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arXiv 0806.4835nucl-thhep-ph
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3 He上光生和电生超夸克

Photo- and Electroproduction of the Hypertriton on 3He

T. Mart, B. I. S. van der Ventel

摘要:

利用现代核波函数和KAON-MAID的初等算符计算了超曲子的光生和电生微分截面。研究发现,正确处理费米运动对于这两个过程至关重要。虽然平均动量近似可以部分模拟费米运动的过程中,“冻结核子”的假设产生非常不同的结果,特别是在较低的能量。由正电荷K介子与超激子相互作用引起的库仑效应可以忽略。较高的分波的影响也被发现是相对较小的,在以前的工作的发现相反。离壳假设被认为是非常敏感的情况下,而不是在光生电。结果表明,现有的实验数据较少,支持初始核子离壳、末态超子在壳的假设。这似乎是合理的,因为在超曲子中的超子比在初始的3 He核中的核子受束缚更少。丢失共振D_{13}(1895)的影响在纵向截面中更为深刻。排除这种共振会使纵向截面减小一个数量级,但不会改变各种离壳假设对截面的影响。

英文摘要:

Differential cross sections of the photo- and electroproduction of the hypertriton have been calculated by utilizing modern nuclear wave functions and the elementary operator of KAON-MAID. It is found that a proper treatment of Fermi motion is essential for the two processes. While the average momentum approximation can partly simulate the Fermi motion in the process, the ``frozen nucleon'' assumption yields very different results, especially at lower energies. The Coulomb effect induced by the interaction between the positively charged kaon and the hypertriton is found to be negligible. The influence of higher partial waves is also found to be relatively small, in contrast to the finding of the previous work. The off-shell assumption is found to be very sensitive in the case of electroproduction rather than in photoproduction. It is shown that the few available experimental data favor the assumption that the initial nucleon is off-shell and the final hyperon is on-shell. This seems to be reasonable, since the hyperon in the hypertriton is less bound than the nucleon in the initial 3He nucleus. The effect of the missing resonance D_{13}(1895) is more profound in the longitudinal cross sections. Excluding this resonance reduces the longitudinal cross sections by one order of magnitude, but does not change the effects of various off-shell assumptions on the cross sections.

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