HEPData Search

Total cross sections for the pp --> pp eta' reaction have been measured in the excess energy range from Q = 1.53 MeV to Q = 23.64 MeV. The experiment has been performed at the internal installation COSY-11 using a stochastically cooled proton beam of the COoler SYnchrotron COSY and a hydrogen cluster target. The determined energy dependence of the total cross section weakens the hypothesis of the S-wave repulsive interaction between the eta' meson and the proton. New data agree well with predictions based on the phase-space distribution modified by the proton-proton final-state-interaction (FSI) only.

1 data table

Table 1

Total cross sections w.r.t the excess energy in the CM system. Statistical errors only are given. As well as the 15 PCT overall systematic uncertainty there is an uncertainty on the energy of 0.44 MeV.

Forward K+ production in subthreshold p A collisions at 1.0-GeV.

The ANKE collaboration Koptev, V. ; Buescher, Markus ; Junghans, H. ; et al.

Phys.Rev.Lett. 87 (2001) 022301, 2001.

Inspire Record 556676 DOI 10.17182/hepdata.31765

K+ meson production in pA (A = C, Cu, Au) collisions has been studied using the ANKE spectrometer at an internal target position of the COSY-Juelich accelerator. The complete momentum spectrum of kaons emitted at forward angles, theta < 12 degrees, has been measured for a beam energy of T(p)=1.0 GeV, far below the free NN threshold of 1.58 GeV. The spectrum does not follow a thermal distribution at low kaon momenta and the larger momenta reflect a high degree of collectivity in the target nucleus.

3 data tables

Table 1

Double differential K+ production cross section for forward K+ angles < 12 degs. Statistical errors only.

Table 2

The invariant cross section for K+ production. Statistical errors only.

Table 3

Ratio of K+ production cross sections for CU/C and AU/C.

Analysing power A(y) in the reaction p(pol.) p --> p p eta close to threshold.

Winter, P. ; Adam, H.H. ; Bauer, F. ; et al.

Phys.Lett.B 544 (2002) 251-258, 2002.

Inspire Record 599591 DOI 10.17182/hepdata.31686

Measurements of the eta meson production with a polarised proton beam in the reaction p(pol) p --> p p eta have been carried out at an excess energy of Q = 40 MeV. The dependence of the analysing power A_y on the polar angle theta^*_q of the eta meson in the center of mass system (CMS) has been studied. The data indicate the possibility of an influence of p- and d-waves to the close to threshold eta production.

1 data table

Table 1

Averaged value of the analyzing power and cross section as a function of the emmission angle of the ETA meson is the CM system.

Total and differential cross sections for the p p --> p p eta' reaction near threshold.

Khoukaz, A. ; Geck, I. ; Quentmeier, C. ; et al.

Eur.Phys.J.A 20 (2004) 345-350, 2004.

Inspire Record 642580 DOI 10.17182/hepdata.43699

The eta-prime meson production in the reaction pp-->pp eta-prime has been studied at excess energies of Q = 26.5, 32.5 and 46.6 MeV using the internal beam facility COSY-11 at the cooler synchrotron COSY. The total cross sections as well as one angular distribution for the highest Q-value are presented. The excitation function of the near threshold data can be described by a pure s-wave phase space distribution with the inclusion of the proton-proton final state interaction and Coulomb effects. The obtained angular distribution of the eta-prime mesons is also consistent with pure s-wave production.

2 data tables

Table 1

Total cross section for the reaction P P --> P P ETAPRIME.

Table 2

Angular distribution of the ETAPRIME in the CM system at an excess energy of 46.6 MeV. There is an additional systematic error of +24%/-35%.

Energy dependence of the Lambda/Sigma0 production cross section ratio in p p interactions.

Kowina, P. ; Wolke, M. ; Adam, H.H. ; et al.

Eur.Phys.J.A 22 (2004) 293-299, 2004.

Inspire Record 644074 DOI 10.17182/hepdata.31762

The production of the Lambda and Sigma0 hyperons has been measured via the pp->pK+Lambda / Sigma0 reaction at the internal COSY-11 facility in the excess energy range between 14 and 60 MeV. The transition of the Lambda/Sigma0 cross section ratio from about 28 at Q<=13 MeV to the high energy level of about 2.5 is covered by the data showing a strong decrease of the ratio between 10 and 20 MeV excess energy. Effects from the final state interactions in the p-Sigma0 channel seem to be much smaller compared to the p-Lambda one. Estimates of the effective range parameters are given for the N-Lambda and the N-Sigma systems.

3 data tables

Table 1

Cross section for LAMBDA production.. Statistical errors only.

Table 2

Cross section for SIGMA0 production.. Statistical errors only.

Table 3

Energy dependence of the LAMBDA/SIGMA0 ratio.

