Nuclear effects in multiparticle production in 800 GeV and 400 GeV proton-nucleus interactions

We study nuclear effects in multiparticle production in proton-emulsion nuclei interactions at 800 GeV and 400 GeV. The observed pseudorapidity distributions are compared with the predictions of a simple quark model. The predicted dependence of the ratio of the normalised multiplicity distribution of the produced shower particles in hadron-nucleus (hA) to hadron-hadron (hh) interactions on the mean number of inelastic collisions in the central region is in good agreement with the experimental data.     

Angular distributions in the dimuon hadronic production at 150 GeV/c

From π^- interactions at 150 GeV/c on a heavy target, we present the final analysis of the dimuon decay angular distribution in the mass interval 4.5–8.5 GeV/c². Results are presented and discussed in various reference frames and are also given in terms of the density matrix elements. Finally the possible contribution of higher-twist effects at largex ₁ is discussed; we find that our data are not compatible with higher twist contributions as proposed by the Berger and Brodsky Model.     

Nuclear effects in 800 GeV proton interactions

We discuss here the nuclear effects in multiparticle production processes in 800 GeV proton-emulsion nuclei interactions. The multiplicity of medium energy particles (N _g ) was used as a measure of the average number of projectile collisions (<v(N _g )>). To study nuclear effects, we determined <v(N _g )> and ratio of normalized rapidity density of all produced charged particles in hadron-nucleus to hadron-hadron interaction,R(N _η ). It was found that the average multiplicity of shower particles increases with <v(N _g )>. From theR(N _η ) distribution, we find; a strong maxima in the target fragmentation region, a plateau in the central region and depletion of particle density in the projectile fragmentation region.     

Nuclear mass number dependence of inclusive pion production by pions and protons at 4.3GeV/c

The inclusive production of π⁺ for 0.4≤p_T<1.0 GeV/c in pion-nucleus and proton-nucleus collisions at 4.3 GeV/c was measured. A strong A-dependence of the cross sections at high p_T is observed to be persistent in the low energy region. The ratio of the cross sections for proton-nucleus and pion-nucleus collisions is also observed to be compatible with the quark-parton picture, for p_T>0.6 GeV/c.     

Multiplicity dependence of intermittency in one and two dimensions in proton-nucleus interactions at 800 GeV

The intermittency effect has been observed in interactions of 800 GeV protons with emulsion-nuclei in one-(pseudorapidity/azimuthal angle) and two-dimensional (pseudorapidity and azimuthal angle) phase spaces in different multiplicity intervals. The intermittency strength is found to decrease with increasing multiplicity. Compared to one dimension, the two dimensional distribution is found to reflect better the intermittent behavior of the interactions. The dependence of various intermittency parameters on order of moment gives clear evidence of self-similar cascade mechanism in the interactions but there is no definite indication of the presence of different phases in the cascade.     

Multiplicity in proton-nucleus interactions in emulsion at 800 GeV

The experimental data on multiplicities of charged particles of different type produced in incoherent interactions of 800 GeV proton with emulsion nuclei are reported and discussed. The data are compared with the results of other experiments on protonnucleus collisions at lower energies. It is shown that the Lund model describes well the data on multiplicities of relativistic particles.     

Target excitation dependence of self-similar cascading rate in multihadron production process at 350 GeV

In the present work target excitation dependence of the self-similar cascading rate has been studied in detail in the framework of Levy stable law using the experimental data of pions obtained from π ^?-AgBr interactions at 350 GeV/c. TheLevy indices µ measured from the analysis fulfill the requirement of the Levy stable region 0 ? µ ? 2. The study gives an evidence of self-similar cascading mechanism responsible for multiparticle production. The different values of µ indicate different rates of cascading for different degrees of target excitation. Moreover, the values of universal scaling exponent (ν) obtained from Ginzburg-Landau theory indicate that no clear evidence of second-order phase transition has been found in the interaction.     

Angular distributions in proton-nucleus interactions in emulsion at 800 GeV

Data on angular distributions of heavily ionizing and shower particles in incoherent protonnucleus collisions in emulsion at 800 GeV are reported and discussed in details. Dependence of angular distributions on the mass number of a target nucleus and on the multiplicity of charged particles is investigated. The data presented are systematically compared with results of emulsion experiments at lower energies and with predictions of the Lund Monte Carlo model FRITIOF.     

System-size dependence of strangeness production in nucleus-nucleus collisions at squareroot[sNN]=17.3 GeV

Emission of pi+/-, K+/-, phi, and Lambda was measured in near-central C+C and Si+Si collisions at 158 AGeV beam energy. Together with earlier data for p+p, S+S, and Pb+Pb, the system-size dependence of relative strangeness production in nucleus-nucleus collisions is obtained. Its fast rise and the saturation observed at about 60 participating nucleons can be understood as the onset of the formation of coherent systems of increasing size.