. Advantages and limits of this novel method will be discussed along with applications.

Orateur: Noé Suchel

10:35 → 11:10 The S-matrix Bootstrap with Neural Networks

I will introduce a new method for solving the unitarity equations in the S-matrix bootstrap framework using neural networks. This approach is designed to be applied to amplitudes that satisfy the Mandelstam representation, which helps ensure an accurate description of the fine structure of the scattering amplitude, particularly their double discontinuity. As an initial validation, we applied both our method and the standard bootstrap technique to a simplified toy model focusing on the S-wave unitarity condition. The resulting allowed regions show strong agreement, which highlights the potential of our method. Based on these promising results, we plan to extend our approach to solve the Mandelstam equation.

Orateur: Damien Leflot

11:10 → 11:55 Café, discussions

11:55 → 12:30 Exploring the Spectrum of Consistent EFTs

I will discuss the implications of consistency conditions coming from Causality and Unitarity on the parameter space of Effective Field Theories (EFTs) of particles with spin $J$. I will show in particular that for $J\geq2$, the mass must be parametrically close to that of the nearest UV excitation, thus reducing the range of applicability of such theories.

Orateur: Sara Ricossa

12:30 → 14:30 Lunch

14:30 → 15:20 Gong show

15:20 → 15:50 Café, discussions

15:50 → 16:25 Local conformal field theory from long range perturbation theory

Conformal field theory (CFT) can be studied using perturbative methods, such as the 4-epsilon expansion and the large N expansion. In this talk, I will introduce an alternative approach: a fixed-dimensional perturbation theory that incorporates long-range, non-local interactions. I will demonstrate that by imposing the conformal Ward Identity, it is possible to recover the data of local CFTs. By re-summing the perturbative series using long-range solitons, we obtain nice results for the critical exponents.

Orateur: Junchen Rong (IHES, France)

16:25 → 17:00 Non-invertible symmetries and scattering amplitudes.

Orateur: Lucia Cordova

17:00 → 19:00 Apéritif, discussions