Mar 06 (Fri)
13:00 MCS0001 HEPMOlalla Castro Alvaredo (City University London): Integrable Quantum Field Theories Perturbed by TTbar
In this talk I will review recent results on the development of a form factor program for integrable quantum field theories (IQFTs) perturbed by irrelevant operators. Under such deformations, integrability is preserved and the two-body scattering phase gets deformed in a simple manner. The consequences of such a deformation are theories that exhibit a Hagedorn transition and have no UV completion. In our work we have mainly asked the question of how the deformation of the S-matrix and the subsequent "pathologies" of the deformed theories affect the properties of the correlation functions of the deformed theory. In this talk I will a present a partial answer to this question, summarising work in collaboration with Stefano Negro, Fabio Sailis and István M. Szécsényi.
Venue: MCS0001
Mar 09 (Mon)
13:00 MCS2068 StatIrini Moustaki (LSE): Some new developments in latent variable models
The talk will present a general latent variable framework for modelling data features such as heteroscedasticity, skewness, and zero-inflation, as well as a semi-parametric framework for the latent-variable distribution. The talk will discuss the model specifics and estimation, and present simulation results and examples from an American election study and educational measurement. Collaborators: Camilo Cardenas-Hurtado, Yunxiao Chen, and Giampiero Marra.
Venue: MCS2068
14:00 MCS3070 HEPJChristopher Tudball (Durham): Decompactification Limits of Non-Compact Gauge Theory
This journal club shall be on the paper {https://arxiv.org/pdf/2602.15680} - work done with Finn Gagliano. It had previously been proposed that theories with non-compact gauge theories were in the swampland (that is, they could not be consistently extended to theories of quantum gravity). Taking the example of the real line as the gauge group, the reasoning was that since this permitted relatively irrational charges, there would be a global symmetry wherein relatively irrationally charged objects transform differently, violating the No Global Symmetries Conjecture. Re-casting this argument in terms of no generalised symmetries, we demonstrate a loophole - namely, by adding uncountably infinitely many charged objects, we break the global symmetries, although in a somewhat subtle way. A theory with uncountably infinitely many fields is troubling, but we demonstrate how to make sense of such a theory as one with one extra spacetime dimension without the non-compact gauge symmetry, akin to undoing a Kaluza-Klein reduction on the real line.
Venue: MCS3070
Mar 10 (Tue)
13:00 MCS2068 APDEThomas Sales (University of Sussex): Fully nonlinear mean field games with nondifferentiable Hamiltonians
Mean field games are systems of partial differential equations modelling the Nash equilibria of dynamic differential games for large populations of players. In their full generality this system is fully nonlinear and may involve a nondifferentiable Hamiltonian - in which case not only is the analysis more involved than the usual quasilinear case (with a differentiable Hamiltonian), but even the statement of the problem is not so obvious. In this talk, we discuss a novel approach to studying this problem by introducing a non-standard variational inequality formulation. Under reasonable assumptions, such as assuming the Hamiltonian satisfies a uniform Cordes condition, we show that this variational inequality formulation admits a solution and moreover this solution is unique under the usual monotonicity assumptions. This talk is based on joint work with Iain Smears (UCL).
Venue: MCS2068
Mar 12 (Thu)
13:00 MCS0001 HEPMTatsuhiro Misumi (Kindai University): Nonperturbative physics from two angles: Resurgence and Lattice fermions
In the first half of this talk, I discuss the Exact-WKB method, with an emphasis on how resurgence organizes perturbative and nonperturbative sectors into a trans-series structure. I then illustrate how the tool provides quantitative understanding on concrete quantum systems, including Schwinger effects and Floquet systems. In the second half, I will turn to lattice fermions, focusing on the analytical and machined-learning-based challenges of realizing chiral fermions on the lattice. By training a neural network to satisfy the Ginsparg-Wilson (GW) relation, we demonstrate that the network spontaneously constructs an overlap or improved-overlap Dirac operators. Furthermore, we demonstrate that by imposing only basic requirements such as locality, without assuming the GW relation a priori, the network spontaneously converges to a solution satisfying a generalized GW relation. This offers a new paradigm for discovering theoretical structures in quantum field theory.
Venue: MCS0001
13:00 MCS2068 G&TZhengyao Huang (Durham): A Sudakov decomposition of optimal transport in the Monge
problem on positively curved manifolds
We will cover Monge's problem on Riemannian manifolds with
positive sectional curvature. Assuming that the source and target
measures are absolutely continuous with respect to the Riemannian volume
measure, we generalize a variational method from the Euclidean setting
to establish the existence of a transport density and an explicit
disintegration of measures along optimal rays. These results extend the
approach of Bianchini-Gloyer-Caravenna to the Riemannian context.
