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The Zhitnitsky and Dine, Fischler and Srednicki (DFSZ) model is a natural extension of the two-Higgsdoublet model containing an additional singlet, endowed with a Peccei-Quinn symmetry, and leading to a physically acceptable axion. In this paper we reexamine this model in the light of some new developments. For generic couplings the model reproduces the minimal Standard Model showing only tiny deviations (extreme decoupling scenario) and all additional degrees of freedom (with the exception of the axion) are very heavy. Recently it has been remarked that the limit where the coupling between the singlet and the two doublets becomes very small is technically natural. Combining this limit with the requirement of exact or approximate custodial symmetry, we may obtain an additional 0+ Higgs at the weak scale, accompanied by relatively light charged and neutral pseudoscalars. The mass spectrum would then resemble that of a generic two-Higgs-doublet model, with naturally adjustable masses in spite of the large scale that the axion introduces. However, the couplings are nongeneric in this model. We use the recent constraints derived from the Higgs- WW coupling together with oblique corrections to constrain the model as much as possible. As an additional result, we work out the nonlinear parametrization of the DFSZ model in the generic case where all scalars except the lightest Higgs and the axion have masses at or beyond the TeV scale. [ABSTRACT FROM AUTHOR]

The proximity of the Peccei-Quinn scale to the scale of supersymmetry breaking in models of pure gravity mediation hints at a common dynamical origin of these two scales. To demonstrate how to make such a connection manifest, we embed the Peccei-Quinn mechanism into the vectorlike model of dynamical supersymmetry breaking à la Izawa and Yanagida as well as Intriligator and Thomas (IYIT). Here, we rely on the anomaly-free discrete Z4R symmetry required in models of pure gravity mediation to solve the μ problem to protect the Peccei-Quinn symmetry from the dangerous effect of higher-dimensional operators. This results in a rich phenomenology featuring a QCD axion with a decay constant of O(1010) GeV and mixed dark matter in the form of weakly interacting massive particles and axions. In addition, exactly five pairs of extra 5 and 5* matter multiplets, directly coupled to the supersymmetry breaking sector and with masses close to the gravitino mass, m3/2 ~100 TeV, are needed to cancel the Z4R anomalies. [ABSTRACT FROM AUTHOR]

Axions in the Peccei-Quinn (PQ) mechanism provide a promising solution to the strong CP problem in the standard model of particle physics. Coherently generated PQ scalar fields could dominate the energy density in the early Universe and decay into relativistic axions, which would conflict with the current dark radiation constraints. We study the possibility that a thermal inflation driven by a U(1) gauged Higgs field dilutes such axions. A well-motivated extra gauged U(1) would be the local B -- L symmetry. We also discuss the implication for the case of U(1)B-L and an available baryogenesis mechanism in such cosmology. [ABSTRACT FROM AUTHOR]

We study a scenario allowing a solution of the strong charge parity problem via the Peccei-Quinn mechanism, implemented in gravity with torsion. In this framework there appears a torsion-related pseudoscalar field known as the Kalb-Ramond axion. We compare it with the so-called Barbero-Immirzi axion recently proposed in the literature also in the context of the gravity with torsion. We show that they are equivalent from the viewpoint of the effective theory. The phenomenology of these torsion-descended axions is completely determined by the Planck scale without any additional model parameters. These axions are very light and very weakly interacting with ordinary matter. We briefly comment on their astrophysical and cosmological implications in view of the recent BICEP2 and Planck data. [ABSTRACT FROM AUTHOR]

