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A bstract Thermal axion production in the early universe goes through several mass thresholds, and the resulting rate may change dramatically across them. Focusing on the KSVZ and DFSZ frameworks for the invisible QCD axion, we perform a systematic analysis of thermal production across thresholds and provide smooth results for the rate. The QCD phase transition is an obstacle for both classes of models. For the hadronic KSVZ axion, we also deal with production at temperatures around the mass of the heavy-colored fermion charged under the Peccei-Quinn symmetry. Within the DFSZ framework, standard model fermions are charged under this symmetry, and additional thresholds are the heavy Higgs bosons masses and the electroweak phase transition. We investigate the cosmological implications with a specific focus on axion dark radiation quantified by an effective number of neutrino species and explore the discovery reach of future CMB-S4 surveys.

A bstract We investigate the production of neutralino dark matter in a cosmological scenario featuring an early matter dominated era ending at a relatively low reheating temperature. In such scenarios different production mechanisms of weakly interacting massive particles (WIMPs), besides the well-studied thermal production, can be important. This opens up new regions of parameter space where the lightest neutralino, as the best-known supersymmetric (SUSY) WIMP, obtains the required relic abundance. Many of these new sets of parameters are also compatible with current limits from colliders as well as direct and indirect WIMP searches. In particular, in standard cosmology bino-like neutralinos, which emerge naturally as lightest neutralino in many models, can have the desired relic density only in some finetuned regions of parameter space where the effective annihilation cross section is enhanced by co-annihilation or an s -channel pole. In contrast, if the energy density of the universe was dominated by long-lived PeV-scale particles (e.g. moduli or Polonyi fields), bino-like neutralinos can obtain the required relic density over wide regions of supersymmetric parameter space. We identify the interesting ranges of mass and decay properties of the heavy long-lived particles, carefully treating the evolution of the temperature of the thermal background.

A bstract The XENON1T collaboration recently reported the excess of events from recoil electrons, possibly giving an insight into new area beyond the Standard Model (SM) of particle physics. We try to explain this excess by considering effective interactions between the sterile neutrinos and the SM particles. In this paper, we present an effective model based on one-particle-irreducible interaction vertices at low energies that are induced from the SM gauge symmetric four-fermion operators at high energies. The effective interaction strength is constrained by the SM precision measurements, astrophysical and cosmological observations. We introduce a novel effective electromagnetic interaction between sterile neutrinos and SM neutrinos, which can successfully explain the XENON1T event rate through inelastic scattering of the sterile neutrino dark matter from Xenon electrons. We find that sterile neutrinos with masses around 90 keV and specific effective coupling can fit well with the XENON1T data where the best fit points preserving DM constraints and possibly describe the anomalies in other experiments.

Growing evidence as the observations of the CMB (cosmic microwave background), galaxy clustering and high-redshift supernovae address a stable dynamically universe dominated by the dark components. In this paper, using a qualitative theory of dynamical systems, we study the stability of a unified dark matter-dark energy framework known as quartessence Chaplygin model (QCM) with three different equation-of-states within ultraviolet (UV) deformed Friedmann–Robertson–Walker (FRW) cosmologies without Big-Bang singularity. The UV deformation is inspired by the non-commutative (NC) Snyder spacetime approach in which by keeping the transformation groups and rotational symmetry there is a dimensionless, Planck scale characteristic parameter \\[\\mu _0\\] with dual implications dependent on its sign that addresses the required invariant cutoffs for length and momentum in nature, in a separate manner. Our stability analysis is done in the \\[(H,\\rho )\\] phase space at a finite domain concerning the hyperbolic critical points. According to our analysis, due to constraints imposed on the signs of \\[\\mu _0\\] from the phenomenological parameters involved in quartessence models \\[(\\Omega _m^*, c_s^2, \\rho _*)\\], for an expanding and accelerating late universe, all three QCMs can be stable in the vicinity of the critical points. The requirement of stability for these quartessence models in case of admission of a minimum invariant length, can yield a flat as well as non-flat expanding and accelerating universe in which Big-Bang singularity is absent. This feedback also phenomenologically credits to braneworld-like framework versus loop quantum cosmology-like one as two possible scenarios which can be NC Snyder spacetime generators (correspond to \\[\\mu _0<0\\] and \\[\\mu _0>0\\], respectively). As a result, our analysis show that between quartessence models with Chaplygin gas equation-of-states and accelerating FRW backgrounds occupied by a minimum invariant length, there is a possibility of viability.

