Underlying Event and Double Parton Scattering Measurements at CMS

Rajat Gupta

doi:10.1016/j.nuclphysbps.2018.03.003

Abstract

Recent results on the double parton scattering studies and measurement of the underlying event activity, performed using proton-proton collisions data collected using the CMS detector are presented. Comparisons to previous results at different center of mass energies are also reported.

Highlights

Production of particles in a hadron-hadron collision involves parton-parton scatterings, initial-state radiation (ISR), final-state radiation (FSR), and beam-beam remnants (BBR) interactions
The large parton densities available in the proton-proton collisions at the CERN LHC result in a significant probability of more than one parton-parton scattering in the same pp collision, a phenomenon known as multiple parton interactions (MPIs)
Double Parton Scattering (DPS) corresponds to events where two hard partonparton interactions occur in a single proton-proton collisions

Summary

Introduction

Production of particles in a hadron-hadron collision involves parton-parton scatterings, initial-state radiation (ISR), final-state radiation (FSR), and beam-beam remnants (BBR) interactions. The large parton densities available in the proton-proton (pp) collisions at the CERN LHC result in a significant probability of more than one parton-parton scattering in the same pp collision, a phenomenon known as multiple parton interactions (MPIs). The combination of particle production from MPIs (excluding parton-parton scattering with highest momentum-transfer) and BBR interactions is called underlying event (UE) activity. There are number of CMS measurements on the UE/MPI/DPS at different energies. We present recent results on measurement of UE activity using events with leading track and leading jet at centre-of-mass energy of 13 TeV [2],. Measurements of the UE activity using events with a Zboson (with muonic decay) at a centre-of-mass energy of 13 TeV [1], and DPS measurement in same sign WW production in p-p collision at centre-of-mass energies of 8 [3] and 13 TeV [4]

UE Measurements at CMS

UE Measurement using leading charged particle tracks and charged jet

UE Measurement using Z-boson process

DPS Measurements at CMS

Findings

Summary