In an attempt to uncover any underlying physics in the standard model (SM), we suggest a μ-τ power law in the lepton sector, such that relatively large 13 mixing angle with bilarge ones can be derived. On the basis of this, we propose a neat and economical model for both the fermion mass hierarchy problem of the SM and a solution to the strong charge parity (CP) problem, in a way that no domain wall problem occurs, based on A4 x U (1)X symmetry in a supersymmetric framework. Here we refer to the global U(1)x symmetry that can explain the above problems as "flavored Peccei-Quinn symmetry." In the model, a direct coupling of the SM gauge singlet flavon fields responsible for spontaneous symmetry breaking to ordinary quarks and leptons, both of which are charged under U(l)x, comes to pass through Yukawa interactions, and all vacuum expectation values breaking the symmetries are connected to each other. So the scale of Peccei-Quinn symmetry breaking is shown to be roughly located around the 1012 GeV section through its connection to the fermion masses. The model predictions are shown to lie on the testable regions in the very near future through on-going experiments for neutrino oscillation, neutrinoless double beta decay, and the axion. We examine the model predictions, arisen from the μ-τ power law, on leptonic CP violation, neutrinoless double beta decay, and atmospheric mixing angle, and show that the fermion mass and mixing hierarchies are in good agreement with the present data. Interestingly, we show the model predictions on the axion mass ma = 2.53 x 10-5 eV and the axion coupling to photon ... 1.33 x 10-15 GeV-1. And subsequently the square of the ratio between them is shown to be one or two orders of magnitude lower than that of the conventional axion model. [ABSTRACT FROM AUTHOR]

A model of high scale inflation is presented where the radial part of the Peccei-Quinn (PQ) field with a non-minimal coupling to gravity plays the role of the inflaton, and the QCD axion is the dark matter. A quantum fluctuation of O(H/2π) in the axion field will result in a smaller angular fluctuation if the PQ field is sitting at a larger radius during inflation than in the vacuum. This changes the effective axion decay constant, ƒa, during inflation and dramatically reduces the production of isocurvature modes. This mechanism opens up a new window in parameter space where an axion decay constant in the range 1012 GeV ≲ ƒa ≲ 1015 GeV is compatible with observably large r. The exact range allowed for ƒa depends on the efficiency of reheating. This model also predicts a minimum possible value of r=10-3. The new window can be explored by a measurement of r possible with SPIDER and the proposed CASPEr experiment search for high ƒa axions. [ABSTRACT FROM AUTHOR]

The Peccei-Quinn anomalous global U(1)PQ symmetry is important for solving the strong CP problem with a cosmologically relevant axion. We add to this the simple (but hitherto unexplored) observation that it also has a residual Z2 symmetry which may be responsible for a second component of dark matter, i.e., an absolutely stable weakly interacting singlet scalar. This new insight provides a theoretical justification for this simplest of all possible dark-matter models. It also connects with the notion of generating radiative neutrino mass through dark matter. Two such specific realizations are proposed. In our general scenario, dark-matter detection is guaranteed at existing direct-detection experiments and/or axion searches. Observable signals at the Large Hadron Collider are discussed. [ABSTRACT FROM AUTHOR]

The axion solution to the strong CP problem calls for an explanation as to why the Lagrangian should be invariant under the global Peccei-Quinn (PQ) symmetry, U(1)PQ, to such a high degree of accuracy. In this paper, we point out that the U(1)PQ can indeed survive as an accidental symmetry in the low-energy effective theory, if the standard model gauge group is supplemented by a gauged and discrete R symmetry, ZRN, forbidding all dangerous operators that explicitly break the Peccei-Quinn symmetry. In contrast to similar approaches, the requirement that the ZRN symmetry be anomaly-free forces us, in general, to extend the supersymmetric standard model by new matter multiplets. Surprisingly, we find a large landscape of viable scenarios that all individually fulfill the current experimental constraints on the QCD vacuum angle as well as on the axion decay constant. In particular, choosing the number of additional multiplets appropriately, the order N of the ZRN symmetry can take any integer value larger than 2. This has interesting consequences with respect to possible solutions of the μ problem, collider searches for vectorlike quarks and axion dark matter. [ABSTRACT FROM AUTHOR]

