Emergent/composite axions

Anastasopoulos, Pascal; Betzios, Panagiotis; Bianchi, Massimo; Consoli, Dario; Kiritsis, Elias

doi:10.1007/jhep10(2019)113

Cited by 28 publications

(63 citation statements)

References 107 publications

(157 reference statements)

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“…There are several realizations of axions in QFT, with two extreme classes: the fundamental axions, [6]- [11], and the emergent or composite axions, [41]. We will produce here a typical simple model of a fundamental axions.…”

Section: A the Structure Of Axion Modelsmentioning

confidence: 99%

“…We will produce here a typical simple model of a fundamental axions. A general prescription of theories of composite axions and further references can be found in [41].…”

Section: A the Structure Of Axion Modelsmentioning

confidence: 99%

“…In such cases the axion is a composite generated by the instanton density. 39 The general quadratic effective action of the emergent axion was derived in [41]. In that case there is also a mass contribution to the axion effective action originating in the UV theory.…”

Section: A2 Other Axion Modelsmentioning

confidence: 99%

“…In a more general setup, recently considered in [41] and motivated in [42], ALPs emerge as composites of a hidden sector with a large number of colors (N c 1), which couples to the Standard Model (SM) via interactions that are irrelevant in the IR. This fact ensures that one can have an invisible emergent axion even if the strong coupling scale Λ h of the hidden gauge theory is much smaller than Λ QCD .…”

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confidence: 99%

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Non-derivative axionic couplings to nucleons at large and small N

Bigazzi

Cotrone

Järvinen

et al. 2020

J. High Energ. Phys.

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Among the possible CP-odd couplings of the axion to ordinary matter, the most relevant ones for phenomenology are the Yukawa couplings to nucleons. We analyze such non-derivative couplings within three complementary approaches: standard effective field theory, the Skyrme model and holographic QCD. In all the cases, the couplings can be related to the CP-odd non-derivative couplings to nucleons of the low-lying mesons and the η . Using the effective field theory approach we derive the expressions for the CP-odd interaction terms as functions of the parameters of the effective Lagrangian. Then, we compute the CP-odd couplings to nucleons of the axion, the η and the pseudo-Goldstone mesons in both the Skyrme and the holographic QCD model with N f = 2, 3 flavors. We relate the coefficients of the non-derivative axion-nucleon couplings to those of the derivative ones. The relations do not explicitly depend on model parameters. This allows us to provide quantitative estimates of these couplings. D. CP violating η -pion-pion coupling 56 E. Alternative numerical estimates of the couplings 57 Introduction and resultsThe Peccei-Quinn proposal [1] for a natural solution of the strong CP problem -the unnaturally small value of the QCD θ angle -implies the existence of a new light neutral pseudoscalar boson, the axion [2, 3]. The original theory, severely constrained by data, was not renormalizable because of the axion coupling to the QCD instanton density [4,5]. In renormalizable axion models, successively proposed in [6,7,8], the axions were also made very weakly interacting with ordinary matter, as required by experimental constraints. These "invisible axions", whose couplings to matter have been deduced using anomalies and the chiral Lagrangian [9]- [14], are nowadays considered among the most promising candidates as dark matter constituents, and also as possible realizations of the inflaton [15]- [20]. As of today, axion-like particles (ALPs) are ubiquitous and serve various purposes. The nomenclature has also evolved but still remains sometimes murky. Axions that solve the strong CP problem are typically called QCD axions. The term "axionlike particle" is often used to refer (only) to other types of axions.Generically, axions display a perturbative shift symmetry and couple to instanton densities. In any reliable quantum field theory (QFT) realization, the symmetry is broken (at best) to a discrete symmetry due to non-perturbative effects. Such effects, related to instantons in weakly-coupled models, induce a mass and, more generally, a potential term, for the QCD axion (see e.g. [13]).ALPs arise very commonly in string theory [21], the simplest example being the Ramond-Ramond (RR) axion of type IIB string theory. They can also arise, after compactification, from internal components of antisymmetric form gauge fields as well as from off-diagonal components of the metric. In these cases, ALPs are related to generalized gauge fields [22,23]. The corresponding gauge symmetries provide the perturbative Peccei-Quinn (PQ) sym...

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Section: A the Structure Of Axion Modelsmentioning

confidence: 99%

“…We will produce here a typical simple model of a fundamental axions. A general prescription of theories of composite axions and further references can be found in [41].…”

Section: A the Structure Of Axion Modelsmentioning

confidence: 99%

Section: A2 Other Axion Modelsmentioning

confidence: 99%

mentioning

confidence: 99%

See 2 more Smart Citations

Non-derivative axionic couplings to nucleons at large and small N

Bigazzi

Cotrone

Järvinen

et al. 2020

J. High Energ. Phys.

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“…To begin with, it has been argued that the dual QFT phase is not in the same universality class of finite temperature Yang-Mills (or QCD for that matters) 11 -some discrete symmetries do not match [37]. 12 Moreover, the deconfined phase dual solution reflects the six-dimensional nature of the holographic model in the UV; for example, the free energy density scales with the sixth power of the temperature. Nevertheless, the solution is very simple and allows to get a lot of geometric intuition on chiral symmetry restoration and deconfinement transition, so we are going to use it as a proof of concept.…”

Section: The Holographic Axion At Large Temperaturementioning

confidence: 99%

The holographic QCD axion

Bigazzi

Caddeo

Cotrone

et al. 2019

J. High Energ. Phys.

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A holographic model of QCD axion is presented. It describes a composite axion in the KSVZ class. Having a gravity dual, based on the Witten-Sakai-Sugimoto model, it is calculable in the strongly coupled regime. Its basic properties are derived, including the low energy Lagrangian, from which the axion couplings to nucleons can be derived. Basic features in the deconfined phase are studied as well. In particular, the temperature dependence of the axion mass is extracted from the topological susceptibility. As an aside, the topological susceptibility of strongly coupled N = 4 SYM at finite temperature is derived for the first time.

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Holographic Theories at Finite θ‐Angle, CP‐Violation, Glueball Spectra and Strong‐Coupling Instabilities

Hamada

Kiritsis

Nitti

2020

Fortschritte der Physik

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A general class of holographic theories with a nontrivial θ‐angle are analyzed. The instanton density operator is dual to a bulk axion field. We calculate the ground‐state solutions with nontrivial source, aUV, for the axion, for both steep and soft dilaton potentials in the IR, and both in d=3 and d=4. We find all cases to be qualitatively similar. We also calculate the spin=2, 0 glueball spectra and show that the glueball masses monotonically decrease as functions of aUV (or θ‐angle). The slopes of glueball masses are different, generically, in different potentials. In the case of steep dilaton potentials, the glueball (masses)2 turn negative before the maximum of aUV is attained. We interpret this as a signal for a favored instanton condensation in the bulk. We also investigate strong CP‐violation in the effective glueball action.

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Emergent/composite axions

Cited by 28 publications

References 107 publications

Non-derivative axionic couplings to nucleons at large and small N

Non-derivative axionic couplings to nucleons at large and small N

The holographic QCD axion

Holographic Theories at Finite θ‐Angle, CP‐Violation, Glueball Spectra and Strong‐Coupling Instabilities

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