Article
Physics, Multidisciplinary
Simran Arora, Pradyumn Kumar Sahoo
Summary: The possibility of crossing the phantom divide line in the extension of symmetric teleparallel gravity or f(Q) gravity is investigated in this study. The cosmic evolution of the effective equation of state parameter for dark energy is studied using exponential, logarithmic, and combined f(Q) theories. It is demonstrated that future crossings of the phantom dividing line are a generic feature of feasible f(Q) gravity models.
ANNALEN DER PHYSIK
(2022)
Article
Physics, Multidisciplinary
M. Koussour
Summary: In this study, we investigate the history of the cosmos using an extension of symmetric teleparallel gravity called Weyl-type f(Q,T) gravity. We derive the Hubble parameter from a proposed deceleration parameter and apply it to the Friedmann equations. The best fit values of the model parameters support a crossing of the phantom divide line, suggesting that Weyl-type f(Q,T) gravity can provide an alternative to dark energy in explaining cosmic acceleration.
CHINESE JOURNAL OF PHYSICS
(2023)
Article
Astronomy & Astrophysics
Mario Ballardini, Angelo Giuseppe Ferrari, Fabio Finelli
Summary: We investigate the observational constraints for three different extended scalar-tensor theories of gravity with a negative kinetic term for the scalar field. We find that these models generally lead to lower values of H0 and cr8 compared to the standard kinetic term models. However, cosmological observations prefer a parameter space where the theory is not healthy, as the scalar field behaves as a ghost. Additionally, we show that early modified gravity with a quartic coupling in the phantom branch can alleviate the H0 tension by fitting multiple cosmic observations.
JOURNAL OF COSMOLOGY AND ASTROPARTICLE PHYSICS
(2023)
Article
Astronomy & Astrophysics
N. Dimakis, Andronikos Paliathanasis
Summary: In this study, a chiral cosmological model with two scalar fields minimally coupled to gravity was considered, leading to a general solution of the field equations in a FLRW spacetime with massless fields and a cosmological constant. The symmetrical minisuperspace configuration resulted in scenarios corresponding to quintessence, quintom, or phantom cases, depending on the parameters. The canonical quantization of the model distinguished between different families of quantum states, and the crossing of the phantom line was related to the existence of free or bound states for the Casimir operator of the fields' symmetry algebra. The classical singularity present in the quintessence solution was also resolved at the quantum level.
CLASSICAL AND QUANTUM GRAVITY
(2021)
Article
Astronomy & Astrophysics
Artyom Astashenok, Alexander Tepliakov
Summary: This paper discusses a Tsallis holographic dark energy model with interaction between dark energy and matter, and analyzes the cosmological dynamics of the universe. Special attention is paid to the possibility of crossing the phantom line, and it is shown that this may occur once or twice for certain values of parameters.
Article
Physics, Particles & Fields
I. Andrade, R. Menezes
Summary: This work examines the existence of localized structures in relativistic systems described by two real scalar fields in two-dimensional spacetime. The inclusion of the cuscuton term in the usual two-field model allows for interesting modifications in the profiles of topological configurations, such as smooth control over their slope and the internal structure of the energy density. The system supports a first-order framework, which enables the determination of the energy of solutions without the need for explicit knowledge of their form.
EUROPEAN PHYSICAL JOURNAL C
(2023)
Article
Astronomy & Astrophysics
Yeong Gyun Kim, Kang Young Lee, Jungil Lee, Soo-hyeon Nam
Summary: In this paper, we discuss the vacuum structure and vacuum stability in classically scale-invariant renormalizable models. This study provides important clues for direct detection of dark matter, and explores the collider signatures and future discovery potentials of the new scalars.
Article
Astronomy & Astrophysics
Andronikos Paliathanasis, Genly Leon
Summary: In this study, we analyze the dynamics of a chiral-like cosmological model with scalar fields having negative kinetic terms, focusing on the asymptotic dynamics for the gravitational field equations in a spatially flat FLRW background. It is shown that when one of the scalar fields is phantom, the cosmological fluid can cross the phantom divide line twice without the appearance of ghosts. The cosmological viability of these four models is also discussed in detail.
