Strange meson enhancement in Pb Pb collisions.

The NA44 collaboration Bearden, I. ; Bøggild, H. ; Boissevain, J. ; et al.
Phys.Lett.B 471 (1999) 6-12, 1999.
Inspire Record 504074 DOI 10.17182/hepdata.31360

The NA44 Collaboration has measured yields and differential distributions of K+, K-, pi+, pi- in transverse kinetic energy and rapidity, around the center-of-mass rapidity in 158 A GeV/c Pb+Pb collisions at the CERN SPS. A considerable enhancement of K+ production per pi is observed, as compared to p+p collisions at this energy. To illustrate the importance of secondary hadron rescattering as an enhancement mechanism, we compare strangeness production at the SPS and AGS with predictions of the transport model RQMD.

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Centrality dependence of pi+-, K+-, p and anti-p production from s(NN)**(1/2) = 130-GeV Au + Au collisions at RHIC.

The PHENIX collaboration Adcox, K. ; Adler, S.S. ; Ajitanand, N.N. ; et al.
Phys.Rev.Lett. 88 (2002) 242301, 2002.
Inspire Record 568437 DOI 10.17182/hepdata.19421

Identified pi^[+/-] K^[+/-], p and p-bar transverse momentum spectra at mid-rapidity in sqrt(s_NN)=130 GeV Au-Au collisions were measured by the PHENIX experiment at RHIC as a function of collision centrality. Average transverse momenta increase with the number of participating nucleons in a similar way for all particle species. The multiplicity densities scale faster than the number of participating nucleons. Kaon and nucleon yields per participant increase faster than the pion yields. In central collisions at high transverse momenta (p_T greater than 2 GeV/c), anti-proton and proton yields are comparable to the pion yields.

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Collective expansion in high energy heavy ion collisions.

The NA44 collaboration Bearden, I.G. ; Boggild, H. ; Boissevain, J. ; et al.
Phys.Rev.Lett. 78 (1997) 2080-2083, 1997.
Inspire Record 426801 DOI 10.17182/hepdata.52345

Transverse mass spectra of pions, kaons, and protons from the symmetric heavy-ion collisions 200 A GeV S+S and 158 A GeV Pb+Pb, measured in the NA44 focusing spectrometer at CERN, are presented. The mass dependence of the slope parameters provides evidence of collective transverse flow from expansion of the system in heavy-ion induced central collisions.

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Observation of enhanced subthreshold K+ production in central collisions between heavy nuclei

Miskowiec, D. ; Ahner, W. ; Barth, R. ; et al.
Phys.Rev.Lett. 72 (1994) 3650-3653, 1994.
Inspire Record 373335 DOI 10.17182/hepdata.19695

In the very heavy collision system Au197+197Au the K+ production process was studied as a function of impact parameter at 1 GeV/nucleon, a beam energy well below the free N-N threshold. The K+ multiplicity increases more than linearly with the number of participant nucleons and the K+/π+ ratio rises significantly when going from peripheral to central collisions. The measured K+ double differential cross section is enhanced by a factor of 6 compared to microscopic transport calculations if secondary processes (ΔN→KΛN and ΔΔ→KΛN) are ignored.

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Energy dependence of pion and kaon production in central Pb + Pb collisions.

The NA49 collaboration Afanasiev, S.V. ; Anticic, T. ; Barna, D. ; et al.
Phys.Rev.C 66 (2002) 054902, 2002.
Inspire Record 586383 DOI 10.17182/hepdata.31729

Measurements of charged pion and kaon production in central Pb+Pb collisions at 40, 80 and 158 AGeV are presented. These are compared with data at lower and higher energies as well as with results from p+p interactions. The mean pion multiplicity per wounded nucleon increases approximately linearly with s_NN^1/4 with a change of slope starting in the region 15-40 AGeV. The change from pion suppression with respect to p+p interactions, as observed at low collision energies, to pion enhancement at high energies occurs at about 40 AGeV. A non-monotonic energy dependence of the ratio of K^+ to pi^+ yields is observed, with a maximum close to 40 AGeV and an indication of a nearly constant value at higher energies.The measured dependences may be related to an increase of the entropy production and a decrease of the strangeness to entropy ratio in central Pb+Pb collisions in the low SPS energy range, which is consistent with the hypothesis that a transient state of deconfined matter is created above these energies. Other interpretations of the data are also discussed.

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Charged pion production in 2-AGeV to 8-AGeV central Au + Au collisions.

The E-0895 collaboration Klay, J.L. ; Ajitanand, N.N. ; Alexander, J.M. ; et al.
Phys.Rev.C 68 (2003) 054905, 2003.
Inspire Record 622260 DOI 10.17182/hepdata.4989

Momentum spectra of charged pions over nearly full rapidity coverage from target to beam rapidity have been measured in the 0-5% most central Au+Au collisions in the beam energy range from 2 to 8 AGeV by the E895 Experiment. Using a thermal parameterization to fit the transverse mass spectra, rapidity density distributions are extracted. The observed spectra are compared with predictions from the RQMD v2.3 cascade model and also to a thermal model including longitudinal flow. The total 4$\pi$ yields of the charged pions are used to infer an initial state entropy produced in the collisions.

