Empirical parameterization of the high energy behaviour of average   charged particle multiplicities in e+e-, ep and pp collisions
  A simple fit of existing data for center-of-mass energies above the b-threshold shows that the average charged particle multiplicities in pp_bar and pp interactions can be parameterized by a simple power law N_ch = N_0*(s/s_0)^(gamma) with gamma close to 1/5. Choosing s_0=m_p^2, where m_p is a proton mass, one finds N_0=2.32. The average charged particle multiplicities in e+e- and e(+/-)p interactions follows the same power law with an offset of +/- 1 unit in N_0. The observed trend leads to the conclusion that in LHC experiments at energy of 7TeV one should expect the average charge multiplicity in the region of N_ch close to 80. 
M. Zavertyaev
hep-ex