Threshold hyperon production in proton proton collisions at COSY-11.

Rozek, T. ; Grzonka, D. ; Adam, H.-H. ; et al.

Phys.Lett.B 643 (2006) 251-256, 2006.

Inspire Record 722758 DOI 10.17182/hepdata.31512

Sigma+ hyperon production was measured at the COSY-11 spectrometer via the p p --> n K+ Sigma+ reaction at excess energies of Q = 13 MeV and Q = 60 MeV. These measurements continue systematic hyperon production studies via the p p --> p K+ Lambda/Sigma0 reactions where a strong decrease of the cross section ratio close-to-threshold was observed. In order to verify models developed for the description of the Lambda and Sigma0 production we have performed the measurement on the Sigma+ hyperon and found unexpectedly that the total cross section is by more than one order of magnitude larger than predicted by all anticipated models. After the reconstruction of the kaon and neutron four momenta, the Sigma+ is identified via the missing mass technique. Details of the method and the measurement will be given and discussed in view of theoretical models.

1 data table

Table 1

Cross section for the reaction P P --> N K+ SIGMA+ at excess energies of 13 and 60 MeV.

Measurement of the $dp \rightarrow {^3He}}\eta$ reaction near threshold\author{J. Smyrski\corauthref{corr}

Smyrski, J. ; Adam, H.-H. ; Budzanowski, A. ; et al.

Phys.Lett.B 649 (2007) 258-262, 2007.

Inspire Record 745085 DOI 10.17182/hepdata.31470

Total and differential cross sections for the dp --> 3He eta reaction have been measured near threshold for 3He center-of-mass momenta in the range from 17.1 MeV/c to 87.5 MeV/c. The data were taken during a slow ramping of the COSY internal deuteron beam scattered on a proton target detecting the 3He ejectiles with the COSY-11 facility. The forward-backward asymmetries of the differential cross sections deviate clearly from zero for center-of-mass momenta above 50 MeV/c indicating the presence of higher partial waves in the final state. Below 50 MeV/c center-of-mass momenta a fit of the final state enhancement factor to the data of the total cross sections results in the 3He eta scattering length of a = |2.9 +/- 0.6| + i (3.2 +/- 0.4) fm.

2 data tables

Table 1

Total cross section for the reaction DEUT P --> HE3 ETA.

Table 2

Forward-Backward asymmetry for the reaction DEUT P --> HE3 ETA.

rivet Analysis
Centrality dependence of the charged-particle multiplicity density at mid-rapidity in Pb-Pb collisions at sqrt(sNN) = 2.76 TeV

The ALICE collaboration Aamodt, Kenneth ; Abrahantes Quintana, Arian ; Adamova, Dagmar ; et al.

Phys.Rev.Lett. 106 (2011) 032301, 2011.

Inspire Record 880049 DOI 10.17182/hepdata.57047

The centrality dependence of the charged-particle multiplicity density at mid-rapidity in Pb-Pb collisions at $\sqrt{s_{\rm NN}}$ = 2.76 TeV is presented. The charged-particle density normalized per participating nucleon pair increases by about a factor 2 from peripheral (70-80%) to central (0-5%) collisions. The centrality dependence is found to be similar to that observed at lower collision energies. The data are compared with models based on different mechanisms for particle production in nuclear collisions.

2 data tables

Table 1

The charged particle multiplicity density measurements for the nine centrality classes. Also given are the mean values of NPART, the number of participating nucleon pairs calulcated fromthe Glauber model. The errors shown are the systematic errors, with the statistical errors being small.

Table 2

The dependence of the charged particle multiplicity density on the number of participants in the collisions.

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MOMENTUM AND ANGULAR DISTRIBUTIONS OF CHARGED SECONDARIES IN 40-GeV/c pi- A INTERACTIONS WITH SINGLE PARTICLE HIGH P(T) TRIGGER

Measurement of the B(d)0 oscillation frequency using kaons, leptons and jet charge

Energy dependence of the near-threshold total cross-section for the p p --> p p eta' reaction.

Forward K+ production in subthreshold p A collisions at 1.0-GeV.

Analysing power A(y) in the reaction p(pol.) p --> p p eta close to threshold.

Total and differential cross sections for the p p --> p p eta' reaction near threshold.

Energy dependence of the Lambda/Sigma0 production cross section ratio in p p interactions.

Threshold hyperon production in proton proton collisions at COSY-11.

Measurement of the $dp \rightarrow {^3He}}\eta$ reaction near threshold\author{J. Smyrski\corauthref{corr}

rivet Analysis
Centrality dependence of the charged-particle multiplicity density at mid-rapidity in Pb-Pb collisions at sqrt(sNN) = 2.76 TeV