10 pages, 1 figure; Corrected errors in Eq.(7) and in the direct detection cross-section of the Higgsino-like dark matter; Revised Fig.1; Added a discussion on the saxion; Added references; to appear in PRD
Kim-Nilles机制将$μ$项与轴子尺度$f_a$联系起来，导致$μ/f_a$级的轴-希格斯-汤川耦合。这可能会带来危险的热产生axinos。如果轴子是稳定的，它的质量必须小到${\cal O}$（0.1 keV），或者再热温度应该低于${\cal O}$（10 GeV），取较低的轴子尺度$10^{10}$ GeV，这样才不会使宇宙过于接近。如果轴子衰变为中性伴子，如果湮灭率为$10^{11}$ GeV以上的$10^{-8}{GeV}^{-2}$量级，则过度产生的中性伴子可以适当地重新湮灭，使观测到的暗物质密度饱和。因此，具有相当大的比诺混合物的最轻的类希格斯诺超对称粒子成为一个很好的暗物质候选者，其核子截面为$10^{-45}$ cm $^2$。
英文摘要：
The Kim-Nilles mechanism relates the $μ$ term with the axion scale $f_a$, leading to the axino-Higgsino-Higgs Yukawa coupling of order $μ/f_a$. This can bring a dangerous thermal production of axinos. If the axino is stable, its mass has to be as small as ${\cal O}$(0.1keV), or the reheat temperature should be lower than ${\cal O}$(10GeV) taking the lower axion scale $10^{10}$ GeV in order not to overclose the Universe. If the axino decays to a neutralino, the overproduced neutralinos can re-annihilate appropriately to saturate the observed dark matter density if the annihilation rate is of order $10^{-8}{GeV}^{-2}$ for the axion scale larger than about $10^{11}$ GeV. Thus, a light Higgsino-like lightest supersymmetric particle with a sizable bino mixture becomes a good dark matter candidate whose nucleonic cross-section is of order $10^{-45}$cm$^2$.
Gamma-ray production in the cosmic-ray -- dark matter scattering as a probe of the axion-like particle -- proton interaction
Federal University of Pelotas（佩洛塔斯联邦大学）；CEA Saclay, Université Paris-Saclay（巴黎萨克雷大学塞莱-萨克莱法国原子能和替代能源委员会研究中心）；Universidade de São Paulo, Instituto de Física de São Carlos（圣保罗大学圣卡洛斯物理研究所）
