Loops and Legs in Quantum Field Theory

Session

Parallel 2

26 Apr 2022, 14:30

Raum Graswangtal

Conveners

Parallel 2

• Matthias Kerner (Universtiy of Zurich)

Parallel 2

• Matthias Kerner (Universtiy of Zurich)

36. Automated calculation of Beam functions at NNLO

Dr Goutam Das (University of Siegen)

26/04/2022, 14:30

We present a novel framework to streamline the calculation of beam functions to next-to-next-to-leading order in perturbation theory. By exploiting the infrared behavior of the collinear splitting functions, we factorize the singularities with suitable phase-space parametrizations and perform the observable-dependent integrations numerically. We have implemented our approach in the publicly...

38. Zero-jettiness beam functions at N3LO

Arnd Behring (KIT)

26/04/2022, 15:00

I report on the calculation of the beam functions for zero-jettiness at next-to-next-to-next-to-leading order in the strong coupling constant. In the limit of vanishing zero-jettiness scattering cross sections factorise into beam, soft and hard functions as well as the leading-order cross section. Here, the beam functions describe collinear emissions off the initial state partons. If these...

60. Decomposition of Triple Collinear Splitting Functions

Oscar Braun-White (IPPP, Durham University)

26/04/2022, 15:30

In the kinematic region where three particles $i$, $j$, $k$ are collinear, the multi-parton scattering amplitudes factorise into a product of a triple collinear splitting function and a multi-parton scattering amplitude with two fewer particles. These triple collinear splitting functions contain both iterated single unresolved contributions, and genuine double unresolved contributions. We make...

76. ZH Production in Gluon Fusion

Stephen Jones (CERN)

26/04/2022, 16:30

We present NLO results in QCD for the production of a Higgs boson in association with a Z-boson in gluon fusion including top-quark mass effects. Our result is obtained by combining virtual corrections evaluated numerically using sector decomposition with virtual corrections obtained in an expansion around small top-quark mass. In addition to the total cross section for this process, we...

52. Two-loop helicity amplitudes for W/Z boson pair production in gluon fusion with exact top mass dependence

Christian Brønnum-Hansen (Karlsruhe Institute of Technology)

26/04/2022, 17:00

We compute the top quark contribution to the two-loop amplitudes for on-shell W/Z boson pair production in gluon fusion. Exact dependence on the top quark mass is retained. For each phase space point the integral reduction is performed numerically and the master integrals are evaluated using the auxiliary mass flow method, allowing fast computation of the amplitude with very high precision.

80. Yang–Mills All-Plus: Two Loops for the Price of One

Sebastian Pögel (University of Mainz)

26/04/2022, 17:30

I present work at two loops on the class of amplitudes with all gluons of
identical helicity in Yang–Mills theory. I show how to
compute their rational terms, the hardest parts, via well-understood
one-loop unitarity techniques.