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MCnet publications in 2020

Constraining SMEFT operators with associated $h\gamma$ production in Weak Boson Fusion

arXiv:2003.06379
IPPP/20/7
MCNET-20-10

by: Biekötter, Anke
Abstract:
We consider the associated production of a Higgs boson and a photon in weak boson fusion in the Standard Model (SM) and the Standard Model Effective Theory (SMEFT), with the Higgs boson decaying to a pair of bottom quarks. Analysing events in a cut-based analysis and with multivariate techniques we determine the sensitivity of this process to the bottom-Yukawa coupling in the SM and to possible CP-violation mediated by dimension-6 operators in the SMEFT.

The chirality-flow formalism

arXiv:2003.05877
LU-TP 20-16
MCNET-20-10

by: Lifson, Andrew
Abstract:
We take a fresh look at Feynman diagrams in the spinor-helicity formalism. Focusing on tree-level massless QED and QCD, we develop a new and conceptually simple graphical method for their calculation. In this pictorial method, which we dub the chirality-flow formalism, Feynman diagrams are directly represented in terms of chirality-flow lines corresponding to spinor inner products, without the need to resort to intermediate algebraic manipulations.

Comments on a new `full colour' parton shower

arXiv:2003.06399
MAN/HEP/2020/001
UWTHPH-2020-9
MCnet-20-10

by: Holguin, Jack
Abstract:
A new parton shower algorithm has been presented with the claim of providing soft-gluon resummation at `full colour' (arXiv:2001.11492). In this paper we show that the algorithm does not succeed in this goal. We show that full colour accuracy requires the Sudakov factors to be defined at amplitude level and that the simple parton-shower unitarity argument employed in arXiv:2001.11492 is not sufficient.