180 research outputs found

    KamLAND Bounds on Solar Antineutrinos and neutrino transition magnetic moments

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    We investigate the possibility of detecting solar electron antineutrinos with the KamLAND experiment. These electron antineutrinos are predicted by spin-flavor oscillations at a significant rate even if this mechanism is not the leading solution to the SNP. KamLAND is sensitive to antineutrinos originated from solar 8{}^8B neutrinos. From KamLAND negative results after 145 days of data taking, we obtain model independent limits on the total flux of solar electron antineutrinos $\Phi({}^8 B)< 1.1-3.5\times 10^4 cm^{-2}\ s^{-1},morethanoneorderofmagnitudesmallerthanexistinglimits,andontheirappearanceprobability, more than one order of magnitude smaller than existing limits, and on their appearance probability P<0.15%(95antineutrinoproductionbyspin−flavorprecession,thisupperboundimpliesanupperlimitontheproductoftheintrinsicneutrinomagneticmomentandthevalueofthesolarmagneticfield (95% CL). Assuming a concrete model for antineutrino production by spin-flavor precession, this upper bound implies an upper limit on the product of the intrinsic neutrino magnetic moment and the value of the solar magnetic field \mu B< 2.3\times 10^{-21}MeV95LMA MeV 95% CL (for LMA (\Delta m^2, \tan^2\theta)values).Limitsonneutrinotransitionmomentsarealsoobtained.Forrealisticvaluesofotherastrophysicalsolarparameterstheseupperlimitswouldimplythattheneutrinomagneticmomentisconstrainedtobe,inthemostconservativecase, values). Limits on neutrino transition moments are also obtained. For realistic values of other astrophysical solar parameters these upper limits would imply that the neutrino magnetic moment is constrained to be, in the most conservative case, \mu\lsim 3.9\times 10^{-12} \mu_B(95CL)forarelativelysmallfield (95% CL) for a relatively small field B= 50kG.Forhighervaluesofthemagneticfieldweobtain: kG. For higher values of the magnetic field we obtain: \mu\lsim 9.0\times 10^{-13} \mu_Bforfield for field B= 200kGand kG and \mu\lsim 2.0\times 10^{-13} \mu_Bforfield for field B= 1000$ kG at the same statistical significance.Comment: 13 pages, 2 figure

    Deep-sea polychaetes (Annelida) from the Malta Escarpment (western Ionian Sea)

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    AbstractThe polychaete assemblages from an escarpment area in the western Ionian Sea are characterised in terms of species richness, evenness and trophic composition. Moreover, the first occurrence of the genus Barantolla in the Mediterranean Sea, and of Lumbrinerides carpinei and Exogone (Parexogone) campoyi in Italian waters, is reported. Aricidea trilobata Laubier and Ramos, 1974 is redescribed on the basis of new material with the new name Aricidea (Acmira) jeaneteae, together with a brief description of two deep-water species belonging to the genus Levinsenia

    KamLAND, solar antineutrinos and the solar magnetic field

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    In this work the possibility of detecting solar electron antineutrinos produced by a solar core magnetic field from the KamLAND recent observations is investigated. We find a scaling of the antineutrino probability with respect to the magnetic field profile in the sense that the same probability function can be reproduced by any profile with a suitable peak field value. In this way the solar electron antineutrino spectrum can be unambiguosly predicted. We use this scaling and the negative results indicated by the KamLAND experiment to obtain upper bounds on the solar electron antineutrino flux. We get ϕνˉ<3.8×10−3ϕ(8B)\phi_{\bar\nu}<3.8\times 10^{-3}\phi(^8B) at 95% CL. For 90% CL this becomes ϕνˉ<3.4×10−3ϕ(8B)\phi_{\bar\nu}<3.4\times 10^{-3}\phi(^8B), an improvement by a factor of 3-5 with respect to existing bounds. These limits are independent of the detailed structure of the magnetic field in the solar interior. We also derive upper bounds on the peak field value which are uniquely determined for a fixed solar field profile. In the most efficient antineutrino producing case, we get (95% CL) an upper limit on the product of the neutrino magnetic moment by the solar field μB<2.8×10−19\mu B< 2.8\times 10^{-19} MeV or B0≤4.9×107GB_0 \leq 4.9 \times 10^7 G for μν=10−12μB\mu_\nu=10^{-12}\mu_B.Comment: 15 pages. References corrected. Minor changes in the tex

