High energy QCD: Multiplicity distribution and entanglement entropy

Abstract

In this paper, we show that QCD at high energies leads to the multiplicity distribution (σn/σin)=(1/N) (N-1/N)n-1 (where N denotes the average number of particles) and to entanglement entropy S=lnN, confirming that the partonic state at high energy is maximally entangled. However, the value of N depends on the kinematics of the parton cascade. In particular, for deep inelastic scattering, N=xG(x,Q), where xG is the gluon structure function, while for hadron-hadron collisions, N∝QS2(Y), where Qs denotes the saturation scale. We checked that this multiplicity distribution describes the LHC data for low multiplicities n