HEPData Search

The differential cross-section for the process p(e,e'p)eta has been measured at Q2 ~ 5.7 and 7.0 (GeV/c)2 for centre-of-mass energies from threshold to 1.8 GeV, encompassing the S11(1535) resonance, which dominates the channel. This is the highest momentum transfer measurement of this exclusive process to date. The helicity-conserving transition amplitude A_1/2, for the production of the S11(1535) resonance, is extracted from the data. This quantity appears to begin scaling as 1/Q3, a predicted signal of the dominance of perturbative QCD, at Q2 ~ 5 (GeV/c)2.

39 data tables

Table 1

Total cross section for the lower Q**2 data as a function of W. The errors are statistics and systematic added in quadrature.

Table 2

Total cross section for the higher Q**2 data as a function of W. The errors are statistics and systematic added in quadrature.

Table 3

Lower Q**2 extracted differential cross section at W = 1.500 GeV and cos(theta(eta) = -0.917, -0.750 and -0.583.

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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.

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.

Elastic and inelastic scattering of K+ from Li-6 and C-12.

Chrien, R.E. ; Sawafta, R. ; Peterson, R.J. ; et al.

Nucl.Phys.A 625 (1997) 251-260, 1997.

Inspire Record 453025 DOI 10.17182/hepdata.36467

Cross sections for inelastic scattering of 635 and 715 MeV/ c K + from 12 C are compared with DWIA calculations in order to check for possible density-dependent effects on K + -nucleon cross sections within nuclei. New fits to 715 MeV/ c K + scattering spectra from 6 Li give elastic and inelastic cross sections and permit an evaluation of the density dependence of these effects. The same DWIA methods are also used to estimate quadrupole non-central contributions to elastic K + scattering from the 1 + ground state of 6 Li, and these are found to be very small.

8 data tables

Table 1

Axis error includes +- 0.0/0.0 contribution (?////NORMALIZATION UNCERTAINTIES ARE INCLUDED).

Table 2

Axis error includes +- 0.0/0.0 contribution (?////NORMALIZATION UNCERTAINTIES ARE INCLUDED).

Table 3

Axis error includes +- 0.0/0.0 contribution (?////NORMALIZATION UNCERTAINTIES ARE INCLUDED).

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The reaction e+ e- ---> gamma gamma (gamma) at Z0 energies

The DELPHI collaboration Abreu, P. ; Adam, W. ; Adami, F. ; et al.

Phys.Lett.B 268 (1991) 296-304, 1991.

Inspire Record 317825 DOI 10.17182/hepdata.29352

The total and differential cross-sections for the reaction e + e − → γγ ( γ ) are measured at centre of mass energies around 91 GeV using an integrated luminosity of 4.7 pb −1 . The aggreement with QED prediction is good. Consequently there is no evidence for non-standard channels which would have the same experimental signature. The lower limits on the QED cuttoff parameters are Λ + > 113 GeV and Λ − > 95 GeV. An upper limit on the effective coupling between a possible excited electron and the gamma is derived. At 95% confidence level the branching ratios for Z 0 decay into π 0 γ, ηψ and γγγ are below 1.5 × 10 −4 , 2.8 × 10 −4 and 1.4 × 10 −4 respectively.

2 data tables

Table 1

Radiative effects are subtracted.

Table 2

Radiative effects subtracted.

K+ elastic scattering from C and Li-6 at 715-MeV/c

Michael, R. ; Barakat, M.B. ; Bart, S. ; et al.

Phys.Lett.B 382 (1996) 29-34, 1996.

Inspire Record 328538 DOI 10.17182/hepdata.28355

Elastic differential cross sections for K + mesons scattered from nat C and 6 Li targets have been measured at an incident momentum of 715 MeV/c and at angles of 7° to 42° in the laboratory frame. The experimental cross sections agree, within errors, with two different parameter-free impulse approximation calculations. To reduce the effects of the systematic errors, the ratio of the experimental cross sections for nat C to 6 Li is compared to the theoretical values, and these ratios do not agree with theory. This discrepancy suggests either a density-dependent alteration of K + -nucleon amplitudes or a failure of the optical potential calculations to describe these nuclides adequately.

2 data tables

Table 1

No description provided.

Table 2

No description provided.

Pion Scattering From C and Ca at 800-{MeV}/$c$

Marlow, Daniel R. ; Barnes, P.D. ; Colella, N.J. ; et al.

Phys.Rev.C 30 (1984) 1662, 1984.

Inspire Record 15083 DOI 10.17182/hepdata.26285

Results from π± elastic and inelastic scattering from C12 and Ca40 are reported. The data were all taken at an incident momentum of 800 MeV/c over an angular range from 4° to 38°. The elastic data are compared to first-order optical model calculations in momentum space; qualitative agreement is obtained. The inelastic data (from C12 only) are compared to distorted-wave Born approximation calculations, and reasonable agreement is found if realistic inelastic transition densities are used.

8 data tables

Table 1

No description provided.

Table 2

THE C12* NUCLEUS IS IN THE STATE 2+ (4.4 MEV).

Table 3

THE C12* NUCLEUS IS IN THE STATE 3- (9.6 MEV).

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KAON SCATTERING FROM C AND CA AT 800-MEV/C

Marlow, Daniel R. ; Barnes, P.D. ; Colella, N.J. ; et al.

Phys.Rev.C 25 (1982) 2619-2637, 1982.

Inspire Record 180999 DOI 10.17182/hepdata.26337

Results from K± elastic and inelastic scattering from C12 and Ca40 are reported. The data were all taken at an incident momentum of 800 MeV/c over an angular range from 2° to 38°. The elastic data are compared to first-order optical model calculations in coordinate and momentum space; good qualitative agreement is obtained. The inelastic data (from C12 only) are compared to distorted-wave Born approximation calculations, and good agreement is found if "realistic" inelastic transition densities are used. Although a first-order optical potential description does not describe the data fully, there are strong indications of the increased penetrability of K+ over K− in this energy range. NUCLEAR REACTIONS C12(K±,K±)C12, Ca40(K±,K±)Ca40, E=442 MeV (800 MeV/c), measured σ(θ) for elastic and inelastic scattering, compared to optical model and DWBA calculations, deduced optical potential parameters; θ=2°−38°, Δθ=1°.

4 data tables

Table 1

X ERROR D(THETA) = 1.0100 DEG.

Table 2

X ERROR D(THETA) = 1.0100 DEG.

Table 3

X ERROR D(THETA) = 1.1000 DEG.

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