基于真实核子-核子相互作用研究氘核的高动量和高激发性质
High-momentum and High-excitation Properties of the Deuteron with Realistic Nucleon-nucleon Interactions
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摘要: 在原子核第一性原理计算中,为提高计算的收敛性,核子-核子相互作用需要通过重整化做软化处理。尽管重整化之后原子核的低能性质几乎保持不变,但是软化后的核力还没有被用于定量研究原子核的高动量和高激发性质,以判断其可能失效的范围。在本工作中,以最简单的氘核为例,利用真实核力研究其高动量和高激发性质。具体来说,利用N3LO手征核力以及基于此软化后的两组核力N3LO-SRG和Daejeon16研究氘核的核子动量分布以及光核反应截面。发现,与手征核力相比,利用两组软核力得到的氘核的核子动量分布在200 MeV以上被显著压低。利用三组核力计算得到的氘核光核反应截面与实验数据基本一致。由于重整化的缘故,N3LO-SRG的结果在15 MeV以上与实验数据略有偏离。在峰值以上,由于等相位变换的原因,Daejeon16的计算结果较N3LO-SRG计算结果偏离实验数据更为显著。Abstract: In nuclear ab initio calculations, nucleon-nucleon interactions are softened via renormalization in order to improve the convergence of calculations. The high-momentum and high-excitation properties of nuclei are not well investigated quantitatively with softened interactions to identify where they may lose predictive power though the low energy observables remain nearly unchanged after the renormalization. In this work, we study nuclear high-momentum properties and high-excitation properties with realistic interactions taking the simplest nucleus, i.e., deuteron, as an example. In particular, we study the nucleon momentum distribution and photoabsorption cross section with a chiral effective field theory interaction at N3LO and two softened interactions based on it, i.e., N3LO-SRG and Daejeon16 interactions. We find that the nucleon momentum distributions of the deuteron calculated with these two soft interactions are significantly suppressed at momenta above 200 MeV in comparison to those calculated with the N3LO chiral interaction. The photoabsorption cross sections of the deuteron calculated with these three interactions are overall in agreement with the experimental data. The N3LO-SRG results deviate slightly from the experimental data above about 15 MeV due to the renormalization process. The Daejeon16 results deviate more apparently from the experimental data above the peak value compared to the N3LO-SRG results due to the phase equivalent transformations.
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