902 research outputs found

    Bose-Einstein correlations at LEP and Tevatron energies

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    Using the Bose-Einstein correlations (BEC) implemented in PYTHIA we investigated a possibility of the CDF experiment at the Tevatron to see the two-particle correlations in the final state of interactions. The approach based on quantum field theory at finite temperature was applied to the ALEPH data at LEP, and the BEC important parameters were retrieved.Comment: 5 pages, 4 figures, 1 table. Based on the talk gived at The 6th international workshop on very high multiplicity physics, JINR Dubna, 16-17 april 2005. In Table 1. the sign of error adde

    Comment on ``Large-space shell-model calculations for light nuclei''

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    In a recent publication Zheng, Vary, and Barrett reproduced the negative quadrupole moment of Li-6 and the low-lying positive-parity states of He-5 by using a no-core shell model. In this Comment we question the meaning of these results by pointing out that the model used is inadequate for the reproduction of these properties.Comment: Latex with Revtex, 1 postscript figure in separate fil

    BIMA Array Observations of the Highly Unusual SiO Maser Source with a Bipolar Nebulosity, IRAS 19312+1950

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    We report the results of mapping observations of the bipolar nebula with SiO maser emission, IRAS 19312+1950, in the CO (J=1-0 and J=2-1), 13CO (J=1-0 and J=2-1), C18O (J=1-0), CS (J=2-1), SO (J_K=3_2-2_1) and HCO+ (J=3-2) lines with the Berkeley-Illinois-Maryland Association array. Evolutional status of this source has been evoking a controversy since its discovery, though SiO maser sources are usually identified as late-type stars with active mass loss. In line profiles, two kinematical components are found as reported in previous single-dish observations: a broad pedestal component and a narrow component. Spatio-kinetic properties of a broad component region traced by 12CO lines are roughly explained by a simple spherical outflow model with a typical expanding velocity of an AGB star, though some properties of the broad component region still conflict with properties of a typical AGB spherical outflow. A narrow component region apparently exhibits a bipolar flow. The angular size of the narrow component region is spatially larger than that of a broad component region. Intensity distribution of the CS emission avoids the central region of the source, and that of an SO broad component emission exhibits a small feature peaked exactly at the mapping center. According to the present results, if a broad component really originates in a spherical outflow, an oxygen-rich evolved stellar object seems to be a natural interpretation for the central star of IRAS 19312+1950.Comment: 27 pages, 11 figures; accepted for publication in Ap

    Ab initio molecular dynamics study of liquid methanol

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    We present a density-functional theory based molecular-dynamics study of the structural, dynamical, and electronic properties of liquid methanol under ambient conditions. The calculated radial distribution functions involving the oxygen and hydroxyl hydrogen show a pronounced hydrogen bonding and compare well with recent neutron diffraction data, except for an underestimate of the oxygen-oxygen correlation. We observe that, in line with infrared spectroscopic data, the hydroxyl stretching mode is significantly red-shifted in the liquid. A substantial enhancement of the dipole moment is accompanied by significant fluctuations due to thermal motion. Our results provide valuable data for improvement of empirical potentials.Comment: 14 pages, 4 figures, accepted for publication in Chemical Physics Letter

    The complex molecular absorption line system at z=0.886 towards PKS1830-211

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    New millimeter wave observations of the molecular absorption line system in the gravitational lens to PKS1830-211 at z=0.88582 is presented. Self-calibrated interferometer data shows unequivocally that the previously detected absorption component is associated with the gravitationally lensed south-west image of the background source. A second absorption line of HCO+(2-1) at z=0.88582 is detected. This component is shifted in velocity by -147 km/s relative to the main absorption line, and is shown to be associated with the north-east image. These two absorption lines are used to constrain the mass of the lensing galaxy. Upper limits to absorption and emission lines from the possible absorption system at z=0.1927, seen in 21cm HI by Lovell et al, are reported.Comment: 16 pages, 7 figures, Accepted for publication in Ap

