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arXiv 1206.6324nucl-thhep-exnucl-ex
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核的手征有效场论中光子和π介子的非相干中微子产生

Incoherent Neutrinoproduction of Photons and Pions in a Chiral Effective Field Theory for Nuclei

Xilin Zhang, Brian D. Serot

摘要:

研究了中微子能量E_v $\leqslant$为0.5 GeV的光子和π介子的非相干中微子产生.这些过程与中微子振荡实验中的背景分析有关,例如MiniBooNE [A. A. Aquilar-Arevalo \textit{et al.}(MiniBooNE协作),物理学评论快报。100,032301(2008)]。计算采用洛伦兹协变有效场论(EFT),该理论包含核子、π介子、Delta(1232)场($Δ$ s)、等差标量场($σ$)和矢量场($ω$)以及等差矢量场($ρ$),并具有SU(2)_{L} $\otimes$ SU(2)_{R}手征对称性非线性实现.在局域费米气体近似下研究了单体电流的贡献。当前的形状因子是由EFT拉格朗日量中的介子优势产生的。矢量流守恒和轴向流部分守恒自动满足,这对光子产生至关重要。作为研究的关键部分,探讨了核中的$Δ$动力学。引入$Δ$ -介子耦合解释了原子核中的$Δ$自旋-轨道(S-L)耦合,这导致了理论上有趣的限制。同时,一种唯象的方法被应用到参数化的$Δ$宽度。基准我们的近似,我们计算的微分截面的准弹性散射和非相干电生的π介子没有最终状态的相互作用(FSI)。对于光子产生,FSI可以被忽略。

英文摘要:

We study the incoherent neutrinoproduction of photons and pions with neutrino energy E_ν $\leqslant$ 0.5 GeV. These processes are relevant to the background analysis in neutrino-oscillation experiments, for example MiniBooNE [A. A. Aquilar-Arevalo \textit{et al.} (MiniBooNE Collaboration), Phys. Rev. Lett. 100, 032301(2008)]. The calculations are carried out using a Lorentz-covariant effective field theory (EFT) which contains nucleons, pions, the Delta (1232) ($Δ$ s), isoscalar scalar ($σ$) and vector ($ω$) fields, and isovector vector ($ρ$) fields, and has SU(2)_{L} $\otimes$ SU(2)_{R} chiral symmetry realized nonlinearly. The contributions of one-body currents are studied in the local fermi gas approximation. The current form factors are generated by meson dominance in the EFT Lagrangian. The conservation of the vector current and the partial conservation of the axial current are satisfied automatically, which is crucial for photon production. The $Δ$ dynamics in nuclei, as a key component in the study, are explored. Introduced $Δ$-meson couplings explain the $Δ$ spin-orbit (S-L) coupling in nuclei, and this leads to interesting constraints on the theory. Meanwhile a phenomenological approach is applied to parametrize the $Δ$ width. To benchmark our approximations, we calculate the differential cross sections for quasi-elastic scattering and incoherent electroproduction of pions without a final state interaction (FSI). The FSI can be ignored for photon production.

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