Derivative couplings of a k-essence dark-energy scalar to a 2HDM+a pseudoscalar make the mediator’s invisible width and kinematics depend on the dark-energy sound speed c_s².
Canonical reference
A Dynamical Solution to the Problem of a Small Cosmological Constant and Late-time Cosmic Acceleration
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abstract
Increasing evidence suggests that most of the energy density of the universe consists of a dark energy component with negative pressure, a ``cosmological constant" that causes the cosmic expansion to accelerate. In this paper, we address the puzzle of why this component comes to dominate the universe only recently rather than at some much earlier epoch. We present a class of theories based on an evolving scalar field where the explanation is based entirely on internal dynamical properties of the solutions. In the theories we consider, the dynamics causes the scalar field to lock automatically into a negative pressure state at the onset of matter-domination such that the present epoch is the earliest possible time, consistent with nucleosynthesis restrictions, when it can start to dominate.
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A two-field quintom model reproduces w0waCDM perturbation features and is mildly favored over it in Bayesian fits to BAO, CMB, and SNIa data.
Interacting k-essence dark energy and non-pressureless dark matter models with two interaction forms are shown to reproduce major cosmological epochs and fit observations comparably to LambdaCDM while admitting late-time de Sitter attractors.
Interacting scalar fields coupled to Gauss-Bonnet gravity yield viable dark energy and dark matter models that match Pantheon+ and DES supernova data while preferring over LambdaCDM at high redshifts with Roman mocks.
DESI data hint that dark energy evolves (w0>−1, wa<0, phantom crossing) at 2.5–4.2σ, but the same expansion history can also be produced by interacting dark sectors, modified gravity, or non-cold dark matter.
This review traces the history of dynamical dark energy, presents the no-go theorem against single-field crossing of w = -1, and surveys viable Quintom constructions including multi-field models and modified gravity in light of DESI DR2 hints.
MCMC constraints on two Lambda(t) models with DESI DR2, CC, and Pantheon+ data yield H0 ~72.5-73 km/s/Mpc, Omega_m0 near standard values in joint fits, and n~0.3 indicating mild deviation from LambdaCDM.
A comprehensive review of modified gravity theories and their cosmological consequences, including a parameterized post-Friedmannian formalism for constraining deviations from General Relativity.
Particle cosmology integrates particle physics with cosmology to interpret the early universe as a natural high-energy laboratory and explain phenomena via theories like inflation, baryogenesis, and dark matter.
citing papers explorer
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Collider Probes of Dark Energy Microphysics
Derivative couplings of a k-essence dark-energy scalar to a 2HDM+a pseudoscalar make the mediator’s invisible width and kinematics depend on the dark-energy sound speed c_s².
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Quintom Model Perturbations
A two-field quintom model reproduces w0waCDM perturbation features and is mildly favored over it in Bayesian fits to BAO, CMB, and SNIa data.
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Interacting $k$-essence field with non-pressureless Dark Matter: Cosmological Dynamics and Observational Constraints
Interacting k-essence dark energy and non-pressureless dark matter models with two interaction forms are shown to reproduce major cosmological epochs and fit observations comparably to LambdaCDM while admitting late-time de Sitter attractors.
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Interacting Scalar Fields as Dark Energy and Dark Matter in Einstein scalar Gauss Bonnet Gravity
Interacting scalar fields coupled to Gauss-Bonnet gravity yield viable dark energy and dark matter models that match Pantheon+ and DES supernova data while preferring over LambdaCDM at high redshifts with Roman mocks.
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Dark Energy in the DESI Era: A Brief Review of Evidence, Beyond-$\Lambda$CDM Interpretations, and Tensions
DESI data hint that dark energy evolves (w0>−1, wa<0, phantom crossing) at 2.5–4.2σ, but the same expansion history can also be produced by interacting dark sectors, modified gravity, or non-cold dark matter.
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The Quintom theory of dark energy after DESI DR2
This review traces the history of dynamical dark energy, presents the no-go theorem against single-field crossing of w = -1, and surveys viable Quintom constructions including multi-field models and modified gravity in light of DESI DR2 hints.
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Observational tests of \texorpdfstring{$\Lambda(t)$}{Lambda(t)} cosmology in light of DESI DR2
MCMC constraints on two Lambda(t) models with DESI DR2, CC, and Pantheon+ data yield H0 ~72.5-73 km/s/Mpc, Omega_m0 near standard values in joint fits, and n~0.3 indicating mild deviation from LambdaCDM.
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Modified Gravity and Cosmology
A comprehensive review of modified gravity theories and their cosmological consequences, including a parameterized post-Friedmannian formalism for constraining deviations from General Relativity.
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Particle Cosmology
Particle cosmology integrates particle physics with cosmology to interpret the early universe as a natural high-energy laboratory and explain phenomena via theories like inflation, baryogenesis, and dark matter.