Refine
Year of publication
Document Type
- Article (102) (remove)
Language
- English (102)
Has Fulltext
- yes (102)
Is part of the Bibliography
- no (102)
Keywords
- LHC (3)
- ALICE (2)
- Polarization (2)
- 900 GeV (1)
- Bee venom allergy (1)
- Charmonia (1)
- Elastic scattering (1)
- Femtoscopy (1)
- Flow (1)
- HBT (1)
Institute
- Physik (96)
- Frankfurt Institute for Advanced Studies (FIAS) (12)
- Informatik (5)
- Medizin (1)
Double-differential cross sections have been measured for high-energy p, d, t, 3He, and 4He particles emitted from uranium targets irradiated with 20Ne ions at energies of 250, 400, and 2100 MeV/nucleon and 4He ions at 400 MeV/nucleon. By using the shape and yield of the proton energy spectra, the shape and yield of the d, t, 3He, and 4He energy spectra can be deduced at all measured angles for all incident projectile energies by assuming that they are formed by a coalescence of cascade nucleons, using a model analogous to that of Butler and Pearson, and Schwarzschild and Zupancic-caron.
We compare the reconstructed hadronization conditions in relativistic nuclear collisions in the nucleon–nucleon centre-of-mass energy range 4.7–2760 GeV in terms of temperature and baryon-chemical potential with lattice QCD calculations, by using hadronic multiplicities. We obtain hadronization temperatures and baryon chemical potentials with a fit to measured multiplicities by correcting for the effect of post-hadronization rescattering. The post-hadronization modification factors are calculated by means of a coupled hydrodynamical-transport model simulation under the same conditions of approximate isothermal and isochemical decoupling as assumed in the statistical hadronization model fits to the data. The fit quality is considerably better than without rescattering corrections, as already found in previous work. The curvature of the obtained “true” hadronization pseudo-critical line κ is found to be 0.0048 ± 0.0026, in agreement with lattice QCD estimates; the pseudo-critical temperature at vanishing is found to be 164.3 ± 1.8 MeV.
We present the first measurements of charge-dependent correlations on angular difference variables η1 − η2 (pseudorapidity) and φ1 − φ2 (azimuth) for primary charged hadrons with transverse momentum 0.15 <= pt <= 2 GeV/c and |η| <= 1.3 from Au–Au collisions at √sNN = 130 GeV. We observe correlation structures not predicted by theory but consistent with evolution of hadron emission geometry with increasing centrality from one-dimensional fragmentation of color strings along the beam direction to an at least two-dimensional hadronization geometry along the beam and azimuth directions of a hadron-opaque bulk medium.
The multiplicity of hadronic species created in elementary, and in nucleus-nucleus collisions, are known to be well reproduced by the statistical hadronization model, in its canonical and grand-canonical versions.To understand the origin of the implied equilibrium we revisit the hadronization models developed for e+e- annihilation to hadrons which imply spatial color pre-confinement clusters forming at the end of the pQCD evolution, which decays into on-shell hadrons/resonances. The classical ensemble description arises as a consequence of decoherence and phase space dominance during cluster formation, and decay.For A+A collisions we assume that hadronization occurs from similar singlet clusters which will overlap spatially owing to the extreme density. This is imaged in the transition to the grand-canonical ensemble.This transition sets in with increasing A and collision centrality. It can be described by a percolation model.
Transverse mass and rapidity distributions for charged pions, charged kaons, protons, and antiprotons are reported for sqrt[sNN]=200 GeV pp and Au+Au collisions at Relativistic Heary Ion Collider (RHIC). Chemical and kinetic equilibrium model fits to our data reveal strong radial flow and long duration from chemical to kinetic freeze-out in central Au+Au collisions. The chemical freeze-out temperature appears to be independent of initial conditions at RHIC energies.
We report first results on elliptic flow of identified particles at midrapidity in Au+Au collisions at sqrt[sNN] = 130 GeV using the STAR TPC at RHIC. The elliptic flow as a function of transverse momentum and centrality differs significantly for particles of different masses. This dependence can be accounted for in hydrodynamic models, indicating that the system created shows a behavior consistent with collective hydrodynamical flow. The fit to the data with a simple model gives information on the temperature and flow velocities at freeze-out.
Particle production in central Pb+Pb collisions was studied with the NA49 large acceptance spectrometer at the CERN SPS at beam energies of 20, 30, 40, 80, and 158 GeV per nucleon. A change of the energy dependence is observed around 30A GeV for the yields of pions and strange particles as well as for the shapes of the transverse mass spectra. At present only a reaction scenario with onset of deconfinement is able to reproduce the measurements.
A data-driven method was applied to Au+Au collisions at √sNN = 200 GeV made with the STAR detector at RHIC to isolate pseudorapidity distance η-dependent and η-independent correlations by using two- and four-particle azimuthal cumulant measurements. We identified a η-independent component of the correlation, which is dominated by anisotropic flow and flow fluctuations. It was also found to be independent of η within the measured range of pseudorapidity |η| < 1. In 20–30% central Au+Au collisions, the relative flow fluctuation was found to be 34%±2%(stat.)±3%(sys.) for particles with transverse momentum pT less than 2 GeV/c. The η-dependent part, attributed to nonflow correlations, is found to be 5% ± 2%(sys.) relative to the flow of the measured second harmonic cumulant at |η| > 0.7.
We report on a polarization measurement of inclusive J/ψ mesons in the di-electron decay channel at mid-rapidity at 2 < pT < 6 GeV/c in p + p collisions at √s = 200 GeV. Data were taken with the STAR detector at RHIC. The J/ψ polarization measurement should help to distinguish between different models of the J/ψ production mechanism since they predict different pT dependences of the J/ψ polarization. In this analysis, J/ψ polarization is studied in the helicity frame. The polarization parameter λθ measured at RHIC becomes smaller towards high pT , indicating more longitudinal J/ψ polarization as pT increases. The result is compared with predictions of presently available models.