    Large Spatial Scale Variability in Bathyal Macrobenthos Abundance, Biomass, a- and b-Diversity along the Mediterranean Continental Margin

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    The large-scale deep-sea biodiversity distribution of the benthic fauna was explored in the Mediterranean Sea, which can beseen as a miniature model of the oceans of the world. Within the framework of the BIOFUN project (‘‘Biodiversity andEcosystem Functioning in Contrasting Southern European Deep-sea Environments: from viruses to megafauna’’), weinvestigated the large spatial scale variability (over .1,000 km) of the bathyal macrofauna communities that inhabit theMediterranean basin, and their relationships with the environmental variables. The macrofauna abundance, biomass,community structure and functional diversity were analysed and the a-diversity and b-diversity were estimated across sixselected slope areas at different longitudes and along three main depths. The macrobenthic standing stock and a-diversitywere lower in the deep-sea sediments of the eastern Mediterranean basin, compared to the western and central basins. Themacrofaunal standing stock and diversity decreased significantly from the upper bathyal to the lower bathyal slope stations.The major changes in the community composition of the higher taxa and in the trophic (functional) structure occurred atdifferent longitudes, rather than at increasing water depth. For the b-diversity, very high dissimilarities emerged at all levels:(i) between basins; (ii) between slopes within the same basin; and (iii) between stations at different depths; this thereforedemonstrates the high macrofaunal diversity of the Mediterranean basins at large spatial scales. Overall, the food sources(i.e., quantity and quality) that characterised the west, central and eastern Mediterranean basins, as well as sediment grainsize, appear to influence the macrobenthic standing stock and the biodiversity along the different slope areas

    Shallow-water gaseohydrothermal plume studies after massive eruption at Panarea, Aeolian Islands, Italy

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    Copyright © 2013 Elsevier. NOTICE: This is the author’s version of a work accepted for publication by Elsevier. Changes resulting from the publishing process, including peer review, editing, corrections, structural formatting and other quality control mechanisms, may not be reflected in this document. Changes may have been made to this work since it was submitted for publication. A definitive version was subsequently published in Journal of Marine Systems, 2014, Vol.131, pp. 1-9 DOI: http://dx.doi.org/10.1016/j.jmarsys.2013.10.001Marine water dynamics in the near field of a massive gas eruption near Panarea (Aeolian Islands volcanic arc, SE Tyrrhenian Sea) is described. ADCP current-meters were deployed during the paroxysmal phase in 2002 and 2003 a few meters from the degassing vent, recording day-long timeseries. Datasets were sorted to remove errors and select good quality ensembles over the entire water column. Standard deviation of error velocity was considered a proxy for inhomogeneous velocity fields over beams. Time series intervals had been selected when the basic ADCP assumptions were fulfilled and random errors minimized. Backscatter data were also processed to identify bubbles in the water column with the aim of locating bubble-free ensembles. Reliable timeseries are selected combining these data. Two possible scenarios have been described: firstly, a high dynamic situation with visible surface diverging rings of waves, entrainment on the lower part of the gas column, detrainment in the upper part and a stagnation line (SL) at mid depth where currents were close to zero and most of the gas bubbles spread laterally; secondly, a lower dynamic situation with water entraining into the gas plume at all depths and no surface rings of diverging waves. Reasons for these different dynamics may be ascribed to changes in gas fluxes (one order of magnitude higher in 2002). Description of SL is important to quantify its position in the water column and timing for entrainment-detrainment, and it can be measured by ADCP and calculated from models.Italian ISMAR-CNR, La Spezia. http://www.ismar.cnr.it/organization/geographic-units/ismar-la-spezi

