发表机构
Indian Institute of Technology Guwahati; Indian Institute of Technology Goa; Indian Institute of Technology (BHU)（印度理工学院古瓦哈提分校; 印度理工学院果阿分校; 印度理工学院（贝拿勒斯印度教大学））
机构由 AI 辅助整理，请以论文原文为准。AI 中文总结
本研究提出辐射狄拉克中微子质量框架，自然产生非对角耦合的非弹性暗物质，解释LZ实验异常事件，同时满足遗迹丰度、中微子质量及直接探测约束。
AI 中文摘要
LUX-ZEPLIN（LZ）实验报告了一个高能核反冲候选事件LZ230616，其反冲能量为$E_R = 248 \pm 23_{\rm stat} \pm 23_{\rm sys}\\,$keV，该事件难以用晕暗物质（DM）的弹性散射来解释。吸热非弹性散射提供了一种自然的解释，但它依赖于非对角而非对角的核子耦合。我们表明，这一特征在辐射狄拉克中微子质量框架内自动产生。标准模型通过三个右手中微子（RHN）、每代一对类矢量中性费米子以及包含一个惰性二重态和一个实单态、受$\mathcal{Z}_2 \times \mathcal{Z}_4$对称性支配的标量扇区进行扩展。$\mathcal{Z}_2$对称性稳定了暗物质，而$\mathcal{Z}_4$对称性禁止了树级狄拉克汤川耦合以及所有可重整的马约拉纳质量项，从而允许通过软破缺的标量三重线性耦合`$\kappa$'在单圈水平上产生狄拉克中微子质量。由于中性暗扇区场可以用实标量质量本征态表示，$Z$玻色子与它们的耦合纯粹是非对角的，弹性$Z$介导散射完全消失，而不仅仅是受到抑制。由`$\kappa$'诱导的单态-二重态混合同时控制非弹性速率和单圈狄拉克中微子质量，因此当$\kappa \to 0$时它们都消失。我们发现，质量在几百GeV到TeV范围、劈裂为$\mathcal{O}(340-360)\\,$keV的暗物质，能同时重现观测到的遗迹丰度、解释LZ事件并产生正确量级的中微子质量，同时满足弹性直接探测极限以及所有相关的理论和实验约束。存活的参数空间中很大一部分在DARWIN的探测范围内。
英文摘要
The LUX-ZEPLIN (LZ) experiment has reported a high-energy nuclear recoil candidate, LZ230616, at $E_R = 248 \pm 23_{\rm stat} \pm 23_{\rm sys}\,$keV, which is difficult to reconcile with elastic scattering of halo dark matter (DM). Endothermic inelastic scattering offers a natural explanation, but it rests on a nucleon coupling that is off-diagonal rather than diagonal. We show that this feature arises automatically within a radiative Dirac neutrino mass framework. The Standard Model is extended by three right-handed neutrinos (RHNs), a pair of vector-like neutral fermions for each generations, and a scalar sector comprising an inert doublet and a real singlet, governed by a $\mathcal{Z}_2 \times \mathcal{Z}_4$ symmetry. The $\mathcal{Z}_2$ symmetry stabilizes the DM, while the $\mathcal{Z}_4$ symmetry forbids the tree-level Dirac Yukawa coupling together with all renormalizable Majorana mass terms, thereby allowing the generation of Dirac neutrino masses at the one-loop level through a softly broken scalar trilinear coupling `$κ$'. Since the neutral dark-sector fields can be expressed in terms of real scalar mass eigenstates, the $Z$ boson couples to them purely off-diagonally and elastic $Z$-mediated scattering is absent identically rather than simply suppressed. The singlet--doublet mixing induced by `$κ$' governs both the inelastic rate and the one-loop Dirac neutrino mass, which therefore vanish as $κ\to 0$. We find that DM masses in the few hundred GeV to TeV range, with splittings of $\mathcal{O}(340-360)\,$ keV, simultaneously reproduce the observed relic abundance, account for the LZ event and yield neutrino masses of the correct order, while respecting elastic direct-detection limits and all relevant theoretical and experimental constraints. A substantial part of the surviving parameter space lies within reach of DARWIN.
Comments8+3 pages, 6 captioned figures, 2 tables, references added
