The recent WMAP and Planck data have confirmed that exotic dark matter together with the vacuum energy (cosmological constant) dominate in the flat Universe. Many extensions of the standard model provide dark matter candidates, in particular Weakly I
nteracting Massive Particles (WIMPs). Thus the direct dark matter detection is central to particle physics and cosmology. Most of the research on this issue has hitherto focused on the detection of the recoiling nucleus. In this paper we study transitions to the excited states, possible in some nuclei, which have sufficiently low lying excited states. Examples considered previously were the first excited states of $^{127}$I and $^{129}$Xe. We examine here $^{83}$Kr, which offers some kinematical advantages and is currently considered as a possible target. We find appreciable branching ratios for the inelastic scattering mediated by the spin cross sections, with an inelastic event rate of $4.4times 10^{-4}$kg$^{-1}$d$^{-1}$. So, the extra signature of the gamma ray following the de-excitation of these states can, in principle, be exploited experimentally. A brief discussion of the experimental feasibility is given
We consider the possibility of detecting relic anti-neutrinos by their resonant absorption in a nucleus, which can undergo electron capture. This possibility appears quite realistic in view of recent developments in Penning Trap Mass Spectrometry and cryogenic micro-calorimetry.
The recent WMAP and Planck data have confirmed that exotic dark matter together with the vacuum energy (cosmological constant) dominate in the flat Universe. Many extensions of the standard model provide dark matter candidates, in particular Weakly I
nteracting Massive Particles (WIMPs). %Supersymmetry provides a natural dark matter candidate, the lightest supersymmetric particle (LSP). Thus the direct dark matter detection is central to particle physics and cosmology. Most of the research on this issue has hitherto focused on the detection of the recoiling nucleus. In this paper we study transitions to the excited states, possible in some nuclei, which have sufficiently low lying excited states. Good examples are the first excited states of I-127 and Xe-129. %focusing on the first excited state at 50 keV of Iodine A=127. We find appreciable branching ratios for the inelastic scattering mediated by the spin cross sections. %find that the transition rate to this excited state is about 5 %percent of the transition to the ground state for low mass WIMPS, but the branching ratio can be much larger in the case pf heaver WIMPS. So, in principle, the extra signature of the gamma ray following the de-excitation of these states can, in principle, be exploited experimentally.
The effect of some possible non standard WIMP velocity distributions, like the Debris Flows recently proposed, on the direct dark matter detection rates is investigated. We find that such distributions may be deciphered from the data, especially if t
he time variation of the event rates due to the annual motion of the Earth is observed
It is shown that the new neutrino with a high mass squared difference and a small mixing angle should reveal itself in the oscillometry measurements. For a judicious monochromatic neutrino source the new oscillation length $L_{42}$ is expected shorte
r than 1.5 m. Thus the needed measurements can be implemented with a gaseous spherical TPC of modest dimensions with a very good energy and position resolution. The best candidates for oscillometry are discussed and the sensitivity to the mixing angle $theta_{14}$ has been estimated: $sin^2{(2theta_{14})}$=0.05 (99{%}) for two months of data handling with $^{51}$Cr.
It is shown that, if the new neutrino implied by the Reactor Neutrino Anomaly exists and is in fact characterized by the suggested relatively high mass squared difference and reasonably large mixing angle, it should clearly reveal itself in the oscil
lometry measurements. For a judicious neutrino source the new oscillation length L14 is expected shorter than 3m. Thus the needed measurements can be implemented with a gaseous spherical TPC of modest dimensions with a very good energy and position resolution, detecting nuclear recoils following the coherent neutrino-nucleus elastic scattering. The best candidates for oscillometry, yielding both monochromatic neutrinos as well as antineutrinos, are discussed. A sensitivity in the mixing angle theta14, (sin(2theta14))^2=0.1 (99 %), can be reached after a few months of data handling.
In the present work we propose to study neutrino oscillations employing sources of monoenergetic neutrinos following electron capture by the nucleus. Since the neutrino energy is very low the smaller of the two oscillation lengths, L23, appearing in
this electronic neutrino disappearance experiment can be so small that the full oscillation can take place inside the detector and one may determine very accurately the neutrino oscillation parameters. Since in this case the oscillation probability is proportional to theta13, one can measure or set a better limit on the unknown parameter theta13. This is quite important, since, if this mixing angle vanishes, there is not going to be CP violation in the leptonic sector. The best way to detect it is by measuring electron recoils in neutrino-electron scattering. One, however, has to pay the price that the expected counting rates are very small. Thus one needs a very intensive neutrino source and a large detector with as low as possible energy threshold and high energy and position resolution. Both spherical gaseous and cylindrical liquid detectors are studied. Different source candidates are considered.
It is well known that neutrinoless double decay is going to play a crucial role in settling the neutrino properties, which cannot be extracted from the neutrino oscillation data. It is, in particular, expected to settle the absolute scale of neutrino
mass and determine whether the neutrinos are Majorana particles, i.e. they coincide with their own antiparticles. In order to extract the average neutrino mass from the data one must be able to estimate the contribution all possible high mass intermediate particles. The latter, which occur in practically all extensions of the standard model, can, in principle, be differentiated from the usual mass term, if data from various targets are available. One, however, must first be able reliably calculate the corresponding nuclear matrix elements. Such calculations are extremely difficult since the effective transition operators are very short ranged. For such operators processes like pionic contributions, which are usually negligible, turn out to be dominant. We study such an effect in a non relativistic quark model for the pion and the nucleon.
The recent WMAP data have confirmed that exotic dark matter together with the vacuum energy (cosmological constant) dominate in the flat Universe. The nature of the dark matter constituents cannot be determined till they are directly detected. Recent
developments in particle physics provide a number of candidates as constituents of dark matter, called Weakly Interacting Massive Particles (WIMPs). Since these interact weakly and are of low energy they cannot excite the target and can only be detected via measuring the recoiling nucleus. For all WIMPs, including the most popular candidate, the lightest supersymmetric particle (LSP), the relevant cross sections arise out of the following mechanisms: i) The coherent mode, due to the scalar interaction. ii) The charge coherent mode, with only proton contribution, as in the recent case of secluded dark matter scenario and iii) The spin contribution arising from the axial current. In this paper we will focus on the spin contribution, which maybe important, especially for light targets.
In the present paper we obtain the WIMP velocity distribution in our vicinity starting from spherically symmetric WIMP density profiles in a self consistent way by employing the Eddington approach. By adding a reasonable angular momentum dependent te
rm in the expression of the energy, we obtain axially symmetric WIMP velocity distributions as well. We find that some density profiles lead to approximate Maxwell-Boltzmann distributions, which are automatically defined in a finite domain, i.e. the escape velocity need not be put by hand. The role of such distributions in obtaining the direct WIMP detection rates, including the modulation, is studied in some detail and, in particular, the role of the asymmetry is explored.