We propose a model of Dirac neutrino masses generated at one-loop level. The origin of this mass is induced from Peccei-Quinn symmetry breaking which was proposed to solve the so-called strong CP problem in QCD; therefore, the neutrino mass is connected with the QCD scale, AQCD. We also study the parameter space of this model, confronting neutrino oscillation data and leptonic rare decays. The phenomenological implications to leptonic flavor physics, such as the electromagnetic moment of charged leptons and neutrinos, are studied. Axion as the dark matter candidate is one of the byproducts in our scenario. Diphoton and Z-photon decay channels in the LHC Higgs search are investigated. We show that the effects of a singly charged singlet scalar can be distinguished from the general two Higgs doublet model. [ABSTRACT FROM AUTHOR]

In a Peccei-Quinn extension of supergravity the h → γγ detection rate can be significantly enhanced due to the reduction of the total Higgs decay width. To assess the viability of various Peccei-Quinn extensions of minimal supergravity we perform a Bayesian analysis on three such scenarios. The main constraints on these models come from the currently observed Higgs-boson like state by the Large Hadron Collider and from the Wilkinson Microwave Anisotropy Probe observation of dark matter abundance. Our comparative study reveals that under these constraints the Peccei-Quinn violating scenarios with axino dark matter are clearly preferred over the minimal supergravity model with the lightest neutralino as a dark matter candidate. [ABSTRACT FROM AUTHOR]

The article discusses the concept of axions in the early universe, close to the origin of space-time, within the theoretical particle physics field, including in regard to the Peccei-Quinn mechanism and the electric dipole moment. The use of models in theoretical physics is discussed.

In the standard model, the renormalization of the QCD vacuum angle θ is extremely tiny, and small θ is technically natural. In the general standard model effective field theory (SMEFT), however, Δθ is quadratically divergent, reflecting the fact that new sources of hadronic CP-violation typically produce O (1) threshold corrections to θ. The observation of such CP-violating interactions would therefore be in tension with solutions to the strong CP problem in which θ = 0 is an ultraviolet boundary condition, pointing to the Peccei-Quinn mechanism as the explanation for why θ is small in the infrared. We study the quadratic divergences in θ arising from dimension-6 SMEFT operators and discuss the discovery prospects for these operators at electric dipole moment experiments, the LHC, and future proton-proton colliders. [ABSTRACT FROM AUTHOR]

We introduce a natural origin of the Peccei-Quinn (PQ) symmetry with a sufficiently good precision. In the standard model, the baryon number symmetry U(1)B arises accidentally due to the SU(3)C color gauge symmetry, and it protects the proton from a decay at a sufficient level. Likewise, if there is an SU(N) gauge symmetry in the hidden sector, an accidental hidden baryon number symmetry U(1) B H can appear. The hidden baryon number is solely obtained by the structure of the SU(N) group. In particular, the quality of the U(1) B H can be arbitrarily good for an asymptotically-free theory with large enough N. The U(1) B H can be identified as a PQ symmetry. Using our findings, we build two types of novel composite axion models: a model where only one SU(N) gauge symmetry is required to both guarantee the quality and break the U(1) B H, and a model with SU(N) × SU(M) gauge symmetry where the exotic quarks responsible to the axion-gluon coupling do not confine into exotic hadrons through the dynamical breaking of the PQ symmetry, and have masses of TeV scales. [ABSTRACT FROM AUTHOR]

We present a Peccei-Quinn (PQ)-symmetric two-Higgs doublet model that naturally predicts a fermionic singlet dark matter in the mass range 10 keV-1 GeV. The origin of the smallness of the mass of this light singlet fermion arises predominantly at the one-loop level, upon soft or spontaneous breakdown of the PQ symmetry via a complex scalar field in a fashion similar to the so-called Dine-Fischler-Sredniki-Zhitnitsky axion model. The mass generation of this fermionic radiative light dark matter (RLDM) requires the existence of two heavy vectorlike SU(2) isodoublets, which are not charged under the PQ symmetry. We show how the RLDM can be produced via the freeze-in mechanism, thus accounting for the missing matter in the Universe. Finally, we briefly discuss possible theoretical and phenomenological implications of the RLDM model for the strong C P problem and the CERN Large Hadron Collider (LHC). [ABSTRACT FROM AUTHOR]

