J. Ranft

Shapes, model dependence and energy dependence of inclusive two-particle correlations treated in the framework of the thermodynamic model

Based on the thermodynamic model for particle production, inclusive two-particle correlations are studied. The model is used to study integrated correlations R(2)(s) and rapidity correlations at accelerator and ISR energies. Particle production is described via the formation of clusters called fireballs. The average mass of these clusters changes as s12w exp (− |η|ν), (0 ⩽ ν, w ⩽ 1) with the primary energy s and fireball rapidity η. The model produces in the limiting cases the same correlations as the multiperipheral model (with w = 0) and the diffractive excitation model (with w = 1) but contains also all intermediate cases (0 < w < 1) in which fireballs increasing in mass and number are formed. The average number of fireballs produced is also calculated. At ISR energies integrated correlations R(2) and rapidity correlations are very different in the cases w = 0, 12 and 1. Therefore, experimental data at high energy on R(2)(s) or on rapidity correlations will allow one to determine the parameter w. Measurements of these different quantities should result in a consistent picture for the production of fireballs.

Particle production in hadron-hadron collisions at collider energies in an exclusive multi-string fragmentation model

AbstractParticle production in soft hadron-hadron collisions at collider energies is investigated in a two-step dual parton model. In the initial collision color-singlets or strings of hadronic matter are formed from constituents of the incident particles. These strings subsequently decay into chains of hadrons, analogously to the

Azimuthal correlations in 40 GeV/c π−p collisions and the independent cluster model

q\bar q

Multihadron production in nucleon--antinucleon annihilation at rest in the statistical bootstrap model. I. Multiplicity distributions according to different bootstrap versions

system in low energye+e− physics. Relying on the Monte-Carlo method we generate exclusive events and evaluate quantities of interest which include inclusive and semi-inclusive pseudorapidity spectra, topological cross-section, correlations and charge transfer distributions.

Effects of interaction of strings in the dual parton model

We present a Monte Carlo version of the dual parton model for the description of particle production in hadron-nucleus and nucleus-nucleus collisions with a complete formation zone intranuclear cascade. All generations of secondary interactions are considered. Furthermore, Fermi motion and Paulis principle are introduced to control the generation of low-energy nucleons. The model is compared with rapidity distributions and grey-particle production in hadron-nucleus interactions as well as with results from nucleus-nucleus collisions. Within the DPM the number of chains with sea-quarks at their ends grows with the complexity of the target and/or projectile nuclei as well as with the collision energy. We discuss this increase of chain-end sea-quarks as a mechanism for strangeness enhancement within the model. Furthermore we study the properties of the model at the energies of future heavy ion colliders.

Identical particle effect in azimuthal correlations at small rapidity separation

Abstract Data on azimuthal correlations and their rapidity dependence are presented in inclusive and semi-inclusive reactions π − p → π + π + X,→ π − π − X and π + π − X at 40 GeV/ c . They show a long range as well as a short range effect. The short range effect, leading to different behaviour of d N /d φ near φ = 0 of like and unlike pion pairs is explained by identical and unidentical particle statistics. The predictions of the independent cluster model for the azimuthal asymmetry are in qualitative agreement with data of this experiment as well as those at 102 and 205 GeV/ c .

Interference of QCD and weak interactions and the detection of vector bosons by hadronic jets: pp and collisions with polarized and unpolarized beams

The concepts of the formation zone and formation zone intranuclear cascade are discussed. The dual parton Monte Carlo model is modified by the leading order formation zone cascade. The properties of the resulting model are presented and discussed. It is found that especially rapidity or pseudorapidity distributions change strongly with the value of the formation zone parameter. A comparison with data leads to a phenomenological value of the formation zone parameter of τ0c≈5 to 10 fm. This corresponds roughly to an average formation zone of 1 fm in the rest frame of the secondary produced.

Effect of Bose-Einstein statistics on two-particle azimuthal and rapidity correlations

Abstract Multihadron production in nucleon-antinucleon annihilation at rest is studied using the statistical bootstrap model. Different versions of the statistical bootstrap model are compared at non-asymptotic and asymptotic energies. The parameter of the model is determined from nucleon-antinucleon annihilation at rest. Data for p p and p n annihilation agree rather well with the model except for certain difficulties with neutral pions. Furthermore we discuss the fireball mass dependence of the bootstrap predictions and in this context the application of the statistical bootstrap model to e − e + → hadrons.