Mini-workshop “Strings, higher spins and amplitudes”

On 25 May 2023 from 10:00 to 17:15
Campus Plaine de Nimy - Pentagone

Organized by

Nicolas Boulanger, Andrea Campoleoni and Evgeny Skvortsov

On the 25th of May UMONS hosted a mini-workshop associated to the New Horizons Solvay Chair held by Sasha Zhiboedov. The goal of the workshop was to allow young researchers working in various Belgian universities to interact in an informal way with the Solvay chair holder.



Salle 0A07, bâtiment Pentagone
09:45 – 10:00   Welcome coffee
10:00 – 11:00 Sasha Zhiboedov (CERN) Energy correlators with heavy sources
11:00 – 11:30 Coffee break
11:30 – 12:15 Chrysoula Markou (UMONS) Massive and spinning colliding strings
12:15 – 13:45 Lunch
Salle Mirzakhani, bâtiment de Vinci
13:45 – 14:30 Marina David (KUL) AdS_7 Black Holes from Rotating M5-branes
14:30 – 15:15 Jeremìas Aguilera Damia (ULB) Non-invertible symmetries along supersymmetric RG flows
15:15 – 15:45 Coffee break
15:45 – 16:30 Alex Arvanitakis (VUB) Non-invertible symmetry, topological defects, and hamiltonian mechanics
16:30 – 17:15 Francesca Mariani (UGent) Near-extremal black holes in de Sitter space


Sasha Zhiboedov (CERN)


Energy correlators with heavy sources

I will discuss energy correlators with heavy sources in CFTs. Heavy operators in CFTs naturally define “macroscopic” states. These states are characterized by an emergent EFT description which depends on the physical nature of the heavy operator and details of the theory (e.g., hydrodynamics, Goldstone EFT, black hole, macroscopic string, etc). In this talk, I will discuss how the physical properties of heavy operators manifest themselves in a collider experiment. As a concrete example, I will consider energy correlators of large charge half-BPS operators in N=4 SYM.


Chrysoula Markou (UMONS)


Massive and spinning colliding strings

The string spectrum comprises an infinity of physical states of arbitrarily high mass and spin; these are all relevant at the string scale and hold key to string theory’s UV consistency. In this talk, we will first discuss the lowest-order self- and gravitational interactions of some of the lowest-lying massive spin-2 string states using string scattering amplitudes. Next, we will address the full spectrum of the bosonic string and some of its tree-level scattering amplitudes in a collective fashion along various Regge trajectories. We will conclude by exploring some of its implications for massive higher-spin interactions.


Marina David (KUL)


AdS_7 Black Holes from Rotating M5-branes

I will present a novel asymptotically locally AdS7 black hole solution in maximal gauged supergravity with three distinct angular momenta and two electric charges. When embedded in 11d supergravity the black hole describes the backreaction of N coincident rotating M5-branes. I will then discuss the thermodynamic properties of the black hole as well as its holographic dual via the 6d superconformal index in the large N limit.


Jeremìas Aguilera Damia (ULB)


Non-invertible symmetries along supersymmetric RG flows

In the last years, there has been renewed interest in studying fundamental aspects of symmetry and, in particular, its inherent relation with topological sectors in Quantum Field Theory. This ideas set the stage for exploring new notions of global symmetry, such as higher form symmetries and, notably, symmetries falling beyond the standard group theory, hence called non-invertible symmetries. Interestingly, these more exotic structures have been found to be present in many well know systems, such as the two dimensional Ising model, four dimensional QED and N=4 super Yang-Mills. It is then relevant to understand the set of constraints that these new tools might impose on the dynamical processes, with the aim to gain more intuition on the physics of strongly coupled systems. In this talk, I will present a step forward in that direction by studying the realization of duality non-invertible symmetries preserved along RG flows triggered by massive deformations of N=4 super Yang-Mills. More precisely, I will show how to detect these symmetries and how are they realized in the infrared phase structure, making contact with standard notions, such as symmetry breaking, but also uncovering novel interesting phenomena.


Alex Arvanitakis (VUB)


Non-invertible symmetry, topological defects, and hamiltonian mechanics

Non-invertible symmetry is a fairly new concept. It is a generalization of the concept of symmetry between two “phases” A and B which are separated by a “wall” with specific properties, called a topological defect. These concepts appear in many problems of condensed matter and high energy physics. I will talk about my recent research where I explained the physics of topological defects and the corresponding non-invertible symmetries using familiar ideas of hamiltonian mechanics (lagrangian correspondences, in fact), and give applications to string theory, spacetime topology, and integrable structures in Chern-Simons theories.


Francesca Mariani (UGent)


Near-extremal black holes in de Sitter space

In this talk I will focus on near-extremal Reissner-Nordström black holes in 3➕1d de Sitter space. These black holes admit three different extremal limits dubbed cold, Nariai and ultracold, with different near-horizon geometries. For each of these three cases I will analyse the thermodynamic response of the system to small deviations away from extremality. The ultracold case in particular shows an interesting interplay between the entropy variation and charge variation, realizing a different symmetry breaking with respect to the other two near-extremal limits. I will then build the effective 2D theory by dimensionally reducing Einstein-Maxwell theory on the two-sphere, and study the perturbations around the near-horizon geometry for each case.


To reach the workshop venue:

  • Trains from Brussels to Mons are running every half an hour, starting around h:25 and h:56 from Midi station (please crosscheck the train schedule!);
  • Direct trains from Leuven to Mons are running every hour. See, for instance, the Leuven-Mons train 7:54-9:12 and the Mons-Leuven train 17:50-19:10 (please crosscheck the train schedule!);
  • The workshop will take place in the UMONS campus “Plaine de Nimy”, that can be reached from Mons train station in 20/25 minutes by walk (see the precise address below). A limited number of blue-bikes is also available at the train station;
  • The first two talks will take place in the building Pentagone, while the lunch and the afternoon session will take place in the building De Vinci (map of the campus).


Workshop supported by


Avenue du Champ de Mars, 6
7000 Mons, Belgium