Hydrodynamical analysis of proton-nucleus collision data at 200 GeV

Numerical results of the one-dimensional hydrodynamical model of proton-nucleus collisions are applied to the data on $p$-${\mathrm{H}}_2$, $p$-Al, $p$-emulsion, and $p$-Ag collisions at 200 GeV. We find that the hydrodynamical model with a velocity of sound of excited hadronic matter of $u=\simeq \frac{1}{{\mathrm{}\left(7.5\right)\mathrm{}}^{\frac{1}{2}}}$ can adequately describe most of the experimental facts connected with the rapidity distributions of charged particles. An essential assumption in our approach is that the (experimentally unknown) number of fast recoiling protons, which experimentally are counted as shower-particle tracks, grows as the target nuclear size grows and that their distribution in rapidity is proportional to the pion distribution obtained from hydrodynamics. A comparison with the predictions of other theoretical models is also made.