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arXiv · 2108.02500

Well-Tempered Minkowski Solutions in Teleparallel Horndeski Theory

Reginald Christian Bernardo·Jackson Levi Said·Maria Caruana·Stephen Appleby
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Abstract

Well-tempering stands among the few classical methods of screening vacuum energy to deliver a late-time, low energy vacuum state. We build on the class of Horndeski models that admit a Minkowski vacuum state despite the presence of an arbitrarily large vacuum energy to obtain a much larger family of models in teleparallel Horndeski theory. We set up the routine for obtaining these models and present a variety of cases, all of which are able to screen a natural particle physics scale vacuum energy using degeneracy in the field equations. We establish that well-tempering is the unique method of utilizing degeneracy in Horndeski scalar-tensor gravity -- and its teleparallel generalisation -- that can accommodate self-tuned flat Minkowski solutions, when the explicit scalar field dependence in the action is minimal (a tadpole and a conformal coupling to the Ricci scalar). Finally, we study the dynamics of the well-tempered teleparallel Galileon. We generate its phase portraits and assess the attractor nature of the Minkowski vacuum under linear perturbations and through a phase transition of vacuum energy.

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Reginald Christian Bernardo, Jackson Levi Said, Maria Caruana, Stephen Appleby. 2021-08-05. Well-Tempered Minkowski Solutions in Teleparallel Horndeski Theory. https://doi.org/10.1088/1361-6382%2Fac36e4

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