arXivDaily arXiv每日学术速递 周一至周五更新
arXiv 1301.7428hep-phastro-ph.COastro-ph.HE
收藏

混合轴子/中性子暗物质的暗辐射约束

Dark Radiation Constraints on Mixed Axion/Neutralino Dark Matter

Kyu Jung Bae, Howard Baer, Andre Lessa

摘要:

最近对WMAP 9数据的分析表明,暗辐射--由对宇宙膨胀有贡献的额外中微子的表观数量Δ N_{eff}来参数化--与标准模型一致,并且在95% CL时,从上面看,Δ N_{eff}约< 0.5。我们考虑了在R宇称守恒超对称(SUSY)模型中产生的混合轴子/中性伴子冷暗物质的情形,其中强CP问题由具有共约轴子(a)/轴子(s)/轴子(\ta)超多重态的强子轴子解决.我们的新结果包括改进的热轴子和saxion生产的计算,并包括saxion衰变的axinos和轴子的影响。我们证明了,如果介子主要是热产生的,且m_{LSP} < m_{\ta} \lesssim m_s,则Δ N_{eff}的上述界容易满足.然而,如果主导机制的saxion生产是通过相干振荡,WMAP 9数据提供了一个强大的约束saxion生产其次是saxion衰变到轴子。此外,我们表明,混合中性伴子/轴子暗物质的情况下,结合WMAP 9,BBN和BBN-100的约束是高度约束。特别是,标准过剩的中性伴子暗物质的超对称模型被排除在所有值的佩西-奎因破缺标度。下一代WIMP直接探测实验可能能够发现或排除混合轴子-中性伴子CDM方案,其中$s\to aa$是主导的轴子衰变模式。

英文摘要:

Recent analyses of WMAP9 data show that dark radiation-- parametrized by the apparent number of additional neutrinos ΔN_{eff} contributing to the cosmic expansion-- is consistent with the Standard Model and bounded from above by about ΔN_{eff} ~< 0.5 at 95% CL. We consider the mixed axion/neutralino cold dark matter scenario which arises in R-parity conserving supersymmetric (SUSY) models wherein the strong CP problem is solved by hadronic axions with a concommitant axion(a)/saxion(s)/axino(\ta) supermultiplet. Our new results include improved calculations of thermal axion and saxion production and include effects of saxion decay to axinos and axions. We show that the above bound on ΔN_{eff} is easily satisfied if saxions are mainly thermally produced and m_{LSP} < m_{\ta} \lesssim m_s. However, if the dominant mechanism of saxion production is through coherent oscillations, the WMAP9 data provides a strong bound on saxion production followed by saxion decays to axions. Furthermore we show that scenarios with mixed neutralino/axion dark matter are highly constrained by combined WMAP9, BBN and Xe-100 constraints. In particular, supersymmetric models with a standard overabundance of neutralino dark matter are excluded for all values of the Peccei-Quinn breaking scale. Next generation WIMP direct detection experiments may be able to discover or exclude mixed axion-neutralino CDM scenarios where $s\to aa$ is the dominant saxion decay mode.

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。

↑