Search

In this work, we study a pseudo-Nambu-Goldstone boson (pNGB) dark matter model extended with a real scalar. The dark sector is assumed to be feebly coupled with the standard model (SM) via a Higgs portal, so that the pNGB dark matter is produced by the freeze-in mechanism. Since the production happened in a very high energy era, we introduce an extra scalar field which is weakly coupled to the SM for stablizing the electroweak vacuum. Our model can reproduce the correct relic abundance of dark matter favored by observations. In addition, we determine the evolution of couplings in higher energy scale by solving the renormalization group equations, and show that the self coupling of the real scalar, $\lambda_S$, and the mixing coupling between the Higgs field and the real scalar, $\lambda_{HS}$ are stringently constrained by the conditions of vacuum stability and couplings perturbativity up to the Planck scale. We also find that the relic abundance of DM is insensitive to the values of $\lambda_S$ and $\lambda_{HS}$ unless the dominant production processes are $\overline{H}+H(S+S)\to\phi+\phi$ via t- and u-channels., Comment: 30 pages, 10 figures

We propose an ultraviolet completion model for pseudo-Nambu-Goldstone dark matter with a hidden $\mathrm{U}(1)$ gauge symmetry. Compared to previous studies, this setup is simpler, introducing less interactions. Dark matter scattering off nucleons is highly suppressed by the ultraviolet scale and direct detection constraints can be easily evaded. The kinetic mixing between the hidden $\mathrm{U}(1)$ and the $\mathrm{U}(1)_\mathrm{Y}$ gauge fields would lead to dark matter decays. We find that the current bound on the dark matter lifetime implies that the ultraviolet scale should be higher than $10^{10}~\mathrm{GeV}$. The phenomenological constraints from the 125 GeV Higgs measurements, the dark matter relic density, and indirect detection of dark matter annihilation are also investigated., Comment: 22 pages, 6 figures

We investigate the potential stochastic gravitational waves from first-order electroweak phase transitions in a model with pseudo-Nambu-Goldstone dark matter and two Higgs doublets. The dark matter candidate can naturally evade direct detection bounds, and can achieve the observed relic abundance via the thermal mechanism. Three scalar fields in the model obtain vacuum expectation values, related to phase transitions at the early Universe. We search for the parameter points that can cause first-order phase transitions, taking into account the existed experimental constraints. The resulting gravitational wave spectra are further evaluated. Some parameter points are found to induce strong gravitational wave signals, which have the opportunity to be detected in future space-based interferometer experiments LISA, Taiji, and TianQin., Comment: 35 pages, 8 figures, accepted for publication in JHEP

In this paper, we will apply the Goldstone equivalence gauge to calculate the $1 \leftrightarrow 2$ processes of a sterile neutrino in the thermal plasma below the standard model (SM) critical temperature $T_c \approx 160 \text{ GeV}$. The sterile neutrino's mass is around the electroweak scale $50 \text{ GeV} \leq m_N \leq 200 \text{ GeV}$, and the acquired thermal averaged effective width $\bar{\Gamma}_{\text{tot}}$ is continuous around the cross-over. We will also apply our results to perform a preliminary calculation of the leptogenesis., Comment: HTL vertex corrections (Eqn.~(A4)) have been included to acquire the gauge invariant results. Data had been updated

We study a dark matter model with one singlet complex scalar and two Higgs doublets. The scalar potential respects a softly broken global symmetry, which makes the imaginary part of the singlet become a pseudo-Nambu-Goldstone boson acting as a dark matter candidate. The pseudo-Nambu-Goldstone nature of the boson leads to the vanishing of its tree-level scattering amplitude off nucleons at zero momentum transfer. Therefore, although the interaction strength could be sufficiently large to yield a viable relic abundance via thermal mechanism, direct detection is incapable of probing this candidate. We further investigate the constraints from Higgs measurements, relic abundance observation, and indirect detection., Comment: 33 pages, 11 figures; revisions to match the published version