Small instanton-induced flavor invariants and the axion potential

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Auteurs principaux: Bedi, Ravneet, Gherghetta, Tony, Grojean, Christophe, Guedes, Guilherme, Kley, Jonathan, Vuong, Pham Ngoc Hoa
Format: Preprint
Publié: 2024
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author Bedi, Ravneet
Gherghetta, Tony
Grojean, Christophe
Guedes, Guilherme
Kley, Jonathan
Vuong, Pham Ngoc Hoa
author_facet Bedi, Ravneet
Gherghetta, Tony
Grojean, Christophe
Guedes, Guilherme
Kley, Jonathan
Vuong, Pham Ngoc Hoa
contents Small instantons which increase the axion mass due to an appropriate modification of QCD at a UV scale $Λ_{\rm SI}$, can also enhance the effect of CP-violating operators to shift the axion potential minimum by an amount, $θ_{\rm ind}$, proportional to the flavorful couplings in the SMEFT. Since physical observables must be flavor basis independent, we construct a basis of determinant-like flavor invariants that arise from instanton calculations containing the effects of dimension-six CP-odd operators at the scale $\require{cancel}Λ_{\cancel{\rm CP}}$. This new basis provides a more reliable estimate of the shift $θ_{\rm ind}$, that is severely constrained by neutron electric dipole moment experiments. In particular, for the case of four-quark, semi-leptonic and gluon dipole operators, these invariants are then used to provide improved limits on the ratio of scales $\require{cancel}Λ_{\rm SI}/Λ_{\cancel{\rm CP}}$ for different flavor scenarios. The CP-odd flavor invariants also provide a classification of the leading effects from Wilson coefficients, and as an example, we show that a semi-leptonic four-fermion operator is subdominant compared to the four-quark operators. More generally, the flavor invariants, together with an instanton NDA, can be used to more accurately estimate small instanton effects in the axion potential that arise from any SMEFT operator.
format Preprint
id arxiv_https___arxiv_org_abs_2402_09361
institution arXiv
publishDate 2024
record_format arxiv
spellingShingle Small instanton-induced flavor invariants and the axion potential
Bedi, Ravneet
Gherghetta, Tony
Grojean, Christophe
Guedes, Guilherme
Kley, Jonathan
Vuong, Pham Ngoc Hoa
High Energy Physics - Phenomenology
Small instantons which increase the axion mass due to an appropriate modification of QCD at a UV scale $Λ_{\rm SI}$, can also enhance the effect of CP-violating operators to shift the axion potential minimum by an amount, $θ_{\rm ind}$, proportional to the flavorful couplings in the SMEFT. Since physical observables must be flavor basis independent, we construct a basis of determinant-like flavor invariants that arise from instanton calculations containing the effects of dimension-six CP-odd operators at the scale $\require{cancel}Λ_{\cancel{\rm CP}}$. This new basis provides a more reliable estimate of the shift $θ_{\rm ind}$, that is severely constrained by neutron electric dipole moment experiments. In particular, for the case of four-quark, semi-leptonic and gluon dipole operators, these invariants are then used to provide improved limits on the ratio of scales $\require{cancel}Λ_{\rm SI}/Λ_{\cancel{\rm CP}}$ for different flavor scenarios. The CP-odd flavor invariants also provide a classification of the leading effects from Wilson coefficients, and as an example, we show that a semi-leptonic four-fermion operator is subdominant compared to the four-quark operators. More generally, the flavor invariants, together with an instanton NDA, can be used to more accurately estimate small instanton effects in the axion potential that arise from any SMEFT operator.
title Small instanton-induced flavor invariants and the axion potential
topic High Energy Physics - Phenomenology
url https://arxiv.org/abs/2402.09361