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arXiv 1608.08205hep-ph
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在阈值附近计算了质子在$J/ψ$光生过程中前向$J/ψ$ -p散射振幅的实部

Accessing the real part of the forward $J/ψ$-p scattering amplitude from $J/ψ$ photo-production on protons around threshold

Oleksii Gryniuk, Marc Vanderhaeghen

发表信息：
Phys. Rev. D 94, 074001 (2016)
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摘要：

我们提供了一个更新的前向$J/ψ$ -p散射振幅的分析，将其虚部与$γp \to J/ψp$和$γp \to c \bar c X$截面数据相关联，并通过一次相减色散关系计算其实部。从微分和总截面数据的全局拟合中，我们提取了自旋平均$J/ψ$ -p s波散射长度$a_{ψp} = 0.046 \pm 0.005$ fm的值，该值可以转化为$B_ψ= 2.7 \pm 0.3$ MeV的核物质中的$J/ψ$结合能。我们估计了$γp \to e^- e^+ p$过程在$J/ψ$共振附近的前后不对称性，这是由于$J/ψ$产生和Bethe-Heitler机制之间的干涉中轻子的交换引起的.我们表明，良好的近似，这种不对称性线性依赖于$a_{ψp}$，并可以达到约-25%的值为即将到来的$J/ψ$阈值生产实验在杰斐逊实验室。因此，它的测量可以为$a_{ψp}$的精细提取提供非常灵敏的观察结果。

英文摘要：

We provide an updated analysis of the forward $J/ψ$-p scattering amplitude, relating its imaginary part to $γp \to J/ψp$ and $γp \to c \bar c X$ cross section data, and calculating its real part through a once-subtracted dispersion relation. From a global fit to both differential and total cross section data, we extract a value for the spin-averaged $J/ψ$-p s-wave scattering length $a_{ψp} = 0.046 \pm 0.005$ fm, which can be translated into a $J/ψ$ binding energy in nuclear matter of $B_ψ= 2.7 \pm 0.3$ MeV. We estimate the forward-backward asymmetry to the $γp \to e^- e^+ p$ process around the $J/ψ$ resonance, which results from interchanging the leptons in the interference between the $J/ψ$ production and the Bethe-Heitler mechanisms. We show that to good approximation this asymmetry depends linearly on $a_{ψp}$, and can reach values around -25% for forthcoming $J/ψ$ threshold production experiments at Jefferson Lab. Its measurement can thus provide a very sensitive observable for a refined extraction of $a_{ψp}$.

机构、总结、中文摘要均由AI分析而来，可能存在错误，请以论文正文为准。

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