The exact eigenstates of the neutrino mass matrix without CP-phase violation

In this paper we obtain the exact mass-eigenstates of the Majorana physical neutrinos. We start by taking into account a general $3\times3$ mass matrix without any CP-phase violation. It is then diagonalized by exactly solving an appropriate set of equations. The solution supplies straightforwardly the mass eigenvalues depending on the diagonal entries and mixing angles. Finally, the consequences of these analytical expressions are discussed assuming various phenomenological restrictions such as conserving the global lepton number $L=L_{e}-L_{\mu}-L_{\tau}$ and the $\mu-\tau$ interchange symmetry. The minimal absolute mass in the neutrino sector is also obtained since the two plausible scenarios invoked above are employed.Comment: 9 pages, no figure

Large theta_13 from a model with broken L_e-L_mu-L_tau symmetry

Recent data in the neutrino sector point towards a relatively large value of the reactor angle, incompatible with a vanishing theta_ 13 at about 3 sigma. In order to explain such a result, we propose a SUSY model based on the broken L_e-L_mu-L_tau symmetry, where large deviations from the symmetric limit theta_12 = pi/4, tan(theta_23) \sim O(1) and theta_13 = 0 mainly come from the charged lepton sector. We show that a description of all neutrino data is possible if the charged lepton mass matrix has a special pattern of complex matrix elements.Comment: 9 pages, 2 figures. v2: comments and references added, as published in JHE

The seesaw mechanism at TeV scale in the 3-3-1 model with right-handed neutrinos

We implement the seesaw mechanism in the 3-3-1 model with right-handed neutrinos. This is accomplished by the introduction of a scalar sextet into the model and the spontaneous violation of the lepton number. We identify the Majoron as a singlet under $SU_L(2)\otimes U_Y(1)$ symmetry, which makes it safe under the current bounds imposed by electroweak data. The main result of this work is that the seesaw mechanism works already at TeV scale with the outcome that the right-handed neutrino masses lie in the electroweak scale, in the range from MeV to tens of GeV. This window provides a great opportunity to test their appearance at current detectors, though when we contrast our results with some previous analysis concerning detection sensitivity at LHC, we conclude that further work is needed in order to validate this search.Comment: about 13 pages, no figure

Mediterranean-Black Sea gateway exchange: Scientific drilling workshop on the BlackGate project

The MagellanPlus workshop "BlackGate"addressed fundamental questions concerning the dynamic evolution of the Mediterranean-Black Sea (MBS) gateway and its palaeoenvironmental consequences. This gateway drives the Miocene-Quaternary circulation patterns in the Black Sea and governs its present status as the world's largest example of marine anoxia. The exchange history of the MBS gateway is poorly constrained because continuous Pliocene-Quaternary deposits are not exposed on land adjacent to the Black Sea or northern Aegean. Gateway exchange is controlled by climatic (glacio-eustatic-driven sea-level fluctuations) and tectonic processes in the catchment as well as tectonic propagation of the North Anatolian Fault Zone (NAFZ) in the gateway area itself. Changes in connectivity trigger dramatic palaeoenvironmental and biotic turnovers in both the Black Sea and Mediterranean domains. Drilling a Messinian to Holocene transect across the MBS gateway will recover high-amplitude records of continent-scale hydrological changes during glacial-interglacial cycles and allow us to reconstruct marine and freshwater fluxes, biological turnover events, deep biospheric processes, subsurface gradients in primary sedimentary properties, patterns and processes controlling anoxia, chemical perturbations and carbon cycling, growth and propagation of the NAFZ, the timing of land bridges for Africa and/or Asia-Europe mammal migration, and the presence or absence of water exchange during the Messinian salinity crisis. During thorough discussions at the workshop, three key sites were selected for potential drilling using a mission-specific platform (MSP): one on the Turkish margin of the Black Sea (Arkhangelsky Ridge, 400mb.s.f., metres below the seafloor), one on the southern margin of the Sea of Marmara (North Imrali Basin, 750mb.s.f.), and one in the Aegean (North Aegean Trough, 650mb.s.f.). All sites target Quaternary oxic-anoxic marl-sapropel cycles. Plans include recovery of Pliocene lacustrine sediments and mixed marine-brackish Miocene sediments from the Black Sea and the Aegean. MSP drilling is required because the JOIDES Resolution cannot pass under the Bosporus bridges. The wider goals are in line with the aims and scope of the International Ocean Discovery Program (IODP) "2050 Science Framework: Exploring Earth by Scientific Ocean Drilling"and relate specifically to the strategic objectives "Earth's climate system", "Tipping points in Earth's history", and "Natural hazards impacting society"

A Late Maeotian age (6.7–6.3 Ma) for the enigmatic “Pebbly Breccia” unit in DSDP Hole 380A of the Black Sea

Various hypotheses exist on the age and origin of the so-called “Pebbly Breccia” unit in the deep-sea record of DSDP Hole 380A of the Euxinian (Black Sea) Basin. Here, we present a detailed study of diatom and nannofossil assemblages of Hole 380A. Our diatom records show a characteristic sequence of appearance of markers species, which we can correlate to the recently established bio-magnetostratigraphic time frame of the Zheleznyi Rog section on the Black Sea coast of the Taman Peninsula (Russia). It shows that the Pebbly Breccia is sandwiched between Upper Maeotian deposits, and must have been deposited at an age between 6.7 and 6.3 Ma. The appearance of nannoplankton and the marine diatom association at above the Pebbly breccia (Unit IVc) suggests a short-term incursion of marine conditions. The age of Unit IVc, based on diatom data, is 6.3–6.1 Ma. The nannoplankton record is mainly represented by species that do not have stratigraphic value. The previously reported presence of Ceratolithus acutus in the Black Sea is explained by misinterpretation of destructed elements of ascidian spicules. We conclude that the Pebbly Breccia is not related to a desiccated Black Sea at Messinian Salinity Crisis times, but it corresponds to a late Maeotian episode of gravitational instability in the SW Black Sea region

