We explore the possibility that a super-light candidate for fuzzy (or wave) Dark Matter (fDM) may be a new composite boson state of fermions, rather than an axion-like Bose-Einstein condensate. We start from string-inspired massless Majorana fermions χ thought as super-modulini fields from string compactifications. We show that massless (or nearly massless) fermions can form a Bose-Einstein condensate and they can acquire a tiny mass term from quantum-gravitational non-perturbative effects such as gravitational instantons. For having a successful candidate for fDM, the so generated Majorana mass is ##IMG## [http://ej.iop.org/images/0295-5075/131/3/30006/epl20243ieqn1.gif] {$m_{\psi}\leq 10^{-22}\ \text{eV}$} , or so; otherwise decoherence would suppress quantum-mechanical effects in the macroscopic limit. Gravity is democratically coupled with every standard model particles; any neutral fermions acquire a Majorana mass equal to ##IMG##

中文翻译：

---

引力瞬间的模糊暗物质和马约拉纳中子质量

我们探索了模糊（或波动）暗物质（fDM）的超轻候选物可能是费米子的新的玻色子复合态的可能性，而不是像斧头般的玻色-爱因斯坦凝聚物。我们从受弦启发的无质量马约拉那费米子χ开始，它们被认为是来自弦压实的超模数场。我们表明，无质量（或几乎无质量）的费米子可以形成玻色-爱因斯坦凝聚体，并且它们可以从量子引力的非微扰效应（例如引力瞬时子）中获得很小的质量项。对于成功的fDM候选人来说，如此产生的Majorana质量为## IMG ## [http://ej.iop.org/images/0295-5075/131/3/30006/epl20243ieqn1.gif] {$ m_ { \ psi} \ leq 10 ^ {-22} \ \ text {eV} $}左右；否则，退相干将在宏观范围内抑制量子力学效应。重力与每个标准模型粒子民主地结合在一起。任何中性费米子都会获得等于## IMG ##的马约拉纳质量