Loop-the-Loop-2: Feynman calculus and its applications to gravity and particle physics

Session

Scattering Amplitudes in Particle Physics

12 Nov 2025, 10:30

28. One-loop Amplitudes for t tbar jet and t tbar photon Productions at the LHC

Souvik Bera

12/11/2025, 10:30

We present analytic expressions for the one-loop QCD helicity amplitudes contributing to top-quark
pair production in association with a photon or a jet at the Large Hadron Collider (LHC), evaluated
through O(ϵ^2) in the dimensional regularisation parameter, ϵ.
These amplitudes are required to construct the two-loop hard functions that enter the NNLO QCD computation.
The helicity...

29. On Loop Integral Numerical Evaluation with LINE

Jonathan Ronca

12/11/2025, 11:00

The future of precision phenomenology depends on accurate and efficient evaluations of Feynman integrals, essential for higher-order radiative corrections. As experimental precision advances, the need for high-performance computational tools capable of handling complex multi-loop calculations becomes increasingly urgent. Efficient and scalable codes are key to making state-of-the-art...

31. The geometric bookkeeping guide for 𝜀-factorised differential equations

Antonela Matijašić

12/11/2025, 11:40

Precision predictions for high-energy experiments rely on accurately evaluating multi‑loop, multi‑scale Feynman integrals in dimensional regularisation. The method of differential equations is now the standard tool for this task, but its full power is only realised when the system can be brought into an 𝜀-factorised form. In this talk, we present an algorithmic framework that constructs such...

30. Electroweak double-box integrals for Møller scattering with three Z bosons

Dmytro Melnichenko

12/11/2025, 12:10

In this work, we have computed the planar and non-planar contributions to the Møller scattering with three massive Z bosons exchanged between the fermion lines. These cases involve complicated geometries like curves of genus 2 and K3 surfaces, which until recently remained inaccessible. We demonstrate how these can be tamed with a newly developed technique for epsilon-factorization of Feynman...

33. Bootstrapping Gravity with Crossing Symmetric Dispersion Relations

Celina Pasiecznik

12/11/2025, 12:40

I will discuss how to derive bounds on Wilson coefficients in gravitational effective field theories using fully crossing symmetric dispersion relations. These sum rules naturally isolate finite subsets of low-energy couplings without relying on the forward limit or specific high-energy completions. I will show how we validate our method by matching bounds computed previously for scalar...

24. Bootstrapping the QCD Soft Anomalous Dimension

Laura Walsh

12/11/2025, 14:30

The soft anomalous dimension encodes infrared divergences that arise from soft virtual particles. Crucially, this object – a matrix in colour space – is universal; it need only be calculated once then can be used for all QCD amplitudes. While the soft anomalous dimension has been directly calculated up to three loops in the massless case, the three loop massive and four loop massless remain...

25. Positivity properties of five-point two-loop Wilson loops with Lagrangian insertion

Shun-Qing Zhang

12/11/2025, 15:00

I will present the geometric integrand expansion, developed by Arkani-Hamed, Henn, and Trnka, for the pentagonal Wilson loop with a Lagrangian insertion in maximally supersymmetric Yang–Mills theory. The discussion will focus on integrated results corresponding to an all-loop class of ladder-type geometries, with particular emphasis on the two-loop observable examined through this geometric...

26. Jet production at lepton colliders: an amplitude perspective

Petr Jakubčík

12/11/2025, 15:40

Modern amplitude technology is a crucial ingredient for the physics programme of future particle colliders. In this talk, I will focus on a classic test of QCD, jet production at an electron-positron collider. I will report on the calculation of a relevant three-loop matrix element, and on the development of an N3LO infrared subtraction scheme for final-state radiation.

27. Parametric annihilators for integral reduction & differential equations

Gaia Fontana

12/11/2025, 16:10

We elaborate on the method of parametric annihilators for deriving relations among integrals. Annihilators are differential operators that annihilate multi-valued integration kernels appearing in suitable integral representations of special functions and Feynman integrals. We describe a method for computing parametric annihilators based on efficient linear solvers and show how to use them to...