30 research outputs found
The chirality-flow formalism
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.Comment: 44 pages, 3 figure
Updates to the One-loop Provider NLOX
We describe the 1.2 update to NLOX, a computer program for calculations in
high-energy particle physics. New features since the 1.0 release and other
changes are described, along with usage documentation.Comment: 8 page
Herwig 7.1 Release Note
A new release of the Monte Carlo event generator Herwig (version 7.1) is now
available. This version introduces a number of improvements, notably: multi-jet
merging with the dipole shower at LO and NLO QCD; a new model for soft
interactions and diffraction; improvements to mass effects and top decays in
the dipole shower, as well as a new tune of the hadronisation parameters.Comment: 7 pages, 7 figures. Herwig is available from
https://herwig.hepforge.org
Herwig 7.2 release note
A new release of the Monte Carlo event generator Herwig (version 7.2) is now available. This version introduces a number of improvements over the major version 7.0, notably: multi-jet merging with the dipole shower at LO and NLO QCD; spin correlations in both the dipole and angular-ordered parton showers; an improved choice of evolution variable in the angular-ordered parton shower; improvements to mass effects and top decays in the dipole shower, improvements to the simulation of multiple-parton interactions, including diffractive processes; a new model for baryonic colour reconnection; improvements to strangeness production; as well as a new tune of the hadronisation parameters and support for generic Lorentz structures in BSM models. This article illustrates new features of versions 7.1 and 7.2