119243792
Effects of (axial)vector mesons on the chiral phase transition: initial results
We investigate the effects of (axial)vector mesons on the chiral phase tran- sition in the framework of an SU(3), (axial)vector meson extended linear sigma model with additional constituent quarks and Polyakov loops. We determine the parameters of the Lagrangian at zero temperature in a hybrid approach, where we treat the mesons at tree-level, while the constituent quarks at 1-loop level. We assume two nonzero scalar condensates and together with the Polyakov-loop variables we determine their tempera- ture dependence according to the 1-loop level field equations.
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.
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.
118548456
Meson vacuum phenomenology in a three-flavor linear sigma model with (axial-)vector mesons
We study scalar, pseudoscalar, vector, and axial-vector mesons with non-strange and strange quantum numbers in the framework of a linear sigma model with global chiral $U(N_f)_L \times U(N_f)_R$ symmetry. We perform a global fit of meson masses, decay widths, as well as decay amplitudes. The quality of the fit is, for a hadronic model that does not consider isospin-breaking effects, surprisingly good. We also investigate the question whether the scalar $\bar{q}q$ states lie below or above 1 GeV and find the scalar states above 1 GeV to be preferred as $\bar{q}q$ states. Additionally, we also describe the axial-vector resonances as $\bar{q}q$ states.
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.
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
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.
117090913
sigma+/- lifetimes and longitudinal acceleration
124472433
Fermi-Dirac correlations in Lambda pairs in hadronic Z decays
122039401
Long-range correlations in hadron-nucleus interactions
An analysis of correlations in rapidity of charged particles produced in proton and antiproton interactions on hydrogen, argon and xenon at 200 GeV is presented. Positive long-range correlations are observed in interactions on heavy targets. The dependence of rapidity correlations between the forward and backward hemisphere on the number of projectile collisions is discussed.