Scaling of fluctuations in pp and pA collisions, and eccentricities in relativistic heavy-ion collisions

Multiplicity fluctuations at midrapidity in pp collisions at high energies are described by a negative binomial distribution and exhibit approximate Koba-Nielsen-Olesen (KNO) scaling. We find that these KNO fluctuations are important also for reproducing the multiplicity distribution in d + Au collisions observed at the Relativistic Heavy-Ion Collider (RHIC), adding to the Glauber fluctuations of the number of binary collisions or participants. We predict that the multiplicity distribution in p + Pb collisions at the Large Hadron Collider (LHC) also deviates little from the KNO scaling function. Finally, we analyze various moments of the eccentricity of the collision zone in A + A collisions at RHIC and LHC and find that particle production fluctuations increase fluctuation dominated moments such as the triangularity epsilon(3) substantially.