688 research outputs found
Classical and Quantum Correlations of Scalar Field in the Inflationary Universe
We investigate classical and quantum correlations of a quantum field in the
inflationary universe using a particle detector model. By considering the
entanglement and correlations between two comoving detectors interacting with a
scalar field, we find that the entanglement between the detectors becomes zero
after their physical separation exceeds the Hubble horizon. Furthermore, the
quantum discord, which is defined as the quantum part of total correlation,
approaches zero on super horizon scale. These behaviors support appearance of
classical nature of the quantum fluctuation generated during the inflationary
era.Comment: 21 pages, accepted for publication in Phys. Rev.
Crystallographic Study of Itokawa Particle, RA-QD02-0127 by Using Energy-Scanning X-Ray Diffraction Method with Synchrotron Radiation
The petrographic study of Itokawa particle, RA-QD02-0127 has been performed by SEM-EDS and optical microscope observations. The purpose of this study is to understand better the metamorphic and impact shock history of asteroid Itokawa, and other S-class asteroids
Identification of Magnetite in Lunar Regolith Breccia 60016: Evidence for Oxidized Conditions at the Lunar Surface
Lunar regolith breccias are temporal archives of magmatic and impact bombardment processes on the Moon. Apollo 16 sample 60016 is an ‘ancient’ feldspathic regolith breccia that was converted from a soil to a rock at ~3.8 Ga. The breccia contains a small (70 × 50 μm) rock fragment composed dominantly of an Fe-oxide phase with disseminated domains of troilite. Fragments of plagioclase (An95-97), pyroxene (En74-75, Fs21-22,Wo3-4) and olivine (Fo66-67) are distributed in and adjacent to the Fe-oxide. The silicate minerals have lunar compositions that are similar to anorthosites. Mineral chemistry, synchrotron X-ray Absorption Near Edge Spectroscopy (XANES) and X-ray Diffraction (XRD) studies demonstrate that the oxide phase is magnetite with an estimated Fe3+/ΣFe ratio of ~0.45. The presence of magnetite in 60016 indicates that oxygen fugacity during formation was equilibrated at, or above, the Fe-magnetite or wűstite-magnetite oxygen buffer. This discovery provides direct evidence for oxidised conditions on the Moon. Thermodynamic modelling shows that magnetite could have been formed from oxidisation-driven mineral replacement of Fe-metal or desulphurisation from Fe-sulphides (troilite) at low temperatures (°C) in equilibrium with H2O steam/liquid or CO2 gas. Oxidising conditions may have arisen from vapour transport during degassing of a magmatic source region, or from a hybrid endogenic-exogenic process when gases were released during an impacting asteroid or comet impact
The Little Review on Leptogenesis
This is a brief review on the scenario of baryogenesis through leptogenesis.
Leptogenesis is an appealing scenario that may relate the observed baryon
asymmetry in the Universe to the low-energy neutrino data. In this review talk,
particular emphasis is put on recent developments on the field, such as the
flavourdynamics of leptogenesis and resonant leptogenesis near the electroweak
phase transition. It is illustrated how these recent developments enable the
modelling of phenomenologically predictive scenarios that can directly be
tested at the LHC and indirectly in low-energy experiments of lepton-number and
lepton-flavour violation.Comment: 15 pages, based on a plenary presentation given at the DISCRETE'08
Symposium, 11-16 December 2008, Valencia, Spai
Pure nematic state in iron-based superconductor
Lattice and electronic states of thin FeSe films on LaAlO substrates are
investigated in the vicinity of the nematic phase transition. No evidence of
structural phase transition is found by x-ray diffraction below K, while results obtained from resistivity measurement and angle-resolved
photoemission spectroscopy clearly show the appearance of a nematic state.
