Abstract. In p-p collisions, there are two leading particles. One is in projectile fragmentation region. The other is in target fragmentation region. The investigations of present paper show that, just like in nucleus-nucleus collisions, the revised Landau hydrodynamic model alone is not enough to have a good description to the measured pseudorapidity distributions of the produced charged particles in p-p collisions. Only after the leading particles are taken into account as well, can the experimental data be matched up properly. The theoretical model works well in p-p collisions in the whole available energy region from s =23.6 to 900 GeV.
1.Relativistic hydrodynamics provides us a theoretical framework for describing the motion of a continuous flowing medium. It is now widely used to depict various processes for system large to the whole universe and small to the matter created in high energy hadronic or nuclear collisions. The experimental observations, such as the elliptic flow, the single-particle spectra, and the two-particle correlation functions for the matter produced in collisions have indeed shown the existence of a collective effect similar to an almost perfect fluid motion [1][2][3][4], and can be reasonably well reproduced by hydrodynamic approach. This gives us a confidence to believe that the relativistic hydrodynamics might be one of the best tools for the description of the space-time evolution of the matter generated in collisions. Hence, in recent years, the relativistic hydrodynamics has become one of the most active research areas, and has got more and more experimental approvals [5][6][7][8][9][10][11][12][13][14][15][16][17][18][19].One of the important applications of the hydrodynamic model is the analysis of the pseudorapidity distributions of the produced charged particles in hadron or heavy ion collisions. A wealth of such distributions has been accumulated in experiments [20][21][22][23][24][25]. In our previous work [6], by taking into account the contributions from leading particles, we have once successfully