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Register a new user2020 Global reassessment of the neutrino oscillation picture
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Added by
Christoph Andreas Ternes
Publication date
2020
fields
Physics
and research's language is
English
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We present an updated global fit of neutrino oscillation data in the simplest three-neutrino framework. In the present study we include up-to-date analyses from a number of experiments. Concerning the atmospheric and solar sectors, we give updated analyses of DeepCore and SNO data, respectively. We have also included the latest electron antineutrino data collected by the Daya Bay and RENO reactor experiments, and the long-baseline T2K and NO$ u$A measurements. These new analyses result in more accurate measurements of $theta_{13}$, $theta_{12}$, $Delta m_{21}^2$ and $|Delta m_{31}^2|$. The best fit value for the atmospheric angle $theta_{23}$ lies in the second octant, but first octant solutions remain allowed at $sim2.4sigma$. Regarding CP violation measurements, the preferred value of $delta$ we obtain is 1.08$pi$ (1.58$pi$) for normal (inverted) neutrino mass ordering. The global analysis prefers normal neutrino mass ordering with 2.5$sigma$. This preference is milder than the one found in previous global analyses. The new results should be regarded as robust due to the agreement found between our Bayesian and frequentist approaches. Taking into account only oscillation data, there is a weak/moderate preference for the normal neutrino mass ordering of $2.00sigma$. While adding neutrinoless double beta decay from the latest Gerda, CUORE and KamLAND-Zen results barely modifies this picture, cosmological measurements raise the preference to $2.68sigma$ within a conservative approach. A more aggressive data set combination of cosmological observations leads to a similar preference, namely $2.70sigma$. This very same cosmological data set provides $2sigma$ upper limits on the total neutrino mass corresponding to $sum u<0.12$ ($0.15$)~eV for normal (inverted) neutrino mass ordering.
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Within the standard three-neutrino framework, the absolute neutrino masses and their ordering (either normal, NO, or inverted, IO) are currently unknown. However, the combination of current data coming from oscillation experiments, neutrinoless double beta decay searches, and cosmological surveys, can provide interesting constraints for such unknowns in the sub-eV mass range, down to O(0.1) eV in some cases. We discuss current limits on absolute neutrino mass observables by performing a global data analysis, that includes the latest results from oscillation experiments, neutrinoless double beta decay bounds from the KamLAND-Zen experiment, and constraints from representative combinations of Planck measurements and other cosmological data sets. In general, NO appears to be somewhat favored with respect to IO at the level of ~2 sigma, mainly by neutrino oscillation data (especially atmospheric), corroborated by cosmological data in some cases. Detailed constraints are obtained via the chi^2 method, by expanding the parameter space either around separate minima in NO and IO, or around the absolute minimum in any ordering. Implications for upcoming oscillation and non-oscillation neutrino experiments, including beta-decay searches, are also discussed.
We perform a global analysis of neutrino oscillation data, including high-precision measurements of the neutrino mixing angle theta_13 at reactor experiments, which have confirmed previous indications in favor of theta_13>0. Recent data presented at the Neutrino 2012 Conference are also included. We focus on the correlations between theta_13 and the mixing angle theta_23, as well as between theta_13 and the neutrino CP-violation phase delta. We find interesting indications for theta_23< pi/4 and possible hints for delta ~ pi, with no significant difference between normal and inverted mass hierarchy.
We revisit our previous work [Phys. Rev. D 95, 096014 (2017)] where neutrino oscillation and nonoscillation data were analyzed in the standard framework with three neutrino families, in order to constrain their absolute masses and to probe their ordering (either normal, NO, or inverted, IO). We include updated oscillation results to discuss best fits and allowed ranges for the two squared mass differences $delta m^2$ and $Delta m^2$, the three mixing angles $theta_{12}$, $theta_{23}$ and $theta_{13}$, as well as constraints on the CP-violating phase $delta$, plus significant indications in favor of NO vs IO at the level of $Deltachi^2=10.0$. We then consider nonoscillation data from beta decay, from neutrinoless double beta decay (if neutrinos are Majorana), and from various cosmological input variants (in the data or the model) leading to results dubbed as default, aggressive, and conservative. In the default option, we obtain from nonoscillation data an extra contribution $Deltachi^2 = 2.2$ in favor of NO, and an upper bound on the sum of neutrino masses $Sigma < 0.15$ eV at $2sigma$; both results - dominated by cosmology - can be strengthened or weakened by using more aggressive or conservative options, respectively. Taking into account such variations, we find that the combination of all (oscillation and nonoscillation) neutrino data favors NO at the level of $3.2-3.7sigma$, and that $Sigma$ is constrained at the $2sigma$ level within $Sigma < 0.12-0.69$ eV. The upper edge of this allowed range corresponds to an effective $beta$-decay neutrino mass $m_beta = Sigma/3 = 0.23$ eV, at the sensitivity frontier of the KATRIN experiment.
We present a fast likelihood method for including event-level neutrino telescope data in parameter explorations of theories for new physics, and announce its public release as part of DarkSUSY 5.0.6. Our construction includes both angular and spectral information about neutrino events, as well as their total number. We also present a corresponding measure for simple model exclusion, which can be used for single models without reference to the rest of a parameter space. We perform a number of supersymmetric parameter scans with IceCube data to illustrate the utility of the method: example global fits and a signal recovery in the constrained minimal supersymmetric standard model (CMSSM), and a model exclusion exercise in a 7-parameter phenomenological version of the MSSM. The final IceCube detector configuration will probe almost the entire focus-point region of the CMSSM, as well as a number of MSSM-7 models that will not otherwise be accessible to e.g. direct detection. Our method accurately recovers the mock signal, and provides tight constraints on model parameters and derived quantities. We show that the inclusion of spectral information significantly improves the accuracy of the recovery, providing motivation for its use in future IceCube analyses.
The neutrino mixing angle theta(13) is at the focus of current neutrino research. From a global analysis of the available oscillation data in a 3-neutrino framework, we previously reported [Phys. Rev. Lett. 101, 141801 (2008)] hints in favor of theta(13)>0 at the 90 % C.L. Such hints are consistent with the recent indications of nu(mu)-->nu(e) appearance in the T2K and MINOS long-baseline accelerator experiments. Our global analysis of all the available data currently provides >3 sigma evidence for nonzero theta(13), with 1-sigma ranges sin^2 theta(13) = 0.021+-0.007 or 0.025+-0.007, depending on reactor neutrino flux systematics. Updated ranges are also reported for the other 3-neutrino oscillation parameters (delta m^2, sin^2 theta(12)) and (Delta m^2, sin^2 theta(23)).
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