探测μ子衰变中的嗜中微子标量粒子
Probing Neutrinophilic Scalars in Muon Decays
- School of Physics, Southeast University（东南大学物理学院）
- Center for High Energy Physics, Peking University（北京大学高能物理中心）
机构由 AI 辅助整理，请以论文原文为准。
AI总结：
本文研究嗜中微子标量粒子对μ子衰变的影响，通过树图和环图修正及四体衰变过程，利用精确的费米常数测量约束其耦合和质量，发现对质量大于GeV量级的标量粒子，现有约束比天体物理和宇宙学限制更严格。
AI中文摘要：
中微子的非标准自相互作用可能由主要耦合到中微子的（轻）标量粒子诱导。在这项工作中，我们研究了嗜中微子标量粒子$\phi$在树图、1环和2环水平上对μ子衰变的影响，同时考虑了狄拉克中微子和马约拉纳中微子两种情况。最具现象学意义的过程是$\phi$对标准模型μ子衰变的1环修正以及四体μ子衰变$\mu^- \to e^- \nu_\mu \nu_\mu \phi,\\, e^- \bar\nu_e \bar\nu_e \phi$，两者均由$\phi$与马约拉纳中微子的耦合$h_{e\mu}$诱导。这些过程中的红外发散相互抵消，产生一个红外安全的包含性衰变宽度。精确的$G_F$测量将耦合$|h_{e\mu}|$约束到大约$0.027$以下，标量质量$m_\phi$被约束到大约$5.9$ TeV以下。对于$m_\phi \gtrsim {\cal O}({\rm GeV})$，$G_F$测量比其他现有的实验室、天体物理和宇宙学约束更为严格。其他一些由$\phi$诱导的过程也是可能的，然而，这些过程被小耦合、微小中微子质量和/或环因子严重抑制。
英文摘要：
The non-standard self-interactions of neutrinos could be induced by (light) scalars that couple primarily to neutrinos. In this work, we investigate the effects of neutrinophilic scalars $ϕ$ on muon decays at the tree, 1-loop and 2-loop levels, considering both Dirac and Majorana neutrinos. The most phenomenologically interesting processes are the 1-loop decay $μ\to e ϕϕ$ and $ϕ$-induced decay $μ\to e γ$ at the 2-loop order from the same coupling $g_{\rm eff}$, and the 1-loop corrections of $ϕ$ to the SM muon decay and the four-body muon decays $μ^- \to e^- ν_μν_μϕ,\, e^- \barν_e \barν_e ϕ$, both induced by the coupling $h_{eμ}$ of $ϕ$ to Majorana neutrinos. The current experimental bounds on $μ\to e γ$ provide the most stringent limits on the coupling $g_{\rm eff}$, up to roughly 0.064, for the scalar mass $m_ϕ\gtrsim 8.7$ MeV. The precise $G_F$ measurements constrain the coupling $|h_{eμ}|$ down to roughly $0.027$, with the scalar mass $m_ϕ$ constrained up to roughly $5.9$ TeV. For $m_ϕ\gtrsim {\cal O}({\rm GeV})$, the $G_F$ measurements are more stringent than other existing laboratory, astrophysical and cosmological constraints. Some other $ϕ$-induced processes are also possible, which are, however, heavily suppressed by the tiny neutrino masses and/or the loop factor.
