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arXiv 0704.3793nucl-th
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热中子能区中子-氘核系统与光子极化参数

Neutron-Deuteron System and Photon Polarization Parameter at Thermal Neutron Energies

H. Sadeghi

摘要:

有效场论(EFT)是唯一的、与模型无关的、系统化的低能量子色动力学,适用于动量小于π介子质量的过程。利用无π介子EFT方法计算了热中子能区的光子极化参数,该参数可在三体系统中观测到,并可达到次-次首阶(N $^2$ LO)。为了对该模型进行比较研究,我们将我们的结果与实际的Argonne $v_{18}$双核子相互作用和Urbana IX或Tucson-Melbourne三核子相互作用进行了比较.三体流对热中子能量下中子-氘核辐射俘获截面中的一些可观测值做出了虽小但重要的贡献。在这种形式中,三核子力需要达到N $^2$ LO才能得到截止无关的结果。我们的结果在低能展开下逐阶收敛,并且在此阶下与截止无关。

英文摘要:

Effective Field Theory(EFT) is, the unique, model independent and systematic low-energy version of QCD for processes involving momenta below the pion mass. A low-energy photo-nuclear observable in three-body systems, photon polarization parameter at thermal neutron energies is calculated by using pionless EFT up to next-to-next to leading order(N$^2$LO). In order to make a comparative study of this model, we compared our results for photon polarization parameter with the realistic Argonne $v_{18}$ two-nucleon and Urbana IX or Tucson-Melbourne three-nucleon interactions. Three-body currents give small but significant contributions to some of the observables in the neutron-deuteron radiative capture cross section at thermal neutron energies. In this formalism the three-nucleon forces are needed up to N$^2$LO for cut-off independent results. Our result converges order by order in low energy expansion and also cut-off independent at this order.

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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