We first introduce a novel profile-based alignment algorithm, the multiple continuous Signal Alignment algorithm with Gaussian Process Regression profiles (SA-GPR). SA-GPR addresses the limitations of currently available signal alignment methods by a
dopting a hybrid of the particle smoothing and Markov-chain Monte Carlo (MCMC) algorithms to align signals, and by applying the Gaussian process regression to construct profiles to be aligned continuously. SA-GPR shares all the strengths of the existing alignment algorithms that depend on profiles but is more exact in the sense that profiles do not need to be discretized as sequential bins. The uncertainty of performance over the resolution of such bins is thereby eliminated. This methodology produces alignments that are consistent, that regularize extreme cases, and that properly reflect the inherent uncertainty. Then we extend SA-GPR to a specific problem in the field of paleoceanography with a method called Bayesian Inference Gaussian Process Multiproxy Alignment of Continuous Signals (BIGMACS). The goal of BIGMACS is to infer continuous ages for ocean sediment cores using two classes of age proxies: proxies that explicitly return calendar ages (e.g., radiocarbon) and those used to synchronize ages in multiple marine records (e.g., an oxygen isotope based marine proxy known as benthic ${delta}^{18}{rm O}$). BIGMACS integrates these two proxies by iteratively performing two steps: profile construction from benthic ${delta}^{18}{rm O}$ age models and alignment of each core to the profile also reflecting radiocarbon dates. We use BIGMACS to construct a new Deep Northeastern Atlantic stack (i.e., a profile from a particular benthic ${delta}^{18}{rm O}$ records) of five ocean sediment cores. We conclude by constructing multiproxy age models for two additional cores from the same region by aligning them to the stack.
We present an up-to-date global analysis of data coming from neutrino oscillation and non-oscillation experiments, as available in April 2018, within the standard framework including three massive and mixed neutrinos. We discuss in detail the status
of the three-neutrino (3nu) mass-mixing parameters, both known and unknown. Concerning the latter, we find that: normal ordering (NO) is favored over inverted ordering (IO) at 3sigma level; the Dirac CP phase is constrained within ~15% (~9%) uncertainty in NO (IO) around nearly-maximal CP-violating values; the octant of the largest mixing angle and the absolute neutrino masses remain undetermined. We briefly comment on other unknowns related to theoretical and experimental uncertainties (within 3nu) or possible new states and interactions (beyond 3nu).
In-situ NMR spin-lattice relaxation measurements were performed on several vapor deposited ices. The measurements, which span more than 6 orders of magnitude in relaxation times, show a complex spin-lattice relaxation pattern that is strongly depende
nt on the growth conditions of the sample. The relaxation patterns change from multi-timescale relaxation for samples grown at temperatures below the amorphous-crystalline transition temperature to single exponential recovery for samples grown above the transition temperature. The slow-relaxation contribution seen in cold-grown samples exhibits a temperature dependence, and becomes even slower after the sample is annealed at 200K. The fast-relaxation contribution seen in these samples, does not seem to change or disappear even when heating to temperatures where the sample is evaporated. The possibility that the fast relaxation component is linked to the microporous structures in amorphous ice samples is further examined using an environmental electron scanning microscope. The images reveal complex meso-scale microporous structures which maintain their morphology up to their desorption temperatures. These findings, support the possibility that water molecules at pore surfaces might be responsible for the fast-relaxation contribution. Furthermore, the results of this study indicate that the pore-collapse dynamics observed in the past in amorphous ices using other experimental techniques, might be effectively inhibited in samples which are grown by relatively fast vapor deposition.
