Measurement of energy flow at large pseudorapidities in pp collisions at sqrt(s) = 0.9 and 7 TeV

TL;DR

This paper measures the energy flow at large pseudorapidities in proton-proton collisions at 0.9 and 7 TeV using the CMS detector, comparing results to Monte Carlo models and highlighting the importance of multiple-parton interactions.

Contribution

First measurement of energy flow at large pseudorapidities in pp collisions at LHC energies, with comparison to various Monte Carlo models and insights into model improvements.

Findings

Including multiple-parton interactions improves model agreement with data.

Energy flow increases with collision energy and jet activity.

Monte Carlo models with MPI better describe the measurements.

Abstract

The energy flow, dE/d(eta), is studied at large pseudorapidities in proton-proton collisions at the LHC, for centre-of-mass energies of 0.9 and 7 TeV. The measurements are made in the pseudorapidity range 3.15 < |eta| < 4.9, for both minimum-bias events and events with at least two high-momentum jets, using the CMS detector. The data are compared to various pp Monte Carlo event generators whose theoretical models and input parameter values are sensitive to the energy-flow measurements. Inclusion of multiple-parton interactions in the Monte Carlo event generators is found to improve the description of the energy-flow measurements.