اشترك بالحزمة الذهبية واحصل على وصول غير محدود شمرا أكاديميا
تسجيل مستخدم جديدComparative analysis of $omega p$, $phi p$, and $J/psi p$ scattering lengths from A2, CLAS, and GlueX threshold measurements
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The high accuracy $phi $-meson photoproduction data from the CLAS experiment in Hall~B of Jefferson Laboratory allow us to determine the near-threshold total cross section of the $gamma ptophi p$ reaction and use it for evaluating the $phi p$ scattering length $alpha_{phi p}$. These data result in an absolute value of $|alpha_{phi p}| = (0.063pm 0.010)$~fm, which is smaller than the typical hadron size. A comparative analysis of $alpha_{phi p}$ with the previously determined scattering lengths for $omega p$ and $J/psi p$ from the A2 and GlueX experiments is performed.
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The quality of the recent GlueX $J/psi $ photoproduction data from Hall~D at Jefferson Laboratory, and the proximity of the data to the energy threshold, gives access to a variety of interesting physics aspects. As an example, an estimation of the $J
/psi$-nucleon scattering length $alpha_{J/psi p}$ is provided within the vector meson dominance model. It results in $|alpha_{J/psi p}| = (3.08pm 0.55 ({rm stat.}) pm 0.45 ({rm syst.}))$~mfm.
84 -
Lubomir Pentchev (Thomas Jefferson National Accelerator Facility
, n Newport News
, Virginia
2020
The $J/psi$-$p$ scattering length, $alpha_{J/psi p}$, can be extracted from the $J/psi$ photoproduction cross section near threshold using the Vector Meson Dominance (VMD) model to relate the reaction $gamma p to J/psi p$ to $J/psi p to J/psi p$. Suc
h estimates based on experimental data result in values for $|alpha_{J/psi p}|$, which are much lower than most of the theoretical predictions. In this work, we study the relations between the different results, depending on the use of the total or the differential cross sections, and the method of extrapolating the data to threshold in the case of a low-statistics data sample, such as the near threshold $J/psi$ photoproduction dataset. We estimate a range for $|alpha_{J/psi p}|$ of $0.003$ to $0.025$~fm as extracted from experimental data within the VMD model and discuss possible reasons for such lower values compared to the theoretical results.
The observed enhancement of $pbar p$-production near the threshold in radiative decays of $J/psi$ and $e^+e^-$-annihilations can be explained with final state interactions among the produced $Nbar N$ system, where the enhancement is essentially deter
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