Axion depending on the Higgs sector inSU(2)L×SU(2)R×U(1)

Using Higgses with quantum numbers of fermion bilinears we discuss the axion in four different Higgs sectors inSU(2)_L×SU(2)_R×U(1). Three of the cases are similar to the “standard axion” in the Salam-Weinberg model and in one case the axion can be made invisible.     

Dynamical interactions of dark energy and dark matter:Yang-Mills condensate and QCD axions

We analyze a model of cold axion dark matter weakly coupled with a dark gluon condensate,reproducing dark energy.We first review how to recover the dark energy behavior using the functional renormalization group approach,and ground our study in the properties of the effective Lagrangian,to be determined non-perturbatively.Then,within the context of G_(SM)×SU(2)_D×U(1)_(P Q),we consider Yang-Mills condensate(YMC)interactions with QCD axions.We predict a transfer of dark energy density into dark matter density,that can be tested in the next generation of experiments dedicated to dark energy measurements.We obtain new bounds on the interactions between the Yang-Mills condensate and axion dark matter from Planck data:the new physics interaction scale related to the axion/gluon condensate mixing is constrained to be higher than the 10~6GeV energy scale.     

SupersymmetricSU (11), the invisible axion,and proton decay

We supersymmetrize the very attractive flavour unification modelSU (11). As with other supersymmetric GUTs the gauge hierarchy problem is simplified, but we may also have observable (τ _p ≈10³³ yrs) proton decay. The required split multiplets are obtained by making the adjoint take a particular direction. Supersymmetry is broken softly at the TeV scale. There is a uniqueU(1) _A symmetry, and hence there are no true Nambu-Goldstone bosons. TheU(1) _A is broken at the GUT scale and there result an invisible axion and neutrino masses.     

Light-Front Quantization of Conformally Gauge-Fixed Polyakov D1-Brane Action in the Presence of a Scalar Axion Field and an U(1) Gauge Field

Light-front quantization of the conformally gauge-fixed Polyakov D1 brane action in the presence of a constant background scalar axion field C(τ, σ) and an U(1) gauge field A _α (τ, σ) is studied. The axion field C and the U(1) gauge field A _α , are seen to behave like the Wess–Zumino (WZ) fields and the term involving these fields is seen to behave like a WZ term for this action.     

Orthopositronium decay into axions

We point out that if the mass of the hypothetical particle called the axion is less than 2m_e, then it can be emitted in the decay of orthopositronium. The lifetime of the decay 1³S₁ → γh is calculated to be about 8 s. We suggest an experiment to look for “single” photons from positronium annihilation. An accurate measurement of the energy E_γ of these photons gives the mass of the axion through the relation m²_axion = 4m_e(m_e ? E_γ).     

Low-scale axion from large extra dimensions

The mass of the axion and its decay rate are known to depend only on the scale of Peccei–Quinn symmetry breaking, which is constrained by astrophysics and cosmology to be between 10⁹ and 10¹² GeV. We propose a new mechanism such that this effective scale is preserved and yet the fundamental breaking scale of U(1)_PQ is very small (a kind of inverse seesaw) in the context of large extra dimensions with an anomalous U(1) gauge symmetry in our brane. The production and decay of the associated Z_A gauge boson, which ends up as two gluons and two axions, is a distinct collider signature of this scenario.     

The minimal axion minimal linear $$\sigma $$ model

The minimal SO(5) / SO(4) linear \(\sigma \) model is extended including an additional complex scalar field, singlet under the global SO(5) and the Standard Model gauge symmetries. The presence of this scalar field creates the conditions to generate an axion à la KSVZ, providing a solution to the strong CP problem, or an axion-like-particle. Different choices for the PQ charges are possible and lead to physically distinct Lagrangians. The internal consistency of each model necessarily requires the study of the scalar potential describing the \(SO(5)\rightarrow SO(4)\), electroweak and PQ symmetry breaking. A single minimal scenario is identified and the associated scalar potential is minimised including counterterms needed to ensure one-loop renormalizability. In the allowed parameter space, phenomenological features of the scalar degrees of freedom, of the exotic fermions and of the axion are illustrated. Two distinct possibilities for the axion arise: either it is a QCD axion with an associated scale larger than \(\sim 10^{5}\) TeV and therefore falling in the category of the invisible axions; or it is a more massive axion-like-particle, such as a 1 GeV axion with an associated scale of \(\sim 200\) TeV, that may show up in collider searches.     

