Accidental SO(10) axion from gauged flavour

Luzio, Luca Di

doi:10.1007/jhep11(2020)074

Cited by 17 publications

(10 citation statements)

References 70 publications

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“…[12][13][14][15][16][17] that this U(1)-violating effect is generically too large to solve the strong CP problem due to the high sensitivity of the Peccei-Quinn mechanism to the U(1)-breaking effectthis is dubbed as the axion quality problem. This observation stimulated a variety of works to construct axion models that evade the quality problem, such as those utilizing additional gauge symmetries [18][19][20][21][22][23][24][25][26][27][28][29][30][31][32][33][34][35][36], heavy axion models [37][38][39][40][41][42][43][44][45][46][47][48][49][50], composite axion models [51][52][53][54][55][56][57][58][59], and so on …”

Section: Introductionmentioning

confidence: 99%

Axion Quality Problem Alleviated by Non-Minimal Coupling to Gravity

Hamaguchi,

Kanazawa,

Nagata

2021

Preprint

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Global symmetries are expected to be violated by gravity, which may cause a serious problem to models based on these symmetries. A famous example is the Peccei-Quinn solution to the strong CP problem in QCD axion models; it requires a global U(1) symmetry to be respected with high quality, and even the Planck-scale suppressed operators that violate the U(1) symmetry would spoil this solution. Indeed, it is known that gravitational instantons do break the U(1) Peccei-Quinn symmetry and induce the U(1)-violating operators, bringing back the strong CP problem to the axion models. This conclusion is, however, dependent highly on the structure of the theory around the Planck scale and, therefore, may be evaded if we go beyond the minimal setup. In this paper, we study the effect of a non-minimal coupling of the Peccei-Quinn field to gravity, ξ, on the gravitational instanton effect. This setup is frequently considered in cosmology as it can realize a successful inflation if ξ 10 5 . We find that the U(1)-breaking effect of the gravitational instantons can sufficiently be suppressed for ξ 2 × 10 3 , which suggests that the U(1) symmetry may be maintained with high quality even in the presence of gravity. Our result thus points to a new way to avoid the quality problem of global symmetries.

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Section: Introductionmentioning

confidence: 99%

Axion Quality Problem Alleviated by Non-Minimal Coupling to Gravity

Hamaguchi,

Kanazawa,

Nagata

2021

Preprint

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“…UV sources of PQ breaking can be avoided in some invisible axion constructions within a variety of extra assumptions or frameworks[66][67][68][69][70][71][72][73][74][75][76][77][78], or be arguably negligible under certain conditions[79].…”

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confidence: 99%

An even lighter QCD axion

Luzio

Gavela

Quílez

et al. 2021

J. High Energ. Phys.

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We explore whether the axion which solves the strong CP problem can naturally be much lighter than the canonical QCD axion. The $$ {Z}_{\mathcal{N}} $$ Z N symmetry proposed by Hook, with $$ \mathcal{N} $$ N mirror and degenerate worlds coexisting in Nature and linked by the axion field, is considered in terms of generic effective axion couplings. We show that the total potential is safely approximated by a single cosine in the large $$ \mathcal{N} $$ N limit, and we determine the analytical formula for the exponentially suppressed axion mass. The resulting universal enhancement of all axion interactions relative to those of the canonical QCD axion has a strong impact on the prospects of axion-like particle experiments such as ALPS II, IAXO and many others: experiments searching for generic axion-like particles have in fact discovery potential to solve the strong CP problem. The finite density axion potential is also analyzed and we show that the $$ {Z}_{\mathcal{N}} $$ Z N asymmetric background of high-density stellar environments sets already significant model-independent constraints: 3 ≤ $$ \mathcal{N} $$ N ≲ 47 for an axion scale fa ≲ 2.4 × 1015 GeV, with tantalizing discovery prospects for any value of fa and down to $$ \mathcal{N} $$ N ∼ 9 with future neutron star and gravitational wave data, down to the ultra-light mass region. In addition, two specific ultraviolet $$ {Z}_{\mathcal{N}} $$ Z N completions are developed: a composite axion one and a KSVZ-like model with improved Peccei-Quinn quality.

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“…The grand unification theories (GUT) were considered as framework for the axion models based on the SU(5) [9] and SO (10) [10] unifications. Later, other varieties based on the SU (5) [11][12][13][14][15][16][17][18][19][20], SO (10) [18,[21][22][23][24][25][26], and E 6 [27] were also studied. In most of the previous SU (5) and SO (10) GUT model buildings, the global U(1) PQ symmetry commutes with the GUT group.…”

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confidence: 99%

“…This leads to the PQ quality problem [11,[28][29][30][31][32], where the global U(1) PQ symmetry should be a good symmetry at sufficiently high scale. It is therefore desirable to have the PQ symmetry arise automatically, and this was discussed in the context of various GUTs [11,26], as well as models with extended gauge symmetries [33][34][35][36][37][38][39][40][41][42][43][44][45][46].…”

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confidence: 99%

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Axion model with the ${\rm SU}(6)$ unification

Chen,

Liu,

Teng

2021

Preprint

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We propose an axion model with the SU(6) unification symmetry. Such a unification model can lead to an automatic global U(1)PQ symmetry from two copies of anti-fundamental fermions. The SU( 6) is first broken to the extended symmetry of SU(3)c ⊗ SU(3)L ⊗ U(1)N , and the Higgs fields for the sequential symmetry breaking contain the physical axion fields. The low-energy theory at the electroweak scale is described by the type-II two-Higgs-doublet model. The physical axion satisfies the Peccei-Quinn quality condition without much fine-tuning of the dimension-6 operator, with the mass range of ∼ O(10 −3 ) − O(0.1) eV. The axion-photon coupling of gaγγ is identical to the type-I DFSZ scenario, and can be probed in the upcoming axion search experiments of LAMPOST and IAXO in the high mass region.

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Accidental SO(10) axion from gauged flavour

Cited by 17 publications

References 70 publications

Axion Quality Problem Alleviated by Non-Minimal Coupling to Gravity

Axion Quality Problem Alleviated by Non-Minimal Coupling to Gravity

An even lighter QCD axion

Axion model with the ${\rm SU}(6)$ unification

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