On the phenomenology of multihadron production in e+e− annihilation

Centrality dependence of mid-rapidity charged particles density in relativistic heavy ion collisions – energy scaling

“…In Ref [4] three parametrizations were used, i.e. < N ch > = a·s b inspired by the fireball and hydrodinamical models for hadron-hadron interactions [11], empirical expression used in the analysis of p + p data [12] < N ch > = a + b·s + c·lns 2 and < N ch > = a + b·exp[c ln(s/Q 2 0 )] [10] and it was shown that they give similar values for χ 2 /d.o.f. if the fits do not include energies lower than 5 GeV.…”

“…Energy scaling of the pseudo-rapidity charged particle density in central rapidity as a function of centrality One of the observables which are sensitive to the particle production mechanism and partonic structure of the colliding objects is the charged particle density and its dependence on the collision geometry. Detailed information on centrality dependence of charged particle density at midrapidity in A + A collisions exists starting from AGS [13,14], at SPS [15,16] and RHIC [11], [17]- [23] energies. The systematic compilation of these results [23] and the recent data from ALICE Collaboration at 2.76 TeV [24] are represented in Fig.2.…”

“…Based on these data one could obtain scaling factors (dN ch /dη) Charged particle density at midrapidity in A + A collisions at AGS [13,14], SPS [15,16] and RHIC [11], [17]- [23] energies Red open stars represent the results for innelastic collisions in -η-¡1 defined as collisions in which at least one charged and particle in -η-¡ 1 was produced. The results of power low fits are indicated by dotted, continuous and dashed lines respectivly [34] ratios are represented in Fig.4 by blue stars and full blue squares, respectively.…”