HEPData Search

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Exclusive electroproduction of Phi mesons at 4.2-GeV.

The CLAS collaboration Lukashin, K. ; Smith, E.S. ; Adams, G.S. ; et al.

Phys.Rev.C 64 (2001) 059901, 2001.

Inspire Record 552246 DOI 10.17182/hepdata.38589

We studied the exclusive reaction e p --> e' p' phi using the phi --> K^+ K^- decay mode. The data were collected using a 4.2 GeV incident electron beam and the CLAS detector at Jefferson Lab. Our experiment covers the range in Q^2 from 0.7 to 2.2 GeV^2, and W from 2.0 to 2.6 GeV. Taken together with all previous data, we find a consistent picture of phi production on the proton. Our measurement shows the expected decrease of the t-slope with the vector meson formation time c Delta tau below 2 fm. At = 0.6 fm, we measure b_phi = 2.27 +- 0.42 GeV^-2. The cross section dependence on W as W^{0.2+-0.1} at Q^2 = 1.3 GeV^2 was determined by comparison with phi production at HERA after correcting for threshold effects. This is the same dependence as observed in photoproduction.

3 data tables

Table 1

Slope of the DSIG/DT distribution in different Q**2 regions.

Table 2

Cross section as a function of Q**2 and W.

Table 3

The differential cross section for exclusive PHI electroproduction off the photon, (TP=T-TMIN).

Transverse momentum distributions of J/psi, psi', Drell-Yan and continuum dimuons produced in Pb Pb interactions at the SPS.

The NA50 collaboration Abreu, M.C ; Alessandro, B ; Alexa, C ; et al.

Phys.Lett.B 499 (2001) 85-96, 2001.

Inspire Record 537484 DOI 10.17182/hepdata.57431

Muon pairs produced in Pb–Pb interactions at 158 GeV/ c per nucleon are used to study the transverse momentum distributions of the J/ ψ , ψ ′ and dimuons in the mass continuum. In particular, the dependence of these distributions on the centrality of the Pb–Pb collision is investigated in detail.

9 data tables

Table 1

Mean values of PT and PT**2 calculated from the IMR distributions.

Table 2

Mean values of PT and PT**2 calculated from the J/PSI distributions.

Table 3

Mean values of PT and PT**2 calculated from the PSI(3685) distributions.

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Observation of an anomaly in the angular distribution of cumulative hadrons near the backward direction.

Vorobev, L.S. ; Gavrilov, V.B. ; Grishuk, Yu.G. ; et al.

Phys.Atom.Nucl. 63 (2000) 145-150, 2000.

Inspire Record 526502 DOI 10.17182/hepdata.17058

The angular distributions of secondary pions, protons, and deuterons originating from π−Pb interactions at an incident-pion momentum of 5 GeV/c was determined in a new run of measurements relying on track reconstruction. While showing a decrease over a large angular interval with increasing emission angle, the yield of cumulative particles of each species was found to be anomalously large near the backward direction.

3 data tables

Table 1

No description provided.

Table 2

No description provided.

Table 3

No description provided.

Phi emission in central Pb + Pb collisions at 158-GeV/u.

The NA49 collaboration Pühlhofer, Falk ; Appelshäuser, H. ; Bächler, J. ; et al.

Nucl.Phys.A 638 (1998) 431-434, 1998.

Inspire Record 481889 DOI 10.17182/hepdata.36218

Data on φ -production obtained by the CERN NA49 experiment for central Pb+Pb collisions at 158 GeV/u are presented. Compared with pp interactions the φ -yield shows substantial strangeness enhancement: the φ /π ratio is found to increase by a factor of 2.6 ± 0.6, which is approximately the square of the K/π enhancement.

2 data tables

Table 1

5% most central collosions, MT - M0 = 0 - 1.4 GeV, preliminary data.

Table 2

5% most central events.

Hadron yields and hadron spectra from the NA49 experiment

The NA49 collaboration Jones, P.G. ; Afanasiev, S.V. ; Alber, T. ; et al.

Nucl.Phys.A 610 (1996) 188C-199C, 1996.

Inspire Record 432742 DOI 10.17182/hepdata.36468

Preliminary inclusive spectra of negative hadrons, net protons and neutral strange particles are presented, measured by the NA49 experiment in central Pb+Pb collisions at 158 GeV per nucleon. Comparison of their yields with those from the lighter S+S system suggests that the yields scale approximately with the number of participating nucleons.

4 data tables

Table 1

CENTRAL COLLISIONS, PRELIMINARY DATA.

Table 2

CENTRAL COLLISIONS, PRELIMINARY DATA.

Table 3

CENTRAL COLLISIONS, PRELIMINARY DATA.

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