Erlangen 2026 – scientific programme

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T: Fachverband Teilchenphysik

T 3: Standard Model Physics I

T 3.1: Talk

Monday, March 16, 2026, 16:15–16:30, KH 00.014

Strategy for constraining multi-parton interactions at the LHC using Z boson events — •Ek-ong Atthaphan and Ynyr Harris — University of Bonn, Bonn, Germany

Multi-Parton Interactions (MPI) occur in every proton-proton collision at the CERN Large Hadron Collider and play a crucial role in the modelling of soft QCD processes and observables at low momentum transfer. In particular, an accurate description of Z-boson production at low transverse momentum requires a detailed understanding of MPI effects. In this talk, a novel method for directly measuring the number of MPI scatters in individual pp events is presented. The MPI multiplicity is extracted from a fit to the azimuthal two-particle correlation function. A comparison of this method applied to ATLAS data and Pythia Monte Carlo simulations demonstrates sensitivity to the MPI model parameters p_T,0 and p_T,min, providing new constraints on their values for LHC collisions.

Keywords: Multi-Parton Interactions; Soft QCD