论文标题
最小模型的最大轴法未对准
Maximal axion misalignment from a minimal model
论文作者
论文摘要
QCD Axion是最有动机的暗物质候选者之一。众所周知，未对准的机制可产生与暗物质一致的QCD轴，对于轴衰变常数$ 10^{12} $ GEV。对于较小的衰减常数，QCD轴，在通货膨胀期间，peccei-quinn对称性断裂，只有一小部分暗物质，除非在称为“大型 - 分离”的情况下，除非轴支场开始振荡非常接近其潜力的顶部。在这种情况下，具有小轴衰变常数的QCD轴暗物质部分由非常致密的结构组成。我们提出了一个简单的动力学模型，以实现大型 - 分离机制。在通货膨胀期间，斧头经典地降低其潜力，接近最小值。通货膨胀后，宇宙将高温和模量（实际标量场）的最小迹象动态变化，这改变了在QCD下带电的矢量样费米子的质量的符号。结果，通货膨胀期间的轴法电势的最小值成为宇宙通过QCD相变冷的电势的最大值，并且轴支开始振荡。在此模型中，我们可以产生QCD轴暗物质，其衰减常数低至$ 6 \ times 10^9 \，{\ rm gev} $，以及最高1 MeV的轴质量。我们还总结了这种机制对暗物质实验和山脉的现象学意义。
The QCD axion is one of the best motivated dark matter candidates. The misalignment mechanism is well known to produce an abundance of the QCD axion consistent with dark matter for an axion decay constant of order $10^{12}$ GeV. For a smaller decay constant, the QCD axion, with Peccei-Quinn symmetry broken during inflation, makes up only a fraction of dark matter unless the axion field starts oscillating very close to the top of its potential, in a scenario called "large-misalignment". In this scenario, QCD axion dark matter with a small axion decay constant is partially comprised of very dense structures. We present a simple dynamical model realising the large-misalignment mechanism. During inflation, the axion classically rolls down its potential approaching its minimum. After inflation, the Universe reheats to a high temperature and a modulus (real scalar field) changes the sign of its minimum dynamically, which changes the sign of the mass of a vector-like fermion charged under QCD. As a result, the minimum of the axion potential during inflation becomes the maximum of the potential after the Universe has cooled through the QCD phase transition and the axion starts oscillating. In this model, we can produce QCD axion dark matter with a decay constant as low as $6\times 10^9\,{\rm GeV}$ and an axion mass up to 1 meV. We also summarise the phenomenological implications of this mechanism for dark matter experiments and colliders.
