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arXiv 1906.02185nucl-thnucl-ex
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${π^-}A$反应中近阈$η^\prime$介子的产生

Near-threshold $η^\prime$ meson production in ${π^-}A$ reactions

E. Ya. Paryev

备注：
12 pages. arXiv admin note: text overlap with arXiv:1806.00303
发表信息：
Nucl.Phys.A 988, 24 (2019)
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摘要：

本文在首次碰撞模型的基础上，考虑了$π^-$介子-质子碰撞中$η^\prime$产生的非相干过程，并基于核谱函数，研究了$π^-$介子-核反应中$η^\prime$介子的近阈产生.该模型考虑了初始$π^-$和最终$η^\prime$介子的吸收、核内质子的结合及其费米运动，以及标量$η^\prime$ -核势（或$η^\prime$介子质量的介质内位移）对这些过程的影响。本文计算了动量为1.7 GeV/c的PDMATHAMN介子在实验室角为0 - 10 $^{\circ}$和10 - 45 $^{\circ}$时从碳核和钨核产生$η^\prime$的微分截面和总截面，该动量接近于自由靶质子产生$η^\prime$的阈动量.我们表明，计算的$η^\prime$生产截面大于那些，研究较早的$η^\prime$光生反应，约两个数量级。我们还表明，目前的微分和总$η^\prime$生产截面的高绝对值在0.2--0.3 GeV/c和0.1--0.6 GeV/c的动量范围内，分别具有高灵敏度的变化，在介质中移动的$η^\prime$质量。这提供了从各自的数据中评估这些动量处的上述偏移的可能性，这些数据可以在GSI π介子束设施或J-PARC的未来实验中进行。

英文摘要：

We study the inclusive near-threshold production of $η^\prime$ mesons in $π^-$ meson-nucleus reactions on the basis of the first-collision model relying on the nuclear spectral function and including incoherent processes of $η^\prime$ production in $π^-$ meson--proton collisions. The model accounts for the absorption of initial $π^-$ and final $η^\prime$ mesons, the binding of intranuclear protons and their Fermi motion, as well as the effect of the scalar $η^\prime$--nucleus potential (or the in-medium shift of the $η^\prime$ meson mass) on these processes. We calculate the differential and total cross sections for $η^\prime$ production off carbon and tungsten nuclei at laboratory angles of 0$^{\circ}$--10$^{\circ}$ and 10$^{\circ}$--45$^{\circ}$ by $π^-$ mesons with momentum of 1.7 GeV/c, which is close to the threshold momentum for $η^\prime$ creation on a free target proton at rest. We show that the calculated $η^\prime$ production cross sections are larger than those, studied earlier in the $η^\prime$ photoproduction reactions, by about two orders of magnitude. We also demonstrate that the high absolute values of the present differential and total $η^\prime$ production cross sections in the momentum ranges of 0.2--0.3 GeV/c and 0.1--0.6 GeV/c, respectively, possess a high sensitivity to changes in the in-medium shift of the $η^\prime$ mass. This offers the possibility of evaluating the above shift at these momenta from the respective data, which could be taken in future experiments at the GSI pion beam facility or at J-PARC.

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