PQ axiverse

A bstract We show that the strong CP problem is solved in a large class of compactifications of string theory. The Peccei-Quinn mechanism solves the strong CP problem if the CP-breaking effects of the ultraviolet completion of gravity and of QCD are small compared to the CP-preserving axion potentia...

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Bibliographic Details
Published in:The journal of high energy physics Vol. 2023; no. 6; pp. 92 - 31
Main Authors: Demirtas, Mehmet, Gendler, Naomi, Long, Cody, McAllister, Liam, Moritz, Jakob
Format: Journal Article
Language:English
Published: Berlin/Heidelberg Springer Berlin Heidelberg 15.06.2023
Springer Nature B.V
Springer Nature
SpringerOpen
Subjects:
Astronomical models
Axions and ALPs
Branes
Broken symmetry
Classical and Quantum Gravitation
Dipole moments
Electric dipoles
Elementary Particles
Flux Compactifications
Gravitational effects
Hierarchies
High energy physics
Hyperspaces
Instantons
Physics
Physics and Astronomy
PHYSICS OF ELEMENTARY PARTICLES AND FIELDS
Quantum chromodynamics
Quantum Field Theories
Quantum Field Theory
Quantum Physics
Regular Article - Theoretical Physics
Relativity Theory
String and Brane Phenomenology
String Theory
Superstring Vacua
Supersymmetry
Superstring Vacua
Axions and ALPs
String and Brane Phenomenology
Flux Compactifications
ISSN:1029-8479, 1029-8479
Online Access:Get full text
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Summary:A bstract We show that the strong CP problem is solved in a large class of compactifications of string theory. The Peccei-Quinn mechanism solves the strong CP problem if the CP-breaking effects of the ultraviolet completion of gravity and of QCD are small compared to the CP-preserving axion potential generated by low-energy QCD instantons. We characterize both classes of effects. To understand quantum gravitational effects, we consider an ensemble of flux compactifications of type IIB string theory on orientifolds of Calabi-Yau hypersurfaces in the geometric regime, taking a simple model of QCD on D7-branes. We show that the D-brane instanton contribution to the neutron electric dipole moment falls exponentially in N 4 , with N the number of axions. In particular, this contribution is negligible in all models in our ensemble with N > 17. We interpret this result as a consequence of large N effects in the geometry that create hierarchies in instanton actions and also suppress the ultraviolet cutoff. We also compute the CP breaking due to high-energy instantons in QCD. In the absence of vectorlike pairs, we find contributions to the neutron electric dipole moment that are not excluded, but that could be accessible to future experiments if the scale of supersymmetry breaking is sufficiently low. The existence of vectorlike pairs can lead to a larger dipole moment. Finally, we show that a significant fraction of models are allowed by standard cosmological and astrophysical constraints.
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USDOE Office of Science (SC)
National Science Foundation (NSF)
SC0013607; PHY-1719877
ISSN:1029-8479
1029-8479
DOI:10.1007/JHEP06(2023)092