    A Spectral Line Survey from 138.3 to 150.7 GHZ toward Orion-KL

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    We present the results of a spectral line survey from 138.3 to 150.7 GHz toward Orion-KL. The observations were made using the 14 m radio telescope of Taeduk Radio Astronomy Observatory. Typical system temperatures were between 500 and 700 K, with the sensitivity between 0.020.060.02 - 0.06 K in units of TA\rm T_A^*. A total of 149 line spectra are detected in this survey. Fifty lines have been previously reported, however we find 99 new detections. Among these new lines, 32 are `unidentified', while 67 are from molecular transitions with known identifications. There is no detection of H or He recombination lines. The identified spectra are from a total of 16 molecular species and their isotopic variants. In the range from 138.3 to 150.7 GHz, the strongest spectral line is the J=3-2 transition of CS molecule, followed by transitions of the H2CO\rm H_2CO, CH3OH\rm CH_3OH, CH3CN\rm CH_3CN, and SO2\rm SO_2. Spectral lines from the large organic molecules such as CH3OH\rm CH_3OH, CH3OCH3\rm CH_3OCH_3, HCOOCH3\rm HCOOCH_3, C2H5CN\rm C_2H_5CN and CH3CN\rm CH_3CN are prominent; with 80 % of the identified lines arising from transitions of these molecules. The rotational temperatures and column densities are derived using the standard rotation diagram analysis for CH3OH\rm CH_3OH (13CH3OH\rm ^{13}CH_3OH), HCOOCH3\rm HCOOCH_3, CH3CN\rm CH_3CN and SO2\rm SO_2 with 10270K\rm 10\sim 270 K and 0.220×1015cm2\rm 0.2\sim 20\times 10^{15} cm^{-2}. These estimates are fairly comparable to the values for the same molecule in other frequency regions by other studies.Comment: 10 figures, 2 tex files for a manuscript and tables, accepted to Ap

    Detection of Voigt Spectral Line Profiles of Hydrogen Radio Recombination Lines toward Sagittarius B2(N)

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    We report the detection of Voigt spectral line profiles of radio recombination lines (RRLs) toward Sagittarius B2(N) with the 100-m Green Bank Telescope (GBT). At radio wavelengths, astronomical spectra are highly populated with RRLs, which serve as ideal probes of the physical conditions in molecular cloud complexes. An analysis of the Hn(alpha) lines presented herein shows that RRLs of higher principal quantum number (n>90) are generally divergent from their expected Gaussian profiles and, moreover, are well described by their respective Voigt profiles. This is in agreement with the theory that spectral lines experience pressure broadening as a result of electron collisions at lower radio frequencies. Given the inherent technical difficulties regarding the detection and profiling of true RRL wing spans and shapes, it is crucial that the observing instrumentation produce flat baselines as well as high sensitivity, high resolution data. The GBT has demonstrated its capabilities regarding all of these aspects, and we believe that future observations of RRL emission via the GBT will be crucial towards advancing our knowledge of the larger-scale extended structures of ionized gas in the interstellar medium (ISM)

    Changes in the Carpathian fauna of Malachiinae beetles (Coleoptera, Melyridae) in the context of temperature increase