A Late Maeotian age (6.7–6.3 Ma) for the enigmatic “Pebbly Breccia” unit in DSDP Hole 380A of the Black Sea

Various hypotheses exist on the age and origin of the so-called “Pebbly Breccia” unit in the deep-sea record of DSDP Hole 380A of the Euxinian (Black Sea) Basin. Here, we present a detailed study of diatom and nannofossil assemblages of Hole 380A. Our diatom records show a characteristic sequence of appearance of markers species, which we can correlate to the recently established bio-magnetostratigraphic time frame of the Zheleznyi Rog section on the Black Sea coast of the Taman Peninsula (Russia). It shows that the Pebbly Breccia is sandwiched between Upper Maeotian deposits, and must have been deposited at an age between 6.7 and 6.3 Ma. The appearance of nannoplankton and the marine diatom association at above the Pebbly breccia (Unit IVc) suggests a short-term incursion of marine conditions. The age of Unit IVc, based on diatom data, is 6.3–6.1 Ma. The nannoplankton record is mainly represented by species that do not have stratigraphic value. The previously reported presence of Ceratolithus acutus in the Black Sea is explained by misinterpretation of destructed elements of ascidian spicules. We conclude that the Pebbly Breccia is not related to a desiccated Black Sea at Messinian Salinity Crisis times, but it corresponds to a late Maeotian episode of gravitational instability in the SW Black Sea region

A Late Maeotian age (6.7–6.3 Ma) for the enigmatic “Pebbly Breccia” unit in DSDP Hole 380A of the Black Sea

Various hypotheses exist on the age and origin of the so-called “Pebbly Breccia” unit in the deep-sea record of DSDP Hole 380A of the Euxinian (Black Sea) Basin. Here, we present a detailed study of diatom and nannofossil assemblages of Hole 380A. Our diatom records show a characteristic sequence of appearance of markers species, which we can correlate to the recently established bio-magnetostratigraphic time frame of the Zheleznyi Rog section on the Black Sea coast of the Taman Peninsula (Russia). It shows that the Pebbly Breccia is sandwiched between Upper Maeotian deposits, and must have been deposited at an age between 6.7 and 6.3 Ma. The appearance of nannoplankton and the marine diatom association at above the Pebbly breccia (Unit IVc) suggests a short-term incursion of marine conditions. The age of Unit IVc, based on diatom data, is 6.3–6.1 Ma. The nannoplankton record is mainly represented by species that do not have stratigraphic value. The previously reported presence of Ceratolithus acutus in the Black Sea is explained by misinterpretation of destructed elements of ascidian spicules. We conclude that the Pebbly Breccia is not related to a desiccated Black Sea at Messinian Salinity Crisis times, but it corresponds to a late Maeotian episode of gravitational instability in the SW Black Sea region

Integrated stratigraphy of the Eocene-Oligocene deposits of the northern Caucasus (Belaya River, Russia): Intermittent oxygen-depleted episodes in the Peri-Tethys and Paratethys

The sedimentary succession along the Belaya River (North Caucasus) provides a record of middle Eocene to Miocene sediments. This time interval is well known for its important climatic transitions (e.g., Middle Eocene Climate Optimum (MECO) and Eocene-Oligocene Transition (EOT)), and changes in basin configuration from Peri-Tethys to Paratethys. The Belaya section contains two intervals marked by oxygen-depleted sediments; the Eocene Kuma Formation of the Peri-Tethys and the Oligocene Maikop Group of the Paratethys. Both are considered important source rocks for hydrocarbon exploration in the Black Sea and Caspian Sea. We present integrated stratigraphic results of the Belaya River section using calcareous nannoplankton biostratigraphy, magnetostratigraphy and 40Ar/39Ar dating. Furthermore, we investigate the geochemical character of the sediments using X-ray fluorescence (XRF) and stable carbon and oxygen isotopes. A middle Eocene age for the lower part of the succession is established from nannoplankton biostratigraphy. The Kuma Formation is dated between 42.1 and 38.4 Ma based on the assumption of constant sediment accumulation rates. A negative oxygen isotope excursion in the middle part of the Kuma Formation could be related to the MECO (~40 Ma). The onset of the Maikop Group is dated around the base of chron C13n at an age of ~33.7 Ma, close to the Eocene-Oligocene boundary. Based on geochemical results, we show that the Kuma Formation and Maikop Group correspond to two different episodes of intensified oceanic oxygen depletion in the succession. We hypothesise that oxygen-depletion as recorded in the Kuma Formation is linked to an increased nutrient input in the open marine Peri-Tethys due to widespread volcanism in the Neotethys subduction zone, while oxygen-depletion as recorded in the Maikop Group is linked to basin restriction caused by the eustatic sea-level fall straddling the Eocene – Oligocene boundary triggering stratified conditions in the semi-isolated Paratethys Sea