CLASSICAL AND QUANTUM GRAVITY
(2021)
Article
Physics, Multidisciplinary
Eleonora Di Valentino, Ankan Mukherjee, Anjan A. Sen
Summary: The study found that constraints from different combinations of data are consistent with each other and all support phantom crossing in the dark energy sector. The combined data is in agreement with the local measurement by Riess et al.
Article
Astronomy & Astrophysics
Zohre Habibolahi, Karim Ghorbani, Parsa Ghorbani
Summary: This article introduces a model that extends the Standard Model with two additional real scalar particles, explaining the relic abundance of dark matter and solving the fine-tuning problem of the Higgs mass.
Article
Astronomy & Astrophysics
Erendira Gutierrez-Luna, Belen Carvente, Victor Jaramillo, Juan Barranco, Celia Escamilla-Rivera, Catalina Espinoza, Myriam Mondragon, Dario Nunez
Summary: This study explores the possibility of incorporating particle physics motivated scalar fields into the dark matter cosmological model. The analysis is performed using one to two scalar fields to examine their impact on the cosmic flow. The results show that the combination of scalar fields has a significant effect on the cosmological expansion.
Article
Astronomy & Astrophysics
Arghyajit Datta, Rishav Roshan, Arunansu Sil
Summary: We investigate a simple variant of type-II seesaw in which the particle spectrum is extended with one singlet right-handed neutrino and an inert Higgs doublet, both odd under an additional Z(2) symmetry. The correlation between the smallness of the mass splitting and the largeness of the mass of the scalar triplet provides insights into the neutrino mass generation and the correct baryon abundance of the Universe.
Article
Physics, Particles & Fields
Sourav Sur, Ashim Dutta, Hiyang Ramo Clothe
Summary: The theory extends the basic formalism of mimetic-metric-torsion gravity theory, showing geometrically how the mimetic scalar field acts as the source of both the trace and axial modes of torsion. It maintains conformal symmetry and spatial parity symmetry, demonstrating a geometric unification of the cosmological dark sector and the feasibility of a super-accelerating regime during the universe's evolution. The theory also predicts a smooth crossing of the phantom barrier at low red-shift and determines the extent of super-acceleration by examining the evolution of relevant torsion parameters.
EUROPEAN PHYSICAL JOURNAL C
(2021)
Article
Physics, Particles & Fields
Christopher Chang, Pat Scott, Tomas E. Gonzalo, Felix Kahlhoefer, Anders Kvellestad, Martin White
Summary: Simplified models are useful for studying the impact of a few new particles on experimental observables without a complete underlying theory. This study uses global fits to investigate simplified dark matter models, focusing on scalar or fermionic dark matter candidates coupling to quarks through a vector mediator. Resonance regions are favored in cases of Dirac or Majorana fermion dark matter, with excesses in LHC monojet searches and relic density limits. Combining vector and axial-vector couplings in the Dirac candidate leads to competing constraints from direct detection and unitarity violation.
EUROPEAN PHYSICAL JOURNAL C
(2023)
Article
Physics, Particles & Fields
Christopher Chang, Pat Scott, Tomas E. Gonzalo, Felix Kahlhoefer, Anders Kvellestad, Martin White
Summary: Simplified models are a useful tool for studying the effects of a small number of new particles on experimental observables and their interplay, without the need for a full underlying theory. In this study, global fits of simplified dark matter models were performed using GAMBIT, incorporating up-to-date likelihoods from indirect detection, direct detection, and collider searches. Various models with scalar or fermionic dark matter candidates coupling to quarks through an s-channel vector mediator were investigated, with significant parameter space surviving for each model.
EUROPEAN PHYSICAL JOURNAL C
(2023)