We propose a QCD axion model that avoids the cosmological domain wall problem, introducing a global SU(3)f family symmetry in which we embed the unwanted Peccei-Quinn (PQ) discrete symmetry. The spontaneous breaking of SU(3)f and PQ symmetry predicts eight NG bosons as well as axion, all of which contribute to the energy density of the Universe as dark radiation. The deviation from the standard model prediction of dark radiation can be observed by future observations of cosmic microwave background fluctuations. Our model also predicts a sizable exotic kaon decay rate, which is marginally consistent with the present collider data and would be tested by future collider experiments. [ABSTRACT FROM AUTHOR]

We survey a few minimal scalar extensions of the standard electroweak model that provide a simple setup for massive neutrinos in connection with an invisible axion. The presence of a chiral U(l) à la Peccei-Quinn drives the pattern of Majorana neutrino masses while providing a dynamical solution to the strong CP problem and an axion as a dark matter candidate. We paradigmatically apply such a renormalizable framework to type-II seesaw and to two viable models for neutrino oscillations where the neutrino masses arise at one and two loops, respectively. We comment on the naturalness of the effective setups as well as on their implications for vacuum stability and electroweak baryogenesis. [ABSTRACT FROM AUTHOR]

The article focuses on the formation of the international collaboration called HotQCD by the physicists in Lawrence Livermore National Laboratory in California and supported by the Computing Grand Challenge Program. It states that the program calculates the properties of the quantum chromodynamics (QCD) phase transition by simulating the conditions that occurred in the big bang. It provides brief summary of the result of the collaboration.

The standard model does not provide an explanation of the observed alignment of quark flavors i.e. why are the up and down quarks approximately aligned in their weak interactions according to their masses? We suggest a resolution of this puzzle using a combination of left-right and Peccei-Quinn (PQ) symmetry. The quark mixings in this model vanish at the tree level and arise out of one loop radiative corrections which explain their smallness. The lepton mixings, on the other hand, appear at the tree level and are therefore larger. We show that all fermion masses and mixings can be fitted with a reasonable choice of parameters. The neutrino mass fit using seesaw mechanism requires the right-handed WR mass bigger than 18 TeV. Due to the presence of PQ symmetry, this model clearly provides a solution to the strong CP problem. [ABSTRACT FROM AUTHOR]

We propose a scenario in which the spontaneous breakdown of the Peccei-Quinn symmetry leads to monopole production. Both the axion and the monopole contribute to dark matter, and the Witten effect on the axion mass is a built-in feature. In the Kim-Shifman-Vainshtein-Zakharov-type axion model, seemingly different vacua are actually connected by the hidden gauge symmetry, which makes the axionic string unstable and separate into two Alice strings. The Alice string is attached to a single domain wall due to the QCD instanton effect, solving the domain-wall problem. This is in the same spirit of the Lazarides-Shafi mechanism, although the discrete Peccei-Quinn symmetry is not embedded into the center of the original gauge symmetry. In the Dine-Fischler-Srednicki-Zhitnitsky-type axion model, the domain-wall problem is avoided by the Witten effect. If the Peccei-Quinn symmetry is explicitly broken by a small amount, monopoles acquire a tiny electric charge and become minicharged dark matter. Interestingly, the quality of the Peccei-Quinn symmetry is closely tied to darkness of dark matter. [ABSTRACT FROM AUTHOR]

