Search results for "Oscillation"
showing 10 items of 1257 documents
Four-neutrino oscillation solutions of the solar neutrino problem
2000
We present an analysis of the neutrino oscillation solutions of the solar neutrino problem in the framework of four-neutrino mixing where a sterile neutrino is added to the three standard ones. We perform a fit to the full data set corresponding to the 825-day Super-Kamiokande data sample as well as to Chlorine, GALLEX and SAGE and Kamiokande experiments. In our analysis we use all measured total event rates as well as all Super-Kamiokande data on the zenith angle dependence and the recoil electron energy spectrum. We consider both transitions via the Mikheyev-Smirnov-Wolfenstein (MSW) mechanism as well as oscillations in vacuum (just-so) and find the allowed solutions for different values …
Updated global analysis of neutrino oscillations in the presence of eV-scale sterile neutrinos
2018
We discuss the possibility to explain the anomalies in short-baseline neutrino oscillation experiments in terms of sterile neutrinos. We work in a 3+1 framework and pay special attention to recent new data from reactor experiments, IceCube and MINOS+. We find that results from the DANSS and NEOS reactor experiments support the sterile neutrino explanation of the reactor anomaly, based on an analysis that relies solely on the relative comparison of measured reactor spectra. Global data from the $\nu_e$ disappearance channel favour sterile neutrino oscillations at the $3\sigma$ level with $\Delta m^2_{41} \approx 1.3$ eV$^2$ and $|U_{e4}| \approx 0.1$, even without any assumptions on predicte…
Solar Neutrinos Before and After KamLAND
2002
We use the recently reported KamLAND measurements on oscillations of reactor anti-neutrinos, together with the data of previously reported solar neutrino experiments, to show that: (1) the total 8B neutrino flux emitted by the Sun is 1.00(1.0 \pm 0.06) of the standard solar model (BP00) predicted flux, (2) the KamLAND measurements reduce the area of the globally allowed oscillation regions that must be explored in model fitting by six orders of magnitude in the Delta m^2-tan^2 theta plane, (3) LMA is now the unique oscillation solution to a CL of 4.7sigma, (4) maximal mixing is disfavored at 3.1 sigma, (5) active-sterile admixtures are constrained to sin^2 eta<0.13 at 1 sigma, (6) the ob…
Global Analysis of Solar Neutrino Oscillations Including SNO CC Measurement
2001
For active and sterile neutrinos, we present the globally allowed solutions for two neutrino oscillations. We include the SNO CC measurement and all other relevant solar neutrino and reactor data. Five active neutrino oscillation solutions (LMA, LOW, SMA, VAC, and Just So2) are currently allowed at 3 sigma; three sterile neutrino solutions (Just So2, SMA, and VAC) are allowed at 3 sigma. The goodness of fit is satisfactory for all eight solutions. We also investigate the robustness of the allowed solutions by carrying out global analyses with and without: 1) imposing solar model constraints on the 8B neutrino flux, 2) including the Super-Kamiokande spectral energy distribution and day-night…
A search for neutrino–antineutrino mass inequality by means of sterile neutrino oscillometry
2015
The investigation of the oscillation pattern induced by the sterile neutrinos might determine the oscillation parameters, and at the same time, allow to probe CPT symmetry in the leptonic sector through neutrino-antineutrino mass inequality. We propose to use a large scintillation detector like JUNO or LENA to detect electron neutrinos and electron antineutrinos from MCi electron capture or beta decay sources. Our calculations indicate that such an experiment is realistic and could be performed in parallel to the current research plans for JUNO and RENO. Requiring at least 5$\sigma$ confidence level and assuming the values of the oscillation parameters indicated by the current global fit, w…
Heavy neutrino searches at the lhc with displaced vertices
2013
Sterile neutrinos with masses in the range (1-100) GeV, have been searched for in a variety of experiments. Here, we discuss the prospects to search for sterile neutrinos at the LHC using displaced vertices. Two different cases are discussed: (i) the standard model extended with sterile neutrinos and (ii) right-handed neutrinos in a left-right symmetric extension of the standard model. A dedicated displaced vertex search will allow to probe parts of the parameter space not accessible to other searches, but will require large luminosity in both cases.
Global bounds on the Type-III Seesaw
2020
We derive general bounds on the Type-III Seesaw parameters from a global fit to flavor and electroweak precision data. We explore and compare three Type-III Seesaw realizations: a general scenario, where an arbitrary number of heavy triplets is integrated out without any further assumption, and the more constrained cases in which only 3 or 2 (minimal scenario) additional heavy states are included. The latter assumption implies rather non-trivial correlations in the Yukawa flavor structure of the model so as to reproduce the neutrino masses and mixings as measured in neutrino oscillations experiments and thus qualitative differences can be found with the more general scenario. In particular,…
Journal of High Energy Physics
2014
The Double Chooz experiment presents improved measurements of the neutrino mixing angle $\theta_{13}$ using the data collected in 467.90 live days from a detector positioned at an average distance of 1050 m from two reactor cores at the Chooz nuclear power plant. Several novel techniques have been developed to achieve significant reductions of the backgrounds and systematic uncertainties with respect to previous publications, whereas the efficiency of the $\bar\nu_{e}$ signal has increased. The value of $\theta_{13}$ is measured to be $\sin^{2}2\theta_{13} = 0.090 ^{+0.032}_{-0.029}$ from a fit to the observed energy spectrum. Deviations from the reactor $\bar\nu_{e}$ prediction observed ab…
Event Excess in the MiniBooNE Search forν¯μ→ν¯eOscillations
2010
The MiniBooNE experiment at Fermilab reports results from a search for {nu}{sub {mu}{yields}{nu}e} oscillations, using a data sample corresponding to 5.66x10{sup 20} protons on target. An excess of 20.9{+-}14.0 events is observed in the energy range 475<E{sub {nu}}{sup QE}<1250 MeV, which, when constrained by the observed {nu}{sub {mu}} events, has a probability for consistency with the background-only hypothesis of 0.5%. On the other hand, fitting for {nu}{sub {mu}{yields}{nu}e} oscillations, the best-fit point has a {chi}{sup 2} probability of 8.7%. The data are consistent with {nu}{sub {mu}{yields}{nu}e} oscillations in the 0.1 to 1.0 eV{sup 2} {Delta}m{sup 2} range and with the evidence…
Isosinglet-neutral heavy-lepton production in Z-decays and neutrino mass
1990
Abstract The possible existence of NHLs is often related to neutrino mass. As a result their production cross section may be correspondingly constrained by observational limits on neutrino masses. We analyze the discovery potential of isosinglet NHLs within various models taking also into account cosmological limits on relic neutrino abundances.