Meier, R.
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Observation of a (Sigma)He-4 bound state in the He-4(K-,pi-) reaction at 600-MeV/c.

Nagae, T. ; Miyachi, T. ; Fukuda, T. ; et al.
Phys.Rev.Lett. 80 (1998) 1605-1609, 1998.
Inspire Record 468090 DOI 10.17182/hepdata.19553

We have observed a clear peak below the Σ+-production threshold in the 4He(K−,π−) reaction at 600MeV/c and θKπ=4∘. This is confirmation of the existence of the bound state of Σ4He, which was reported in the 4He(stoppedK−,π−) reaction. As in the case of stopped kaons, no such peak was found in the 4He(K−,π+) spectrum. Quantitatively reliable parameters for this level have been established. The binding energy and the width of the bound state are 4.4±0.3(stat)±1(syst) MeV and 7.0±0.7(stat)−0.0+1.2(syst) MeV, respectively.

1 data table
Table 1

$HE4/S represents the HE4/SIGMA+ bound state.


Subthreshold production of low momentum K+ in p + C at 1.2-GeV.

Badala, A. ; Barbera, R. ; Bassi, M. ; et al.
Phys.Rev.Lett. 80 (1998) 4863-4866, 1998.
Inspire Record 471821 DOI 10.17182/hepdata.19554

The double differential cross section of low momentum kaons ( ≤0.3GeV/c) from p+C collisions at subthreshold bombarding energies has been for the first time measured by the use of the CLAMSUD magnetic spectrometer installed at the CELSIUS storage ring. Invariant cross sections extracted from the data show a source rapidity shifted below the nucleon-nucleon rapidity, in agreement with the existence of multistep processes in the K+ production cross section. The total cross section of the inclusive reaction 12C(p,K+) at 1.2 GeV was extracted and compared with recent data systematics as a function of the proton bombarding energy.

1 data table
Table 1

No description provided.


Longitudinal and transverse cross sections in the H-1(e,e' K+)Lambda reaction.

Niculescu, G. ; Mohring, R.M. ; Gueye, P. ; et al.
Phys.Rev.Lett. 81 (1998) 1805-1808, 1998.
Inspire Record 479881 DOI 10.17182/hepdata.19546

The 1H(e,e′K+)Λ reaction was studied as a function of the squared four-momentum transfer, Q2, and the virtual photon polarization, ɛ. For each of four Q2 settings, 0.52, 0.75, 1.00, and 2.00 (GeV/c)2, the longitudinal and transverse virtual photon cross sections were extracted in measurements at three virtual photon polarizations. The Q2 dependence of the σL/σT ratio differs significantly from current theoretical predictions. This, combined with the precision of the measurement, implies a need for revision of existing calculations.

1 data table
Table 1

The systematic and statistical errors are added in quadrature. OMEGA is the solid angle of K+ in CMS.


Threshold structure of the quasifree p + n --> d + eta reaction.

Calen, H. ; Dyring, J. ; Fransson, K. ; et al.
Phys.Rev.Lett. 80 (1998) 2069-2072, 1998.
Inspire Record 468434 DOI 10.17182/hepdata.19524

The quasifree p+n→d+η reaction cross section has been measured at the threshold using 1295 MeV protons in the CELSIUS storage ring and an internal cluster-jet deuterium target. The kinematics is chosen such that the target proton can be assumed to be a spectator. The Fermi momentum of the target neutron is used to extract the energy dependence of the cross section by reconstructing the kinematics on an event-by-event basis. The data cover excess energies from threshold to 10 MeV in the center of mass of the final dη system. Approaching the threshold the cross section is enhanced compared to what is expected from phase space. This behavior is typical for a strong final-state interaction.

1 data table
Table 1

Cross section as a function of the C.M. excess energy.


Measurement of the target asymmetry of eta and pi0 photoproduction on the proton.

Bock, A. ; Anton, G. ; Beulertz, W. ; et al.
Phys.Rev.Lett. 81 (1998) 534-537, 1998.
Inspire Record 474492 DOI 10.17182/hepdata.19492

At the tagged photon facility PHOENICS at the Bonn accelerator ELSA a measurement of the target asymmetry of the reaction γp→pη from threshold to 1150 MeV has been performed. Simultaneously the reaction γp→pπ0 has been measured in the first resonance region. Results are presented for both reactions. The target asymmetry data are suited to put considerable constraints on the model parameters used for the theoretical description of meson photoproduction.

3 data tables
Table 1

The errors include statistical and systematic errors added in quadrature. The target asymmetry determines as the rates belonging to different polarization states: (N_pol-up-N_pol_down)/(N_pol-up+N_pol_down).

Table 2

The errors include statistical and systematic errors added in quadrature. The target asymmetry determines as the rates belonging to different polarization states: (N_pol-up-N_pol_down)/(N_pol-up+N_pol_down).

