Scale-invariance as the origin of dark radiation?

Recent cosmological data favor R2 -inflation and some amount of non-standard dark radiation in the Universe. We show that a framework of high energy scale invariance can explain these data. The spontaneous breaking of this symmetry provides gravity with the Planck mass and particle physics with the electroweak scale. We found that the corresponding massless Nambu–Goldstone bosons – dilatons – are produced at reheating by the inflaton decay right at the amount needed to explain primordial abundances of light chemical elements and anisotropy of the cosmic microwave background. Then we extended the discussion on the interplay with Higgs-inflation and on general class of inflationary models where dilatons are allowed and may form the dark radiation. As a result we put a lower limit on the reheating temperature in a general scale invariant model of inflation

Improved constraints on the coupling constants of axion-like particles to nucleons from recent Casimir-less experiment

We obtain improved constraints on the coupling constants of axion-like particles to nucleons from a recently performed Casimir-less experiment. For this purpose, the differential force between a Au-coated sphere and either the Au or the Si sector of a rotating disc, arising due to two-axion exchange, is calculated. Over a wide region of axion masses, from 1.7×10-3  eV to 0.9 eV, the obtained constraints are up to a factor of 60 stronger than the previously known ones following from the Cavendish-type experiment and measurements of the effective Casimir pressure

Sgoldstino-Higgs mixing in models with low-scale supersymmetry breaking

We consider a supersymmetric extension of the Standard Model with low-scale supersymmetry breaking. Besides usual superpartners it contains additional chiral goldstino supermultiplet whose scalar components — sgoldstinos — can mix with scalars from the Higgs sector of the model. We show that this mixing can have considerable impact on phenomenology of the lightest Higgs boson and scalar sgoldstino. In particular, the latter can be a good candidate for explanation of 2 σ LEP excess with mass around 98 GeV

Toward the correspondence between Q-clouds and sphalerons

Non-linear classical equations of motion may admit degenerate solutions at fixed charges. Whereas the solutions with lower energies are classically stable, those with larger energies are unstable and are referred to as Q-clouds. We consider a theory in which a homogeneous charged condensate is classically stable and argue that Q-clouds correspond to sphalerons between the stable Q-balls and the condensate. For a model with an analytical solution, we present the Arrhenius formula for the quantum production of Q-balls from a condensate at high temperatures

On holography for (pseudo-)conformal cosmology

We propose a holographic dual for (pseudo-)conformal cosmological scenario, with a scalar field that forms a moving domain wall in adS 5 . The domain wall separates two vacua with unequal energy densities. Unlike in the existing construction, the 5d solution is regular in the relevant space–time domain

Black Hole Atom as a Dark Matter Particle Candidate

We propose the new dark matter particle candidate—the “black hole atom,” which is an atom with the charged black hole as an atomic nucleus and electrons in the bound internal quantum states. As a simplified model we consider the the central Reissner-Nordström black hole with the electric charge neutralized by the internal electrons in bound quantum states. For the external observers these objects would look like the electrically neutral Schwarzschild black holes. We suppose the prolific production of black hole atoms under specific conditions in the early universe

The Glashow resonance in neutrino–photon scattering

Reactions νlγ→W+l− (l=e,μ,τ) near the threshold s=mW+ml are analyzed. Two independent calculations of the corresponding cross sections (straightforward calculations using the Standard Electroweak Lagrangian and calculations in the framework of the parton model) are compared. It is shown that the Standard Electroweak Theory strongly suggests that these reactions proceed via the Glashow resonances. Accordingly, a hypothesis that the on-shell W bosons in the reactions νlγ→W+l− are the Glashow resonances is put forward. A role of these reactions for testing T symmetry is discussed. A model with T-violating Glashow resonances for description of the distribution of the TeV–PeV neutrino events recently observed by the IceCube Collaboration is presented

Strong decays of vector mesons to pseudoscalar mesons in the relativistic quark model

Strong decays of vector ( S13 ) mesons to the pair of pseudoscalar ( S01 ) mesons are considered in the framework of the microscopic decay mechanism and the relativistic quark model based on the quasipotential approach. The quark–antiquark potential, which was previously used for the successful description of meson spectroscopy and electroweak decays, is employed as the source of the qq¯ pair creation. The relativistic structure of the decay matrix element, relativistic contributions and boosts of the meson wave functions are comprehensively taken into account. The calculated rates of strong decays of light, heavy-light mesons and heavy quarkonia agree well with available experimental data

Relic gravity waves and 7 keV dark matter from a GeV scale inflaton

We study the mechanism of generation of 7 keV sterile neutrino Dark Matter (DM) in the model with light inflaton χ , which serves as a messenger of scale invariance breaking. In this model the inflaton, in addition to providing reheating to the Standard Model (SM) particles, decays directly into sterile neutrinos. The latter are responsible for the active neutrino oscillations via seesaw type I mechanism. While the two sterile neutrinos may also produce the lepton asymmetry in the primordial plasma and hence explain the baryon asymmetry of the Universe, the third one being the lightest may be of 7 keV and serve as DM. For this mechanism to work, the mass of the inflaton is bound to be light (0.1–1 GeV) and uniquely determines its properties, which allows to test the model. For particle physics experiments these are: inflaton lifetime ( 10−5–10−12 s ), branching ratio of B-meson to kaon and inflaton ( 10−6–10−4 ) and inflaton branching ratios into light SM particles like it would be for the SM Higgs boson of the same mass. For cosmological experiments these are: spectral index of scalar perturbations ( ns≃0.957–0.967 ), and amount of tensor perturbations produced at inflation (tensor-to-scalar ratio r≃0.15–0.005 )