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Charged particle production in S S collisions at 200-GeV/c per nucleon

The WA94 collaboration Andrighetto, A. ; Antinori, F. ; Bayes, A.C. ; et al.
Phys.Lett.B 412 (1997) 148-154, 1997.
Inspire Record 460283 DOI 10.17182/hepdata.28242

Charged particle production in central S-S collisions at 200 GeV/ c per nucleon has been studied by the WA94 experiment at the CERN-SPS. Particle identification has been provided by the Omega RICH, while a silicon telescope in the Omega spectrometer and an array of MultiWire Proportional Chambers have been used to trace particles through the RICH detector. Production ratios and transverse mass spectra for π ± , K ± and p( p ) at central rapidity and p T > 1.3 GeV/ c are presented.

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Charged kaon and pion production at midrapidity in proton nucleus and sulphur nucleus collisions.

The NA44 collaboration Boggild, H. ; Boissevain, J. ; Dodd, J. ; et al.
Phys.Rev.C 59 (1999) 328-335, 1999.
Inspire Record 474831 DOI 10.17182/hepdata.25575

The NA44 collaboration has measured charged kaon and pion distributions at midrapidity in sulphur and proton collisions with nuclear targets at 200 and 450 GeV/c per nucleon, respectively. The inverse slopes of kaons are larger than those of pions. The difference in the inverse slopes of pions, kaons and protons, all measured in our spectrometer, increases with system size and is consistent with the buildup of collective flow for larger systems. The target dependence of both the yields and inverse slopes is stronger for the sulphur beam suggesting the increased importance of secondary rescattering for SA reactions. The rapidity density, dN/dy, of both K+ and K- increases more rapidly with system size than for pi+ in a similar rapidity region. This trend continues with increasing centrality, and according to RQMD, it is caused by secondary reactions between mesons and baryons. The K-/K+ ratio falls with increasing system size but more slowly than the pbar/p ratio. The pi-/pi+ ratio is close to unity for all systems. From pBe to SPb the K+/p ratio decreases while K-/pbar increases and ({K+*K-}/{p*pbar})**1/2 stays constant. These data suggest that as larger nuclei collide, the resulting system has a larger transverse expansion, baryon density and an increasing fraction of strange quarks.

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Charged hadron distributions in p A and A-A collisions at the CERN SPS

The NA44 collaboration Dodd, Jeremy ; Bøggild, H. ; Boissevain, J. ; et al.
Nucl.Phys.A 590 (1995) 523C-526C, 1995.
Inspire Record 407678 DOI 10.17182/hepdata.36504

Single particle distributions of π ± , K ± , p , p and d near mid-rapidity from 450 GeV/c p A and 200 GeV/c per nucleon SA collisions are presented. Inverse slope parameters are extracted from the transverse mass spectra, and examined for indications of collective phenomena. Proton and antiproton yields are determined for different projectile-target combinations. First results from 160 GeV/c per nucleon PbPb collisions are presented.

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Production of pi+-, K+-, p, and anti-p in relativistic Au + Pt, Si + Pt, and p + Pt collisions

The E886 collaboration Diebold, G.E. ; Bassalleck, B. ; Burger, T. ; et al.
Phys.Rev.C 48 (1993) 2984-2994, 1993.
Inspire Record 364483 DOI 10.17182/hepdata.26015

During the recent commissioning of Au beams at the Brookhaven Alternating Gradient Synchrotron facility, experiment 886 measured production cross sections for π±, K±, p, and p¯ in minimum bias Au+Pt collisions at 11.5A GeV/c. Invariant differential cross sections, Ed3σ/dp3, were measured at several rigidities (p/Z≤1.8 GeV/c) using a 5.7° (fixed-angle) focusing spectrometer. For comparison, particle production was measured in minimum bias Si+Pt collisions at 14.6A GeV/c using the same apparatus and in p+Pt collisions at 12.9 GeV/c using a similar spectrometer at KEK. When normalized to projectile mass, Aproj, the measured π± and K± cross sections are nearly equal for the p+Pt and Si+Pt reactions. In contrast to this behavior, the π− cross section measured in Au+Pt shows a significant excess beyond Aproj scaling of the p+Pt measurement. This enhancement suggests collective phenomena contribute significantly to π− production in the larger Au+Pt colliding system. For the Au+Pt reaction, the π+ and K+ yields also exceed Aproj scaling of p+Pt collisions. However, little significance can be attributed to these excesses due to larger experimental uncertainties for the positive rigidity Au beam measurements. For antiprotons, the Si+Pt and Au+Pt cross sections fall well below Aproj scaling of the p+Pt yields indicating a substantial fraction of the nuclear projectile is ineffective for p¯ production. Comparing with p+Pt multiplicities, the Si+Pt and Au+Pt antiproton yields agree with that expected solely from ‘‘first’’ nucleon-nucleon collisions (i.e., collisions between previously unstruck nucleons). In light of expected p¯ annihilation in the colliding system, such projectile independence is unexpected without additional (projectile dependent) sources of p¯ production. In this case, the data indicate an approximate balance exists between absorption and additional sources of antiprotons. This balance is remarkable given the wide range of projectile mass spanned by these measurements.

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