Venue: MCS2068
Mar 13 (Fri)
13:00 MCS0001 HEPMCostantinos Papageorgakis (Queen Mary University London): Deep Finite Temperature Bootstrap
We introduce a novel method to bootstrap crossing equations in Conformal Field Theory and apply it to finite temperature theories on S_1×R_d\u22121. Traditional bootstrap approaches relying on positivity constraints or truncation schemes are not applicable to this problem. Instead, we capture infinite towers of operators using suitable tail functions, which are bootstrapped numerically together with explicit CFT data. Our method employs three key ingredients: the Kubo-Martin-Schwinger (KMS) condition, thermal dispersion relations, and Neural Networks that model spin-dependent tail functions. We test the method on Generalized Free Fields and apply it to bootstrap double-twist thermal data in holographic CFTs.
Venue: MCS0001
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Usual Venue: MCS2068
Contact: yohance.a.osborne@durham.ac.uk
Mar 10 13:00 Thomas Sales (University of Sussex): Fully nonlinear mean field games with nondifferentiable Hamiltonians
Mean field games are systems of partial differential equations modelling the Nash equilibria of dynamic differential games for large populations of players. In their full generality this system is fully nonlinear and may involve a nondifferentiable Hamiltonian - in which case not only is the analysis more involved than the usual quasilinear case (with a differentiable Hamiltonian), but even the statement of the problem is not so obvious. In this talk, we discuss a novel approach to studying this problem by introducing a non-standard variational inequality formulation. Under reasonable assumptions, such as assuming the Hamiltonian satisfies a uniform Cordes condition, we show that this variational inequality formulation admits a solution and moreover this solution is unique under the usual monotonicity assumptions. This talk is based on joint work with Iain Smears (UCL).
Venue: MCS2068
Usual Venue: MCS3070
Contact: andrew.krause@durham.ac.uk
No upcoming seminars have been scheduled (not unusual outside term time).
Usual Venue: MCS2068
Contact: herbert.gangl@durham.ac.uk
No upcoming seminars have been scheduled (not unusual outside term time).
Usual Venue: OC218
Contact: mohamed.anber@durham.ac.uk
For more information, see HERE.
No upcoming seminars have been scheduled (not unusual outside term time).
Usual Venue: MCS3052
Contact: andrew.krause@durham.ac.uk
No upcoming seminars have been scheduled (not unusual outside term time).
Usual Venue: MCS2068
Contact: fernando.galaz-garcia@durham.ac.uk
Mar 12 13:00 Zhengyao Huang (Durham): A Sudakov decomposition of optimal transport in the Monge
problem on positively curved manifolds
We will cover Monge's problem on Riemannian manifolds with
positive sectional curvature. Assuming that the source and target
measures are absolutely continuous with respect to the Riemannian volume
measure, we generalize a variational method from the Euclidean setting
to establish the existence of a transport density and an explicit
disintegration of measures along optimal rays. These results extend the
approach of Bianchini-Gloyer-Caravenna to the Riemannian context.
Venue: MCS2068
Mar 19 13:00 Andy Wand (Glasgow): Non-positive open books of Stein fillable contact 3-manifolds
We will discuss motivation for and approaches to the
question of when the monoid in the mapping class group of a surface with
boundary corresponding to monodromies of open book decompositions of
Stein fillable contact 3-manifolds differs from the monoid of mapping
classes which admit factorizations into positive Dehn twists. In
particular, combining new(ish) results with previous work of several
people, we give a complete solution to this problem, showing that the
monoids coincide only for planar surfaces. This is joint work with
Vitalijs Brejevs.
Venue: MCS2068
Apr 02 13:00 Thiago de Paiva (Peking University): A simpler braid description for all links in the 3-sphere
By Alexander's theorem, every link in the 3-sphere can be
represented as the closure of a braid. Lorenz links and twisted torus
links are two families that have been extensively studied and are well
described in terms of braids. In this talk, we present a natural
generalization of Lorenz links and twisted torus links that produces all
links in the 3-sphere, providing a simpler braid description for every
link in the 3-sphere.
Venue: MCS2068
Apr 30 13:00 Anthea Monod (Imperial): TBA
Usual Venue: MCS3070
Contact: mendel.t.nguyen@durham.ac.uk
Mar 09 14:00 Christopher Tudball (Durham): Decompactification Limits of Non-Compact Gauge Theory
This journal club shall be on the paper {https://arxiv.org/pdf/2602.15680} - work done with Finn Gagliano. It had previously been proposed that theories with non-compact gauge theories were in the swampland (that is, they could not be consistently extended to theories of quantum gravity). Taking the example of the real line as the gauge group, the reasoning was that since this permitted relatively irrational charges, there would be a global symmetry wherein relatively irrationally charged objects transform differently, violating the No Global Symmetries Conjecture. Re-casting this argument in terms of no generalised symmetries, we demonstrate a loophole - namely, by adding uncountably infinitely many charged objects, we break the global symmetries, although in a somewhat subtle way. A theory with uncountably infinitely many fields is troubling, but we demonstrate how to make sense of such a theory as one with one extra spacetime dimension without the non-compact gauge symmetry, akin to undoing a Kaluza-Klein reduction on the real line.
