Search results for "Instrumentation"
showing 10 items of 4914 documents
Subleading effects in the 1-2 sector: Non-standard neutrino interactions
2005
We have reconsidered the status of the large mixing angle (LMA) oscillation (OSC) interpretation of the solar neutrino data in a more general framework where non-standard neutrino interactions (NSI) are present. Using the latest data from all solar neutrino experiments and KamLAND we have found the existence of three LMA solutions, instead of the unique solution which holds in the absence of NSI, LMA-I. In addition to LMA-I, there is another solution with smaller Δ m 2 (LMA-0), and a new “dark-side” solution (LMA-D) with sin 2 θ = 0.70 . We comment on the potential of KamLAND and future solar neutrino experiments using 7Be and 8B neutrinos to lift the degeneracy between the LMA-I, LMA-0 and…
Neutrino mixing and masses from long baseline and atmospheric oscillation experiments
1998
We argue that regardless of the outcome of future Long Baseline experiments, additional information will be needed to unambiguously decide among the different scenarios of neutrino mixing. We use, for this purpose, a simple test of underground data: an asymmetry between downward and upward going events. Such an asymmetry, in which matter effects can be crucial, tests electron and muon neutrino data separately and can be compared with the theoretical prediction without relying on any simulation program.
Low-energy anti-neutrinos from the sun
1997
We consider the sensitivity of future neutrino experiments in the low energy region, such as BOREXINO or HELLAZ, to a solar electron antineutrino signal. We show that, if neutrino conversions within the Sun result in partial polarization of initial solar neutrino fluxes, then a new opportunity arises to observe the electron antineutrinos and thus to probe the Majorana nature of the neutrinos. This is achieved by comparing the slopes of the energy dependence of the differential neutrino electron scattering cross section for different neutrino conversion scenarios. We also show how the \nu_e -> \bar{\nu}_e conversions may take place for low energy solar neutrinos while being unobservable at t…
Status of the Gribov-Pontecorvo solution to the solar neutrino problem
2001
We discuss the status of the Gribov-Pontecorvo (GP) solution to the solar neutrino problem. This solution naturally appears in bimaximal neutrino mixing and reduces the solar and atmospheric neutrino problems to vacuum oscillations of three active neutrinos. The GP solution predicts an energy-independent suppression of the solar neutrino flux. It is disfavoured by the rate of the Homestake detector, but its statistical significance greatly improves, when the chlorine rate and the boron neutrino flux are slightly rescaled, and when the Super-Kamiokande neutrino spectrum is included in the analysis. Our results show that rescaling of the chlorine signal by only 10% is sufficient for the GP so…
Advantages of locating LAGUNA in Pyhäsalmi mine
2011
Abstract LAGUNA is the next-generation underground Megaton-scale detector for the search for proton decay, for neutrino astrophysics and for the investigation of neutrino properties. A brief description of the three considered detector technologies is given and the main physics goals presented. While many of the research topics for LAGUNA are not affected by the geographical location of the detector, there are two areas where it is very important: low-energy neutrino measurements and long-baseline neutrino oscillations. Evaluation of the physics arguments in both cases indicates Pyhasalmi mine as the best European site for LAGUNA.
Neutrino oscillations refitted
2014
Here we update our previous global fit of neutrino oscillations by including the recent results which have appeared since the Neutrino-2012 conference. These include the measurements of reactor anti-neutrino disappearance reported by Daya Bay and RENO, together with latest T2K and MINOS data including both disappearance and appearance channels. We also include the revised results from the third solar phase of Super-Kamiokande, SK-III, as well as new solar results from the fourth phase of Super-Kamiokande, SK-IV. We find that the preferred global determination of the atmospheric angle $\theta_{23}$ is consistent with maximal mixing. We also determine the impact of the new data upon all the o…
Testing neutrino mixing at future collider experiments
2000
Low energy supersymmetry with bilinear breaking of R-parity leads to a weak-scale seesaw mechanism for the atmospheric neutrino scale and a radiative mechanism for the solar neutrino scale. The model has striking implications for collider searches of supersymmetric particles. Assuming that the lightest SUSY particle is the lightest neutralino we demonstrate that (i) The neutralino decays inside the detector even for tiny neutrino masses. (ii) Measurements of the neutrino mixing angles lead to predictions for the ratios of various neutralino branching ratios implying an independent test of neutrino physics at future colliders, such as the Large Hadron Collider or a Linear Collider.
A Supersymmetric Solution to the Solar and Atmospheric Neutrino Problems
1999
The simplest unified extension of the Minimal Supersymmetric Standard Model with bi-linear R--Parity violation provides a predictive scheme for neutrino masses which can account for the observed atmospheric and solar neutrino anomalies in terms of bi-maximal neutrino mixing. The maximality of the atmospheric mixing angle arises dynamically, by minimizing the scalar potential, while the solar neutrino problem can be accounted for either by large or by small mixing oscillations. One neutrino picks up mass by mixing with neutralinos, while the degeneracy and masslessness of the other two is lifted only by loop corrections. Despite the smallness of neutrino masses R-parity violation is observab…
Minimalistic Neutrino Mass Model
2000
We consider the simplest model which solves the solar and atmospheric neutrino puzzles, in the sense that it contains the smallest amount of beyond the Standard Model ingredients. The solar neutrino data is accounted for by Planck-mass effects while the atmospheric neutrino anomaly is due to the existence of a single right-handed neutrino at an intermediate mass scale between 10^9 GeV and 10^14 GeV. Even though the neutrino mixing angles are not exactly predicted, they can be naturally large, which agrees well with the current experimental situation. Furthermore, the amount of lepton asymmetry produced in the early universe by the decay of the right-handed neutrino is very predictive and ma…
Combining first KamLAND results with solar neutrino data
2002
We consider the impact of the recent KamLAND data on neutrino oscillations, the first terrestrial neutrino experiment that can probe the solar neutrino anomaly. By combining the first 145.1 days of KamLAND data with the full sample of latest solar neutrino data we find an enhanced rejection against non-LMA oscillations, allowed only at more than 4 sigma with respect to LMA. Furthermore, the new data have a strong impact in narrowing down the allowed range of Delta_m^2 inside the LMA region. In contrast, our global analysis indicates that the new data have little impact on the location of the best fit point. In particular the solar neutrino mixing remains significantly non-maximal (3 sigma).