73 research outputs found
Constraining the absolute neutrino mass scale and Majorana CP violating phases by future neutrinoless double beta decay experiments
Assuming that neutrinos are Majorana particles, in a three generation
framework, current and future neutrino oscillation experiments can determine
six out of the nine parameters which fully describe the structure of the
neutrino mass matrix. We try to clarify the interplay among the remaining
parameters, the absolute neutrino mass scale and two CP violating Majorana
phases, and how they can be accessed by future neutrinoless double beta
() decay experiments, for the normal as well as for the
inverted order of the neutrino mass spectrum. Assuming the oscillation
parameters to be in the range presently allowed by atmospheric, solar, reactor
and accelerator neutrino experiments, we quantitatively estimate the bounds on
, the lightest neutrino mass, that can be infered if the next generation
decay experiments can probe the effective Majorana mass
() down to
1 meV. In this context we conclude that in the case neutrinos are
Majorana particles: (a) if m_0 \gsim 300 meV, {\em i.e.}, within the range
directly attainable by future laboratory experiments as well as astrophysical
observations, then m_{ee} \gsim 30 meV must be observed;
(b) if meV, results from future decay
experiments combined with stringent bounds on the neutrino oscillation
parameters, specially the solar ones, will place much stronger limits on the
allowed values of than these direct experiments.Comment: 26 pages, 11 encapsulated postscript figures. A new figure and minor
changes are included. To be published in Phys. Rev.
Control of rotorcraft retreating blade stall using air-jet vortex generators
A series of low-speed wind tunnel tests were carried out on an oscillating airfoil fitted with two rows of air-jet vortex generators (AJVGs). The airfoil used had an RAE 9645 section and the two spanwise arrays of AJVGs were located at x/c=0.12 and 0.62. The devices and their distribution were chosen to assess their ability to modify/control dynamic stall; the goal being to enhance the aerodynamic performance of helicopter rotors on the retreating blade side of the disc. The model was pitched about the quarter chord with a reduced frequency
(k) of 0.1 in a sinusoidal motion defined by a=15o+10sin_ t. The measured data indicate that, for continuous blowing from the front row of AJVGs with a momentum blowing coefficient (C μ) greater than 0.008, modifications to the stalling process are encouraging. In particular, the pitching moment behavior exhibits delayed stall and there is a marked reduction in the normal force hysteresis
Resolving theta_{23} Degeneracy by Accelerator and Reactor Neutrino Oscillation Experiments
If the lepton mixing angle theta_{23} is not maximal, there arises a problem
of ambiguity in determining theta_{23} due to the existence of two degenerate
solutions, one in the first and the other in the second octant. We discuss an
experimental strategy for resolving the theta_{23} octant degeneracy by
combining reactor measurement of theta_{13} with accelerator nu_{mu}
disappearance and nu_{e} appearance experiments. The robustness of the
theta_{23} degeneracy and the difficulty in lifting it only by accelerator
experiments with conventional nu_{mu} (and nu_{mu}-bar) beam are demonstrated
by analytical and numerical treatments. Our method offers a way to overcome the
difficulty and can resolve the degeneracy between solutions sin^2 theta_{23} =
0.4 and sin^2 theta_{23} = 0.6 if sin^2 (2 theta_{13}) \gsim 0.05 at 95% CL by
assuming the T2K phase II experiment and a reactor measurement with an exposure
of 10 GW.kt.yr. The dependence of the resolving power of the octant degeneracy
on the systematic errors of reactor experiments is also examined.Comment: 23 pages, 9 figures, version to appear in PR
Supernova Neutrino-Nucleus Astrophysics
In this brief review we explore the role of neutrino-nucleus interactions in
core-collapse supernovae and discuss open questions. In addition implications
of neutrino mass and mixings in such environments are summarized.Comment: Revtex 4 figure
Quantum Dissipative Effects and Neutrinos : current constraints and future perspectives
We establish the most stringent experimental constraints coming from recent
terrestrial neutrino experiments on quantum mechanical decoherence effects in
neutrino systems. Taking a completely phenomenological approach, we probe
vacuum oscillations plus quantum decoherence between two neutrino species in
the channels , and , admitting that the quantum decoherence parameter is related
to the neutrino energy as : ,
with and 2. Our bounds are valid for a neutrino mass squared
difference compatible with the atmospheric, the solar and, in many cases, the
LSND scale. We also qualitatively discuss the perspectives of the future long
baseline neutrino experiments to further probe quantum dissipation.Comment: 26 pages, 8 encapsulated postscript figure
Reactor Measurement of theta_12; Principles, Accuracies and Physics Potentials
We discuss reactor measurement of \theta_{12} which has a potential of
reaching the ultimate sensitivity which surpasses all the methods so far
proposed. The key is to place a detector at an appropriate baseline distance
from the reactor neutrino source to have an oscillation maximum at around a
peak energy of the event spectrum in the absence of oscillation. By a detailed
statistical analysis the optimal distance is estimated to be \simeq (50-70) km
x [8 x 10^{-5} eV^2/\Delta m^2_{21}], which is determined by maximizing the
oscillation effect in the event number distribution and minimizing geo-neutrino
background contamination. To estimate possible uncertainty caused by
surrounding nuclear reactors in distance of \sim 100 km, we examine a concrete
example of a detector located at Mt. Komagatake, 54 km away from the
Kashiwazaki-Kariwa nuclear power plant in Japan, the most powerful reactor
complex in the world. The effect turns out to be small. Under a reasonable
assumption of systematic error of 4% in the experiment, we find that
sin^2{\theta_{12}} can be determined to the accuracy of \simeq 2% (\simeq 3%),
at 68.27% CL for 1 degree of freedom, for 60 GW_th kton yr (20 GW_th kton yr)
operation. We also discuss implications of such an accurate measurement of
\theta_{12}.Comment: 31 pages, 8 figures. version to appear in PR
Neutrino oscillation parameters from MINOS, ICARUS and OPERA combined
We perform a detailed analysis of the capabilities of the MINOS, ICARUS and
OPERA experiments to measure neutrino oscillation parameters at the atmospheric
scale with their data taken separately and in combination. MINOS will determine
and to within 10% at the 99% C.L. with
10 kton-years of data. While no one experiment will determine with much precision, if its value lies in the combined
sensitivity region of the three experiments, it will be possible to place a
lower bound of O(0.01) at the 95% C.L. on this parameter by combining the data
from the three experiments. The same bound can be placed with a combination of
MINOS and ICARUS data alone.Comment: Version to appear in PR
Quest for the dynamics of conversion
We perform a quantitative analysis of the capability of K2K, MINOS, OPERA and
a neutrino factory in a muon collider to discriminate the standard mass induced
vacuum oscillation from the pure decoherence solution to the atmospheric
neutrino problem and thereby contribute to unravel the dynamics that governs
the observed disappearence.Comment: 34 pages, 12 figure
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