Venue: MCS3070
Usual Venue: MCS0001
Contact: p.e.dorey@durham.ac.uk,enrico.andriolo@durham.ac.uk,tobias.p.hansen@durham.ac.uk
Mar 06 13:00 Olalla Castro Alvaredo (City University London): Integrable Quantum Field Theories Perturbed by TTbar
In this talk I will review recent results on the development of a form factor program for integrable quantum field theories (IQFTs) perturbed by irrelevant operators. Under such deformations, integrability is preserved and the two-body scattering phase gets deformed in a simple manner. The consequences of such a deformation are theories that exhibit a Hagedorn transition and have no UV completion. In our work we have mainly asked the question of how the deformation of the S-matrix and the subsequent "pathologies" of the deformed theories affect the properties of the correlation functions of the deformed theory. In this talk I will a present a partial answer to this question, summarising work in collaboration with Stefano Negro, Fabio Sailis and István M. Szécsényi.
Venue: MCS0001
Mar 12 13:00 Tatsuhiro Misumi (Kindai University): Nonperturbative physics from two angles: Resurgence and Lattice fermions
In the first half of this talk, I discuss the Exact-WKB method, with an emphasis on how resurgence organizes perturbative and nonperturbative sectors into a trans-series structure. I then illustrate how the tool provides quantitative understanding on concrete quantum systems, including Schwinger effects and Floquet systems. In the second half, I will turn to lattice fermions, focusing on the analytical and machined-learning-based challenges of realizing chiral fermions on the lattice. By training a neural network to satisfy the Ginsparg-Wilson (GW) relation, we demonstrate that the network spontaneously constructs an overlap or improved-overlap Dirac operators. Furthermore, we demonstrate that by imposing only basic requirements such as locality, without assuming the GW relation a priori, the network spontaneously converges to a solution satisfying a generalized GW relation. This offers a new paradigm for discovering theoretical structures in quantum field theory.
Venue: MCS0001
Mar 13 13:00 Costantinos Papageorgakis (Queen Mary University London): Deep Finite Temperature Bootstrap
We introduce a novel method to bootstrap crossing equations in Conformal Field Theory and apply it to finite temperature theories on S_1×R_d\u22121. Traditional bootstrap approaches relying on positivity constraints or truncation schemes are not applicable to this problem. Instead, we capture infinite towers of operators using suitable tail functions, which are bootstrapped numerically together with explicit CFT data. Our method employs three key ingredients: the Kubo-Martin-Schwinger (KMS) condition, thermal dispersion relations, and Neural Networks that model spin-dependent tail functions. We test the method on Generalized Free Fields and apply it to bootstrap double-twist thermal data in holographic CFTs.
Venue: MCS0001
Mar 20 13:00 Donal O'Connell (Edinburgh University): TBA
Mar 27 13:00 Sean Hartnoll (Cambridge University): TBA
Usual Venue: MCS3070
Contact: joe.thomas@durham.ac.uk
No upcoming seminars have been scheduled (not unusual outside term time).
Usual Venue: MCS2068
Contact: hyeyoung.maeng@durham.ac.uk,andrew.iskauskas@durham.ac.uk
Mar 09 13:00 Irini Moustaki (LSE): Some new developments in latent variable models
The talk will present a general latent variable framework for modelling data features such as heteroscedasticity, skewness, and zero-inflation, as well as a semi-parametric framework for the latent-variable distribution. The talk will discuss the model specifics and estimation, and present simulation results and examples from an American election study and educational measurement. Collaborators: Camilo Cardenas-Hurtado, Yunxiao Chen, and Giampiero Marra.
Venue: MCS2068
Mar 16 13:00 Mengchu Li (Birmingham): Segmenting Human–LLM Co-authored Text via Change Point Detection
The rise of large language models (LLMs) has created an urgent need to distinguish between human-written and machine-generated text to ensure authenticity and societal trust. Existing detectors typically provide a binary classification for an entire passage; however, this is insufficient for human-LLM co-authored text, where the objective is to localize specific segments authored by each. To bridge this gap, we propose algorithms to segment text into human- and machine-authored pieces. Our key observation is that such a segmentation task is conceptually similar to classical change point detection in time series analysis. Leveraging this analogy, we adapt change point detection to LLM-generated text detection, develop a weighted algorithm and a generalized algorithm to accommodate heterogeneous sentence lengths, and establish the minimax optimality of our procedure. Empirically, our approach substantially outperforms existing baseline algorithms, reducing localization errors by up to 50%.
Venue: MCS2068
Mar 23 13:00 Rasa Remenyte-Prescott (Nottingham): TBA
