15935653
Effect of flavour oscillations on the detection of supernova neutrinos
Neutrinos and antineutrinos of all three flavours are emitted during the post-bounce phase of a core-collapse supernova with having average energies more than that of They can be detected by the new earthbound detectors like SNO and Super-Kamiokande which are sensitive to neutrinos of all three flavours. In this letter we consider the effect of flavour oscillations on the neutrino flux and their expected number of events at the detector. We do a three-generation analysis and for the mass and mixing schemes we first consider the threefold maximal mixing model consistent with the solar and the atmospheric neutrino data and next a scenario with one m2~10-11 eV2 (solar range) and the other m2~10-18 eV2, for which the oscillation length is of the order of the supernova distance. In both these scenarios there are no matter effects in the resultant neutrino spectrum and one is concerned with vacuum oscillations. We find that though neutrino oscillations result in a depletion in the number of e and coming from the supernova, the actual signals at the detectors are appreciable enhanced as the e and energy spectra become harder.
126402826
Extension of Minimal Fermionic Dark Matter Model
46702702
A possible explanation of low energy γ-ray excess from galactic centre and Fermi bubble by a Dark Matter model with two real scalars
We promote the idea of multi-component Dark Matter (DM) to explain results from both direct and indirect detection experiments. In these models as contribution of each DM candidate to relic abundance is summed up to meet WMAP/Planck measurements of Ω{sub DM}, these candidates have larger annihilation cross-sections compared to the single-component DM models. We illustrate this fact by introducing an extra scalar to the popular single real scalar DM model. We also present detailed calculations for the vacuum stability bounds, perturbative unitarity and triviality constraints on this model. As direct detection experimental results still show some conflict, we kept our options open, discussing different scenarios with different DM mass zones. In the framework of our model we make an interesting observation: the existing direct detection experiments like CDMS II, CoGeNT, CRESST II, XENON 100 or LUX together with the observation of excess low energy γ-ray from galactic centre and Fermi bubble by Fermi Gamma-ray Space Telescope (FGST) already have the capability to distinguish between different DM halo profiles.
17989564
Dark Matter -- Possible Candidates and Direct Detection
The cosmological observations coupled with theoretical calculations suggest the existence of enormous amount of unseen and unknown matter or dark matter in the universe. The evidence of their existence, the possible candidates and their possible direct detections are discussed.
118455395
Quintom scalar field : Varying dark energy equation of state obtained from recent SNe Ia, BAO and OHD data
From the analysis of Supernova Ia data alongwith Observational Hubble Data (OHD) and Baryon Acoustic Oscillation (BAO) data, we attempt to find out the nature of a scalar potential that may be responsible for the Dark Energy of the universe. We demonstrate that in order to explain the varying dark energy equation of state ($\omega_X(z)$) as obtained in a model independent way from the analyses of observational data, we need to invoke a quintom scalar field having a "quintessence" part for $\omega_X(z) > -1$ and a "phantom" part for $\omega_X(z) < -1$. We consider a Gaussian type potential for these scalar fields and compare the dark energy equation of state derived from such potential with the one computed from the data analysis.
11939062
Unparticle decay of neutrinos and it's effect on ultra high energy neutrinos
The unparticle is proposed by Georgi as a conceptual new physics beyond the standard model to describe the low energy sector of a nontrivial scale invariant sector of an effective theory. We consider the neutrino decay in unparticle scenario and investigate the effect of such decay for the case of ultra high energy neutrinos from GRB. The effect on the detection yield of these neutrinos are also probed for a kilometer scale ice-Cerenkov detector.
120089980
ELECTROMAGNETIC MASS DIFFERENCES.
Abstract In Cottingham's approach to electromagnetic masses ( δm ) one encounters the problem of unknown subtractions in the fixed mass dispersion relations for the virtual Compton scattering amplitude. We avoid this problem and express δm in terms of measurable quantities, assuming knowledge of light-cone singularities of the electro-magnetic current commutator.
116971806
Problems in electromagnetic mass-difference calculations.
121043964
INELASTIC e--p SCATTERING DATA AND A NEW PARTON MODEL.
119967965
Effect of a transverse momentum distribution in the parton model
The parton model for the inelastic lepton-nucleon scattering is generalized to include a realistic momentum distribution of the partons. In this formalism each parton is given a component of momentum which is orthogonal in a four-vector sense to the nucleon momentum. An approximation scheme is developed to take into account the effect of this orthogonal (transverse) momentum distribution of the partons. It is found to generate an additional scale-invariant contribution to the structure function $\ensuremath{\nu}{W}_{2}(\ensuremath{\nu}, {Q}^{2})$ as well as a non-scale-invariant contribution, as is expected. The scale-invariance-breaking term is found to be a power series in $\frac{{Q}^{2}}{{\ensuremath{\nu}}^{2}}$ and vanishes as $\ensuremath{\nu}$ or ${Q}^{2}$ goes to infinity for a fixed $\ensuremath{\omega}=\frac{2M\ensuremath{\nu}}{{Q}^{2}}$. The effect of the transverse momentum distribution is explicitly displayed and discussed for a few momentum distribution functions. The data on inelastic $e\ensuremath{-}p$ scattering are then analyzed for any significant deviations from scale invariance, and it is concluded that there is evidence for such deviations. On the assumption that the systematic errors in the data are small, we make some fits which display the dependence on ${Q}^{2}$. Finally, an attempt is made to fit the data with the formalism developed in the initial part of the paper. For this purpose use is made of a model for the partons, proposed previously by the authors to explain the data in the approximation that scale invariance is satisfied. Some comments are made on the properties of partons which are necessary to fit the data and on the present status of scale-invariance breaking.
121251309
SOME QUARK--PARTON-MODEL INEQUALITIES FOR THE NEUTRON AND PROTON INELASTIC STRUCTURE FUNCTIONS.