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    Over last century in Europe a tendency of change in species ranges has occurred for insects of different taxonomic groups. We analyzed the changes that have taken place in the distribution of some soft-winged beetles (Malachiinae, Melyridae) species in the Carpathian region. The obtained data are based on a study of museum beetles’ collections and the authors’ collected materials. Data comparison relating to species distribution shows that the Carpathian fauna during the second half of the 20th century increased by 12 species. Some species have significantly changed their ranges. Species of Southern European and Mediterranean (Anthomalachius strangulatus, Clanoptilus spinipennis), Central-East European (Apalochrus femoralis, Clanoptilus falcifer) origin spread to the East Carpathian region. And vice versa, some species (e.g. Malachius scutellaris) from Central European and the Carpathian regions have spread beyond their borders of ranges to the East and North. Malachiinae species are anthophilic insects. Their life cycles, flight period, and distribution depend on the phenology of host plants. Acceleration of phenophases of the host plants and intensification of the metamorphosis processes due to increase in air temperature has caused an earlier appearance of soft-winged beetles in recent years and contributed to expansion of the ranges of some species of them. In our opinion, expansion of the species ranges and penetration of new beetle species into the Carpathian region from surrounding areas are related to the climate changes, in particular to warming. This thesis is confirmed by multiyear air temperature data of the Transcarpathian Centre of Hydrometeorology. On a background of increase in regional air temperature by about 0.8 °C an average air temperature in foothills of Ukrainian Carpathians has increased by 1.7 °C during last 50–60 years

    The Binet-Legendre Metric in Finsler Geometry

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    For every Finsler metric FF we associate a Riemannian metric gFg_F (called the Binet-Legendre metric). The transformation FgFF \mapsto g_F is C0C^0-stable and has good smoothness properties, in contrast to previous constructions. The Riemannian metric gFg_F also behaves nicely under conformal or bilipshitz deformation of the Finsler metric FF. These properties makes it a powerful tool in Finsler geometry and we illustrate that by solving a number of named Finslerian geometric problems. We also generalize and give new and shorter proofs of a number of known results. In particular we answer a question of M. Matsumoto about local conformal mapping between two Minkowski spaces, we describe all possible conformal self maps and all self similarities on a Finsler manifold. We also classify all compact conformally flat Finsler manifolds, solve a conjecture of S. Deng and Z. Hou on the Berwaldian character of locally symmetric Finsler spaces, and extend the classic result of H.C. Wang about the maximal dimension of the isometry groups of Finsler manifolds to manifolds of all dimensions. Most proofs in this paper go along the following scheme: using the correspondence FgFF \mapsto g_Fwe reduce the Finslerian problem to a similar problem for the Binet-Legendre metric, which is easier and is already solved in most cases we consider. The solution of the Riemannian problem provides us with the additional information that helps to solve the initial Finslerian problem. Our methods apply even in the absence of the strong convexity assumption usually assumed in Finsler geometry. The smoothness hypothesis can also be replaced by that of partial smoothness, a notion we introduce in the paper. Our results apply therefore to a vast class of Finsler metrics not usually considered in the Finsler literature.Comment: 33 pages, 5 figures. This version is slightly reduced fron versions 1 and 2. The paper has been published in Geometry & Topolog

    The Arecibo Arp 220 Spectral Census I: Discovery of the Pre-Biotic Molecule Methanimine and New Cm-wavelength Transitions of Other Molecules

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    An on-going Arecibo line search between 1.1 and 10 GHz of the prototypical starburst/megamaser galaxy, Arp 220, has revealed a spectrum rich in molecular transitions. These include the ``pre-biotic'' molecules: methanimine (CH2_{2}NH) in emission, three v2=1v_{2}=1 direct l-type absorption lines of HCN, and an absorption feature likely to be from either 18^{18}OH or formic acid (HCOOH). In addition, we report the detection of two, possibly three, transitions of λ\lambda4-cm excited OH not previously detected in Arp~220 which are seen in absorption, and a possible absorption feature from the 6.668-GHz line of methanol. This marks the first distant extragalactic detection of methanimine, a pre-biotic molecule. Also, if confirmed, the possible methanol absorption line presented here would represent the first extragalactic detection of methanol at a distance further than 10 Mpc. In addition, the strong, previously undetected, cm-wave HCN v2=1v_{2}=1 direct l-type lines will aid the study of dense molecular gas and active star-forming regions in this starburst galaxy.Comment: 25 pages, 10 figures. Accepted for publication in A
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