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Lepton and Pion Pair Production in $\gamma \gamma$ Collisions Measured Near the Threshold at Dci

Courau, A. ; Falvard, A. ; Haissinski, J. ; et al.
Nucl.Phys.B 271 (1986) 1-20, 1986.
Inspire Record 232808 DOI 10.17182/hepdata.38240

This paper reports a complete analysis of data taken at DCI to measure lepton and pion pair production close to the threshold in two-photon processes: e + e − → e + e − (e + e − , μ + μ − , π + π − ). Preliminary results have been previously published including one-half of the total statistics. Final results presented here are in good agreement with QED for lepton pair production. The measured cross section for pion pair production is twice as large as that expected from Born terms only — a two standard deviation effect.

1 data table
Table 1

Normalised to number of observed electron pairs. Fully corrected for acceptance, radiative effects etc.


Strangeness enhancement in central S + S collisions at 200-GeV/nucleon.

The NA35 collaboration Baechler, J. ; Bartke, J. ; Bialkowska, H. ; et al.
Nucl.Phys.A 525 (1991) 221C-226C, 1991.
Inspire Record 328899 DOI 10.17182/hepdata.36820

None

4 data tables
Table 1

No description provided.

Table 2

No description provided.

Table 3

No description provided.

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Centrality dependence of charged particle multiplicity in Au Au collisions at s(N N)**(1/2) = 130-GeV.

The PHENIX collaboration Adcox, K. ; Adler, S.S. ; Ajitanand, N.N. ; et al.
Phys.Rev.Lett. 86 (2001) 3500-3505, 2001.
Inspire Record 539140 DOI 10.17182/hepdata.50270

We present results for the charged-particle multiplicity distribution at mid-rapidity in Au - Au collisions at sqrt(s_NN)=130 GeV measured with the PHENIX detector at RHIC. For the 5% most central collisions we find $dN_{ch}/d\eta_{|\eta=0} = 622 \pm 1 (stat) \pm 41 (syst)$. The results, analyzed as a function of centrality, show a steady rise of the particle density per participating nucleon with centrality.

1 data table
Table 1

130 GeV is sqrt(S) per nucleon-nucleon collision. N(C=N_NUCLEONS) and N(C=N_COLLISONS) are the number of participating nucleons and binary collisions. The statistical errors are negligible and only systematic errors are quoted. COL(NAME=CENTRALITY) is centrality.


Measurement of the mid-rapidity transverse energy distribution from s(N N)**(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. 87 (2001) 052301, 2001.
Inspire Record 555603 DOI 10.17182/hepdata.31419

The first measurement of energy produced transverse to the beam direction at RHIC is presented. The mid-rapidity transverse energy density per participating nucleon rises steadily with the number of participants, closely paralleling the rise in charged-particle density, such that E_T / N_ch remains relatively constant as a function of centrality. The energy density calculated via Bjorken's prescription for the 2% most central Au+Au collisions at sqrt(s_NN)=130 GeV is at least epsilon_Bj = 4.6 GeV/fm^3 which is a factor of 1.6 larger than found at sqrt(s_NN)=17.2 GeV (Pb+Pb at CERN).

1 data table
Table 1

130 GeV is sqrt(S) per nucleon-nucleon collision. The statistical errors are negligible and only systematic errors are quoted. COL(NAME=CENTRALITY) is centrality.


K*(892)0 production in relativistic heavy ion collisions at S(NN)**(1/2) = 130-GeV.

The STAR collaboration Adler, C. ; Ahammed, Z. ; Allgower, C. ; et al.
Phys.Rev.C 66 (2002) 061901, 2002.
Inspire Record 587235 DOI 10.17182/hepdata.54898

We report the first observation of $K^{\star}(892)^{0}\to\pi K$ in relativistic heavy ion collisions. The transverse momentum spectrum of $(K^{\star0}+\bar{K}^{\star0})/2$ from central Au+Au collisions at $\sqrt{s_{_{NN}}}=130$ GeV is presented. The ratios of the $K^{\star0}$ yield derived from these data to the yields of negative hadrons, charged kaons, and $\phi$ mesons have been measured in central and minimum bias collisions and compared with model predictions and comparable $e^{+}e^{-}$, $pp$, and $\bar{p}p$ results. The data indicate no dramatic reduction of $K^{\star0}$ production in relativistic heavy ion collisions despite expected losses due to rescattering effects.

4 data tables
Table 1

Transverse mass spectrum of K*0 with YRAP = -0.5 to 0.5 for the 14 PCT most central interactions. Numerical values requested from the authors.

