Gravitational Effects on the Neutrino Oscillation

The propagation of neutrinos in a gravitational field is studied. A method of calculating a covariant quantum-mechanical phase in a curved space-time is presented. The result is used to calculate gravitational effects on the neutrino oscillation in the presence of a gravitational field. We restrict our discussion to the case of the Schwartzschild metric. Specifically, the cases of the radial propagation and the non-radial propagation are considered. A possible application to gravitational lensing of neutrinos is also suggested.Comment: 15 pages, RevTex, No figures. Minor modifications and some typos correcte

On the Interpretation of the Atmospheric Neutrino Data in Terms of Flavor Changing Neutrino Interactions

Flavour changing (FC) neutrino-matter interactions have been proposed as a solution to the atmospheric neutrino anomaly. Here we perform the analysis of the full set of the recent 52 kTy Super-Kamiokande atmospheric neutrino data, including the zenith angle distribution of the contained events as well as the higher energy upward-going stopping and through-going muon events. Our results show that the FC mechanism can describe the full data sample with a chi^2_{min}=44/(33 d.o.f) which is acceptable at the 90% confidence level. The combined analysis confines the amount of FC to be either close to maximal or to the level of about (10-50)%.Comment: 15 pages, 4 Postscript figures, uses ReVTeX. Updated analysis to 52 kTy Super-Kamiokande data. A new figure for the up-down asymmetry is included. Some comments and references are adde

Testing 3+1 and 3+2 neutrino mass models with cosmology and short baseline experiments

Recent results from short--baseline neutrino oscillation experiments and Cosmic Microwave Background anisotropy measurements suggest the presence of additional sterile neutrinos. In this paper we properly combine these data sets to derive bounds on the sterile neutrino masses in the 3+1 and 3+2 frameworks, finding a potentially good agreement between the two datasets. However, when galaxy clustering is included in the analysis a tension between the oscillation and cosmological data is clearly present

Finite temperature effects on the neutrino decoupling in the early Universe

Leading finite temperature effects on the neutrino decoupling temperature in the early Universe have been studied. We have incorporated modifications of the dispersion relation and the phase space distribution due to the presence of particles in the heat bath at temperature around MeV. Since both the expansion rate of the Universe and the interaction rate of a neutrino are reduced by finite temperature effects, it is necessary to calculate thermal corrections as precisely as possible in order to find the net effect on the neutrino decoupling temperature. We have performed such a calculation by using the finite temperature field theory. It has been shown that the finite temperature effects increase the neutrino decoupling temperature by 4.4%, the largest contribution coming from the modification of the phase space due to the thermal bath.Comment: 18 pages, LaTeX (uses RevTeX), 6 figures added as PS files, submitted to Phys.Rev.

Flavor-oscillation clocks, continuous quantum measurements and a violation of Einstein equivalence principle

The relation between Einstein equivalence principle and a continuous quantum measurement is analyzed in the context of the recently proposed flavor-oscillation clocks, an idea pioneered by Ahluwalia and Burgard (Gen. Rel Grav. Errata 29, 681 (1997)). We will calculate the measurement outputs if a flavor-oscillation clock, which is immersed in a gravitational field, is subject to a continuous quantum measurement. Afterwards, resorting to the weak equivalence principle, we obtain the corresponding quantities in a freely falling reference frame. Finally, comparing this last result with the measurement outputs that would appear in a Minkowskian spacetime it will be found that they do not coincide, in other words, we have a violation of Einstein equivalence principle. This violation appears in two different forms, namely: (i) the oscillation frequency in a freely falling reference frame does not match with the case predicted by general relativity, a feature previously obtained by Ahluwalia; (ii) the probability distribution of the measurement outputs, obtained by an observer in a freely falling reference frame, does not coincide with the results that would appear in the case of a Minkowskian spacetime.Comment: 16 pages, accepted in Mod. Phys. Letts.

Minimal supergravity sneutrino dark matter and inverse seesaw neutrino masses

We show that within the inverse seesaw mechanism for generating neutrino masses minimal supergravity is more likely to have a sneutrino as the lightest superparticle than the conventional neutralino. We also demonstrate that such schemes naturally reconcile the small neutrino masses with the correct relic sneutrino dark matter abundance and accessible direct detection rates in nuclear recoil experiments.Comment: 4 pages, 4 figure

Light neutralino in the MSSM: An update with the latest LHC results

We discuss the scenario of light neutralino dark matter in the minimal supersymmetric standard model, which is motivated by the results of some of the direct detection experiments --- DAMA, CoGENT, and CRESST. We update our previous analysis with the latest results of the LHC. We show that new LHC constraints disfavour the parameter region that can reproduce the results of DAMA and CoGENT.Comment: 4 pages, 4 figures, to appear in the conference proceedings of TAUP 2011, Munich Germany, 5-9 September 201

Cosmological Constraints on Theories with Large Extra Dimensions

In theories with large extra dimensions, constraints from cosmology lead to non-trivial lower bounds on the fundamental scale M_F, corresponding to upper bounds on the radii of the compact extra dimensions. These constraints are especially relevant to the case of two extra dimensions, since only if M_F is 10 TeV or less do deviations from the standard gravitational force law become evident at distances accessible to planned sub-mm gravity experiments. By examining the graviton decay contribution to the cosmic diffuse gamma radiation, we derive, for the case of two extra dimensions, a conservative bound M_F > 110 TeV, corresponding to r_2 < 5.1 times 10^-5 mm, well beyond the reach of these experiments. We also consider the constraint coming from graviton overclosure of the universe and derive an independent bound M_F > 6.5 h^(-1/2) TeV, or r_2 < .015 h mm.Comment: 10 pages, references adde

Comment on "Gravitationally Induced Neutrino-Oscillation Phases"

We critically examine the recent claim (gr-qc/9603008) of a ``new effect'' of gravitationally induced quantum mechanical phases in neutrino oscillations. A straightforward exercise in the Schwarzschild coordinates appropriate to a spherically symmetric non-rotating star shows that, although there is a general relativistic effect of the star's gravity on neutrino oscillations, it is not of the form claimed, and is too small to be measured.Comment: Plain LaTeX, 7 pages, no figure