It is known that if the Peccei-Quinn symmetry-breaking field is displaced from its minimum during inflation, the axion isocurvature spectrum is generically strongly blue tilted with a break transition to a flat spectrum. We fit this spectrum (incorporated into the "vanilla" Λ-CDM cosmological model) to the Planck and BOSS DR11 data to assess how much the existing data can accommodate the presence of axionic blue-tilted isocurvature perturbations. We find that the preferred parameter region is consistent with all of the dark matter being composed of QCD axions in the context of inflationary cosmology with an expansion rate of order 108 GeV, the axion decay constant of order 1013 GeV, and the initial misalignment angle of order unity. The data are consistent with there being no isocurvature perturbations at the level of just above one sigma. Intriguingly, isocurvature with a spectral break may at least partially explain the low-ℓ vs high-ℓ anomalies seen in the CMB data. [ABSTRACT FROM AUTHOR]

The axion causes two serious cosmological problems, domain wall and isocurvature perturbation problems. Linde pointed out that the isocurvature perturbations are suppressed when the Peccei-Quinn (PQ) scalar field takes a large value ∼Mpl (Planck scale) during inflation. In this case, however, the PQ field with large amplitude starts to oscillate after inflation, and large fluctuations of the PQ field are produced through parametric resonance, which leads to the formation of domain walls. We consider a supersymmetric axion model and examine whether domain walls are formed by using lattice simulation. It is found that the domain wall problem does not appear in the SUSY axion model when the initial value of the PQ field is less than 103×v, where v is the PQ symmetry breaking scale. [ABSTRACT FROM AUTHOR]

The invisible variant axion model is one of the very attractive models which solves the strong CP problem but does not provoke the domain wall problem. At the electroweak scale, this model requires at least two Higgs doublets, one of which carries a nonzero Peccei-Quinn (PQ) charge and the other is neutral. We consider a scenario where only the right-handed top quark is charged under the PQ symmetry and couples with the PQ-charged Higgs doublet. As a general prediction of this model, the top quark can decay to the observed standard model-like Higgs boson h and the charm or up quark, t→hc/u, which recently exhibited slight excesses at LHC run-I and run-II and will soon be testable at the LHC run-II. If the rare top decay excess stays at the observed central value, we show that tanβ∼1 or smaller is preferred by the Higgs data. The chiral nature of the Higgs flavor-changing interaction is a distinctive feature of this model and testable using the angular distribution of the t→ch decays at the LHC. [ABSTRACT FROM AUTHOR]

We introduce a class of unified supersymmetric axion theories with unified and Peccei-Quinn (PQ) symmetries broken by the same set of fields at a scale ~2×1016 GeV. A typical domain wall number of order 30 leads to an axion decay constant fa of order 1015 GeV. Inflation generates a large saxion condensate, giving a reheat temperature TR below the QCD scale for supersymmetry breaking of order 1-10 TeV. Axion field oscillations commence in the saxion matter-dominated era near the QCD scale, and recent lattice computations of the temperature dependence of the axion mass in this era allow a controlled calculation of the axion dark matter abundance. The observed abundance can be successfully explained by an initial axion misalignment angle of order unity, θi~1. A highly correlated set of predictions is discussed for fa, TR, the supersymmetric Higgs mass parameter μ, the amount of dark radiation ΔNeff, the proton decay rate Γ(p→e+π0), isocurvature density perturbations and the B mode of the cosmic microwave background. The last two are particularly interesting when the energy scale of inflation is also of order 1016 GeV. [ABSTRACT FROM AUTHOR]

Blue CDM-photon isocurvature perturbations are attractive in terms of observability and may be typical from the perspective of generic mass relations in supergravity. We present and apply three theorems useful for blue isocurvature perturbations arising from linear spectator scalar fields. In the process, we give a more precise formula for the blue spectrum associated with the axion model of Kasuya and Kawasaki [Axion Isocurvature Fluctuations with Extremely Blue Spectrum, Phys. Rev. D 80,023516 (2009).], which can in a parametric corner give a factor of 0(10) correction. We explain how a conserved current associated with Peccei-Quinn symmetry plays a crucial role and explicitly plot several example spectra including the breaks in the spectra. We also resolve a little puzzle arising from a naive multiplication of isocurvature expression that sheds light on the gravitational imprint of the adiabatic perturbations on the fields responsible for blue isocurvature fluctuations. [ABSTRACT FROM AUTHOR]

