GR@PPA 2.8: initial-state jet matching for weak boson production processes at hadron collisions

TL;DR

The paper presents an improved initial-state jet matching method in the GR@PPA event generator, enabling accurate simulation of weak boson production processes at hadron colliders with continuous transverse momentum spectra.

Contribution

It introduces an initial-state jet matching technique applied to weak boson production in GR@PPA, ensuring accurate event generation across the entire kinematic range.

Findings

Reproduces transverse momentum spectra continuously

Includes exact spin correlations and phase-space effects at tree level

Integrates with general-purpose event generators for full simulation

Abstract

The initial-state jet matching method introduced in our previous studies has been applied to the event generation of single $W$ and $Z$ production processes and diboson ($W^{+}W^{-}$, $WZ$ and $ZZ$) production processes at hadron collisions in the framework of the GR@PPA event generator. The generated events reproduce the transverse momentum spectra of weak bosons continuously in the entire kinematical region. The matrix elements (ME) for hard interactions are still at the tree level. As in previous versions, the decays of weak bosons are included in the matrix elements. Therefore, spin correlations and phase-space effects in the decay of weak bosons are exact at the tree level. The program package includes custom-made parton shower programs as well as ME-based hard interaction generators in order to achieve self-consistent jet matching. The generated events can be passed to general-purpose event generators to make the simulation proceed down to the hadron level.