High statistics measurement of the cross sections of gamma gamma --> pi+ pi- production.

The Belle collaboration Mori, T. ; Uehara, S. ; Watanabe, Y. ; et al.
J.Phys.Soc.Jap. 76 (2007) 074102, 2007.
Inspire Record 749358 DOI 10.17182/hepdata.51842

We report on a high statistics measurement of the total and differential cross sections of the process gamma gamma -> pi^+ pi^- in the pi^+ pi^- invariant mass range 0.8 GeV/c^2 < W < 1.5 GeV/c^2 with 85.9 fb^{-1} of data collected at sqrt{s}=10.58 GeV and 10.52 GeV with the Belle detector. A clear signal of the f_0(980) resonance is observed in addition to the f_2(1270) resonance. An improved 90% confidence level upper limit Br.(eta'(958) -> pi^+ pi^-) < 2.9 x 10^{-3} is obtained for P- and CP-violating decay of the eta'(958) meson using the most conservative assumption about the interference with the background.

1 data table match query

Total cross section.


High-statistics measurement of neutral pion-pair production in two-photon collisions

The Belle collaboration Uehara, S. ; Watanabe, Y. ; Adachi, I. ; et al.
Phys.Rev.D 78 (2008) 052004, 2008.
Inspire Record 786406 DOI 10.17182/hepdata.50151

We report a high-statistics measurement of differential cross sections for the process gamma gamma -> pi^0 pi^0 in the kinematic range 0.6 GeV <= W <= 4.0 GeV and |cos theta*| <= 0.8, where W and theta* are the energy and pion scattering angle, respectively, in the gamma gamma center-of-mass system. Differential cross sections are fitted to obtain information on S, D_0, D_2, G_0 and G_2 waves. The G waves are important above W ~= 1.6 GeV. For W <= 1.6 GeV the D_2 wave is dominated by the f_2(1270) resonance while the S wave requires at least one additional resonance besides the f_0(980), which may be the f_0(1370) or f_0(1500). The differential cross sections are fitted with a simple parameterization to determine the parameters (the mass, total width and Gamma_{gamma gamma}B(f_0 -> pi^0 pi^0)) of this scalar meson as well as the f_0(980). The helicity 0 fraction of the f_2(1270) meson, taking into account interference for the first time, is also obtained.

4 data tables match query

Differential cross section for W = 1.27, 1.29 and 1.31 GeV.

Differential cross section for W = 1.33, 1.35 and 1.37 GeV.

Differential cross section for W = 1.39, 1.41 and 1.43 GeV.

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Differential Cross-Sections for the pi0 Photoproduction at Theta (CM) = 90-Degrees and K (Lab) = 380-MeV-820-MeV

Jung, M. ; Kattein, J. ; Leu, P. ; et al.
BONN-HE-76-15, 1976.
Inspire Record 111677 DOI 10.17182/hepdata.50235

None

1 data table match query

No description provided.


Mass identified particle production in proton anti-proton collisions at s**(1/2) = 300-GeV, 540-GeV, 1000-GeV, and 1800-GeV

The E735 collaboration Alexopoulos, T. ; Allen, C. ; Anderson, E.W. ; et al.
Phys.Rev.D 48 (1993) 984-997, 1993.
Inspire Record 363171 DOI 10.17182/hepdata.22669

The yields and average transverse momenta of pions, kaons, and antiprotons produced at the Fermilab p¯p collider at s=300, 540, 1000, and 1800 GeV are presented and compared with data from the energies reached at the CERN collider. We also present data on the dependence of average transverse momentum 〈pt〉 and particle ratios as a function of charged particle density dNcdη; data for particle densities as high as six times the average value, corresponding to a Bjorken energy density 6 GeV/fm3, are reported. These data are relevant to the search for quark-gluon phase of QCD.

2 data tables match query

No description provided.

No description provided.


Proton Compton scattering at 0.55-to-4.5-gev energy and 0.12-to-1.0-(gev/c)-squared momentum transfer

Deutsch, M. ; Cleetus, K.J. ; Golub, L. ; et al.
Phys.Rev.D 8 (1973) 3828-3847, 1973.
Inspire Record 93270 DOI 10.17182/hepdata.22057

Results are presented on the elastic scattering of photons by protons. The incident photon energy ranged from 0.55 GeV to 4.5 GeV, and the four-momentum transfer t ranged from 0.12 to 1.0 (GeV/c)2. The data at large angles, 60°<θ*<115°, are characterized by a pronounced excitation of the D13(1518) resonance, a shoulder in the 1688-MeV mass region, and a precipitous drop thereafter in the cross section as a function of incident energy. The low-t data are characterized by a diffraction slope of 5 (GeV/c)−2. The data are inconsistent with the predictions of the vector-dominance model if the latter is restricted to ρ0, ω, and φ vector mesons.

1 data table match query

No description provided.


Measurements of the Deuteron and Proton Magnetic Form-factors at Large Momentum Transfers

Bosted, Peter E. ; Katramatou, A.T. ; Arnold, R.G. ; et al.
Phys.Rev.C 42 (1990) 38-64, 1990.
Inspire Record 283632 DOI 10.17182/hepdata.26165

Measurements of the deuteron elastic magnetic structure function B(Q2) are reported at squared four-momentum transfer values 1.20≤Q2≤2.77 (GeV/c)2. Also reported are values for the proton magnetic form factor GMp(Q2) at 11 Q2 values between 0.49 and 1.75 (GeV/c)2. The data were obtained using an electron beam of 0.5 to 1.3 GeV. Electrons backscattered near 180° were detected in coincidence with deuterons or protons recoiling near 0° in a large solid-angle double-arm spectrometer system. The data for B(Q2) are found to decrease rapidly from Q2=1.2 to 2 (GeV/c)2, and then rise to a secondary maximum around Q2=2.5 (GeV/c)2. Reasonable agreement is found with several different models, including those in the relativistic impulse approximation, nonrelativistic calculations that include meson-exchange currents, isobar configurations, and six-quark configurations, and one calculation based on the Skyrme model. All calculations are very sensitive to the choice of deuteron wave function and nucleon form factor parametrization. The data for GMp(Q2) are in good agreement with the empirical dipole fit.

