Centrality and pseudorapidity dependence of the transverse energy flow in pPb collisions at sqrt(s_NN) = 5.02 TeV

TL;DR

This paper measures the distribution of transverse energy as a function of pseudorapidity in pPb collisions at 5.02 TeV, revealing centrality dependence and differences from event generator predictions.

Contribution

It provides the first detailed measurement of transverse energy distribution in pPb collisions across pseudorapidity and compares centrality dependence with model predictions.

Findings

Transverse energy per participant pair is comparable to peripheral PbPb collisions.

Centrality dependence is stronger on the lead side than the proton side.

Significant discrepancies between data and event generator predictions.

Abstract

The almost hermetic coverage of CMS is used to measure the distribution of transverse energy as a function of pseudo-rapidity for pPb collisions at $\sqrt{s_{NN}} = 5.02$ TeV. For minimum bias collisions $(1/N)~dE_T/d\eta$ reaches 23 GeV which implies an $E_T$ per participant pair comparable to that of peripheral PbPb collisions at $\sqrt{s_{NN}} = 2.76$ TeV. The centrality dependence of transverse energy production has been studied using centrality measures defined in three different angular regions. There is a strong auto-correlation between $(1/N)~dE_T/d\eta$ and the $\eta$ range used to define centrality %both for data and the EPOS-LHC and HIJING event generators. The centrality dependence of the data is much stronger for $\eta$ values on the lead side than the proton side and shows significant differences from that predicted by either event generator.