Herwig++ 2.3 Release Note

TL;DR

Herwig++ 2.3 introduces significant enhancements including lepton-hadron collision capabilities, NLO process inclusion via POWHEG, BSM decay modeling, and improved parton shower reconstruction, advancing Monte Carlo event simulation accuracy.

Contribution

This release extends Herwig++ with new collision types, NLO process integration, BSM decay features, and improved kinematic reconstruction, representing a substantial upgrade over previous versions.

Findings

Enhanced simulation accuracy for lepton-hadron collisions

Inclusion of NLO processes with positive weights via POWHEG

Improved modeling of BSM decays and parton shower kinematics

Abstract

A new release of the Monte Carlo program Herwig++ (version 2.3) is now available. This version includes a number of improvements including: the extension of the program to lepton-hadron collisions; the inclusion of several processes accurate at next-to-leading order in the POsitive Weight Hardest Emission Generator (POWHEG) scheme; the inclusion of three-body decays and finite-width effects in Beyond the Standard Model (BSM) physics processes; a new procedure for reconstructing the kinematics of the parton shower based on the colour structure of the hard scattering process; a new model for baryon decays including excited baryon multiplets; the addition of a soft component to the multiple scattering model of the underlying event; new matrix elements for Deep Inelastic Scattering (DIS) and e+e- processes.