The Non-triviality of Dynamical Chern-Simons Gravity and the Standard Model

Fuente: arXiv
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Autores principales: Alexander, Stephon, Bernardo, Heliudson, Creque-Sarbinowski, Cyril
Formato: Preprint
Publicado: 2024
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author Alexander, Stephon
Bernardo, Heliudson
Creque-Sarbinowski, Cyril
author_facet Alexander, Stephon
Bernardo, Heliudson
Creque-Sarbinowski, Cyril
contents Given the growing interest in gravitational-wave and cosmological parity-violating effects in dynamical Chern-Simons (dCS) gravity, it is crucial to investigate whether the scalar-gravitational Pontryagin term in dCS persists when formulated in the context of the $\text{U(1)}_{\text{B}-\text{L}}$ anomaly in the Standard Model (SM). In particular, it has been argued that dCS gravity can be reduced to Einstein gravity after ''rotating away'' the gravitational-Pontryagin coupling into the phase of the Weinberg operator $\unicode{x2013}$ analogous to the rotation of the axion zero-mode into the quark mass matrix. We find that dCS is nontrivial if the scalar field $ϕ$ has significant space-time dependence from dynamics. We provide a comprehensive consideration of the dCS classical and quantum symmetries relevant for embedding a dCS sector in the SM. We find that, because of the B-L chiral gravitational anomaly, the scalar-Pontryagin term cannot be absorbed by a field redefinition. Assuming a minimal extension of the SM, we also find that a coupling of the dCS scalar with right-handed neutrinos induces both the scalar-Pontryagin coupling and an axion-like phase in the dimension-five Weinberg operator. We comment on the issue of gauging the $\text{U(1)}_{\text{B}-\text{L}}$, the observational effects with these two operators present for upcoming experiments, and the origin of dCS gravity in string theory.
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institution arXiv
publishDate 2024
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spellingShingle The Non-triviality of Dynamical Chern-Simons Gravity and the Standard Model
Alexander, Stephon
Bernardo, Heliudson
Creque-Sarbinowski, Cyril
High Energy Physics - Theory
Cosmology and Nongalactic Astrophysics
General Relativity and Quantum Cosmology
High Energy Physics - Phenomenology
Given the growing interest in gravitational-wave and cosmological parity-violating effects in dynamical Chern-Simons (dCS) gravity, it is crucial to investigate whether the scalar-gravitational Pontryagin term in dCS persists when formulated in the context of the $\text{U(1)}_{\text{B}-\text{L}}$ anomaly in the Standard Model (SM). In particular, it has been argued that dCS gravity can be reduced to Einstein gravity after ''rotating away'' the gravitational-Pontryagin coupling into the phase of the Weinberg operator $\unicode{x2013}$ analogous to the rotation of the axion zero-mode into the quark mass matrix. We find that dCS is nontrivial if the scalar field $ϕ$ has significant space-time dependence from dynamics. We provide a comprehensive consideration of the dCS classical and quantum symmetries relevant for embedding a dCS sector in the SM. We find that, because of the B-L chiral gravitational anomaly, the scalar-Pontryagin term cannot be absorbed by a field redefinition. Assuming a minimal extension of the SM, we also find that a coupling of the dCS scalar with right-handed neutrinos induces both the scalar-Pontryagin coupling and an axion-like phase in the dimension-five Weinberg operator. We comment on the issue of gauging the $\text{U(1)}_{\text{B}-\text{L}}$, the observational effects with these two operators present for upcoming experiments, and the origin of dCS gravity in string theory.
title The Non-triviality of Dynamical Chern-Simons Gravity and the Standard Model
topic High Energy Physics - Theory
Cosmology and Nongalactic Astrophysics
General Relativity and Quantum Cosmology
High Energy Physics - Phenomenology
url https://arxiv.org/abs/2403.15657