Two-pion exchange as a leading-order contribution in chiral effective field theory
Two-pion exchange as a leading-order contribution in chiral effective field theory
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DOI：
10.1103/physrevc.106.024004
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发表时间：
2021-11
影响因子：
3.1
通讯作者：
Chinmayee Mishra;A. Ekström;G. Hagen;T. Papenbrock;L. Platter
中科院分区：
文献类型：
--
作者：
Chinmayee Mishra;A. Ekström;G. Hagen;T. Papenbrock;L. Platter
π介子交换是核结构计算中核子-核子相互作用的重要组成部分，而在手征有效场理论中，单π介子交换（OPE）处于主导地位。在2S +1 LJ = 1 S 0分波中，OPE和适当重整化所需的接触项不能产生散射相移的定性和定量特征. Cuto的变化也揭示了一个令人惊讶的低击穿动量Λ B <$330 MeV在这个分波。在这里，我们表明，潜在的OPE，两个π交换（TPE），和一个单一的接触解决这些问题，并产生准确的和重整化群（RG）不变的相移在1 S 0分波。我们证明了一个领先的顺序潜在的TPE可以系统地改善通过添加一个接触二次动量。对于动量截止值Λ（cid：46）500 MeV，从TPE回路中去除相关物理需要通过额外的接触来补偿，以保持RG不变性。势中包含等压线自由度并不改变TPE的强贡献。
Pion exchange is the central ingredient to nucleon-nucleon interactions used in nuclear structure calculations, and one pion exchange (OPE) enters at leading order in chiral effective field theory. In the 2 S +1 L J = 1 S 0 partial wave, however, OPE and a contact term needed for proper renormalization fail to produce the qualitative, and quantitative, features of the scattering phase shifts. Cutoff variation also revealed a surprisingly low breakdown momentum Λ b ≈ 330 MeV in this partial wave. Here we show that potentials consisting of OPE, two pion exchange (TPE), and a single contact address these problems and yield accurate and renormalization group (RG) invariant phase shifts in the 1 S 0 partial wave. We demonstrate that a leading-order potential with TPE can be systematically improved by adding a contact quadratic in momenta. For momentum cutoffs Λ (cid:46) 500 MeV, the removal of relevant physics from TPE loops needs to be compensated by additional contacts to keep RG invariance. Inclusion of the ∆ isobar degree of freedom in the potential does not change the strong contributions of TPE.