Universität Bonn

Trimester Program: "Probabilistic methods in quantum field theory"


May 5 - August 15, 2025

Organizers: Roland Bauerschmidt, Eveliina Peltola, Ellen Powell, Rémi Rhodes, Eero Saksman

Description: Quantum field theories (QFTs) have been successfully applied, throughout the last 70 years, to model and analyze diverse physical phenomena; in particular, critical behavior in statistical mechanics, and interactions of fundamental particles. However, a rigorous mathematical framework to construct and understand these theories is still limited. This program will further pursue this direction, building on recent developments towards QFT coming from random geometry and probability theory. In particular, the goal is to bring together researchers with different viewpoints and expertise on this multifaceted topic.

With this combined expertise, the program aims at addressing some of the main challenges and key open questions in the field, including in the following areas: 

  • advances in quantum gauge theories in 3D and 4D
  • rigorous constructions of exactly solvable quantum field theories, especially in 2D
  • more generally, analysis of probabilistic aspects of quantum field theories
  • the theory of phase transitions, in particular for systems with continuous symmetry, and related phenomena

The program will include an introductory summer school and three workshops. For further information concerning these events, please see the above-mentioned links to the corresponding websites.

The online application platform to participate in this Trimester Program has been closed.


Participants

PERSON
AFFILIATION

Aru Juhan

Bauerschmidt Roland

Berestycki, Nathanael

Camia, Federico

Chandra, Ajay

Chevyrev, Ilya

Duch, Pawel

Ganguly, Shirshendu

Giuliani, Alessandro

Gordina, Maria

Guillarmou, Colin

Gwynne, Ewain

Helmuth, Tyler

Holden Nina

Huang, Yi-Zhi

Klevtsov, Semyon

Kupiainen, Antti

Lacoin Hubert

Lévy, Thierry

Qian, Wei

Schippers, Eric

Sepulveda, Avelio

Shen, Hao

Sun, Xin

Viklund, Fredrik

Wang, Yilin

Wu, Hao

Wu, Wei

Zeitouni, Ofer

Zhu, Rongchan

Zhu, Xiangchan

EPFL

Courant Institute of Mathematical Sciences

University of Vienna

New York University Abu Dhabi

Imperial College London

University of Edinburgh

EPFL SB MATH

UC Berkeley

Università degli Studi Roma Tre

University of Connecticut

Univ. Paris Saclay

University of Chicago

Durham University

New York University

Rutgers University

University of Strasbourg

Helsinki University

IMPA

Sorbonne Université

City University of Hong Kong

University of Manitoba

Universidad de Chile

University of Wisconsin-Madison

Peking University

KTH Royal institute of technology

Institut des Hautes Etudes Scientifiques

Tsinghua University

NYU Shanghai

Weizmann Institute

Beijing Institute of Technology

Chinese academy of Sciences

 
 

 
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AFFILIATION
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  Trimester Seminar Series

TBA (date)

Location: TBA

Title: TBA

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Summer School "Probabilistic methods in quantum field theory"

May 12 - 16, 2025

Venue: HIM lecture hall (Poppelsdorfer Allee 45, Bonn)

Organizers: Roland Bauerschmidt, Eveliina Peltola, Ellen Powell, Rémi Rhodes, Eero Saksman

Lecturers:

  • Morris Ang (University of California San Diego)
  • Malin Palö Forsström (Chalmers University of Technology)
  • Christophe Garban (University of Lyon)
  • Antti Kupiainen (University of Helsinki)

Description: 

Quantum field theories (QFTs) have been successfully applied to model and analyze diverse physical phenomena; in particular, critical behavior in statistical mechanics, and interactions of fundamental particles.
However, a rigorous mathematical framework to construct and understand these theories is still limited.

In the past two decades, making sense of Conformal Field Theory (CFT) from a probabilistic perspective has become a question of considerable interest, and significant breakthroughs have been made; for example, in contructing the Liouville CFT, and CFT quantities from critical lattice models.
Other important models of QFTs, that have attracted considerable attention in recent years, are gauge theories, which form the basis for the standard model, for which an important approach goes through lattice approximations.

Also, the macroscopic features of many critical lattice models are believed to be described by CFTs.
Interfaces in these models have been shown to be described by the Schramm–Loewner Evolution (SLE) random curves.
Another central theme in this area, motivated by the aim of describing large-scale behavior
of random planar map models, is that of so-called Liouville quantum gravity (LQG).
The relationship of SLE and LQG has been recently discovered to be rather intimate.

This Summer School explores these exciting areas of research at the intersection of probability theory and mathematical physics.


The online application platform to participate in the school will be accessible from November 4, 2024 to January 26, 2025 (11:59 PM CEST): https://math-events.uni-bonn.de/e/him2025-tp2-school 

Early career Trimester Program participants who visit HIM during the period of this school are eligible to attend this event.


