118814310
Thermal, chemical and spectral equilibration in heavy-ion collisions
Abstract We have considered the equilibration in relativistic heavy ion collisions at energies 1–7 A GeV using our transport model. We applied periodic boundary conditions to close the system in a box. We found that the thermal equilibration takes place in the first 20–40 fm/ c whose time is comparable to the duration of a heavy ion collision. The chemical equilibration is a much slower process and the system does not equilibrate in a heavy ion collision. We have shown that in the testparticle simulation of the Boltzmann equation the mass spectra of broad resonances follow instantaneously their in-medium spectral functions as expected from the Markovian approximation to the Kadanoff–Baym equations employed via the (local) gradient expansion.
123071989
Subthreshold $\phi$ meson production in heavy-ion collisions
Within a BUU type transport model we study Φ meson production in subthreshold Ni + Ni and Ru + Ru reactions. For the first time we included in our model the elementary reaction channels ρ + N, Δ → Φ + N, π + N((1520) → Φ + N and πρ → Φ. In spite of a substantial increase of the Φ multiplicities by these channels, our results stay significantly below the preliminary experimental data.
56157029
Zero temperature properties of mesons in a vector meson extended linear sigma model
A three flavor linear sigma model with vector and axial-vector mesons is discussed. Preliminary results concerning on the symmetry breaking pattern, the question of parameterization, as well as the resulting meson masses are presented.
123530530
Baryonic channels of dilepton production
A calculation of the Dalitz-decay width of baryon resonances is presented and applied to dilepton production in proton-proton collisions in the BEVALAC/SIS energy range. The results indicate, that for these energies the contribution of Dalitz decay of higher baryon resonances (i.e. other that the δ(1232)) are negligible.
15180819
From pion nucleon scattering to vector mesons in nuclear matter
Abstract We construct a relativistic and unitary approach to ‘high’ energy pion nucleon scattering taking into account the inelastic πΔ, ρ N , ω N , K Σ, K Λ and η N channels [1]. Our scheme dynamically generates the s- and d-wave nucleon and isobar resonances N *(1535), N *(1650), N *(1520), N *(1700), Δ*(1620) and Δ*(1700). We also describe the ρ- and ω-nucleon scattering amplitudes which in turn provide the leading density modification of the ρ and ω mass distribution in nuclear matter. We find repulsive mass shifts for both vector mesons at small nuclear density but predict considerable strength in low energy resonance-hole like vector meson modes.
16881732
Evaluation of QCD sum rules for HADES
QCD sum rules are evaluated at finite nucleon densities and temperatures to determine the change of pole mass parameters for the lightest vector mesons $\rho$, $\omega$ and $\phi$ in a strongly interacting medium at conditions relevant for the starting experiments at HADES. The role of the four-quark condensate is highlighted. A few estimates (within a fire ball model and BUU calculations) of dilepton spectra in heavy-ion collisions at 1 AGeV are presented.
120076725
Dependence of multiplicity and rapidity distributions on the number of projectile collisions in 200-GeV/c proton-nucleus interactions
Interactions of 200-GeV/c protons on hydrogen, neon, argon, and xenon were studied with a streamer-chamber spectrometer. The number of projectile collisions inside the nucleus and the number of secondary collisions in the intranuclear cascade were estimated. The dependence of multiplicity and rapidity distributions on the number of projectile collisions was analyzed. The predictions of the additive quark model were found to be in qualitative agreement with the results of the experiment.
117777421
sigma- Production and decay properties in K-p --> sigma-pi+
123564276
Production of K∗(892) in K+N interactions at 3 GeV/c
We have studied the reactions K+d→K+π−pp,K+d→Koπopp,K+d→Koπ+pp, obtained from an exposure of the Saclay 81-cm bubble chamber filled with deuterium and exposed at CERN to a separated 3 GeV/c K+ beam. 
 
In reactions (1) and (2) there is abundant production of K∗0(892) and some production of K∗(1420). From the density matrix elements, it is found that K∗0(892) is produced mainly by pion exchange. The K∗(892) four-momentum-transfer distribution in reaction (1) agrees with the predictions of the OPE model, as modified by Durr and Pilkuhn. A marked asymmetry of the decay distribution of the K+π− system is observed and discussed in the framework of a unitarized Veneziano model. In reaction (3), on the other hand, the production of K∗+(892) and N∗+(1236) is found to proceed mainly by vector exchange.
124472433
Fermi-Dirac correlations in Lambda pairs in hadronic Z decays
122292810
A total energy trigger at large angles used in a calorimetric study of 150 GeV and 300 GeV pion and proton interactions on hydrogen
Abstract Hard hadronic scattering was studied by selecting 150 GeV and 300 GeV π − p and pp events with large energy in a 240 cell calorimeter covering 45† to 135† in the c.m.s. polar angle and the full 2 π azimuth. A downstream calorimeter measured the remaining energy flow at smaller angles. For large energy deposited in the segmented calorimeter the proton induced cross section drops below the pion induced cross section, as expected in a constituent scattering picture. However, neither a simple energy scaling of the cross section nor a dominant jet structure of the events is observed. No evidence was found for recently proposed higher-twist mechanisms leading to events