Electric dipole moment of Dirac fermionic dark matter

The direct limit of electric dipole moment and direct searches for dark matter by electric dipole interaction are investigated with including the electromagnetic nuclear form factor, in case that the dark matter candidate is a Dirac particle. The electric dipole moment of dark matter constrained by direct searches must be lower than 7×¹⁰−22e cm for dark matter mass of 100 GeV to satisfy the current experimental exclusion limits at XENON10 and CDMS II. The CP violation of electric dipole moment and the dark matter discovery by electric dipole interaction in the future are considered.     

Minimal Dirac fermionic dark matter with nonzero magnetic dipole moment

A neutral Dirac fermion ψ   with a nonzero magnetic dipole moment is supplied as a singlet within the context of the standard model and is considered as a dark matter candidate near the electroweak scale (10–1000 GeV$10\text{–}1000\text{GeV}$). We discuss its dynamics with the ordinary matters through the magnetic dipole moment. The magnetic dipole moment constrained by the relic abundance may be as large as ¹⁰⁻¹⁸–¹⁰⁻¹⁷e⋅cm${10}^{-18}\text{–}{10}^{-17}e\cdot \text{cm}$. We show that the elastic scattering is due to a spin–spin interaction for the direct detections and the predictions are under experimental exclusion limits of the current direct detectors, XENON10 and CDMS II, and consider the possibility of dark matter detection in the future.     

Thermally generated gauge singlet scalars as self-interacting dark matter

We show that a gauge singlet scalar S, with a coupling to the Higgs doublet of the form lambda(S)S+SH+H and with the S mass entirely generated by the Higgs expectation value, has a thermally generated relic density Omega(S)approximately equal to 0.3 if m(S)approximately equal to (2.9-10.5) (Omega(S)/0.3)(1/5)(h/0.7)(2/5) MeV. Remarkably, this is very similar to the range [m(S) = (6.6-15.4)eta(2/3) MeV] required in order for the self-interaction (eta/4) (S+S)(2) to account for self-interacting dark matter when eta is not much smaller than 1. The corresponding coupling is lambda(S)approximate(2.7 x 10(-10)-3.6 x 10(-9)) (Omega(S)/0.3)(2/5)(h/0.7)(4/5), implying that such scalars are very weakly coupled to the standard model sector.     

Cosmic Gamma-ray from inverse Compton process in unstable dark matter scenario

Motivated by the PAMELA anomaly in the fluxes of cosmic-ray e⁺$e^{+}$ and e⁻$e^{-}$, we study the cosmic γ  -ray induced by the inverse Compton (IC) scattering process in unstable dark matter scenario assuming that the anomaly is due to the e^±$e^{\pm }$ emission by the decay of dark matter. We calculate the fluxes of IC-induced γ-ray produced in our Galaxy and that from cosmological distance, and show that both of them are significant. If the γ-ray flux is precisely determined by Fermi Gamma-ray Space Telescope for various line-of-sight directions, it will provide an important test of the decaying dark matter scenario.     

Cosmic γ-rays from dark matter and antimatter annihilation

In this paper, we present details of the physics of cosmic γ-ray production by the annihilation of dark matter particles and cosmological antimatter. For the latter process, considerations of γ-ray absorption and scattering at high redshifts is important and we review the physics of these processes also. Cosmic γ-ray spectra are calculated and presented and compared with present observational data on cosmic γ-ray fluxes at high galactic latitudes. A comparison with the γ-ray flux from cosmic-ray interactions is made and the observability of annihilation γ-rays is considered.     

A conformal gauge mediation and dark matter with only one mass parameter

If the supersymmetry (SUSY) is a solution to the hierarchy problem, it is puzzling that any SUSY particle has not been discovered yet. We show that there is a low-scale conformal gauge mediation model which contains all necessary ingredients, i.e. not only a SUSY-breaking dynamics and a gauge mediation mechanism, but also a candidate for the dark matter. The model has only one free mass parameter, that is, the mass for messengers. In this model, the dark matter is provided by a composite particle in the SUSY-breaking sector, and the observed value of the dark matter density uniquely fixes the mass of messengers at the order of 10² TeV. Then, the sfermion and gaugino masses are fixed to be of order ¹⁰²–¹⁰³ GeV${10}^2\text{–}{10}^3\text{GeV}$ without any arbitrariness, thus the SUSY particles are expected not to be discovered at the Tevatron or LEP, while having a discovery possibility at the LHC.     

The search for dark matter gauge bosons with the Mainz Microtron

A pilot experiment in the search for light gauge bosons at the spectrometer setup of the A1 collaboration at MAMI is presented. Light gauge bosons arise naturally in a wide range of theoretical approaches beyond the standard model and are in accordance with several pieces of experimental evidence not yet understood in the standard model. A first test measurement at MAMI showed that existing limits on the coupling of such a light gauge boson can be improved by nearly an order of magnitude by fixed target experiments at existing electron accelerators.     

Dirac monopoles for general gauge theories

This paper develops a non-local potential formalism for general gauge theories. With the help of this mathematical apparatus an argument for quantisation of the generalised charge is given, assuming that the Dirac monopoles are present.     

Thermoluminescence of Cosmic matter

Summary A simplified model of thermoluminescence in silicates is presented and the astronomical applications of the phenomenon are shown. Finally our experimental apparatus and preliminary tests are presented and compared with those in the literature. Paper presented at the V Cosmic Physics National Conference, S. Miniato, November 27–30, 1990.     

Cosmic matter and the nonexpanding universe

The authors examine how some observations involving plasma physics in space are compatible with a recent red-shift theory. An increasingly large number of observations consistently reveal the existence of a much larger amount of intergalactic matter than presently accepted. A radio signal coming from directions between galaxies is discussed. An average density of matter in space of about 0.01 atom/cm³ is derived. It is shown that this density of matter is compatible with many reliable observations. These results lead to a nonexpanding cosmological model     

PAMELA and dark matter

Assuming that the positron excess in PAMELA satellite data is a consequence of annihilations of cold dark matter, we consider from a model-independent perspective if the data show a preference for the spin of dark matter, and find that they do not. We then perform a general analysis of annihilations into two-body states to determine what weighted combination of channels best describes the data.     

Dirac and Majorana neutrinos in matter

We consider the matter effects on neutrinos moving in background on the basis of the corresponding quantum wave equations. Both Dirac and Majorana neutrino cases are discussed. The effects for Dirac neutrino reflection and trapping as well as neutrino—antineutrino annihilation and ν pair creation in matter at the interface between two media with different densities are considered. The spin light of neutrinos in matter is also discussed. The text was submitted by the authors in English.     

Isospin-violating dark matter

Searches for dark matter scattering off nuclei are typically compared assuming that the dark matter?s spin-independent couplings are identical for protons and neutrons. This assumption is neither innocuous nor well motivated. We consider isospin-violating dark matter (IVDM) with one extra parameter, the ratio of neutron to proton couplings, and include the isotope distribution for each detector. For a single choice of the coupling ratio, the DAMA and CoGeNT signals are consistent with each other and with current XENON constraints, and they unambiguously predict near future signals at XENON and CRESST. We provide a quark-level realization of IVDM as WIMPless dark matter that is consistent with all collider and low-energy bounds.