Измерено сечение упругого рассеяния фотонов на if-ме- зонах в области S, = (6,5 ± 0,5)1? и &™ = 13(Р ± 3(Р. Из подученных экспериментальных данных определена поляризу емость п-мезона а^+ = (20 ± 12)- Iff*3 см 3
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Axis error includes +- 0.0/0.0 contribution (?////UNCERTAINTY IN DATA PROCESSING).
Axis error includes +- 0.0/0.0 contribution (?////UNCERTAINTY IN DATA PROCESSING).
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SIG OBTAINED FROM INTEGRATION OF D(SIG)/D(T).
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Axis error includes +- 5/5 contribution (UNCERTAINTY IN RATED EFFICIENCY).
Axis error includes +- 5/5 contribution (UNCERTAINTY IN RATED EFFICIENCY).
No description provided.
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Axis error includes +- 1/1 contribution.
Axis error includes +- 1/1 contribution.
None
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The angular distribution of 24 7 ± 10 Mev gamma rays produced in the synchrotron of the Lebedev Physics Institute, which were scattered elastically on hydrogen, has been investigated. Differential cross sections were obtained for c.m. scattering angles of 148, 132, 108, 93, 70, and 55°. The experimental results are compared with calculations based on onedimensional dispersion relations with an additional contribution from a single-meson intermediate state taken into account.
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The values of the differential cross sections for the Compton effect on the proton are given for $\gamma$-quantum energies from ~230 to ~250 MeV. These values of the cross sections are the result of a more accurate analysis and of making absolute the experimental data obtained by us earlier.
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The first measurement of diffractive scattering of quasi-real photons with large momentum transfer gamma p -> gamma Y, where Y is the proton dissociative system, is made using the H1 detector at HERA. The measurement is performed for initial photon virtualities Q^2 < 0.01 GeV^2. Cross sections are measured as a function of W, the incident photon-proton entre of mass energy, and t, the square of the four-momentum transferred at the proton vertex, in the range 175 < W < 247 GeV and 4<|t|<36 GeV^2. The W dependence is well described by a model based on perturbative QCD using a leading logarithmic approximation of the BFKL evolution. The measured |t| dependence is harder than that predicted by the model and those observed in exclusive vector meson production.
Cross section for the process E+ P --> E+ GAMMA DD as a function of W.
Cross section for the process GAMMA P --> GAMMA DD as a function of W.
Cross section for the process E+ P --> E+ GAMMA DD as a function of T.
A measurement of elastic deeply virtual Compton scattering gamma* p -> gamma p using e-p collision data recorded with the H1 detector at HERA is presented. The analysed data sample corresponds to an integrated luminosity of 145 pb^-1. The cross section is measured as a function of the virtuality Q^2 of the exchanged photon and the centre-of-mass energy W of the gamma*p system in the kinematic domain 6.5 < Q^2 < 80 GeV^2, 30 < W < 140 GeV and |t| < 1 GeV^2, where t denotes the squared momentum transfer at the proton vertex. The cross section is determined differentially in t for different Q^2 and W values and exponential t-slope parameters are derived. The measurements are compared to a NLO QCD calculation based on generalised parton distributions. In the context of the dipole approach, the geometric scaling property of the DVCS cross section is studied for different values of t.
The DVCS cross section as a function of Q**2 for W = 82 GeV.
The DVCS cross section as a function of W for Q**2 = 8 GeV**2.
The DVCS cross section as a function of W for 3 Q**2 values.
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