Spontaneous Lorentz symmetry breaking and one-loop effective action in the metric-affine bumblebee gravity

A Delhom, T Mariz, JR Nascimento… - … of Cosmology and …, 2022 - iopscience.iop.org
The metric-affine bumblebee model in the presence of fermionic matter minimally coupled to
the connection is studied. We show that the model admits an Einstein frame representation …

Stability of non-degenerate Ricci-type Palatini theories

J Annala, S Räsänen - Journal of Cosmology and Astroparticle …, 2023 - iopscience.iop.org
We study the stability of theories where the gravitational action has arbitrary algebraic
dependence on the three first traces of the Riemann tensor: the Ricci tensor, the co-Ricci …

[图书][B] Instabilities in field theory: a primer with applications in modified gravity

A Delhom, AJ Cano, FJM Torralba - 2023 - Springer
This book presents the most common types of instabilities arising in classical field theories,
namely tachyonic, Laplacian, ghost-like or strong coupling instabilities, also commenting on …

A diffeomorphism invariant family of metric-affine actions for loop cosmologies

A Delhom, GJ Olmo, P Singh - Journal of Cosmology and …, 2023 - iopscience.iop.org
In loop quantum cosmology (LQC) the big bang singularity is generically resolved by a big
bounce. This feature holds even when modified quantization prescriptions of the …

Consistent particle physics in metric-affine gravity from extended projective symmetry

W Barker, S Zell - arXiv preprint arXiv:2402.14917, 2024 - arxiv.org
It is well-known that the Einstein-Hilbert action exhibits a projective invariance in metric-
affine gravity, generated by a single vector (just like diffeomorphisms). However, this …

[PDF][PDF] An exact stationary axisymmetric vacuum solution within a metric–affine bumblebee gravity

AA Araújo Filho, JR Nascimento… - arXiv preprint arXiv …, 2024 - researchgate.net
Within the framework of the spontaneous Lorentz symmetry breaking, we consider a metric–
affine generalization of the gravitational sector of the Standard–Model Extension (SME) …

Instabilities in field theories: Lecture notes with a view into modified gravity

A Delhom, A Jiménez-Cano, FJM Torralba - arXiv preprint arXiv …, 2022 - arxiv.org
Modified theories of gravity usually present new degrees of freedom, as well as higher order
derivatives, wrong signs in certain terms and complicated couplings already present in the …

Kinematics in metric-affine geometry

A Agashe - Physica Scripta, 2023 - iopscience.iop.org
In a given geometry, the kinematics of a congruence of curves is described by a set of three
quantities called expansion, rotation, and shear. The equations governing the evolution of …

Compact objects in modified gravity: junction conditions and other viability criteria

A Casado-Turrión - arXiv preprint arXiv:2312.03757, 2023 - arxiv.org
This thesis aims at improving our understanding of the strong-field regime of gravity, where
deviations from General Relativity (GR) are expected to be found on theoretical grounds. In …

Non-metricity signatures on the Higgs boson signal strengths at the LHC

V Ilisie - Journal of High Energy Physics, 2022 - Springer
A bstract In this work we study the high-energy Higgs boson phenomenology associated to
the non-metricity scale Λ Q at the LHC. Non-metricity is present in more generic non …