    Water Masses Variability in Inner Kongsfjorden (Svalbard) During 2010–2020

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    Kongsfjorden is an Arctic fjord located in the Svalbard archipelago. Its hydrography is influenced by the warm and saline Atlantic Water (AW) in the West Spitsbergen Current and the cold and fresh Polar Water circulating on the shelf. We assess the so-called atlantification of Kongsfjorden in the 2010–2020 decade by inspecting modifications in water properties and water masses variability through moored data and summer CTD surveys. Atlantification in this fjord has emerged as an increasing temperature and salinity, resulting from enhanced advection of Atlantic waters from the West Spitsbergen Current. The water column in inner Kongsfjorden warmed by 0.13°C/yr at 35 m and 0.06°C/yr at 85 m depth from 2010 to 2020, while salinity increased by 0.3 PSU. Depth-averaged temperatures have increased by 0.26°C/yr in the warmest months of the year, whereas they appear relatively stable in the coldest months. Both temperature and salinity present a linear regression change point in January 2017, with latter years featuring decreasing values. Highly diluted AW is found at the beginning of the decade, which give way to more and more pure AW in latter years, culminating in extensive intrusions in 2016 and 2017 determining the warmest and saltiest conditions over the decade in inner Kongsfjorden. Observations in the 2010–2020 decade confirm that Kongsfjorden has transitioned to an Atlantic-type fjord, featuring depleted sea ice conditions and rather regular shallow intrusions of AW in summer and frequently also in winter. Although single intrusions of AW are associated with dynamical events on the shelf, we found that the long-term temperature evolution in the inner Kongsfjord is consistent with the meridional temperature transport of the West Spitsbergen Current. The AW current flowing northward from lower latitudes along the western Svalbard archipelago thus has profoundly driven local conditions in the inner fjord in this decade

    Predictions from non trivial Quark-Lepton complementarity

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    The complementarity between the quark and lepton mixing matrices is shown to provide robust predictions. We obtain these predictions by first showing that the matrix V_M, product of the quark (CKM) and lepton (PMNS) mixing matrices, may have a zero (1,3) entry which is favored by experimental data. We obtain that any theoretical model with a vanishing (1,3) entry of V_M that is in agreement with quark data, solar, and atmospheric mixing angle leads to θ13PMNS=(9−2+1)∘\theta_{13}^{PMNS}=(9{^{+1}_{-2}})^\circ. This value is consistent with the present 90% CL experimental upper limit. We also investigate the prediction on the lepton phases. We show that the actual evidence, under the only assumption that the correlation matrix V_M product of CKM and PMNS has a zero in the entry (1,3), gives us a prediction for the three CP-violating invariants J, S_1, and S_2. A better determination of the lepton mixing angles will give stronger prediction for the CP-violating invariants in the lepton sector. These will be tested in the next generation experiments. Finally we compute the effect of non diagonal neutrino mass in "l_i -> l_j gamma" in SUSY theories with non trivial Quark-Lepton complementarity and a flavor symmetry. The Quark-Lepton complementarity and the flavor symmetry strongly constrain the theory and we obtain a clear prediction for the contribution to "mu -> e gamma" and the "tau" decays "tau -> e gamma" and "tau -> mu gamma". If the Dirac neutrino Yukawa couplings are degenerate but the low energy neutrino masses are not degenerate, then the lepton decays are related among them by the V_M entries. On the other hand, if the Dirac neutrino Yukawa couplings are hierarchical or the low energy neutrino masses are degenerate, then the prediction for the lepton decays comes from the CKM hierarchy.Comment: 15 pages, 5 figures, ws-ijmpa class included, Proceedings of the CTP Symposium on Sypersymmetry at LH

    KamLAND, terrestrial heat sources and neutrino oscillations

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    We comment on the first indication of geo-neutrino events from KamLAND and on the prospects for understanding Earth energetics. Practically all models of terrestrial heat production are consistent with data within the presently limited statistics, the fully radiogenic model being closer to the observed value (≈9\approx 9 geo-events). In a few years KamLAND should collect sufficient data for a clear evidence of geo-neutrinos, however discrimination among models requires a detector with the class and size of KamLAND far away from nuclear reactors. We also remark that the event ratio from Thorium and Uranium decay chains is well fixed N(Th)/N(U)≃0.25N(Th)/N(U) \simeq 0.25, a constraint that can be useful for determining neutrino oscillation parameters. We show that a full spectral analysis, including this constraint, further reduces the oscillation parameter space compared to an analysis with an energy threshold Evis>2.6MeVE_{vis}>2.6 MeV.Comment: 12 pages, RevTeX file, 3 ps figures included in the correct order, corrected some typos and added references. Accepted for publication on Phys. Lett.
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