(\Sigma (1385)\) results with STAR Salur, S
The European physical journal. C, Particles and fields,
05/2005, Letnik:
40, Številka:
2
Journal Article
Recenzirano
Odprti dostop
This paper introduces the Solenoidal Tracker experiment at the Relativistic Heavy Ion Collider. The corrected pT spectra and the yields of the \(\Sigma (1385)^{\pm}\) and their antiparticles in the ...most central Au + Au and elementary p + p collisions are presented. Comparison of the \(\Sigma (1385)\)\(\langle p_{T} \rangle\) measurement with the other particles corroborates the fact that the \(\langle p_{T} \rangle\) behavior for hyperons (mass> 1.2 GeV) is similar in p + p and Au + Au collisions. The \(\Sigma (1385)/\Lambda\) ratio, along with other resonance-to-stable-particle ratios, suggests that a regeneration mechanism recovers the signal loss due to re-scattering in the final state in Au + Au collisions.
The yields and spectra of strange hadrons have each been measured by STAR as a function of centrality in
S
NN
=
200
GeV
AuAu collisions. By comparing to pp and dAu at
S
NN
=
200
GeV
and in AuAu at
S
...NN
=
62
GeV
the dependence on system size and energy is studied. Strange resonances, such as Σ(1385) and Λ(1520), are used to examine the dynamical evolution between production and freeze-out for these systems. Particle production is investigated by comparison to thermal models, which assume a scaling of the yield with N
part. Our hyperon measurements in AuAu indicate that N
bin may be a more appropriate scale for the strangeness correlation volume. Thus canonical suppression can not be simply parameterized with the geometrical overlap volume but will depend on the individual quark content of each particle. This theory is tested by comparing the data from different collision systems and centralities.
Abstract We report a new measurement of the production of electrons from open heavy-flavor hadron decays (HFEs) at mid-rapidity (|y| < 0.7) in Au+Au collisions at s NN $$ \sqrt{s_{\textrm{NN}}} $$ = ...200 GeV. Invariant yields of HFEs are measured for the transverse momentum range of 3.5 < p T < 9 GeV/c in various configurations of the collision geometry. The HFE yields in head-on Au+Au collisions are suppressed by approximately a factor of 2 compared to that in p + p collisions scaled by the average number of binary collisions, indicating strong interactions between heavy quarks and the hot and dense medium created in heavy-ion collisions. Comparison of these results with models provides additional tests of theoretical calculations of heavy quark energy loss in the quark-gluon plasma.
We report precision measurements of hypernuclei _{Λ}^{3}H and _{Λ}^{4}H lifetimes obtained from Au+Au collisions at sqrts_{NN}=3.0 GeV and 7.2 GeV collected by the STAR experiment at the ...Relativistic Heavy Ion Collider, and the first measurement of _{Λ}^{3}H and _{Λ}^{4}H midrapidity yields in Au+Au collisions at sqrts_{NN}=3.0 GeV. _{Λ}^{3}H and _{Λ}^{4}H, being the two simplest bound states composed of hyperons and nucleons, are cornerstones in the field of hypernuclear physics. Their lifetimes are measured to be 221±15(stat)±19(syst) ps for _{Λ}^{3}H and 218±6(stat)±13(syst) ps for _{Λ}^{4}H. The p_{T}-integrated yields of _{Λ}^{3}H and _{Λ}^{4}H are presented in different centrality and rapidity intervals. It is observed that the shape of the rapidity distribution of _{Λ}^{4}H is different for 0%-10% and 10%-50% centrality collisions. Thermal model calculations, using the canonical ensemble for strangeness, describes the _{Λ}^{3}H yield well, while underestimating the _{Λ}^{4}H yield. Transport models, combining baryonic mean-field and coalescence (jam) or utilizing dynamical cluster formation via baryonic interactions (phqmd) for light nuclei and hypernuclei production, approximately describe the measured _{Λ}^{3}H and _{Λ}^{4}H yields. Our measurements provide means to precisely assess our understanding of the fundamental baryonic interactions with strange quarks, which can impact our understanding of more complicated systems involving hyperons, such as the interior of neutron stars or exotic hypernuclei.
A RICH detector with a CsI photo-cathode and liquid perfluorohexane radiator has been installed in the STAR experiment at RHIC. The liquid is continuously cleaned and distributed to a quartz ...containment vessel within the detector by a closed recirculation system. A VUV spectrometer is connected to the system which monitors the optical transparency of the liquid. This measurement provides one of the pieces of information necessary to model the number of Cherenkov photons which reach the pad plane. A description of the liquid recirculation system and the cleaning procedure for the liquid as well as the spectrometer is presented along with results of their performance.
PDF
