Factorization in QCD and Beyond

6 May 2026, 09:00 → 8 May 2026, 17:00 Europe/London

Elm Lecture Theatre

The Higgs Centre will be running a three-day workshop on Factorization in QCD and Beyond on 6-8 May, 2026.

This is an in-person event, starting on Wednesday the 6th at 9am and ending on Friday the 8th at 5pm. 

The workshop addresses recent progress and open problems related to factorization at both amplitude and observable level. The main focus is

·         the method of regions and Glauber effects,
·         collinear factorization and its violation,
·         the Regge limit,
·         connections to open problems in gravity.

This workshop will constitute a small number of talks in a relaxed atmosphere, and ample time for discussion. 

Deadline for registration: 27 February 2026

REGISTRATION HAS NOW CLOSED

Organisers:

Einan Gardi (University of Edinburgh)
Franz Herzog (University of Edinburgh)
Lorenzo Magnea (University of Turin and INFN, Italy)
Simone Marzani (University of Genova and INFN, Italy)
Lorenzo Tancredi (Technical University of Munich, Germany)

Speakers:

Thomas BECHER (Bern)
Federico Buccioni (TUM)
Simon CARON-HUOT (McGill)
Vittorio DEL DUCA (LNF, Frascati)
Giulio FALCIONI (UNITO)
Jeff FORSHAW (Manchester)
Giulio GAMBUTI (ETH Zürich)
Stephen JONES (Durham)
Alex KOVNER (UConn)
Yao MA (ETH Zürich)
German RODRIGO (CSIC)
Ira ROTHSTEIN (Carnegie Mellon University)
Raju VENUGOPALAN (Brookhaven)

 

Sponsorship:
This event is funded with support from Higgs Centre for Theoretical Physics, European Research Council (ERC) and Science is Cool Cultural Association (SCOOL)

          

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Wednesday 6 May

1 Yao Ma - The Method of Regions: Fundamentals, Subtleties, and All-order Prescriptions

The Method of Regions is a powerful technique for extracting the asymptotic behavior of Feynman integrals, yet its first and most critical step -- the systematic identification of all relevant regions -- remains subtle in Minkowski space. While the Euclidean case is fully understood via the "expansion-by-subgraphs" pattern, the Minkowski situation is more intricate. Recent years have seen significant progress through the classification of regions into "facet regions" and "hidden regions". In this talk, I will review the state-of-the-art understanding of their structures, with particular emphasis on a recent all-order momentum-space prescription for facet regions of any massless graph in wide-angle kinematics [arXiv:2601.22144]. I will also outline the open challenges, especially concerning hidden regions.

2 Stephen Jones - Beyond Facet Regions in Parameter Space

The expansion of integrals and amplitudes in particular kinematic limits is a useful method for gaining insight into their analytic structure. However, developing robust, efficient and verifiable algorithms to identify the relevant loop momentum regions is not a trivial task. One well known avenue for finding the regions is the use of Feynman or Lee-Pomeransky parameters. I will review the existing construction of "facet" regions in parameter space, which capture the behaviour of Euclidean integrals, and discuss how additional regions (Potential/Glauber/Landshoff, generally "hidden") appear due to cancellations between monomials in parameter space for physical scattering kinematics. I will present an update on ongoing efforts to find and classify "hidden" regions and a promising method for solving the related, yet simpler, problem of rewriting Feynman integrals as a sum of integrals with real, positive integrands in the Minkowski regime.

11:00 Coffee Break

3 Federico Buccioni - The spacelike collinear splitting amplitude at two loops

12:30 Lunch

4 Thomas Becher - Factorization Beyond Coherence

Over the past few years, it has become increasingly clear that standard soft-collinear factorization does not hold for hadron-collider observables in general. This breakdown is caused by Glauber effects, which destroy strict collinear factorization and color coherence. They impact many observables: Not only do they induce Super-Leading Logarithms (SLLs) in non-global jet cross sections, but Coherence-Violating Logarithms (CVLs) affect even the simplest global event shapes. In my talk, I will show how coherence violation can be systematically analyzed and accounted for in factorization theorems based on Soft-Collinear Effective Theory, and I will derive the leading CVL for N-jettiness. I will also explain an intricate mechanism that restores PDF factorization below the lowest perturbative scale in non-global observables.