Table 3

The errors include statistical and systematic errors added in quadrature. The target asymmetry determines as the rates belonging to different polarization states: (N_pol-up-N_pol_down)/(N_pol-up+N_pol_down).


Production of Phi and omega mesons in near-threshold p p reactions.

The DISTO collaboration Balestra, F. ; Bedfer, Y. ; Bertini, R. ; et al.
Phys.Rev.Lett. 81 (1998) 4572-4575, 1998.
Inspire Record 481641 DOI 10.17182/hepdata.19496

The ratio of the exclusive production cross sections for φ and ω mesons has been measured in pp reactions at Tbeam=2.85GeV. The observed φ/ω ratio is (3.7±0.7−0.9+1.2)×10−3. After phase space corrections, this ratio is about a factor of 10 enhanced relative to naive predictions based upon the Okubo-Zweig-Iizuka rule, in comparison to an enhancement by a factor of ∼3 previously observed at higher energies. The modest increase of this enhancement near the production threshold is compared to the much larger increase of the φ/ω ratio observed in specific channels of p¯p annihilation experiments.

1 data table
Table 1

No description provided.


Differential cross section of the p n --> p p(1)S(0)) pi- reaction extracted from p d --> p p p pi-.

Duncan, F. ; Hahn, H. ; Aclander, C. ; et al.
Phys.Rev.Lett. 80 (1998) 4390-4393, 1998.
Inspire Record 471244 DOI 10.17182/hepdata.19508

The double differential cross section for pn→pp(1S0)π− at three beam energies has been extracted from the quasifree process pd→pppπ−. A comparison is carried out with single differential cross section measurements for 3He(π−,pn)n, where the pion is thought to be absorbed onto a pp(1S0) “diproton” state. A significant difference is observed in the shape of the angular distribution between the production and absorption data. This difference is ascribed to the effects of the 3He nuclear environment characterizing the absorption process; however, an adequate theoretical explanation is not available.

3 data tables
Table 1

Only statistical errors are given in the table. Final P P system is in 1S0 ((2S+1) L J) state.

Table 2

Only statistical errors are given in the table. Final P P system is in 1S0 ((2S+1) L J) state.

Table 3

Only statistical errors are given in the table. Final P P system is in 1S0 ((2S+1) L J) state.


Search for psi(2S) production in e+ e- annihilations at 4.03-GeV

The BES collaboration Bai, J.Z. ; Bian, J.G. ; Blum, I. ; et al.
Phys.Rev.D 57 (1998) 3854-3859, 1998.
Inspire Record 468969 DOI 10.17182/hepdata.22270

A search is performed for the production of the ψ(2S) in e+e− annihilation at a center-of-mass energy of 4.03 GeV using the BES detector operated at the Beijing Electron Positron Collider (BEPC). The kinematic features of the reconstructed ψ(2S) signal are consistent with its being produced only in association with an energetic photon resulting from initial state radiation (ISR). Limits are placed on ψ(2S) production from the decay of unknown charmonia or metastable hybrids that might be produced in e+e− annihilations at 4.03 GeV. Under the assumption that the observed cross section for ψ(2S) production is due entirely to ISR, the partial width Γee of the ψ(2S) is measured to be 2.07±0.32keV.

1 data table
Table 1

PSI(UNSPEC) is considered as a new 3D2 charmonium state. CHI/C(UNSPEC) is considered as any unknown charmonium state. EXOTIC is considered as a metastable hybrid.


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.


Kaon and proton ratios from central Pb + Pb collisions at the CERN SPS.

The NA44 collaboration Kaneta, M. ; Bearden, I.G. ; Bøggild, H. ; et al.
Nucl.Phys.A 638 (1998) 419-422, 1998.
Inspire Record 481886 DOI 10.17182/hepdata.36250

K − /K + and p ¯ / p ratios measured in 158 A·GeV Pb+Pb collisions are shown as a function of transverse momentum P T and centrality in top 8.5% central region. Little centrality dependence of the K − / K + and p ¯ / p ratios is observed. The transverse mass m T distribution and dN/dy of K + , K − , p and p ¯ around mid-rapidity are obtained. The temperature T ch and the chemical potentials for both light and strange quarks (μ q , μ s ) at chemical freeze-out are determined by applying simple thermodynamical model to the present data. The resultant μ q , μ s and T ch are compared with those obtained from similar analysis of SPS S+A and AGS Si+A data. The chemical freeze-out temperature T ch at CERN energies is higher than thermal freeze-out temperature T fo which is extracted from m T distribution of charged hadrons. At AGS energies T ch is close to T fo .

2 data tables
Table 1

Data obtained from the fit of MT spectra.

Table 2

Data obtained from the fit of MT spectra.