# Pion induced Drell-Yan: the transverse momentum structure of the pion

## TL;DR

This paper analyzes the transverse momentum structure of the pion in unpolarized Drell-Yan processes using an NJL model, comparing evolved distributions with experimental data and highlighting significant QCD evolution effects.

## Contribution

It introduces a consistent method to incorporate QCD evolution into NJL model predictions for pion transverse momentum distributions and compares them with experimental data.

## Key findings

- Good agreement with pion-nucleus Drell-Yan data up to 2 GeV transverse momentum
- Significant evolution effects on distribution shapes and average transverse momentum
- Determination of the hadronic scale as the only free parameter

## Abstract

We present an analysis of unpolarized Drell-Yan pair production in pion-nucleus scattering with a particular focus into the pion dynamics. The study consists in analyzing the effect of the partonic longitudinal and, especially, transverse distributions of the pion in a Nambu--Jona-Lasinio (NJL) framework, with Pauli-Villars regularization. In order to consistently take into account the QCD evolution effects, we have estimated the hadronic scale corresponding to the NJL model's degrees of freedom through a minimization procedure at NLO: The NLO evolved pion distributions have been compared to rapidity differential Drell-Yan cross sections data. That hadronic scale so determined represents the only free parameter in our approach. The NJL transverse momentum PDF, evolved up to next-to-leading logarithmic accuracy, is then tested against the transverse momentum spectrum of dilepton pairs up to a transverse momentum of 2 GeV. We found a fair agreement with available pion-nucleus data. We find sizable evolution effects on the shape of the distributions and on the generated average transverse momentum of the dilepton pair.