论文标题
冷中子 - deuteron捕获和wigner-su（4）对称性
Cold Neutron-Deuteron Capture and Wigner-SU(4) Symmetry
论文作者
论文摘要
我们使用Pionless无效的野外理论（EFT（$π\！\！\！\！\！\！\！\！/$），我们将冷中子 - deuteron（$ nd $）捕获横截面，$σ_{nd} $，到近代转到领先顺序（NNLO））。在领先顺序下，我们发现$σ_{nd} = 0.315 \ pm 0.217 $ MB，而实验结果为0.508（15）MB [jurney，bendt and Browne in Phys中。 Rev. C 25，2810（1982）]的实验室中子速度为2200 m/s。在近代阶（NLO）上，我们表明$σ_{nd} $对低能常数（LEC），$ l_1^{（0）} $，$ l_1^{（0）} $，是NLO上出现的两个Nucleon Isovector电流。 NLO的$ L_1^{（0）} $的拟合度适合Triton磁矩，得出$σ_{nd} = 0.393 \ pm 0.164 $ MB的NLO预测，其中错误来自从$ L_1^{（0）} $ FIT中传播错误的错误。在近代到领导级（NNLO）时，我们发现$σ_{nd} $和Triton磁矩的重新归一化组不变性需要新的三核电磁力计数器。将nnlo校正安装到$ l_1^{（0）} $（表示$ l_1^{（1）} $）与冷的中子 - 普罗顿捕获（$σ_{np} $）产生的NNLO预测的$σ_{nd} = 0.447 \ pm 0.447 \ pm 0.130 $ mb，来自Prop的错误，来自ProP的错误。 $ l_1^{（1）} $ fit。我们还研究$ L_1^{（0）} $的不同配件和$ L_1^{（1）} $至$σ_{np} $，$σ_{nd} $和/或Triton Mongrment。例如，将$ l_1^{（0）} $同时拟合到$σ_{np} $，$σ_{nd} $，以及nlo的triton磁矩，并拟合$ l_1^{（1）$ $σ_{nd} = 0.480 \ pm 0.114 $ MB和$ 0.511 \ pm 0.042 $ mb，其中从EFT（$π\！\！\！\！/$）功率计数的eft估计错误。此外，我们讨论了wigner-su（4）对称如何改变$σ_{nd} $的幼稚eft（$π\！\！\！\！/$）。
We calculate the cold neutron-deuteron ($nd$) capture cross section, $σ_{nd}$, to next-to-next-to leading order (NNLO) using the model-independent approach of pionless effective field theory (EFT($π\!\!\!/$)). At leading order we find $σ_{nd} = 0.315 \pm 0.217$ mb, while the experimental result is 0.508(15) mb [Jurney, Bendt and Browne in Phys. Rev. C 25, 2810 (1982)] for a laboratory neutron velocity of 2200 m/s. At next-to-leading-order (NLO), we show that $σ_{nd}$ is sensitive to the low energy constant (LEC), $L_1^{(0)}$, of the two-nucleon isovector current appearing at NLO. A fit of $L_1^{(0)}$ at NLO to the triton magnetic moment yields a NLO prediction of $σ_{nd}=0.393 \pm 0.164$ mb, where the error comes from propagating the error from the $L_1^{(0)}$ fit. At next-to-next-to-leading-order (NNLO), we find that a new three-nucleon magnetic moment counterterm is required for renormalization group invariance of both $σ_{nd}$ and the triton magnetic moment. Fitting the NNLO correction to $L_1^{(0)}$ (denoted $L_1^{(1)}$) to cold neutron-proton capture ($σ_{np}$) yields a NNLO prediction of $σ_{nd}=0.447 \pm 0.130$ mb, where the error comes from propagating the error from the $L_1^{(1)}$ fit. We also study different fittings of $L_1^{(0)}$ and $L_1^{(1)}$ to $σ_{np}$, $σ_{nd}$, and/or the triton magnetic moment. For example, fitting $L_1^{(0)}$ simultaneously to $σ_{np}$, $σ_{nd}$, and the triton magnetic moment at NLO, and fitting $L_1^{(1)}$ simultaneously to $σ_{np}$ and $σ_{nd}$ at NNLO, yields $σ_{nd} = 0.480 \pm 0.114$ mb and $0.511 \pm 0.042$ mb, respectively, where errors are naively estimated from EFT($π\!\!\!/$) power counting. In addition, we discuss how Wigner-SU(4) symmetry may alter the naive EFT($π\!\!\!/$) expansion of $σ_{nd}$.
