Article
Astronomy & Astrophysics
Riccardo March, Orfeu Bertolami, Marco Muccino, Claudio Gomes, Simone Dell'Agnello
Summary: We investigate a nonminimally coupled curvature-matter gravity theory that involves a Yukawa-type fifth force and a non-Newtonian extra force arising from the nonminimal coupling in the solar interior and atmosphere. The extra force depends on the spatial gradient of space-time curvature R. We examine the conditions under which these forces can be screened by the chameleon mechanism and be consistent with the Cassini measurement of the parametrized post-Newtonian parameter gamma. Constraints from spectroscopic observations of the solar atmosphere are also considered.
Article
Astronomy & Astrophysics
Ariel Edery
Summary: We study the effects of nonminimal coupling of the Nielsen-Olesen vortex to Einstein gravity with a cosmological constant. We find that the nonminimal coupling term plays a dual role in the potential of the scalar field and the Einstein-Hilbert term for gravity, leading to the existence of a critical coupling. In the AdS(3) background, the vacuum expectation value of the scalar field near the critical coupling exhibits a power-law behavior. Additionally, we observe that the deficit angle of the asymptotic conical spacetime depends on the nonminimal coupling, rather than just the mass.
Article
Astronomy & Astrophysics
Sarah B. Fisher, Eric D. Carlson
Summary: We explore alternate theories of gravity by replacing the gravitational term in the Lagrangian with a function f(1)(R) and multiplying the matter Lagrangian by a function f(2)(R). We argue that nuclear physics experiments provide strong constraints on such theories. Specifically, by using energy conditions on the pressure in the He-4 nucleus, we obtain a limit on the parameters of the functions f(1)(R) and f(2)(R) that is more than thirty orders of magnitude stronger than the previous limit.
Article
Astronomy & Astrophysics
Erik Jimenez-Vazquez, Miguel Alcubierre
Summary: We study the critical gravitational collapse of a massless scalar field nonminimally coupled to gravity and determine the values of critical amplitude, critical exponent, and echoing exponent. We find that the behavior is similar to that of a minimally coupled scalar field for small coupling, but becomes more violent and rich in high coupling. A special slicing condition is introduced to avoid gauge pathologies in the strong-coupling regime.
Article
Astronomy & Astrophysics
Kit Lloyd-Stubbs, John McDonald
Summary: This model considers the issue of baryogenesis by adding lepton number-violating quadratic mass terms to the inflaton potential of a nonminimally coupled inflation model. The lepton-violating mass terms generate a lepton asymmetry in a complex inflaton field via the mass term Affleck-Dine mechanism, which is then transferred to the Standard Model sector. The model is minimal, requiring only the SM sector, RH neutrinos, and a nonminimally coupled inflaton sector. Baryon isocurvature fluctuations can be observable in metric inflation but are negligible in Palatini inflation. The model is compatible with detectable reheating temperatures in the observable primordial gravitational waves predicted by metric inflation.
Article
Astronomy & Astrophysics
Kishan Sankharva, Shiv Sethi
Summary: In this paper, we consider a nonminimally coupled scalar field as a candidate for cold dark matter and compare it with minimally coupled scalar fields. For the nonminimally coupled field, the energy density behaves as radiation in the early universe and is constrained by a coupling constant. Isocurvature modes are also considered in our analysis.
Article
Astronomy & Astrophysics
Anirban Chatterjee, Saddam Hussain, Kaushik Bhattacharya
Summary: We studied models of nonminimally coupled relativistic fluid and k-essence scalar field in a flat Friedmann-Lemaitre-Robertson-Walker universe, introducing a nonminimal coupling term at the Lagrangian level. Through a variational approach with respect to independent variables, we analyzed the coupled field-fluid framework explicitly and found that both models based on inverse power-law potential are capable of producing accelerating attractor solutions satisfying adiabatic sound speed conditions.
Article
Astronomy & Astrophysics
Michaela G. Lawrence, David Seery, Christian T. Byrnes
Summary: The study explores a disformal coupling between Standard Model matter and a cubic Galileon scalar sector, which evades strict constraints from the integrated Sachs-Wolfe effect. Despite the presence of a cosmological 'screening-like' phenomenon, the disformal coupling is too weak to be constrained by recent events such as GW170817 or by the dispersion of electromagnetic radiation at different wavelengths.
JOURNAL OF COSMOLOGY AND ASTROPARTICLE PHYSICS
(2021)
Article
Astronomy & Astrophysics
Hossein Ghaffarnejad, Hoda Gholipour
Summary: By solving the field equations of non-minimally coupled Einstein-Maxwell gravity in a homogenous and anisotropic background metric with cylindrical symmetry in the x direction of local cartesian coordinates system, this study examines the directional effects of the EM vector potential on the anisotropy trajectory of the spacetime expansion scale factor. Through the dynamical system approach, the stability nature of the cosmic system is investigated in cases where the EM vector potential is parallel or perpendicular to the x direction, revealing interesting behaviors of EM waves as dark energy or baryonic visible matter with varying levels of anisotropy in different inflationary solutions.
