Phase locked inflation. Effectively trans-Planckian natural inflation

Harigaya, Keisuke; Ibe, Masahiro

doi:10.1007/jhep11(2014)147

Cited by 18 publications

(14 citation statements)

References 76 publications

(128 reference statements)

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“…The linear realization of the alignment mechanism with two axions was first studied in ref. [39] and later extended to multiple fields [40], where a peculiar structure of the U(1) charge assignment was noted. A more concrete realization along this line was given in refs.…”

Section: Jhep06(2016)150mentioning

confidence: 98%

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Quality of the Peccei-Quinn symmetry in the aligned QCD axion and cosmological implications

Higaki

Jeong

Kitajima

et al. 2016

J. High Energ. Phys.

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We show that the required high quality of the Peccei-Quinn symmetry can be naturally explained in the aligned QCD axion models where the QCD axion arises from multiple axions with decay constants much smaller than the axion window, e.g., around the weak scale. Even in the presence of general Planck-suppressed Peccei-Quinn symmetry breaking operators, the effective strong CP phase remains sufficiently small in contrast to the standard axion models without the alignment. The QCD axion potential has small or large modulations due to the symmetry breaking operators, which can significantly affect the axion cosmology. When the axions are trapped in different minima, domain walls appear and their scaling behavior suppresses the axion isocurvature perturbations at super-horizon scales. Our scenario predicts many axions and saxions coupled to gluons, and they may be searched for at collider experiments. In particular, the recently found diphoton excess at 750 GeV could be due to one of such (s)axions.

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Section: Jhep06(2016)150mentioning

confidence: 98%

“…In this section we first review the aligned axion model [33][34][35][40][41][42], and apply the idea to the QCD axion to see how the QCD axion could arise from multiple axions with low axion decay constants through the alignment mechanism.…”

Section: Aligned Qcd Axionmentioning

confidence: 99%

Quality of the Peccei-Quinn symmetry in the aligned QCD axion and cosmological implications

Higaki

Jeong

Kitajima

et al. 2016

J. High Energ. Phys.

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“…A peculiar structure of the charge assignment for the N axions was noted in ref. [28], and a concrete realization was given in refs. [29,30].…”

Section: Introductionmentioning

confidence: 99%

Topological defects and nano-Hz gravitational waves in aligned axion models

Higaki

Jeong

Kitajima

et al. 2016

J. High Energ. Phys.

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We study the formation and evolution of topological defects in an aligned axion model with multiple Peccei-Quinn scalars, where the QCD axion is realized by a certain combination of the axions with decay constants much smaller than the conventional PecceiQuinn breaking scale. When the underlying U(1) symmetries are spontaneously broken, the aligned structure in the axion field space exhibits itself as a complicated string-wall network in the real space. We find that the string-wall network likely survives until the QCD phase transition if the number of the Peccei-Quinn scalars is greater than two. The stringwall system collapses during the QCD phase transition, producing a significant amount of gravitational waves in the nano-Hz range at present. The typical decay constant is constrained to be below O(100) TeV by the pulsar timing observations, and the constraint will be improved by a factor of 2 in the future SKA observations.

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“…We require either 1) the axion rotation is damped after the electroweak phase transition, 2) the electroweak phase transition occurs earlier than the SM prediction, or 3) c B O(1) because of a large coefficient of the weak anomaly.When the Higgs couples to particles with masses above the electroweak scale, it is possible that the electroweak phase transition occurs at a high temperature, and the Higgs eventually relaxes to the electroweak scale. We present a toy model in the Supplemental Material.A large weak anomaly coefficient is possible in multifield extensions of the Kim-Nilles-Peloso mechanism [47][48][49][50][51][52], as considered in [53]. Assuming axion dark matter, the axion-photon coupling iswhere α is the fine structure constant.…”

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confidence: 99%

Axiogenesis

2020

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We propose a mechanism called axiogenesis where the cosmological excess of baryons over antibaryons is generated from the rotation of the QCD axion. The Peccei-Quinn (PQ) symmetry may be explicitly broken in the early universe, inducing the rotation of a PQ charged scalar field. The rotation corresponds to the asymmetry of the PQ charge, which is converted into the baryon asymmetry via QCD and electroweak sphaleron transitions. In the concrete model we explore, interesting phenomenology arises due to the prediction of a small decay constant and the connections with new physics at the LHC and future colliders and with axion dark matter.Introduction.-One of the goals of fundamental physics is to understand the origin of the Universe. For this purpose, the Standard Model (SM) of particle physics needs an extension to explain the cosmological excess of matter over antimatter. Mechanisms to generate the baryon asymmetry have been intensively studied in the literature under the name of baryogenesis [1][2][3][4][5][6][7][8].The SM also needs an extension to explain the smallness of CP violation in QCD [9] which on theoretical grounds is expected to be large [10]. This is known as the strong CP problem and can be elegantly solved by the Peccei-Quinn (PQ) mechanism [11,12]. The so-called the PQ symmetry is spontaneously broken to yield a pseudo Nambu-Goldstone boson, the axion [13,14]. The PQ symmetry is explicitly broken by the quantum effects of QCD of the Adler-Bell-Jeckiw type [15,16]. The quantum effects give a potential to the axion and drive the axion field value to the point where CP symmetry is restored, solving the strong CP problem. The axion is also a dark matter candidate [17][18][19], which makes the PQ mechanism even more attractive.We discover that when the PQ mechanism is introduced into the SM, the baryon (B) and lepton (L) asymmetries are generated in a wide class of models. We call the following baryogenesis scheme as axiogenesis, which in general includes two main ingredients: 1) an asymmetry of the PQ charge is generated in the early universe as a coherent rotation in the axion direction and 2) the PQ asymmetry is later transferred to the B + L asymmetry via the QCD and electroweak sphaleron transitions. We contrast axiogenesis with other existing baryogenesis models after we introduce a concrete example. (We may convert the B + L asymmetry into the B − L asymmetry by some B − L breaking interaction. The investigation of such a scenario will be considered in a future work [20].)The PQ symmetry is an approximate global symmetry which is explicitly broken by the QCD anomaly. Given that the symmetry is not exact, it is conceivable that the PQ symmetry is significantly broken in the early universe, and the rotation of the axion is induced. In fact, it is expected that quantum gravity does not allow for a global symmetry [21][22][23][24][25] and the PQ symmetry is at best understood as an accidental symmetry explicitly broken by higher dimensional operators [26][27][28][29]. Even when one requires that t...

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Phase locked inflation. Effectively trans-Planckian natural inflation

Cited by 18 publications

References 76 publications

Quality of the Peccei-Quinn symmetry in the aligned QCD axion and cosmological implications

Quality of the Peccei-Quinn symmetry in the aligned QCD axion and cosmological implications

Topological defects and nano-Hz gravitational waves in aligned axion models

Axiogenesis

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