Strange particle spectra from collisions in STAR at RHIC

Abstract

Production of strange hadrons in high energy p+p collisions provides baseline information to which results from A+A collisions may be compared in the search for possible signatures of a deconfined state. However, p+p collisions also demonstrate some surprising effects of their own and should be investigated for the insight they may provide. We present mid-rapidity transverse mass spectra and ⟨pT⟩ for K0S, Λ and Ξ produced in p+p collisions measured by the STAR collaboration at RHIC. Comparisons will be made with available model calculations as well as lower energy results and Au+Au results from the same detector.

Summary of Strange Quark Matter 2003 experimental results

“…New measurements of the particle spectra in STAR at RHIC indicate that the − + + spectra cannot be fit using the same parametrization that fits the π ± , K ± , protons and 2 New data from STAR on the mass dependence of the mean transverse momentum for various particles in p+p collisions at RHIC [33] exhibit a similar, although weaker, increase with the particle mass indicating an additional component besides transverse flow in the transverse expansion, possibly mini-jets [34]. and 158 (bottom) A GeV.…”

An update from STAR—using strangeness to probe relativistic heavy ion collisions

“…It is not expected that these collisions should exhibit collective motion, although this possibility cannot yet be completely eliminated, and hence this trend has been attributed to multiple mini-jet production [38]. Also consistent with multiple mini-jet production is the dependence of p ⊥ on the dN ch /dy observed by STAR for the K 0 s [37]. These measurements show that care needs to be taken when interpreting the Au-Au collision measurements, especially for the most peripheral events.…”

“…We have long interpreted the dependence on the measured inverse slopes of the p ⊥ spectra, or p ⊥ , in A-A collisions as evidence for radial flow [34]. Figure 10 shows the p ⊥ as a function of particle mass as extracted from power law fits to the measured p ⊥ spectra [7][8][9][10]37]; a clear mass dependence is observed. It is not expected that these collisions should exhibit collective motion, although this possibility cannot yet be completely eliminated, and hence this trend has been attributed to multiple mini-jet production [38].…”

Multi-strange baryon correlations in p+p and d+Au collisions at

“…Although correlations are observed in both the p+p data and that of simulated particles from PYTHIA, a comparison of the two spectra shows that the simulation does not reproduce the data. While the PYTHIA integrated yield is higher (dN/dy = 0.003 18 for PYTHIA, dN/dy = 0.001 81 ± 0.000 08 for the p+p data [9]), it grossly underpredicts the yields in the region of interest (p T > 2 GeV/c), at the same time overstating the yields below p T = 0.8 GeV/c (figure 2). This might be altered by adjusting various PYTHIA parameters, such as tuning the hard processes parameters and allowing for parton rescattering, or making NLO pQCD calculations.…”