通过原初黑洞的不对称捕获实现共振增强重子生成
Resonantly-Enhanced Baryogenesis through Asymmetric Capture by Primordial Black Holes
- The Indian Institute of Science（印度科学学院）
- Universiti Teknologi Malaysia（马来西亚理工大学）
机构由 AI 辅助整理，请以论文原文为准。
AI总结：
本文提出利用原初黑洞不对称捕获重子粒子，通过近简并费米子共振CP破坏增强重子生成，得到与观测一致的重子不对称，并预言了可被U-DECIGO探测的引力波信号。
AI中文摘要：
原初黑洞（PBH）可以通过不对称捕获携带重子电荷的粒子来产生宇宙重子不对称（BAU），但该机制的先前实现通常产生的重子不对称远低于观测值，因为相关的CP破坏散射不对称性受到圈级抑制。我们表明，这一限制可以通过两个近简并不稳定费米子$Y_{1,2}$混合系统中的共振CP破坏来克服，这两个费米子的质量劈裂与其衰变宽度相当。相干$Y_1$--$Y_2$态的稀有产生，随后伴随CP不对称的返回和损失衰变，在拉格朗日量层面保持全局重子电荷的同时，产生积分衰变概率中$\mathcal{O}(0.1)$量级的差异。将这一共振源嵌入PBH捕获输运系统，即可产生观测到的重子不对称。我们首先在零温、瞬时蒸发处理中重现该机制，得到$\eta_B^{T=0}\simeq2.37\times10^{-10}\simeq2.72 \eta_B^{\rm obs}$。我们发现，在纳入热修正以及连续PBH蒸发和熵产生后，所得的BAU变为$\eta_B = 8.72\times 10^{-11}$，与观测值一致。该模型的一个有趣发现是，即使PBH吸收仍然活跃，我们仍会有BAU $\eta_{B}^{\text{no evap}} \sim 9.1 \times 10^{-12} \sim 0.105 \eta_B^{\rm obs}$。我们进一步研究了与PBH形成相关的原初扰动所伴随的引力波信号。相应的标量诱导引力波谱在$f \sim 0.16\text{--}0.17~\mathrm{MHz}$处达到峰值，峰值强度为$h^2\Omega_{\rm GW}^{\rm peak} \sim (3\text{--}7)\times 10^{-8}$。在理想化灵敏度假设下，U-DECIGO对基准谱可实现信噪比高于10。
英文摘要：
Primordial black holes (PBHs) can generate the Baryon Asymmetry of the Universe (BAU) through asymmetric capture of baryon-charge-carrying particles, but previous realizations of this mechanism typically yield an asymmetry well below the observed value because the relevant CP-violating scattering asymmetry is loop suppressed. We show that this limitation can be overcome through resonant CP violation in a mixed system of two nearly degenerate unstable fermions, $Y_{1,2}$, whose mass splitting is comparable to their decay widths. Rare production of the coherent $Y_1$--$Y_2$ state, followed by CP-asymmetric return and loss decays, generates an $\mathcal{O}(0.1)$ difference in integrated decay probabilities while preserving the global baryon charge at the Lagrangian level. Embedding this resonant source in the PBH-capture transport system yields the observed baryon asymmetry. We first reproduce the mechanism in a zero-temperature, sudden-evaporation treatment, which gives $η_B^{T=0}\simeq2.37\times10^{-10}\simeq2.72 η_B^{\rm obs}$. We find that after including thermal corrections and continuous PBH evaporation and entropy production, the resulting BAU becomes $η_B = 8.72\times 10^{-11}$ in agreement with the observed value. An interesting finding of the model is that even if PBH absorption remains active, we would still have BAU $η_{B}^{\text{no evap}} \sim 9.1 \times 10^{-12} \sim 0.105 η_B^{\rm obs}$. We further investigate gravitational-wave signatures associated with the primordial fluctuations responsible for PBH formation. The corresponding scalar-induced gravitational-wave spectra peak at $f \sim 0.16\text{--}0.17~\mathrm{MHz}$, with $h^2Ω_{\rm GW}^{\rm peak} \sim (3\text{--}7)\times 10^{-8}$. Under idealized sensitivity assumptions, U-DECIGO can achieve signal-to-noise ratios above 10 for the benchmark spectra.
