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The average total energy as well as its hadronic and electromagnetic components are measured with the CMS detector at pseudorapidities - 6.6 < η< - 5.2 in proton-proton collisions at a centre-of-mass energy s=13TeV. The results are presented as a function of the charged particle multiplicity in the region | η| < 2. This measurement is sensitive to correlations induced by the underlying event structure over a very wide pseudorapidity region. The predictions of Monte Carlo event generators commonly used in collider experiments and ultra-high energy cosmic ray physics are compared to the data. All generators considered overestimate the fraction of energy going into hadrons.
Sirunyan, A. M., Tumasyan, A., Adam, W., Ambrogi, F., Bergauer, T., Brandstetter, J., … Woods, N. (2019). Measurement of the average very forward energy as a function of the track multiplicity at central pseudorapidities in proton-proton collisions at √s=13TeV. European Physical Journal C, 79(11). https://doi.org/10.1140/epjc/s10052-019-7402-3