Peccei-Quinn Genesis

TL;DR

The paper tackles the joint origin of dark matter and the baryon asymmetry by embedding Peccei-Quinn dynamics in a pole-inflation framework. It introduces a cogenesis mechanism where spontaneous leptogenesis at the seesaw scale, driven by the axion's kinetic motion, generates the B-L asymmetry, while the same axion kinetic misalignment accounts for dark matter. Using the KSVZ axion model with seesaw couplings, the authors compute a specific baryon-asymmetry coefficient c_B = -0.13 and relate the Yukawa coupling y_N to the axion decay constant f_a, constraining the parameter space. The analysis shows that viable cogenesis occurs in a narrow window with f_a ≈ (4−9)×10^8 GeV and PQ-violating operators of dimension n ≈ 9–11, thereby providing a unified solution to the strong CP problem, neutrino masses, baryogenesis, and inflation, with reheating around T_RH ~ 10^6 GeV.

Abstract

We propose a cogenesis mechanism that unifies the origin of QCD axion dark matter and the baryon asymmetry of the Universe in the framework of Peccei-Quinn pole inflation. The model integrates the Peccei-Quinn symmetry with the seesaw mechanism for neutrino masses. This allows for spontaneous leptogenesis, which generates the required $B-L$ asymmetry around the seesaw scale. The necessary initial axion kinetic misalignment is naturally sourced by a PQ field driving pole inflation. Analysis within the KSVZ axion model demonstrates that achieving simultaneous correct DM abundance and baryon asymmetry limits the axion decay constant to be smaller than about $10^9$ GeV. This framework offers a unified solution to four fundamental problems: the strong CP problem, neutrino mass, matter-antimatter asymmetry, and inflation.

Figures (3)

• Figure 1: Region of successful cogenesis in the parameter space ($y_Q$, $\Lambda$). Reheating occurs in the region to the right of the red dashed line. The blue-dashed line shows $y_Q=\sqrt{3}y_N$. The boundary of the orange and yellow shaded regions corresponds to $\mathcal{R}=1$
• Figure 2: Parameter space for the successful cogenesis for different values of $y_Q$ in terms of the cutoff scale $\Lambda$ vs. the PQ breaking scale $f_a$. Allowed regions are indicated by orange, green, and brown, denoting PQ-violating potentials with dimensionalities $n=9$, 10, and 11, respectively. The required values for the coupling $\lambda_n$ are also depicted by almost vertical lines. The left (right) side of the blue line is for ${\cal R}<1$ ($>1$).
• Figure 3: Time evolution of $c_N$ for $\zeta=1,2,\dots,10$, appearing in eq. (\ref{['Ythend']}). The plots show that $c_N$ rapidly converges to a constant value for a given $\zeta$. Here, $wt=10$ with $w=10^{11}$ GeV, and $t_e$ is the time at the end of inflation. The red and blues lines indicate the times when $\rho=\rho_c/10$ and $\rho=\rho_c/20$, respectively.