Workshop: "Random geometry and its connections to QFT"

May 19 - 23, 2025

Venue: HIM lecture hall (Poppelsdorfer Allee 45, Bonn)

Organizers: Roland Bauerschmidt, Eveliina Peltola, Ellen Powell, Rémi Rhodes, Eero Saksman

Description: 

Random geometry refers to the study of random geometric structures, such as curves and surfaces.
One of the most notable examples is the Schramm–Loewner Evolution (SLE), which has been shown to describe the scaling limits of interfaces in 2D critical models.
Significant progress has been made through its interplay with the Gaussian Free Field (GFF), deepening the understanding of the geometric properties of both SLE and the GFF.

The macroscopic features of lattice models are believed to be described by quantum field theories (QFTs).
Critical lattice models are expected to enjoy an additional conformal symmetry, and such QFTs are termed conformal field theories (CFTs).
For instance, the Ising model, a prototypical example with an order-disorder phase transition, has seen mathematical breakthroughs that have fully established its continuum description.
However, extending these results to other models, such as the Potts or random cluster models, remains a major challenge, e.g. due to the absence of similar powerful integrability techniques.

Another major theme in this workshop is Liouville quantum gravity (LQG),
a concept that can be approached through Liouville CFT, random planar maps, or the "mating-of-trees" framework.
These perspectives have recently seen significant advances and are increasingly interconnected, providing new insights into large-scale random geometry behavior.

This workshop will focus on these central themes and the challenges they pose, including:

- the construction of CFTs from lattice models
- probabilistic approaches to CFTs, such as the LQG, Liouville CFT, and its implications for 2D quantum gravity
- the development of new techniques for understanding scaling limits of
general lattice models


In case you are interested in participating in this event, please apply via the Trimester Program application platform. Please observe the application deadline.

Trimester Program guests, who were invited and have confirmed to be at HIM during the period of this workshop, are eligible to attend this event.


Workshop: "Integrable QFT: conformal bootstrap, bosonization, near-critical perturbations, and Coulomb gas"

June 23 -27, 2025

Venue: HIM lecture hall (Poppelsdorfer Allee 45, Bonn)

Organizers: Roland Bauerschmidt, Eveliina Peltola, Ellen Powell, Rémi Rhodes, Eero Saksman

Description: 

Two-dimensional conformal field theories (CFTs) are iconic examples of integrable quantum field theories.
Since their introduction by Belavin, Polyakov, and Zamolodchikov in 1984, they have advanced through developments in theoretical physics and mathematics, particularly via the conformal bootstrap method.
However, the connection between the constructive approach to CFT, through statistical physics models, and the probabilistic foundations of the bootstrap remains unclear.
Probability theory also has a role to play beyond exact solvability; more generally, in integrable QFT but the present understanding is then even more sparse.

This workshop will explore recent progress in the field, addressing key topics such as:

- minimal models and their connection to lattice models and
Schramm-Loewner evolution (SLE)
- probabilistic constructions of CFTs, notably the Liouville model and its implications for 2D quantum gravity
- bosonization and its role in integrability, particularly in the Sine-Gordon
and Thirring models
- the study of nonlinear sigma models and their importance in understanding
quantum spin chains


In case you are interested in participating in this event, please apply via the Trimester Program application platform. Please observe the application deadline.

Trimester Program guests, who were invited and have confirmed to be at HIM during the period of this workshop, are eligible to attend this event.


Workshop: "Gauge theories and spin systems: Yang-Mills theory, continuous symmetry, and disorder"

July 28 - August 1, 2025

Venue: HIM lecture hall (Poppelsdorfer Allee 45, Bonn)

Organizers: Roland Bauerschmidt, Eveliina Peltola, Ellen Powell, Rémi Rhodes, Eero Saksman

Description: 

Quantum gauge theories, such as Yang-Mills theories with gauge group SU(N), play a fundamental role in particle physics and are central to one of the Clay Millennium Prize problems.
Lattice approximations of these theories reveal deep connections with spin systems,
which are models from condensed matter physics that generalize the Ising model.
A striking parallel between these fields is observed in the behavior of 2D spin systems and 4D gauge theories, both of which display asymptotic freedom and mass generation.
However, the mathematical understanding of non-abelian gauge theories and spin systems remains a significant challenge.

This workshop aims to bring together experts to explore these developments and tackle open problems, including:

- long-time study of stochastic Yang-Mills flow
- the development of probabilistic approaches for non-abelian and continuous symmetry models
- connections between lattice gauge theory and random geometric methods


In case you are interested in participating in this event, please apply via the Trimester Program application platform. Please observe the application deadline.

Trimester Program guests, who were invited and have confirmed to be at HIM during the period of this workshop, are eligible to attend this event.


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