Within the standard 3nu mass-mixing framework, we present an up-to-date global analysis of neutrino oscillation data (as of January 2016), including the latest available results from experiments with atmospheric neutrinos (Super-Kamiokande and IceCub
e DeepCore), at accelerators (first T2K anti-nu and NOvA nu runs in both appearance and disappearance mode), and at short-baseline reactors (Daya Bay and RENO far/near spectral ratios), as well as a reanalysis of older KamLAND data in the light of the bump feature recently observed in reactor spectra. We discuss improved constraints on the five known oscillation parameters (delta m^2, |Delta m^2|, sin^2theta_12, sin^2theta_13, sin^2theta_23), and the status of the three remaining unknown parameters: the mass hierarchy, the theta_23 octant, and the possible CP-violating phase delta. With respect to previous global fits, we find that the reanalysis of KamLAND data induces a slight decrease of both delta m^2 and sin^2theta_12, while the latest accelerator and atmospheric data induce a slight increase of |Delta m^2|. Concerning the unknown parameters, we confirm the previous intriguing preference for negative values of sin(delta) [with best-fit values around sin(delta) ~ -0.9], but we find no statistically significant indication about the theta_23 octant or the mass hierarchy (normal or inverted). Assuming an alternative (so-called LEM) analysis of NOvA data, some delta ranges can be excluded at >3 sigma, and the normal mass hierarchy appears to be slightly favored at 90% C.L. We also describe in detail the covariances of selected pairs of oscillation parameters. Finally, we briefly discuss the implications of the above results on the three non-oscillation observables sensitive to the (unknown) absolute nu mass scale: the sum of nu masses, the effective nu_e mass, and the effective Majorana mass.
Nuclear reactors provide intense sources of electron antineutrinos, characterized by few-MeV energy E and unoscillated spectral shape Phi(E). High-statistics observations of reactor neutrino oscillations over medium-baseline distances L ~ O(50) km wo
uld provide unprecedented opportunities to probe both the long-wavelength mass-mixing parameters (delta m^2 and theta_12) and the short-wavelength ones (Delta m^2 and theta_13), together with the subtle interference effects associated with the neutrino mass hierarchy (either normal or inverted). In a given experimental setting - here taken as in the JUNO project for definiteness - the achievable hierarchy sensitivity and parameter accuracy depend not only on the accumulated statistics but also on systematic uncertainties, which include (but are not limited to) the mass-mixing priors and the normalizations of signals and backgrounds. We examine, in addition, the effect of introducing smooth deformations of the detector energy scale, E -> E(E), and of the reactor flux shape, Phi(E) -> Phi(E), within reasonable error bands inspired by state-of-the-art estimates. It turns out that energy-scale and flux-shape systematics can noticeably affect the performance of a JUNO-like experiment, both on the hierarchy discrimination and on precision oscillation physics. It is shown that a significant reduction of the assumed energy-scale and flux-shape uncertainties (by, say, a factor of 2) would be highly beneficial to the physics program of medium-baseline reactor projects. Our results also shed some light on the role of the inverse-beta decay threshold, of geoneutrino backgrounds, and of matter effects in the analysis of future reactor oscillation data.
Theoretical estimates for the half life of neutrinoless double beta decay in candidate nuclei are affected by both particle and nuclear physics uncertainties, which may complicate the interpretation of decay signals or limits. We study such uncertain
ties and their degeneracies in the following context: three nuclei of great interest for large-scale experiments (76-Ge, 130-Te, 136-Xe), two representative particle physics mechanisms (light and heavy Majorana neutrino exchange), and a large set of nuclear matrix elements (NME), computed within the quasiparticle random phase approximation (QRPA). It turns out that the main theoretical uncertainties, associated with the effective axial coupling g_A and with the nucleon-nucleon potential, can be parametrized in terms of NME rescaling factors, up to small residuals. From this parametrization, the following QRPA features emerge: (1) the NME dependence on g_A is milder than quadratic; (2) in each of the two mechanisms, the relevant lepton number violating parameter is largely degenerate with the NME rescaling factors; and (3) the light and heavy neutrino exchange mechanisms are basically degenerate in the above three nuclei. We comment on the challenging theoretical and experimental improvements required to reduce such particle and nuclear physics uncertainties and their degeneracies.
