17,324 research outputs found

    Charmonium-hadron interactions from QCD

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    The heavy quark system is an excellent probe to learn about the QCD dynamics at finite density. First, we discuss the properties of the J/ψJ/\psi and DD meson at finite nucleon density. We discuss why their properties should change at finite density and then introduce an exact QCD relation among these hadron properties and the energy momentum tensor of the medium. Second, we discuss attempts to calculate charmonium-hadron total cross section using effective hadronic models and perturbative QCD. We emphasize a recent calculation, where the cross section is derived using QCD factorization theorem. We conclude by discussing some challenges for SIS 200.Comment: 8 pages, Presented at 6th International Conference on Strange Quarks in Matter: 2001: A Flavorspace Odyssey (SQM2001), Frankfurt, Germany, 25-29 Sep 2001, submitted to J. Phys.

    Global monopole solutions in Horava gravity

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    In Horava's theory of gravity coupled to a global monopole source, we seek for static, spherically symmetric spacetime solutions for general values of λ\lambda. We obtain the explicit solutions with deficit solid angles, in the IR modified Horava gravity model, at the IR fixed point λ=1\lambda=1 and at the conformal point λ=1/3\lambda=1/3. For the other values of 1>λ>01>\lambda>0 we also find special solutions to the inhomogenous equation of the gravity model with detailed balance, and we discuss an possibility of astrophysical applications of the λ=1/2\lambda=1/2 solution that has a deficit angle for a finite range.Comment: 7 pages, added reference

    Temperature-dependent Raman spectroscopy in BaRuO3_3 systems

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    We investigated the temperature-dependence of the Raman spectra of a nine-layer BaRuO3_3 single crystal and a four-layer BaRuO3_3 epitaxial film, which show pseudogap formations in their metallic states. From the polarized and depolarized spectra, the observed phonon modes are assigned properly according to the predictions of group theory analysis. In both compounds, with decreasing temperature, while A1gA_{1g} modes show a strong hardening, EgE_g (or E2gE_{2g}) modes experience a softening or no significant shift. Their different temperature-dependent behaviors could be related to a direct Ru metal-bonding through the face-sharing of RuO6_6. It is also observed that another E2gE_{2g} mode of the oxygen participating in the face-sharing becomes split at low temperatures in the four layer BaRuO3_3 . And, the temperature-dependence of the Raman continua between 250 \sim 600 cm1^{-1} is strongly correlated to the square of the plasma frequency. Our observations imply that there should be a structural instability in the face-shared structure, which could be closely related to the pseudogap formation of BaRuO3_3 systems.Comment: 8 pages, 6 figures. to be published in Phys. Rev.

    Towards A Background Independent Quantum Gravity

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    We recapitulate the scheme of emergent gravity to highlight how a background independent quantum gravity can be defined by quantizing spacetime itself.Comment: 25 pages, 2 figures, Proceedings of 7th International Conference "Quantum Theory and Symmetries" (QTS-7) in Prague, Czech Republic, August, 201

    Optical investigation on the electronic structures of Y_{2}Ru_{2}O_{7}, CaRuO_{3}, SrRuO_{3}, and Bi_{2}Ru_{2}O_{7}

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    We investigated the electronic structures of the bandwidth-controlled ruthenates, Y2_{2}Ru2_{2}O7_{7}, CaRuO3_{3}, SrRuO3_{3}, and Bi2_{2}Ru2% _{2}O7_{7}, by optical conductivity analysis in a wide energy region of 5 meV \sim 12 eV. We could assign optical transitions from the systematic changes of the spectra and by comparison with the O 1ss x-ray absorption data. We estimated some physical parameters, such as the on-site Coulomb repulsion energy and the crystal-field splitting energy. These parameters show that the 4dd orbitals should be more extended than 3dd ones. These results are also discussed in terms of the Mott-Hubbard model.Comment: 12 pages (1 table), 3 figure

    Making Maps Of The Cosmic Microwave Background: The MAXIMA Example

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    This work describes Cosmic Microwave Background (CMB) data analysis algorithms and their implementations, developed to produce a pixelized map of the sky and a corresponding pixel-pixel noise correlation matrix from time ordered data for a CMB mapping experiment. We discuss in turn algorithms for estimating noise properties from the time ordered data, techniques for manipulating the time ordered data, and a number of variants of the maximum likelihood map-making procedure. We pay particular attention to issues pertinent to real CMB data, and present ways of incorporating them within the framework of maximum likelihood map-making. Making a map of the sky is shown to be not only an intermediate step rendering an image of the sky, but also an important diagnostic stage, when tests for and/or removal of systematic effects can efficiently be performed. The case under study is the MAXIMA data set. However, the methods discussed are expected to be applicable to the analysis of other current and forthcoming CMB experiments.Comment: Replaced to match the published version, only minor change