GENERAL RELATIVITY AND GRAVITATION
(2021)
Article
Astronomy & Astrophysics
A. K. Lloyd-Stubbs, J. McDonald
Summary: In this study, we investigate the existence and properties of Q-balls with a complex inflaton in nonminimally coupled inflation models using the Palatini formulation of gravity. We find Q-ball solutions that are compatible with inflation and derive a range of inflaton mass squared for which this is the case. The presence of Q-balls suggests the possibility of condensate fragmentation and the potential formation of primordial black holes.
Article
Astronomy & Astrophysics
Kitaro Taniguchi, Ryotaro Kase
Summary: This study investigates the Vainshtein screening mechanism and the coupling between scalar field and ordinary matter field in Horndeski theories. It finds that the effectiveness of this mechanism in linear and nonlinear perturbations depends on the coupling terms.
Article
Astronomy & Astrophysics
Edmund J. Copeland, Francesc Cunillera, Adam Moss, Antonio Padilla
Summary: This study examines field theory monodromy inflation at strong coupling using numerical analysis. It finds that models with uniquely positive Wilson coefficients are ruled out, but models with coefficients that can take on both signs can satisfy current data and strong constraints through term cancellation. Additionally, the study discovers that field theory monodromy models can be enhanced by introducing a mechanism called vacuum energy sequestering, which cancels off radiative corrections to vacuum energy and makes the models more attractive from a theoretical perspective.
JOURNAL OF COSMOLOGY AND ASTROPARTICLE PHYSICS
(2022)
Article
Astronomy & Astrophysics
R. E. Eaves
Summary: The study explores the relationship between the speed of light and gravitational constant, using experimental data to determine the range of variation in the speed of light over time. It is noted that constraints on the speed of light variation are based on data from within the Solar system rather than cosmological observations. Additionally, a relationship between the speed of light and the fine-structure constant is identified as potentially offering tighter constraints.
MONTHLY NOTICES OF THE ROYAL ASTRONOMICAL SOCIETY
(2021)
Article
Astronomy & Astrophysics
Shinsuke Kawai, Jinsu Kim
Summary: We study the formation of primordial black holes and the generation of gravitational waves in cosmological models that are direct supersymmetric analogs of nonminimally coupled Higgs inflation model. By analyzing the multifield dynamics, we identify the parameter region that leads to abundant production of primordial black holes which could account for a significant portion of the current dark matter abundance. We also calculate the spectrum of gravitational waves and discuss their detectability using future ground-based and space-borne gravitational wave observatories.
Article
Astronomy & Astrophysics
Erico Goulart, Santiago Esteban Perez Bergliaffa
Summary: Symmetric-hyperbolicity guarantees well-posedness and leads to a set of two inequalities for matrices whose elements are determined by a given theory. When applied to nonlinear electromagnetism linearly coupled to curvature, the inequalities can lead to strong constraints on the relevant quantities.
Article
Astronomy & Astrophysics
Orest Hrycyna, Marek Szydlowski
JOURNAL OF COSMOLOGY AND ASTROPARTICLE PHYSICS
(2015)
Article
Astronomy & Astrophysics
Orest Hrycyna
Article
Physics, Multidisciplinary
Orest Hrycyna, Marek Szydlowski
ANNALEN DER PHYSIK
(2010)
Article
Physics, Mathematical
Marek Szydlowski, Orest Hrycyna, Aleksander Stachowski
INTERNATIONAL JOURNAL OF GEOMETRIC METHODS IN MODERN PHYSICS
(2014)
Article
Astronomy & Astrophysics
Orest Hrycyna, Marek Szydlowski
JOURNAL OF COSMOLOGY AND ASTROPARTICLE PHYSICS
(2010)
Article
Astronomy & Astrophysics
Orest Hrycyna, Marek Szydlowski
JOURNAL OF COSMOLOGY AND ASTROPARTICLE PHYSICS
(2013)
Article
Astronomy & Astrophysics
Orest Hrycyna, Marek Szydlowski
Article
Astronomy & Astrophysics
Herve Bergeron, Orest Hrycyna, Przemyslaw Malkiewicz, Wlodzimierz Piechocki
Article
Astronomy & Astrophysics
Orest Hrycyna, Marek Szydlowski, Michal Kamionka
Article
Astronomy & Astrophysics
Aleksandra Kurek, Orest Hrycyna, Marek Szydlowski
Article
Astronomy & Astrophysics
Orest Hrycyna, Marek Szydlowski
Article
Physics, Particles & Fields
Orest Hrycyna
EUROPEAN PHYSICAL JOURNAL C
(2020)
Article
Astronomy & Astrophysics
Orest Hrycyna
Summary: Dynamical systems methods were used to investigate a cosmological model with a non-minimally coupled scalar field and asymptotically quadratic potential function. The study found an unstable asymptotic de Sitter state for certain values of the non-minimal coupling constant parameter, leading to a non-singular beginning of the universe. The proposed evolutional model is generic, structurally stable, and independent of the specific choice of initial conditions in phase space.
Proceedings Paper
Astronomy & Astrophysics
Orest Hrycyna
3RD CONFERENCE OF THE POLISH SOCIETY ON RELATIVITY, 2016
(2017)
Proceedings Paper
Astronomy & Astrophysics
Orest Hrycyna, Marek Szydlowski
MULTIVERSE AND FUNDAMENTAL COSMOLOGY: MULTICOSMOFUN '12
(2013)