5 Jeff Forshaw - Subleading colour and superleading logarithms

We will present recent progress in the computation of subleading colour corrections to parton showers and superleading logarithms

15:30 Coffee Break

6 Factorization in collinear limits - Discussion Leader: German Rodrigo

Potential Contributions:
Aniruddha Venkata
Sebastian Jaskiewicz
Saad Nabeelbacus

Thursday 7 May

7 Giulio Falcioni - Gauge theories amplitudes in the (multi-)Regge limit

In the high energy limit, the scattering amplitudes of non abelian gauge theory feature large logarithmic corrections to all the perturbative orders. The exchange of one reggeized gluon plays a crucial role to resum such logarithms. However, the amplitudes have a much richer structure. In particular, at the level of the next-to-next-to leading logarithms the amplitudes include the contributions of both the reggeized gluon and of a Regge cut. I will review an approach to disentangle the two different contributions, based on the rapidity evolution of Wilson line correlators. I will discuss the application of this method to three different scattering processes.

10:00 Coffee Break

8 Giulio Gambuti - Probing high-energy QCD through the lens of scattering amplitudes

In the high-energy or Regge limit, gauge-theory scattering amplitudes can be described in terms of universal building blocks. I will review aspects of amplitude factorisation, effects that break it, how they are captured by the shockwave (or Balitsky/JIMWLK) formalism and the extension of this framework to second order in the (rapidity) logarithmic expansion (NNLL). Working at this order, I will discuss the extraction of the two-loop Lipatov vertex and three-loop gluon Regge trajectory in QCD and N=4 super Yang-Mills via matching to recently computed scattering amplitudes.

11:45 Lunch

9 Simon Caron-Huot - Timelike-Spacelike correspondence and high-energy evolution in QCD

The approximate conformal symmetry of perturbative QCD relates different evolution equations. One instance, which I will review in this language, is the relation between the DGLAP evolution of (“spacelike") parton distribution and (“timelike”) splitting functions. I will explain our calculation of the "non-conformal" part of the three-loop BFKL/BK rapidity evolution based on this idea in 2508.03794.

10 Alex Kovner - Resumming anticollinear DGLAP logarithms in the JIMWLK evolution

I explain how anitcollinear DGLAP logarithms are resummed in the framework of high energy JIMWLK evolution and report on the effect of the resummation in the linear (BFKL) regime. I also comment on the physics of the choice of scale in the running coupling constant in JIMWLK.

15:15 Coffee Break

11 The Regge limit - Discussion Leader: Fabrizio Caola

19:30 Conference Dinner

Friday 8 May

12 Ira Rothstein - The Regge Limit of Gravity: Factorization and Calculability

While gravity is a UV incomplete theory which breaks down at the Planck scale, the class of observables for which hard scattering ((s,t,u) >Mpl^2) is disallowed should be calculable within the theory is a systematic way. However, at present calculations seem to contradict that presumtion. Using a recently developed theory of gravitational Glauber SCET, I will show that the issue lies in the assumed form of the resummed amplitude in impact parameter space and will prove that the amplitude takes a more generalized form which is consistent with present higher loop calculations.

10:00 Coffee Break

13 Vittorio del Duca - Gravity amplitudes in the high-energy limit

We examine gravity amplitudes in the high-energy limit through three different constructions: a Glauber EFT, shock-wave formalism and iterated unitarity cuts, and show that they are all equally good at computing gravity amplitudes in the high-energy limit, at leading power and leading logarithmic accuracy.

11:45 Lunch

14 Higgs Centre Colloquium: Martin Beneke - The return of the WIMP: Onium in the Sky with Loops

An electroweak weakly interacting particle (WIMP) with TeV scale mass constitutes a minimalistic dark matter candidate. Extensive work in recent years has uncovered physical effects which -- despite the intrinsic weak interaction strength -- can dramatically change the signatures of dark matter annihilation. Owing to the large dark-matter mass, the relevant electroweak interactions exhibit many features more familiar from onium bound states and jets of the strong colour interaction. In this colloquium I discuss the diverse physical and field theoretical phenomena associated with TeV mass WIMPs approaching them with effective field theory and resummation methods better known from QCD.

14:00 Coffee Break

15 Raju Venugopalan - Shockwave double copy of radiation in QCD and gravity

We discuss the scattering of shockwaves in QCD and in Einstein gravity. We demonstrate the
double copy structure of radiation in the two theories. We show further that the radiation pattern is that of a laser-like squeezed state, and outline interesting possible consequences in both theories.

16 Open Discussion