Measurement of the average very forward energy as a function of the track multiplicity at central pseudorapidities in proton-proton collisions at $$\sqrt{s}=13\,\text {TeV} $$

Abstract

Abstract The average total energy as well as its hadronic and electromagnetic components are measured with the CMS detector at pseudorapidities $$-6.6&lt;\eta &lt;-5.2$$<mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML"><mml:mrow><mml:mo>-</mml:mo><mml:mn>6.6</mml:mn><mml:mo>&lt;</mml:mo><mml:mi>η</mml:mi><mml:mo>&lt;</mml:mo><mml:mo>-</mml:mo><mml:mn>5.2</mml:mn></mml:mrow></mml:math> in proton-proton collisions at a centre-of-mass energy $$\sqrt{s}=13\,\text {TeV} $$<mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML"><mml:mrow><mml:msqrt><mml:mi>s</mml:mi></mml:msqrt><mml:mo>=</mml:mo><mml:mn>13</mml:mn><mml:mspace/><mml:mtext>TeV</mml:mtext></mml:mrow></mml:math>. The results are presented as a function of the charged particle multiplicity in the region $$|\eta |&lt;2$$<mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML"><mml:mrow><mml:mo>|</mml:mo><mml:mi>η</mml:mi><mml:mo>|</mml:mo><mml:mo>&lt;</mml:mo><mml:mn>2</mml:mn></mml:mrow></mml:math>. 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.