1 data table match query

The measured cross section have been devided by those obtained using the dipole form for the proton form factors: G_E=1/(1+Q2/0.71)**2, G_E(Q2)=G_M(Q2)/mu,where Q2 in GeV2, mu=2.79.


Proton form factors from elastic electron-proton scattering

Janssens, T. ; Hofstadter, R. ; Hughes, E.B. ; et al.
Phys.Rev. 142 (1966) 922-931, 1966.
Inspire Record 49127 DOI 10.17182/hepdata.26698

Absolute measurements of the elastic electron-proton cross section have been made with a precision of about 4% for values of the square of the four-momentum transfer, q2, in the range 6.0 to 30.0 F−2 and for electron scattering angles in the range 45° to 145°. To within the experimental errors, it is found that the charge and magnetic form factors of the proton have a common dependence on q2 when normalized to unity at q2=0, and that an accurate representation of the behavior of the form factor and that of the cross sections themselves can be given in terms of a three-pole approximation to the dispersion theory of nucleon form factors.

13 data tables match query

Axis error includes +- 2./2. contribution (RANDOM ERROR).

Axis error includes +- 2./2. contribution (RANDOM ERROR).

Axis error includes +- 2./2. contribution (RANDOM ERROR).

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Differential Cross-Sections of the Proton Compton Scattering in the Energy Between 450-MeV and 950-MeV

Toshioka, K. ; Chiba, M. ; Kato, S. ; et al.
Nucl.Phys.B 141 (1978) 364-378, 1978.
Inspire Record 120614 DOI 10.17182/hepdata.34955

The differential cross sections of the proton Compton scattering around the second resonance have been measured at a c.m. angle of 90° for incident photon energies between 450 MeV and 950 MeV in steps of 50 MeV, and at an angle of 60° for energies between 600 MeV and 800 MeV. The results show that the peak of the 2nd resonance agrees with that of the pion photoproduction process. We also calculated the proton Compton scattering based on unitarity and fixed- t dispersion relations. The calculation describes well the data of the cross section and the recoil proton polarization.

1 data table match query

No description provided.


Compton scattering by the proton through Theta(CMS) = 75-degrees and 90-degrees in the Delta resonance region

Hünger, A ; Peise, J ; Robbiano, A ; et al.
Nucl.Phys.A 620 (1997) 385-416, 1997.
Inspire Record 458618 DOI 10.17182/hepdata.36349

Differential cross sections for Compton scattering by the proton have been measured in the energy interval between 200 and 500 MeV at scattering angles of θ cms = 75° and θ cms = 90° using the CATS, the CATS/TRAJAN, and the COPP setups with the Glasgow Tagger at MAMI (Mainz). The data are compared with predictions from dispersion theory using photo-meson amplitudes from the recent VPI solution SM95. The experiment and the theoretical procedure are described in detail. It is found that the experiment and predictions are in agreement as far as the energy dependence of the differential cross sections in the Δ-range is concerned. However, there is evidence that a scaling down of the resonance part of the M 1+ 3 2 photo-meson amplitude by (2.8 ± 0.9)% is required in comparison with the VPI analysis. The deduced value of the M 1+ 3 2 - photoproduction amplitude at the resonance energy of 320 MeV is: |M 1+ 3 2 | = (39.6 ± 0.4) × 10 −3 m π + −1 .

1 data table match query

No description provided.


Structure of the Proton

Chambers, E.E. ; Hofstadter, R. ;
Phys.Rev. 103 (1956) 1454-1463, 1956.
Inspire Record 945003 DOI 10.17182/hepdata.26939

The structure and size of the proton have been studied by means of high-energy electron scattering. The elastic scattering of electrons from protons in polyethylene has been investigated at the following energies in the laboratory system: 200, 300, 400, 500, and 550 Mev. The range of laboratory angles examined has been 30° to 135°. At the largest angles and the highest energy, the cross section for scattering shows a deviation below that expected from a point proton by a factor of about nine. The magnitude and variation with angle of the deviations determine a structure factor for the proton, and thereby determine the size and shape of the charge and magnetic-moment distributions within the proton. An interpretation, consistent at all energies and angles and agreeing with earlier results from this laboratory, fixes the rms radius at (0.77±0.10) ×10−13 cm for each of the charge and moment distributions. The shape of the density function is not far from a Gaussian with rms radius 0.70×10−13 cm or an exponential with rms radius 0.80×10−13 cm. An equivalent interpretation of the experiments would ascribe the apparent size to a breakdown of the Coulomb law and the conventional theory of electromagnetism.

1 data table match query

In the experiment just relative cross sections were measured. The absolute values were ascribed at each energy after multiplying experimental data by a co nstant factor to obtain the best fit with theory assuming the diffuse proton model with charge and magnetic moment rms radii 0.08 fm.. The values in the table are extracted from the graphs (see figs. 6 - 9) byZOV.