    MAXIMA: an experiment to measure temperature anisotropy in the cosmic microwave background

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    We describe the MAXIMA experiment, a balloon-borne measurement designed to map temperature anisotropy in the Cosmic Microwave Background (CMB) over a wide range of angular scales (multipole range 80 < l < 800). The experiment consists of a 1.3 m diameter off-axis Gregorian telescope and a receiver with a 16 element array of bolometers cooled to 100 mK. The frequency bands are centered at 150, 240, and 410 GHz. The 10' FWHM beam sizes are well matched to the scale of acoustic peaks expected in the angular power spectrum of the CMB. The first flight of the experiment in its full configuration was launched in August 1998. A 122 sq-deg map of the sky was made near the Draco constellation during the 7 hour flight in a region of extremely low galactic dust contamination. This map covers 0.3% of the sky and has 3200 independent beamsize pixels. We describe the MAXIMA instrument and its performance during the recent flight.Comment: To appear in proceedings of `3K Cosmology', ed. F Melchiorri, Conference held Oct 5-10 1998, Rome, 13 pages LaTeX (using aipproc2.sty & aipproc2.cls), Postscript with higher resolution graphics available at http://cfpa.berkeley.edu/group/cmb/gen.htm

    Magnetic Determination of Hc2H_{c2} under Accurate Alignment in (TMTSF)2_2ClO4_4

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    Cantilever magnetometry has been used to measure the upper critical magnetic field Hc2H_{c2} of the quasi-one dimensional molecular organic superconductor (TMTSF)2_2ClO4_4. From simultaneous resistivity and torque magnetization experiments conducted under precise field alignment, Hc2H_{c2} at low temperature is shown to reach 5T, nearly twice the Pauli paramagnetic limit imposed on spin singlet superconductors. These results constitute the first thermodynamic evidence for a large Hc2H_{c2} in this system and provide support for spin triplet pairing in this unconventional superconductorComment: Submitted July 1, 2003, Accepted December 9, 2003, Physical Review Letter

    First Results from the AMoRE-Pilot neutrinoless double beta decay experiment

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    The Advanced Molybdenum-based Rare process Experiment (AMoRE) aims to search for neutrinoless double beta decay (0νββ\nu\beta\beta) of 100^{100}Mo with \sim100 kg of 100^{100}Mo-enriched molybdenum embedded in cryogenic detectors with a dual heat and light readout. At the current, pilot stage of the AMoRE project we employ six calcium molybdate crystals with a total mass of 1.9 kg, produced from 48^{48}Ca-depleted calcium and 100^{100}Mo-enriched molybdenum (48depl^{48\textrm{depl}}Ca100^{100}MoO4_4). The simultaneous detection of heat(phonon) and scintillation (photon) signals is realized with high resolution metallic magnetic calorimeter sensors that operate at milli-Kelvin temperatures. This stage of the project is carried out in the Yangyang underground laboratory at a depth of 700 m. We report first results from the AMoRE-Pilot 0νββ0\nu\beta\beta search with a 111 kg\cdotd live exposure of 48depl^{48\textrm{depl}}Ca100^{100}MoO4_4 crystals. No evidence for 0νββ0\nu\beta\beta decay of 100^{100}Mo is found, and a upper limit is set for the half-life of 0νββ\nu\beta\beta of 100^{100}Mo of T1/20ν>9.5×1022T^{0\nu}_{1/2} > 9.5\times10^{22} y at 90% C.L.. This limit corresponds to an effective Majorana neutrino mass limit in the range mββ(1.22.1)\langle m_{\beta\beta}\rangle\le(1.2-2.1) eV

    Status and performance of the AMoRE-I experiment on neutrinoless double beta decay

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    AMoRE is an international project to search for the neutrinoless double beta decay of 100^{100}Mo using a detection technology consisting of magnetic microcalorimeters (MMCs) and molybdenum-based scintillating crystals. Data collection has begun for the current AMORE-I phase of the project, an upgrade from the previous pilot phase. AMoRE-I employs thirteen 48depl.^\mathrm{48depl.}Ca100^{100}MoO4_4 crystals and five Li2_2100^{100}MoO4_4 crystals for a total crystal mass of 6.2 kg. Each detector module contains a scintillating crystal with two MMC channels for heat and light detection. We report the present status of the experiment and the performance of the detector modules.Comment: 8 pages, 4 figures, published in Journal of Low Temperature Physics (2022
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