A simple interpretation of multiparticle distributions in different pseudorapidity intervals

The fact that negative binomial distributions with varying parameters give a good fit to most multiparticle production data also in centered pseudorapidity intervals, is explained as the evidence that there exist two different kinds of clusters, which populate with different probabilities the rapidity interval.     

Azimuthal correlations in high-energy multiparticle production

Some features of the two-particle correlation phenomena, studied by means of azimuthal angle variables, are discussed. Assuming Gaussian forms for the single transverse momentum distributions, it is proposed to described the two-particle correlation with only one parameter. The influence of the kinematical constraints on the proposed correlation parameter is discussed, using a limited transverse momentum phase-space model.     

Pairing in multiparticle amplitudes: Inclusive distributions

A model for multi-pion production in the central region in high-energy collisions is studied which describes factorizable emission of pion pairs. A mathematical identification between the exclusive cross section for pion emission in our model (with all interference terms) and the configurational probability distribution function for a classical system of interacting molecules in equilibrium is exploited to obtain an expansion for the asymptotic single-particle inclusive distribution, the two-particle inclusive correlation function, and the exponent of s in the total cross section by means of cluster diagrams. An integral equation is exhibited for summing the terms corresponding to the cluster diagrams.A specific model is then considered, which we call “s-channel pole dominance”. In this model the amplitude is assumed to be large only when the subenergies of pairs of pions are near the mass of a low-lying two-pion resonance, and the transverse momentum of each resonance is small. The dependence of the amplitude on other variables is ignored, so that we effectively have independent emission of two-pion resonances with non-zero width. It is seen that an I = 0 or I = 1 resonance results in a positive two-particle inclusive I = 2 correlation function at small rapidity separations, as s → ∞, and that the correlation function can have an exponential “tail” in rapidity of qualitatively longer range than the resonance. A crude numerical simulation of a broad I = 0 spinless resonance is discussed, and the resulting I = 2 inclusive correlation function is seen to be quite large at small rapidity separations, and to have the same exponential “tail” as the I = 0 correlation function.     

Impact parameter description of multiparticle and elastic scattering

Impact parameter variables are defined for a multiparticle production process. The equation of unitarity for elastic scattering is written at high energy in terms of these variables. The overall impact parameter can be expressed in terms of the impact parameters of all the produced particles. The unitarity equation becomes an “optical theorem” at each impact parameter — diffractive scattering is given by beam depletion. These features allow this technique to give a much clearer interpretation of unitarity in any model than has therefore been possible. This technique can be used to study existing models, and to suggest new ones.     

Bounds for multiparticle distributions in minijet events from semi-hard QCD

It is shown that, as a consequence of the centrality of the semi-hard amplitude, it is possible to obtain an upper and a lower bound for the ratio n_SH/n of the minijet average multiplicity over the inelastic average multiplicity and an upper bound for the ratio C_{2 SH}/C₂ of the corresponding normalized second moments of the particle distributions. In minijet events multiplicities are higher and the KNO distributions are narrower.     

Scaling laws for inelastic partial-wave amplitudes and the high-energy behaviour of multiparticle production

t-channel unitarity equations are derived for n-particle overlap functions. Together with s-channel unitarity they lead to scaling laws for the inelastic s-channel partial-wave amplitudes $\text{?}{}_{\mathrm{l}}{}^{\mathrm{(n)}}\text{(s)}$ in the limits $\text{s → ∞, l → ∞ x = l (}\text{μ}\text{√s}\text{)}{}^3\text{=}\text{fixed}$. Assuming the validity of the scaling law in the whole range, allowed by s-channel unitarity — i.e. for $\text{l > L (s) = (α(4μ}{}^2\text{) ? 1) (}\text{s}\text{4μ}\text{)}\text{log}\text{(}\text{s}\text{s}{}_1\text{)}$ we obtain constant production cross sections σ⁽ⁿ⁾(s) at high energies s → ∞ up to s factors.     

Modern approaches for the theoretical description of multiparticle scattering and nuclear reactions

A review of novel approaches to solution of multiparticle scattering problems in the area above three-body breakup together with the review of new computational technologies which provide very effective and ultrafast realization of the novel approaches with ordinary PC are given. The novel direction presented here is based on two key points: a new formulation of the quantum scattering theory in a discrete Hilbert space of stationary wave packets and the massive-parallel solution of the resulted matrix equations with usage of ultrafast graphic processors (the so called GPU-computations). For the reader??s convenience, a short review of the modern GPU calculations for the medicine, physics, military applications etc. is presented.     

A Monte Carlo simulation of distributions of recoiling protons in high-energy hadron-nucleus reactions

We report on a Monte Carlo simulation of the multiplicity and angular distributions of recoiling protons in high-energy hadron-nucleus reactions.     

Quark model for high-energy scattering: A test of additivity from joint decay distributions

Experimental data about the decay distributions in double resonance production are used to test the predicitions of the quark model depending only on the additivity assumption. Within the rather large experimental inaccuracies good agreement is found.     

Hydrodynamic description of D meson production in high-energy heavy-ion collisions

The large values and constituent-quark-number scaling of the elliptic flow of low-pT D mesons imply that charm quarks,initially produced through hard processes,...