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arXiv 0909.0186nucl-thhep-ph
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反质子-核电磁湮灭作为获取质子类时形状因子的一种方法

Antiproton-nucleus electromagnetic annihilation as a way to access the proton timelike form factors

H. Fonvieille, V. Karmanov

摘要:

与反应pbar + p -> e+ e-相反,在反应pbar + d-> n e + e-中,(e+ e-)对的不变质量M必然比(pbar p)质量大得多,在反应pbar + d -> n e+ e-中,M的值可以接近或低于(pbar p)质量。在反质子-氘核的电磁湮灭中,这使得我们能够在(pbar p)阈值附近的类时区域q ^2中获得质子电磁形状因子。我们估计了反质子束流动量为1.5GeV/c时的截面dsigma(pbar +d --> e+ e-n)/dM。我们发现,在(pbar p)阈值附近,这个截面约为1 pb/MeV。文中还讨论了重核靶的情况。实验可行性的元素的过程pbar + d --> n e+ e-在熊猫项目的背景下。

英文摘要:

Contrary to the reaction pbar + p --> e+ e- with a high momentum incident antiproton on a free target proton at rest, in which the invariant mass M of the (e+ e-) pair is necessarily much larger than the (pbar p) mass, in the reaction pbar + d --> n e+ e- the value of M can take values near or below the (pbar p) mass. In the antiproton-deuteron electromagnetic annihilation, this allows to access the proton electromagnetic form factors in the time-like region of q^2 near the (pbar p) threshold. We estimate the cross section dsigma(pbar +d --> e+ e- n)/dM for an antiproton beam momentum of 1.5 GeV/c. We find that near the (pbar p) threshold this cross section is about 1 pb/MeV. The case of heavy nuclei target is also discussed. Elements of experimental feasibility are presented for the process pbar + d --> n e+ e- in the context of the Panda project.

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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