Solving the strong CP problem with massless grand-color quarks

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Hauptverfasser: Bedi, Ravneet, Gherghetta, Tony, Harigaya, Keisuke
Format: Preprint
Veröffentlicht: 2024
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author Bedi, Ravneet
Gherghetta, Tony
Harigaya, Keisuke
author_facet Bedi, Ravneet
Gherghetta, Tony
Harigaya, Keisuke
contents We propose a solution to the strong CP problem that specifically relies on massless quarks and has no light axion. The QCD color group $SU(3)_c$ is embedded into a larger, simple gauge group (grand-color) where one of the massless, colored fermions enjoys an anomalous chiral symmetry, rendering the strong CP phase unphysical. The grand-color gauge group $G_{\rm GC}$ is Higgsed down to $SU(3)_c\times G_{c'}$, after which $G_{c'}$ eventually confines at a lower scale, spontaneously breaking the chiral symmetry and generating a real, positive mass to the massless, colored fermion. Since the chiral symmetry has a $G_{c'}$ anomaly, there is no corresponding light Nambu-Goldstone boson. The anomalous chiral symmetry can be an accidental symmetry that arises from an exact discrete symmetry without introducing a domain wall problem. Potential experimental signals of our mechanism include vector-like quarks near the TeV scale, pseudo Nambu-Goldstone bosons below the 10 GeV scale, light dark matter decay, and primordial gravitational waves from the new strong dynamics.
format Preprint
id arxiv_https___arxiv_org_abs_2408_11246
institution arXiv
publishDate 2024
record_format arxiv
spellingShingle Solving the strong CP problem with massless grand-color quarks
Bedi, Ravneet
Gherghetta, Tony
Harigaya, Keisuke
High Energy Physics - Phenomenology
We propose a solution to the strong CP problem that specifically relies on massless quarks and has no light axion. The QCD color group $SU(3)_c$ is embedded into a larger, simple gauge group (grand-color) where one of the massless, colored fermions enjoys an anomalous chiral symmetry, rendering the strong CP phase unphysical. The grand-color gauge group $G_{\rm GC}$ is Higgsed down to $SU(3)_c\times G_{c'}$, after which $G_{c'}$ eventually confines at a lower scale, spontaneously breaking the chiral symmetry and generating a real, positive mass to the massless, colored fermion. Since the chiral symmetry has a $G_{c'}$ anomaly, there is no corresponding light Nambu-Goldstone boson. The anomalous chiral symmetry can be an accidental symmetry that arises from an exact discrete symmetry without introducing a domain wall problem. Potential experimental signals of our mechanism include vector-like quarks near the TeV scale, pseudo Nambu-Goldstone bosons below the 10 GeV scale, light dark matter decay, and primordial gravitational waves from the new strong dynamics.
title Solving the strong CP problem with massless grand-color quarks
topic High Energy Physics - Phenomenology
url https://arxiv.org/abs/2408.11246