Weak interaction effects in positronium

Within the context of the Weinberg-Salam (standard) model we study possible effects of weak interactions in positronium (Ps), such as parity mixing and weak decays of Ps states. As expected, weak interaction amplitudes in Ps turn out to be extremely small, their magnitude being characterized byG·m _e ² ?3·10^?12 whereG is Fermi's constant andm _e the electron mass. We show that the standard model forbids parity-violating correlations in a large class of Ps reactions and decays due to CP conservation in the lepton sector. We then consider situations in which parity-odd effects in Ps will occur in the standard model and may even be large enough to be observable. Beyond the context of the standard model we discuss the decay of orthopositronium into a photon and the hypothetical axion under the assumption that the mass of the axion is smaller than twice the mass of the electron.     

Opening the axion window

In this paper I consider models where the strong CP problem is solved by means of a Peccei-Quinn symmetry carried by exotic colored fermions. An example is Kim's recently proposed composite invisible axion model. Axions from such models don't couple to electrons, and have model dependent photon couplings which may differ from the standard coupling by a factor of 10^?2 ? 10⁺¹. As a result, laboratory detection of relic axions may be very difficult, and astrophysical bounds on the axion mass are weakened. Pulsar observations place no strong bound on such an axion unless the core is known not to be superfluid. Normal fusion stars allow an axion mass as large as $\text{m}{}_{\mathrm{<mtext>a</mtext>}}\text{? 20}\text{eV}$ for certain models.     

Search for solar axions emitted in the M1-transition of 7Li* with Borexino CTF

Results of background measurements with a prototype of the Borexino detector were used to search for 478 keV solar axions emitted in the M1-transitions of ⁷Li^*. The Compton conversion of axion to a photon A+e→e+γ, axioelectric effect A+e+Z→e+Z, decay of axion in two photons A→2γ and Primakoff conversion on nuclei A+Z→γ+Z are considered. The upper limit on constants of interaction of axion with electrons, photons and nucleons – g_Aeg_AN≤(1.0–2.4)×10^-10 at m_A≤450 keV and g_Aγg_AN≤5×10^-9 GeV^-1 at m_A≤10 keV are obtained (90%c.l.). For heavy axions with mass at 100<m_A<400 keV the limits g_Ae<(0.7–2.0)×10^-8 and g_Aγ<10^-9–10^-8 are obtained in assumption that g_AN depends on m_A as for KSVZ axion model. These limits are stronger than obtained in previous laboratory-based experiments using nuclear reactor and artificial radioactive sources. PACS 14.80.Mz; 29.40.Mc; 26.65.+t     

Search for solar axions generated by the Primakoff effect with resonance absorption by <Superscript>169</Superscript>Tm

We searched for resonant excitation of the first excited state of the ¹⁶⁹Tm nucleus by axions formed inside the Sun by the Primakoff effect, A + ¹⁶⁹Tm → ¹⁶⁹Tm* → ¹⁶⁹Tm + γ (8.41keV). Gamma quanta with an energy of 8.41keV were registered by a sectionalized Si(Li) detector installed in a low-background setup. As a result, we set a new upper limit for the photon to axion coupling constant, g _Aγ (GeV⁻¹)m _A (eV) ≤ 1.06 × 10⁻⁵, which for a hadronic axion model corresponds to a mass limit of m _A ≤ 169 eV at a 90% confidence level.     

Maximum Entropy Inferences on the Axion Mass in Models with Axion-Neutrino Interaction

In this work, we use the maximum entropy principle (MEP) to infer the mass of an axion which interacts to photons and neutrinos in an effective low energy theory. The Shannon entropy function to be maximized is defined in terms of the axion branching ratios. We show that MEP strongly constrains the axion mass taking into account the current experimental bounds on the neutrinos masses. Assuming that the axion is massive enough to decay into all the three neutrinos and that MEP fixes all the free parameters of the model, the inferred axion mass is in the interval 0.1 eV < m _A < 0.2 eV, which can be tested by forthcoming experiments such as IAXO. However, even in the case where MEP fixes just the axion mass and no other parameter, we found that 0.1 eV < m _A < 6.3 eV in the DFSZ model with right-handed neutrinos. Moreover, a light axion, allowed to decay to photons and the lightest neutrino only, is determined by MEP as a viable dark matter candidate.     