Scalar fields pervade theoretical physics and are a fundamental ingredient to solve the dark matter problem, to realize the Peccei-Quinn mechanism in QCD or the string-axiverse scenario. They are also a useful proxy for more complex matter interactions, such as accretion disks or matter in extreme conditions. Here, we study the collision between scalar "clouds" and rotating black holes. For the first time we are able to compare analytic estimates and strong field, nonlinear numerical calculations for this problem. As the black hole pierces through the cloud it accretes according to the Bondi-Hoyle prediction, but is deflected through a purely kinematic gravitational "anti-Magnus" effect, which we predict to be present also during the interaction of black holes with accretion disks. After the interaction is over, we find large recoil velocities in the transverse direction. The end-state of the process belongs to the vacuum Kerr family if the scalar is massless, but can be a hairy black hole when the scalar is massive. [ABSTRACT FROM AUTHOR]

While LHC8 Higgs mass and sparticle search constraints favor a multi-TeV value of soft SUSY breaking terms, electroweak naturalness favors a superpotential Higgsino mass μ~100-200 GeV: the mismatch results in an apparent little hierarchy characterized by μ«msoft (with msoft~m3/2 in gravity mediation). It has been suggested that the little hierarchy arises from a mismatch between Peccei-Quinn (PQ) and hidden sector intermediate scales vPQ«mhidden. We examine the Murayama-Suzuki-Yanagida model of radiatively driven PQ symmetry breaking which not only generates a weak scale value of μ but also produces intermediate scale Majorana masses for right-hand neutrinos. For this model, we show ranges of parameter choices with multi-TeV values of m3/2 which can easily generate values of μ~100-200 GeV so that the apparent little hierarchy suggested from data emerges quite naturally. In such a scenario, dark matter would be comprised of an axion plus a Higgsino-like weakly-interacting massive particle admixture where the axion mass and Higgsino masses are linked by the value of the PQ scale. The required light Higgsinos should ultimately be detected at a linear e+e- collider with √s>2m(Higgsino). [ABSTRACT FROM AUTHOR]

We exploit the complementarity among supersymmetry, inflation, axions, big bang nucleosynthesis (BBN), and cosmic microwave background radiation (CMB) to constrain supersymmetric axion models in the light of the recent Planck and BICEP results. In particular, we derive BBN bounds coming from altering the light element abundances by taking into account hadronic and electromagnetic energy injection, and CMB constraints from black-body spectrum distortion. Last, we outline the viable versus excluded region of these supersymmetric models that might account for the mild dark radiation observed. [ABSTRACT FROM AUTHOR]

We continue our exploration of the nearly Peccei-Quinn symmetric limit shared by common singlet extensions of the minimal supersymmetric standard model. This limit has been established as a viable framework for studying subelectroweak scale dark matter phenomenology and has interesting and direct connections to new exotic Higgs decay physics. We present analytic calculations to motivate the important phenomenological features mentioned above. We also discuss benchmark points in this model framework that accommodate the observed Galactic center gamma-ray excess. We emphasize connections between phenomenology of dark matter direct detection and indirect detection, and new exotic decay channels for the 125 GeV Higgs boson. We conclude by identifying two benchmark modes of exotic Higgs decays for h→τ+τ-ET and h→bbET final states and estimate their sensitivity prospects at the LHC. [ABSTRACT FROM AUTHOR]

We show how the neutrino can sacrifice itself to quantum gravity and save the axion solution to the strong-CP problem. This mechanism puts an upper bound on the lightest neutrino mass. [ABSTRACT FROM AUTHOR]