The proposed PINGU project (Precision IceCube Next Generation Upgrade) is expected to collect O(10^5) atmospheric muon and electron neutrino in a few years of exposure, and to probe the neutrino mass hierarchy through its imprint on the event spectra
in energy and direction. In the presence of nonnegligible and partly unknown shape systematics, the analysis of high-statistics spectral variations will face subtle challenges that are largely unprecedented in neutrino physics. We discuss these issues both on general grounds and in the currently envisaged PINGU configuration, where we find that possible shape uncertainties at the (few) percent level can noticeably affect the sensitivity to the hierarchy. We also discuss the interplay between the mixing angle theta_23 and the PINGU sensitivity to the hierarchy. Our results suggest that more refined estimates of spectral uncertainties are needed in next-generation, large-volume atmospheric neutrino experiments.
The standard three-neutrino (3nu) oscillation framework is being increasingly refined by results coming from different sets of experiments, using neutrinos from solar, atmospheric, accelerator and reactor sources. At present, each of the known oscill
ation parameters [the two squared mass gaps (delta m^2, Delta m^2) and the three mixing angles (theta_12}, theta_13, theta_23)] is dominantly determined by a single class of experiments. Conversely, the unknown parameters [the mass hierarchy, the theta_23 octant and the CP-violating phase delta] can be currently constrained only through a combined analysis of various (eventually all) classes of experiments. In the light of recent new results coming from reactor and accelerator experiments, and of their interplay with solar and atmospheric data, we update the estimated N-sigma ranges of the known 3nu parameters, and revisit the status of the unknown ones. Concerning the hierarchy, no significant difference emerges between normal and inverted mass ordering. A slight overall preference is found for theta_23 in the first octant and for nonzero CP violation with sin delta < 0; however, for both parameters, such preference exceeds 1 sigma only for normal hierarchy. We also discuss the correlations and stability of the oscillation parameters within different combinations of data sets.
Proposed medium-baseline reactor neutrino experiments offer unprecedented opportunities to probe, at the same time, the mass-mixing parameters which govern $ u_e$ oscillations both at short wavelength (delta m^2 and theta_{12}) and at long wavelength
(Delta m^2 and theta_{13}), as well as their tiny interference effects related to the mass hierarchy (i.e., the relative sign of Delta m^2 and delta m^2). In order to take full advantage of these opportunities, precision calculations and refined statistical analyses of event spectra are required. In such a context, we revisit several input ingredients, including: nucleon recoil in inverse beta decay and its impact on energy reconstruction and resolution, hierarchy and matter effects in the oscillation probability, spread of reactor distances, irreducible backgrounds from geoneutrinos and from far reactors, and degeneracies between energy scale and spectrum shape uncertainties. We also introduce a continuous parameter alpha, which interpolates smoothly between normal hierarchy (alpha=+1) and inverted hierarchy (alpha=-1). The determination of the hierarchy is then transformed from a test of hypothesis to a parameter estimation, with a sensitivity given by the distance of the true case (either alpha=+1 or alpha=-1) from the undecidable case (alpha=0). Numerical experiments are performed for the specific set up envisaged for the JUNO project, assuming a realistic sample of O(10^5) reactor events. We find a typical sensitivity of ~2 sigma to the hierarchy in JUNO, which, however, can be challenged by energy scale and spectrum shape systematics, whose possible conspiracy effects are investigated. The prospective accuracy reachable for the other mass-mixing parameters is also discussed.
In a previous article [Phys. Rev. D 79, 053001 (2009)] we estimated the correlated uncertainties associated to the nuclear matrix elements (NME) of neutrinoless double beta decay (0 nu beta beta) within the quasiparticle random phase approximation (Q
RPA). Such estimates encompass recent independent calculations of NMEs, and can thus still provide a fair representation of the nuclear model uncertainties. In this context, we compare the claim of 0 nu beta beta decay in Ge-76 with recent negative results in Xe-136 and in other nuclei, and we infer the lifetime ranges allowed or excluded at 90% C.L. We also highlight some issues that should be addressed in order to properly compare and combine results coming from different 0 nu beta beta decay candidate nuclei.
