Tomalak Oleksandr, Chen Qing, Hill Richard J, McFarland Kevin S
Department of Physics and Astronomy, University of Kentucky, Lexington, KY, 40506, USA.
Theoretical Physics Department, Fermilab, Batavia, IL, 60510, USA.
Nat Commun. 2022 Sep 8;13(1):5286. doi: 10.1038/s41467-022-32974-x.
Neutrino oscillation experiments at accelerator energies aim to establish charge-parity violation in the neutrino sector by measuring the energy-dependent rate of ν appearance and ν disappearance in a ν beam. These experiments can precisely measure ν cross sections at near detectors, but ν cross sections are poorly constrained and require theoretical inputs. In particular, quantum electrodynamics radiative corrections are different for electrons and muons. These corrections are proportional to the small quantum electrodynamics coupling α ≈ 1/137; however, the large separation of scales between the neutrino energy and the proton mass (GeV), and the electron mass and soft-photon detection thresholds (MeV) introduces large logarithms in the perturbative expansion. The resulting flavor differences exceed the percent-level experimental precision and depend on nonperturbative hadronic structure. We establish a factorization theorem for exclusive charged-current (anti)neutrino scattering cross sections representing them as a product of two factors. The first factor is flavor universal; it depends on hadronic and nuclear structure and can be constrained by high-statistics ν data. The second factor is non-universal and contains logarithmic enhancements, but can be calculated exactly in perturbation theory. For charged-current elastic scattering, we demonstrate the cancellation of uncertainties in the predicted ratio of ν and ν cross sections. We point out the potential impact of non-collinear energetic photons and the distortion of the visible lepton spectra, and provide precise predictions for inclusive observables.
加速器能量下的中微子振荡实验旨在通过测量中微子束中与能量相关的ν出现率和ν消失率，来确定中微子领域的电荷宇称破坏。这些实验可以精确测量近探测器处的ν截面，但ν截面的约束较差，需要理论输入。特别是，量子电动力学辐射修正对于电子和μ子是不同的。这些修正与小的量子电动力学耦合α≈1/137成正比；然而，中微子能量与质子质量（GeV）以及电子质量与软光子探测阈值（MeV）之间的大尺度分离，在微扰展开中引入了大对数。由此产生的味差异超过了百分之一水平的实验精度，并且取决于非微扰强子结构。我们为排他性带电流（反）中微子散射截面建立了一个因子分解定理，将它们表示为两个因子的乘积。第一个因子是味普适的；它取决于强子和核结构，可以由高统计量的ν数据来约束。第二个因子是非普适的，包含对数增强，但可以在微扰理论中精确计算。对于带电流弹性散射，我们证明了预测的ν和ν截面比值中的不确定性的抵消。我们指出了非共线高能光子的潜在影响以及可见轻子谱的畸变，并为包容性可观测量提供了精确预测。