These results indicate formation of a pure nematic state in the iron-based
superconductor and provide conclusive evidence that the nematic state
originates from the electronic degrees of freedom. This pure nematicity in the
thin film implies difference in the electron-lattice interaction from bulk FeSe
crystals. FeSe films provide valuable playgrounds for observing the pure
response of "bare" electron systems free from the electron-lattice interaction,
and should make important contribution to investigate nematicity and its
relationship with superconductivity
Technical design and performance of the NEMO3 detector
The development of the NEMO3 detector, which is now running in the Frejus
Underground Laboratory (L.S.M. Laboratoire Souterrain de Modane), was begun
more than ten years ago. The NEMO3 detector uses a tracking-calorimeter
technique in order to investigate double beta decay processes for several
isotopes. The technical description of the detector is followed by the
presentation of its performance.Comment: Preprint submitted to Nucl. Instrum. Methods A Corresponding author:
Corinne Augier ([email protected]
A CAI in the Ivuna CI1 Chondrite
We have recently discovered the first well-preserved calcium aluminum-rich inclusion (CAI) in a CI1 chondrite (Ivuna). Previously, all CI1 chondrites were thought to be devoid of preserved CAI and chondrules due to the near total aqueous alteration to which their parent body (bodies) have been subjected. The CAI is roughly spherical, but with a slight teardrop geometry and a maximum diameter of 170 microns (fig. 1). It lacks any Wark-Lovering Rim. Incipient aqueous alteration, and probably shock, have rendered large portions of the CAI poorly crystalline. It is extremely fine-grained, with only a few grains exceeding 10 microns. We have performed electron microprobe analyses (EPMA), FEG-SEM imaging and element mapping, as well as electron back-scattered diffraction (EBSD) and synchrotron X-ray diffraction (SXRD) in order to determine the fundamental characteristics of this apparently unique object
Study of 2 beta-decay of Mo-100 and Se-82 using the NEMO3 detector
After analysis of 5797 h of data from the detector NEMO3, new limits on neutrinoless double beta decay of Mo-100 (T-1/2 > 3.1 x 10(23) y, 90% CL) and Se-82 (T-1/2 > 1.4 x 10(23) y, 90% CL) have been obtained. The corresponding limits on the effective majorana neutrino mass are: 1.4 x 10(22) y (90% CL) for Mo-100 and T-1/2 > 1.2 x 10(22) y (90% CL) for Se-82. Corresponding bounds on the Majoron-neutrino coupling constant are < (0.5-0.9) x 10(- 4) and <(0.7-1.6) x 10(- 4). Two-neutrino 2beta-decay half-lives have been measured with a high accuracy, (T1/2Mo)-Mo-100 = [7.68 +/- 0.02(stat) +/- 0.54(syst)] x 10(18) y and (T1/2Se)-Se-82 = [10.3 +/- 0.3(stat) +/- 0.7(syst)] x 10(19) y. (C) 2004 MAIK "Nauka/Interperiodica"
Scintillation-only Based Pulse Shape Discrimination for Nuclear and Electron Recoils in Liquid Xenon
In a dedicated test setup at the Kamioka Observatory we studied pulse shape
discrimination (PSD) in liquid xenon (LXe) for dark matter searches. PSD in LXe
was based on the observation that scintillation light from electron events was
emitted over a longer period of time than that of nuclear recoil events, and
our method used a simple ratio of early to total scintillation light emission
in a single scintillation event. Requiring an efficiency of 50% for nuclear
recoil retention we reduced the electron background to 7.7\pm1.1(stat)\pm1.2
0.6(sys)\times10-2 at energies between 4.8 and 7.2 keVee and to
7.7\pm2.8(stat)\pm2.5 2.8(sys)\times10-3 at energies between 9.6 and 12 keVee
for a scintillation light yield of 20.9 p.e./keV. Further study was done by
masking some of that light to reduce this yield to 4.6 p.e./keV, the same
method results in an electron event reduction of 2.4\pm0.2(stat)\pm0.3
0.2(sys)\times10-1 for the lower of the energy regions above. We also observe
that in contrast to nuclear recoils the fluctuations in our early to total
ratio for electron events are larger than expected from statistical
fluctuations.Comment: 25 pages, 15 figure
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