PanScales parton showers for hadron collisions: formulation and fixed-order studies

We formulate PanScales parton showers for hadron collisions so as to achieve next-to-leading logarithmic (NLL) accuracy across a broad set of observables. We do so specifically for colour singlet production. Relative to the existing PanScales final-state showers, the main new question is that of how to redistribute momentum imbalances from initial-state branching across the remainder of the event. We present tests of the showers at fixed order, including the treatment of full colour for soft-collinear emissions and of spin correlations in both the soft and collinear domains. We also include comparisons to a formulation of a standard dipole shower, the current leading-logarithmic state of the art. A forthcoming companion paper [1] will explore all-order tests of the new showers.

Automated summary

In this paper, we present tests of the PanScales parton showers for colour singlet production at fixed order, including the treatment of momentum imbalances from initial-state branching and the full colour handling for soft-collinear emissions and spin correlations.