Generalized Holographic and Ricci Dark Energy: Cosmological Diagnostics and Scalar Field Realizations

Abstract: In this work, we present two generalized formulations of the Holographic and Ricci dark energy (DE) models, given by $ \rho_{GH} = 3c^2M^{2}_{pl} \left[ 1-\epsilon\left(1-\frac{R}{H^2}\right) \right]H^2$ and $\rho_{GR} = 3c^2M^{2}_{pl}\left[ 1-\eta\left(1-\frac{H^2}{R}\right) \right]R$ where $H$ and $R$ denote the Hubble parameter and the Ricci scalar, while $\epsilon$ and $\eta$ are model parameters related by $\epsilon = 1 - \eta$. We derived explicit analytical expressions for key cosmological quantities, including the Hubble parameter, the DE density $\rho_D$, the DE pressure $p_D$, the equation of state parameter of DE $\omega_D$ and the deceleration parameter $q$. The analysis was carried out for four distinct cases: (i) the standard model in its original formulation; (ii) the inclusion of spatial curvature; (iii) the addition of interactions between the dark sectors; and (iv) the presence of both interaction and curvature. Moreover, we also considered the limiting case of a DE Dominated Universe. To further characterize the dynamical features of the models, we investigated several diagnostic tools, namely the Statefinder parameters, the cosmographic approach, the $Om(z)$ diagnostic and the squared speed of the sound $v_s^2$ to assess stability against perturbations. Moreover, we established a correspondence between the DE models we studied and some scalar field theories, including tachyon, k-essence, dilaton, quintessence, Dirac-Born-Infeld, Yang-Mills and Nonlinear Electrodynamics (NLED) fields.