LoopFest XXIV

Session

Parallel Session a

27 May 2026, 16:00

Physics Department (Bldg. 510), Large Seminar Room (Brookhaven National Laboratory)

Conveners

Parallel Session a

• Federico Buccioni (CERN)

4. Factorization and Resummation for PDFs at threshold

Marvin Schnubel (Nikhef)

27/05/2026, 16:00

We study factorization at next-to-leading power (NLP) in deep inelastic scattering (DIS) in the endpoint region within the framework of soft-collinear effective theory (SCET). The full QCD process is matched onto two SCET currents, whose matrix elements factorize into individual component functions. By employing endpoint reshuffling theorems that relate these component functions at endpoint...

13. The KLN theorem meets collinear factorisation

Zeno Capatti (University of Bern)

27/05/2026, 16:20

The KLN theorem establishes that infrared divergences in parton‑model diagrams cancel when summed alongside diagrams that account for the simultaneous hard interaction of multiple partons within the same hadron. Meanwhile, it is well established that initial-state infrared poles and logarithms are governed by collinear factorisation. In this talk, I introduce a formalism where an initial-state...

64. Collinear limits of multi-leg scattering amplitudes

Sebastian Jaskiewicz

27/05/2026, 16:40

Scattering amplitudes are expected to admit a factorised structure in specific kinematic limits, such as the Regge, soft and collinear limits. However, less is known about the precise mechanisms through which factorisation of n-particle amplitudes is realised at high perturbative orders, where more complex colour and kinematic structures arise. Starting with the soft anomalous dimension, in...

65. Automated Calculation of Soft Functions for Non-global Observables

Rudi Rahn (University of Amsterdam)

27/05/2026, 17:00

The analytic resummation of non-global logarithms is more involved than resummation in the global case, it for example involves intricate factorisation theorems with ingredient functions of arbitrary final state hard multiplicities. In addition, disparate treatment of distinct emissions allows for a larger set of functional dependences in non-global observables. In this talk I will present...

73. Magic Relations and Critical Varieties of Feynman Integrals

Giulio Crisanti

27/05/2026, 17:20

Magic relations are a class of integration-by-parts identities that are generated in a sector which does not itself appear in the identity. They are of particular interest because their presence causes several otherwise successful methods in the Feynman-integral computational pipeline to break down. In this talk, we present a first step toward a systematic characterisation of such identities....

57. An Analytic Regression Path to Precision QCD

Xiaoyuan Zhang (MIT)

27/05/2026, 17:40

In precision studies of QCD, obtaining exact analytic expressions for physical observables is important for both phenomenological predictions and uncovering theoretical structure, yet is often hindered by the complexity of Feynman integrals. While perturbative bootstrap programs have achieved remarkable success for scattering amplitudes in theories like N=4 super Yang-Mills, their extension to...

53. Toward an All-order Understanding of Region Structures

Yao Ma (ETH Zurich)

The expansion-by-regions technique is a powerful tool for analyzing the asymptotic behavior of Feynman integrals, and the first critical step is to identify all relevant regions. In Euclidean kinematics, this has been understood to all orders, formulated as an "expansion-by-subgraphs" procedure. In Minkowski kinematics, however, the situation is much more subtle.

Much progress has been made...