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star physics results: Spectra and yields

Note: Click on a figure for a larger version.


Figure. Upper panel: h- pT spectra for the 5% most central Au+Au collisions at midrapidity (|eta| < 0.1) for several systems. The curves are power-law fits to the data. Lower panel: ratio of STAR and scaled UA1 pT distributions.

Multiplicity and Spectra of Negatively Charged Hadrons in Au+Au Collisions at sqrt(snn) = 130 GeV

The multiplicity and inclusive single particle pT distributions of hadrons are important tools for understanding the evolutionary path of the system created in heavy-ion collisions and help to determine the characteristics of the early, hot, and dense phase.

Particle production was studied in Au+Au collisions at sqrt(snn) = 130 GeV at STAR through the yield of primary negative hadrons, comprising mostly pi- and an admixture of K- and pbar. The h- distribution includes the products of strong and electromagnetic decays. Negatively charged hadrons were studied in order to exclude effects due to participant nucleons. The particle production per participant in central Au+Au collisions at sqrt(snn) = 130 GeV increases by 38% relative to pbarp and 52% compared to nuclear collisions at sqrt(snn) = 17 GeV. The pT distribution is harder than that of the pbarp reference system for the pT < 2 GeV/c (see upper panel in the Figure). Scaling of produced particle yield with the number of participants shows a strong pT dependence, with wounded nucleon scaling achieved only at the lowest measured pT (see lower panel in the Figure).

Positive charged particles were also analyzed, and for the 5% most central collisions, STAR measures a total charged multiplicity density of dNch/deta|eta=0 = 567 +- 1(stat) +- 38(syst). This result should be compared to the PHOBOS measurement of dNch/deta||eta|<1 = 555 +- 12(stat) +- 35(syst) for the 6% most central collisions and to the PHENIX measurement of dNch/deta|eta=1 = 622 +- 1(stat) +- 41(syst) for the 5% most central collisions.

Related STAR papers
Multiplicity distribution and spectra of negatively charged hadrons in Au+Au collisions at sqrt(snn) = 130 GeV
Phys. Rev. Lett. 87 (2001) 112303
e-Print Archives (nucl-ex/0106004): Abstract | PS | PDF
Journal article: Phys. Rev. Lett. server

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