# Double Parton Distributions of the Pion

## TL;DR

This paper investigates double parton distributions in the pion using lattice QCD, testing the factorization assumption in double parton scattering at high energies like those at the LHC.

## Contribution

It provides the first lattice QCD calculation of four-point functions related to double parton scattering in the pion, assessing the validity of the factorization approximation.

## Key findings

- Lattice results support the factorization assumption within certain energy scales.
- Comparison between convoluted form factors and four-point data shows reasonable agreement.
- The study demonstrates the feasibility of lattice techniques for DPS studies in hadrons.

## Abstract

The effects of double hard interactions are no longer negligible at energy scales reached at the LHC. Double parton scattering (DPS) processes are often described by taking the product of two single parton scattering processes assuming that interference effects are very small. We calculate four point functions (4pt-functions), which appear in the the DPS cross section, employing lattice techniques. We consider a pion at rest and test the validity of the afore-mentioned factorization assumption by convoluting two pion form factors and comparing the result to the 4pt data. For our calculations we use a $N_f = 2$ gauge ensemble on a $40^3 \times 64$ lattice, with lattice spacing $a = 0.071$ fm and pion mass $m_{\pi} = 288.8$ MeV.