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تسجيل مستخدم جديدPhotoproduction of the $omega$ meson off the proton near threshold
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An experimental study of $omega$ photoproduction on the proton was conducted by using the Crystal Ball and TAPS multiphoton spectrometers together with the photon tagging facility at the Mainz Microtron MAMI. The $gamma ptoomega p$ differential cross sections are measured from threshold to the incident-photon energy $E_gamma=1.40$ GeV ($W=1.87$ GeV for the center-of-mass energy) with 15-MeV binning in $E_gamma$ and full production-angle coverage. The quality of the present data near threshold gives access to a variety of interesting physics aspects. As an example, an estimation of the $omega N$ scattering length $alpha_{omega p}$ is provided.
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Photoproduction of the $omega$ meson on the proton has been experimentally studied near the threshold. The total cross sections are determined at incident energies ranging from 1.09 to 1.15 GeV. The 1/2 and 3/2 spin-averaged scattering length $a_{ome
ga p}$ and effective range $r_{omega p}$ between the $omega$ meson and proton are estimated from the shape of the total cross section as a function of the incident photon energy: $a_{omega p} = left(-0.97^{+0.16_{rm stat}}_{-0.16_{rm stat}}{}^{+0.03_{rm syst}}_{-0.00_{rm syst}}right)+i left(0.07^{+0.15_{rm stat}}_{-0.14_{rm stat}}{}^{+0.17_{rm syst}}_{-0.09_{rm syst}}right)$ fm and $r_{omega p}=left(+2.78^{+0.68_{rm stat}}_{-0.54_{rm stat}}{}^{+0.11_{rm syst}}_{-0.13_{rm syst}}right)+ileft(-0.01^{+0.46_{rm stat}}_{-0.50_{rm stat}}{}^{+0.07_{rm syst}}_{-0.00_{rm syst}}right)$ fm, resulting in a repulsive force. The real and imaginary parts for $a_{omega p}$ and $r_{omega p}$ are determined separately for the first time. A small $P$-wave contribution does not affect the obtained values.
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