With regard to the leptonic magnetic dipole moment anomaly as well as the W -boson mass excess, we study the DFSZ axion model. Considering theoretical and experimental constraints, we show that the muon and electron g - 2 anomalies can be explained within the parameter space of the model for extra Higgs bosons with mass spectra around the electroweak scale and for an almost equivalent contribution of one-and two-loop diagrams. A negative electron g - 2 could be achieved by introducing heavy neutrinos. Furthermore, the W -boson mass excess can be consistently addressed within the mass range of the matter content testable at collider experiments.

With regard to the leptonic magnetic dipole moment anomaly as well as the W-boson mass excess, we study the DFSZ axion model. Considering theoretical and experimental constraints, we show that the muon and electron [Formula omitted] anomalies can be explained within the parameter space of the model for extra Higgs bosons with mass spectra around the electroweak scale and for an almost equivalent contribution of one-and two-loop diagrams. A negative electron [Formula omitted] could be achieved by introducing heavy neutrinos. Furthermore, the W-boson mass excess can be consistently addressed within the mass range of the matter content testable at collider experiments.

Abstract With regard to the leptonic magnetic dipole moment anomaly as well as the W-boson mass excess, we study the DFSZ axion model. Considering theoretical and experimental constraints, we show that the muon and electron $$g-2$$ g - 2 anomalies can be explained within the parameter space of the model for extra Higgs bosons with mass spectra around the electroweak scale and for an almost equivalent contribution of one-and two-loop diagrams. A negative electron $$g-2$$ g - 2 could be achieved by introducing heavy neutrinos. Furthermore, the W-boson mass excess can be consistently addressed within the mass range of the matter content testable at collider experiments.

The impact of axion-like particles on the light polarization around the horizon of suppermassive black hole (SMBH) is discussed in the light of the latest polarization measurement of the Event Horizon Telescope (EHT). We investigate different sources of the polarization due to axion interaction with photons and the magnetic field of SMBH. These can modify the linear and circular polarization parameters of the emitted light. We have shown that a significant circular polarization can be produced via the photon scattering from the background magnetic field with axions as off-shell particles. This can further constrain the parameter space of ultralight axion-like particles and their couplings with photons. The future precise measurements of circular polarization can probe the features of ultralight axions in the near vicinity of SMBH.

Motivated by the stunning projections for future CMB surveys, we evaluate the amount of dark radiation produced in the early Universe by two-body decays or binary scatterings with thermal bath particles via a rigorous analysis in momentum space. We track the evolution of the dark radiation phase space distribution, and we use the asymptotic solution to evaluate the amount of additional relativistic energy density parameterized in terms of an effective number of additional neutrino species \\(\\Delta N_{\\rm eff}\\). Our approach allows for studying light particles that never reach equilibrium across cosmic history, and to scrutinize the physics of the decoupling when they thermalize instead. We incorporate quantum statistical effects for all the particles involved in the production processes, and we account for the energy exchanged between the visible and invisible sectors. Non-instantaneous decoupling is responsible for spectral distortions in the final distributions, and we quantify how they translate into the corresponding value for \\(\\Delta N_{\\rm eff}\\). Finally, we undertake a comprehensive comparison between our exact results and approximated methods commonly employed in the existing literature. Remarkably, we find that the difference can be larger than the experimental sensitivity of future observations, justifying the need for a rigorous analysis in momentum space.

With regard to the leptonic magnetic dipole moment anomaly as well as the \\(W\\)-boson mass excess, we study the DFSZ axion model. Considering theoretical and experimental constraints, we show that the muon and electron \\(g-2\\) anomalies can be explained within the parameter space of the model for extra Higgs bosons with mass spectra around the electroweak scale and for an almost equivalent contribution of one- and two-loop diagrams. A negative electron \\(g-2\\) could be achieved by introducing heavy neutrinos. Furthermore, the \\(W\\) boson mass excess can be consistently addressed within the mass range of the matter content testable at collider experiments.