论文标题
CMB中的DFSZ轴轴
The DFSZ axion in the CMB
论文作者
论文摘要
我们首次对DFSZ QCD轴模型的宇宙学约束进行专门分析。鉴于最近的Xenon-1T过量和恒星冷却的提示，这种结构特别有趣。在DFSZ模型中，对于$ M_A \ gtrsim 0.1 $ EV，乳头和μ子的散射可以产生热轴的相当大的宇宙背景，其行为与大量的中微子相似。但是，旋转耦合取决于两个Higgs Doublets的VEV之间的对齐，并且相对于KSVZ方案，可以显着抑制或增强。使用最新的Planck和BAO数据，我们发现$ M_A \ LEQ 0.2〜 \ text {ev} $ at $ 95 \％$ c.l.，当轴耦合到Pions $ C_ {Aπ} $是最大的。相反，当$ c_ {aπ} $很小时，对$ m_a $的约束可以大大放松。 In particular, we point out that in the so-called DFSZ-II model, where the axion coupling to leptons does not vanish simultaneously with $c_{aπ}$, production via muons gives $m_a\leq 0.6~\text{eV}$ at $95\%$ C.L., whereas in the DFSZ-I model bounds on $m_a$ can be fully lifted.然后，我们将宇宙学数据与最新的DFSZ轴轴相结合，并从Xenon-1T实验中耦合到电子，在这种情况下发现，轴支质量被约束在窗口中$ 0.07〜 \ text {ev ev} \ sext {ev} \ sillsim sim m_a \ sim m_a \ siels mealsim 1.8 \ silysim 1.8 \ \，（0.3）〜\，（0.3）〜\ text $ dfi {evi {ev} 模型。与出色的冷却提示的类似分析给出了$ 3〜 \ text {Mev} \ Lessim m_a \ Lessim 0.2〜 \ text {ev} $对于DFSZ-II，而DFSZ-I情况中没有任何约束。即将举行的CMB阶段4实验将能够进一步测试这种情况。例如，对于DFSZ-I轴，应将Xenon-1T窗口以$2σ$的价格进行全面探测。
We perform for the first time a dedicated analysis of cosmological constraints on DFSZ QCD axion models. Such constructions are especially interesting in light of the recent Xenon-1T excess and of hints from stellar cooling. In DFSZ models, for $m_a\gtrsim 0.1$ eV, scatterings of pions and muons can produce a sizable cosmic background of thermal axions, that behave similarly to massive neutrinos. However, the pion coupling depends on the alignment between the vevs of two Higgs doublets, and can be significantly suppressed or enhanced with respect to the KSVZ scenario. Using the latest Planck and BAO data, we find $m_a\leq 0.2~\text{eV}$ at $95\%$ C.L., when the axion coupling to pions $c_{aπ}$ is maximal. Constraints on $m_a$, instead, can be significantly relaxed when $c_{aπ}$ is small. In particular, we point out that in the so-called DFSZ-II model, where the axion coupling to leptons does not vanish simultaneously with $c_{aπ}$, production via muons gives $m_a\leq 0.6~\text{eV}$ at $95\%$ C.L., whereas in the DFSZ-I model bounds on $m_a$ can be fully lifted. We then combine cosmological data with recent hints of a DFSZ axion coupled to electrons from the Xenon-1T experiment, finding in this case that the axion mass is constrained to be in the window $0.07 ~\text{eV} \lesssim m_a \lesssim 1.8\, (0.3)~\text{eV}$ for the DFSZ-I (DFSZ-II) model. A similar analysis with stellar cooling hints gives $3 ~\text{meV} \lesssim m_a \lesssim 0.2 ~\text{eV}$ for DFSZ-II, while no constraint arises in the DFSZ-I case. Forthcoming CMB Stage 4 experiments will be able to further test such scenarios; for instance the Xenon-1T window should be fully probed at $2σ$ for a DFSZ-I axion.
