arXiv 1608.062232016-08-22hep-thastro-ph.COhep-ph

耗散轴向膨胀

Dissipative Axial Inflation

Alessio Notari, Konrad Tywoniuk

备注：: 22 pages, 27 figures
DOI：: 10.1088/1475-7516/2016/12/038

摘要：

我们详细分析了标量场通过轴向项$\fracϕ{f_γ} F \tilde{F}$耦合到无质量阿贝尔规范场的背景宇宙学演化，例如在轴子的情况下。在这种情况下，已知规范场会经历快子增长，因此可以在背景上作为辐射能量密度$ρ_R$的有效耗散进行反作用，这可以导致暴胀而不需要平坦的电势。我们分析了系统，动量$k$小于截止$f_γ$，包括数值上的反反应。我们考虑从一个给定的静态初始条件的演变，并明确表明，如果$f_γ$是小于场偏移$ϕ_0$的约一个因素，至少${\cal O} (20)$，有一个摩擦效应，打开之前，该领域可以下降，然后可以导致一个非常长的阶段的通货膨胀与通用的潜力。此外，我们发现叠加振荡，这将得到印在任何类型的扰动，标量和张量。这种振荡的周期为4-5倍，振幅通常小于百分之几，并随$f_γ$线性减小。我们还强调，均匀密度上的共动曲率扰动应该是敏感的慢滚参数有关的$ρ_R$，而不是$\dotϕ^2/2$，虽然我们推迟了计算的功率谱和非高斯到未来的工作，我们只是简单地定义和计算合适的慢滚参数。最后，我们强调，如果$1/f_γ$与U（1）（光子）的耦合比$1/f_G$与非阿贝尔规范场（胶子）的耦合大得多，则这种情况在轴子情况下可能实现，因为后者设置了势的范围，从而设置了最大允许$ϕ_0\sim f_G$。

英文摘要：

We analyze in detail the background cosmological evolution of a scalar field coupled to a massless abelian gauge field through an axial term $\fracϕ{f_γ} F \tilde{F}$, such as in the case of an axion. Gauge fields in this case are known to experience tachyonic growth and therefore can backreact on the background as an effective dissipation into radiation energy density $ρ_R$, which which can lead to inflation without the need of a flat potential. We analyze the system, for momenta $k$ smaller than the cutoff $f_γ$, including numerically the backreaction. We consider the evolution from a given static initial condition and explicitly show that, if $f_γ$ is smaller than the field excursion $ϕ_0$ by about a factor of at least ${\cal O} (20)$, there is a friction effect which turns on before that the field can fall down and which can then lead to a very long stage of inflation with a generic potential. In addition we find superimposed oscillations, which would get imprinted on any kind of perturbations, scalars and tensors. Such oscillations have a period of 4-5 efolds and an amplitude which is typically less than a few percent and decreases linearly with $f_γ$. We also stress that the comoving curvature perturbation on uniform density should be sensitive to slow-roll parameters related to $ρ_R$ rather than $\dotϕ^2/2$, although we postpone a calculation of the power spectrum and of non-gaussianity to future work and we simply define and compute suitable slow roll parameters. Finally we stress that this scenario may be realized in the axion case, if the coupling $1/f_γ$ to U(1) (photons) is much larger than the coupling $1/f_G$ to non-abelian gauge fields (gluons), since the latter sets the range of the potential and therefore the maximal allowed $ϕ_0\sim f_G$.

机构、总结、中文摘要均由AI分析而来，可能存在错误，请以论文正文为准。

摘要：

英文摘要：

相关论文