New Constraints on the Axion–Photon Coupling Constant for Solar Axions

Resonance excitation of the ⁸³Kr first nuclear level (E = 9.4 keV) by solar axions formed via the Primakoff mechanism is sought. The γ- and X-ray photons and the conversion and Auger electrons arising from the excited-level relaxation are detected with a gas proportional counter of a low-background detector in the underground Baksan Neutrino Observatory. The following experimental constraint is obtained for the product of the axion–photon coupling constant and the axion mass:|g_Aγ × m_A| ≤ 6.3 × 10 ^-17 In the framework of the hadronic-axion model, this corresponds to a new axion-mass constraint of m_A ≤ 12.7 eV at 95% C.L.     

Destruction of axion miniclusters in the Galaxy

Previously, it has been established that axion dark matter (DM) is clustered to form clumps (axion miniclusters) with masses M ≈ 10^–12 M _⊙. The passages of such clumps through the Earth are very rare events occurring once in 10⁵ years. It has also been shown that the Earth’s passage through DM streams, which are the remnants of clumps destroyed by tidal gravitational forces from Galactic stars, is a much more probable event occurring once in several years. In this paper, we have performed detailed calculations of the destruction of miniclusters by taking into account their distribution in orbits in the Galactic halo. We have investigated two DM halo models, the Navarro–Frenk–White and isothermal density profiles. Apart from the Galactic disk stars, we have also taken into account the halo and bulge stars. We show that about 2–5% of the axion miniclusters are destroyed when passing near stars and transform into axion streams, while the clump destruction efficiency depends on the DM halo model. The expected detection rate of streams with an overdensity exceeding an order of magnitude is 1–2 in 20 years. The possibility of detecting streams by their tidal gravitational effect on gravitational-wave interferometers is also considered.     

Cosmology of spontaneously broken gauge family symmetry with axion solution of strong CP-problem

TheSU(3) _H model of spontaneously broken local family symmetry is considered as a simplest version of realistic quantum flavourdynamics, giving reasonable explanation of the mass hierarchy and mixing pattern of quarks and leptons. This scheme can naturally possess one or two additional globalU(1) symmetries, which can play the role of Peccei-Quinn symmetry. The model predicts: existence of the neutrino Majorana masses with definite hierarchy, existence of familon being simultaneously invisible axion (or arion) and Majoron, relationship between neutrino lifetimes relative to familon decays. Thereby, the model provides the unified physical ground for all the main types of dark matter, considered in the theory of large scale structure of the universe.     

The horizontal axion alternative: The interplay of vacuum structure and flavor interactions

We classify all minimal N-generational SU(3) × SU(2) × U(1) axion models according to the structure of their vacuum manifold M, showing that n ≡ π₀(M) is such that 1 ? n ? N. For n < N, the purely axial U(1)_A must be explicitly broken in the Yukawa sector, implying that U(1)_PQ necessarily distinguishes some quark families. In fact, a complete distinction, i.e. a fully horizontal realization of U(1)_PQ does exist for arbitrary N, leading to definite flavor interaction patterns with non-trivial relative structure of the mass matrices M_u versus M_d. For each n, in particular for the domain-wall-free n = 1 case, we find a unique Yukawa pattern embeddable in unified SU(5), whereas SO(10) can only host n = N. It is emphasized that axion invisibility guarantees the invisibility of flavor changing neutral currents.     

Axion search in a monochromatic γ-transition: A new lower limit for the axion mass

A search for axion emission in ¹³⁷Ba¹ was performed, looking for the decay of the a₀'s in two photons. The existence of a₀'s with m_a?160 (200) keV can be excluded with rather mild assumptions.     

Born-Infeld axion-dilaton electrodynamics and electromagnetic confinement

A generalization of Born-Infeld non-linear vacuum electrodynamics involving axion and dilaton fields is constructed with couplings dictated by electromagnetic duality and SL(2,R) symmetries in the weak field limit. Besides the Newtonian gravitational constant the model contains a single fundamental coupling parameter b₀. In the absence of axion and dilaton interactions it reduces in the limit b₀?∞ to Maxwell?s linear vacuum theory while for finite b₀ it reduces to the original Born-Infeld model. The spherically symmetric static sector of the theory is explored in a flat background spacetime in the Jordan frame where numerical evidence suggests the existence of axion-dilaton bound states possessing confined electric flux.     

Mass of the up quark and chiral symmetry at infinite momentum

We find here that a very low mass for the X⁰ meson (m_X0=305.5 MeV) is predicted from a study of the pseudoscalar mesons in the framework of chiral symmetry at infinite momentum when the up quark mass vanishes (as an alternative to axion).