Table 2

K*0 to negative hadron ratio using hadron data from Adler et al PRL 87,112303(2001).

Table 3

K*0 to kaon ratio using STAR kaon data.

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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.

21 data tables
Table 1

Transverse momentum spectra for PI+ in the midrapidity range for the centrality region 0 to 5 PCT. Errors are combined statistical and systematics.

Table 2

Transverse momentum spectra for PI- in the midrapidity range for the centrality region 0 to 5 PCT. Errors are combined statistical and systematics.

Table 3

Transverse momentum spectra for K+ in the midrapidity range for the centrality region 0 to 5 PCT. Errors are combined statistical and systematics.

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First measurement of proton proton elastic scattering at RHIC.

Bueltmann, Stephen L. ; Chiang, I.H. ; Chrien, R.E. ; et al.
Phys.Lett.B 579 (2004) 245-250, 2004.
Inspire Record 618968 DOI 10.17182/hepdata.31705

The first result of the pp2pp experiment at RHIC on elastic scattering of polarized protons at sqrt{s} = 200 GeV is reported here. The exponential slope parameter b of the diffractive peak of the elastic cross section in the t range 0.010 <= |t| <= 0.019 (GeV/c)^2 was measured to be b = 16.3 +- 1.6 (stat.) +- 0.9 (syst.) (GeV/c)^{-2} .

1 data table
Table 1

Measured slope of the elastic cross section.


First measurement of A(N) at s**(1/2) = 200-GeV in polarized proton proton elastic scattering at RHIC.

Bultmann, S. ; Chiang, I.H. ; Chrien, R.E. ; et al.
Phys.Lett.B 632 (2006) 167-172, 2006.
Inspire Record 688172 DOI 10.17182/hepdata.31570

We report on the first measurement of the single spin analyzing power (A_N) at sqrt(s)=200GeV, obtained by the pp2pp experiment using polarized proton beams at the Relativistic Heavy Ion Collider (RHIC). Data points were measured in the four momentum transfer t range 0.01 < |t| < 0.03 (GeV/c)^2. Our result, averaged over the whole t-interval is about one standard deviation above the calculation, which uses interference between electromagnetic spin-flip amplitude and hadronic non-flip amplitude, the source of A_N. The difference could be explained by an additional contribution of a hadronic spin-flip amplitude to A_N.

1 data table
Table 1

The single spin analyzing power for 3 T intervals.


Double Spin Asymmetries A_NN and A_SS at sqrt{s}=200 GeV in Polarized Proton-Proton Elastic Scattering at RHIC

The pp2pp collaboration Bultmann, S. ; Chiang, I.H. ; Chrien, R.E. ; et al.
Phys.Lett.B 647 (2007) 98-103, 2007.
Inspire Record 729168 DOI 10.17182/hepdata.31499

We present the first measurements of the double spin asymmetries A_NN and A_SS at sqrt{s}=200 GeV, obtained by the pp2pp experiment using polarized proton beams at the Relativistic Heavy Ion Collider (RHIC). The data were collected in the four momentum transfer t range 0.01<|t|<0.03 (GeV/c)^2. The measured asymmetries, which are consistent with zero, allow us to estimate upper limits on the double helicity-flip amplitudes phi_2 and phi_4 at small t as well as on the difference Delta(sigma_T) between the total cross sections for transversely polarized protons with antiparallel or parallel spin orientations.

3 data tables
Table 1

Double spin asymmetries.

Table 2

Double spin asymmetries.

Table 3

T dependence of the double spin asymmetry ASS3 with statistical errors only.


Pion and kaon production in central Pb+Pb collisions at 20A and 30A GeV: Evidence for the onset of deconfinement

The NA49 collaboration Alt, C. ; Anticic, T. ; Baatar, B. ; et al.
Phys.Rev.C 77 (2008) 024903, 2008.
Inspire Record 762554 DOI 10.17182/hepdata.25169

Results on charged pion and kaon production in central Pb+Pb collisions at 20A and 30A GeV are presented and compared to data at lower and higher energies. A rapid change of the energy dependence is observed around 30A GeV for the yields of pions and kaons as well as for the shape of the transverse mass spectra. The change is compatible with the prediction that the threshold for production of a state of deconfined matter at the early stage of the collisions is located at low SPS energies.

13 data tables
Table 1

Transverse mass spectra for pion production in the central rapidity region for collisions at 20 GeV per nucleon.

Table 2

Transverse mass spectra for pion production in the central rapidity region for collisions at 30 GeV per nucleon.

Table 3

Transverse mass spectra for kaon production in the central rapidity region for collisions at 20 GeV per nucleon.

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