Brady, F.P.
NA49
Rapidity Dependence
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Production of Phi mesons in p + p, p + Pb and central Pb + Pb collisions at E(beam) = 158-A-GeV

The NA49 collaboration Afanasiev, S.V. ; Anticic, T. ; Bächler, J. ; et al.
Phys.Lett.B 491 (2000) 59-66, 2000.
Inspire Record 537897 DOI 10.17182/hepdata.27038

Yields and phase space distributions of φ -mesons emitted from p+p (minimum bias trigger), p+Pb (at various centralities) and central Pb+Pb collisions are reported ( E beam =158 A GeV). The decay φ →K + K − was used for identification. The φ / π ratio is found to increase by a factor of 3.0±0.7 from inelastic p+p to central Pb+Pb. Significant enhancement in this ratio is also observed in subclasses of p+p events (characterized by high charged-particle multiplicity) as well as in the forward hemisphere of central p+Pb collisions. In Pb+Pb no shift or significant broadening of the φ -peak is seen.

7 data tables
Table 1

Transverse mass distribution for PHI mesons produced in PB PB collisions averaged over the rapidity region 3.0 to 3.8.

Table 2

Transverse mass distribution for PHI mesons produced in P P collisions averaged over the rapidity region 2.9 to 4.5.

Table 3

Rapidity distributions for PHI mesons produced in PB PB collisions.

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Xi and Antixi production in 158-GeV/nucleon Pb + Pb collisions.

The NA49 collaboration Appelshäuser, H. ; Bächler, J. ; Bailey, S.J. ; et al.
Phys.Lett.B 444 (1998) 523-530, 1998.
Inspire Record 477539 DOI 10.17182/hepdata.31330

We report measurements of Xi and Xi-bar hyperon absolute yields as a function of rapidity in 158 GeV/c Pb+Pb collisions. At midrapidity, dN/dy = 2.29 +/- 0.12 for Xi, and 0.52 +/- 0.05 for Xi-bar, leading to the ratio of Xi-bar/Xi = 0.23 +/- 0.03. Inverse slope parameters fitted to the measured transverse mass spectra are of the order of 300 MeV near mid-rapidity. The estimated total yield of Xi particles in Pb+Pb central interactions amounts to 7.4 +/- 1.0 per collision. Comparison to Xi production in properly scaled p+p reactions at the same energy reveals a dramatic enhancement (about one order of magnitude) of Xi production in Pb+Pb central collisions over elementary hadron interactions.

2 data tables
Table 1

Data are given at the midrapidity value.

Table 2

Requested data from authors.