19,199 research outputs found

    On determination of the geometric cosmological constant from the OPERA experiment of superluminal neutrinos

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    The recent OPERA experiment of superluminal neutrinos has deep consequences in cosmology. In cosmology a fundamental constant is the cosmological constant. From observations one can estimate the effective cosmological constant Λeff\Lambda_{eff} which is the sum of the quantum zero point energy Λdarkenergy\Lambda_{dark energy} and the geometric cosmological constant Λ\Lambda. The OPERA experiment can be applied to determine the geometric cosmological constant Λ\Lambda. It is the first time to distinguish the contributions of Λ\Lambda and Λdarkenergy\Lambda_{dark energy} from each other by experiment. The determination is based on an explanation of the OPERA experiment in the framework of Special Relativity with de Sitter space-time symmetry.Comment: 7 pages, no figure

    The Pseudoscalar Meson and Heavy Vector Meson Scattering Lengths

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    We have systematically studied the S-wave pseudoscalar meson and heavy vector meson scattering lengths to the third order with the chiral perturbation theory, which will be helpful to reveal their strong interaction. For comparison, we have presented the numerical results of the scattering lengths (1) in the framework of the heavy meson chiral perturbation theory and (2) in the framework of the infrared regularization. The chiral expansion converges well in some channels.Comment: 10 pages, 1 figures, 4 tables. Corrected typos, Improved numerical results, and More dicussions. Accepted for publication by Phys.Rev.

    Evolution of Galactic Outflows at z0z\sim0-22 Revealed with SDSS, DEEP2, and Keck spectra

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    We conduct a systematic study of galactic outflows in star-forming galaxies at z0z\sim0-22 based on the absorption lines of optical spectra taken from SDSS DR7, DEEP2 DR4, and Keck Erb et al. We carefully make stacked spectra of homogeneous galaxy samples with similar stellar mass distributions at z0z\sim0-22, and perform the multi-component fitting of model absorption lines and stellar continua to the stacked spectra. We obtain the maximum (v_\rm{max}) and central (v_\rm{out}) outflow velocities, and estimate the mass loading factors (η\eta), a ratio of the mass outflow rate to the star formation rate (SFR). Investigating the redshift evolution of the outflow velocities measured with the absorption lines whose depths and ionization energies are similar (Na I D and Mg I at z0z\sim0-11; Mg II and C II at z1z\sim1-22), we identify, for the first time, that the average value of v_\rm{max} (v_\rm{out}) significantly increases by 0.05-0.3 dex from z0z\sim0 to 22 at a given SFR. Moreover, we find that the value of η\eta increases from z0z\sim0 to 22 by η(1+z)1.2±0.3\eta \propto (1 + z)^{1.2\pm0.3} at a given halo circular velocity v_\rm{cir} , albeit with a potential systematics caused by model parameter choices. The redshift evolution of v_\rm{max} (v_\rm{out}) and η\eta is consistent with the galaxy-size evolution and the local velocity-SFR surface density relation, and explained by high-gas fractions in high-redshift massive galaxies, which is supported by recent radio observations. We obtain a scaling relation of \eta \propto v_\rm{cir}^a for a=0.2±1.1a = -0.2 \pm 1.1 in our z0z\sim0 galaxies that agrees with the momentum-driven outflow model (a=1a = -1) within the uncertainty.Comment: 13 pages, 10 figures, ApJ in pres

    Proton-Antiproton Annihilation in Baryonium

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    A possible interpretation of the near-threshold enhancement in the (ppˉ)(p\bar{p})-mass spectrum in J/ψγppˉJ/\psi{\to}\gamma p{\bar p} is the of existence of a narrow baryonium resonance X(1860). Mesonic decays of the (ppˉ)(p\bar{p})-bound state X(1860) due to the nucleon-antinucleon annihilation are investigated in this paper. Mesonic coherent states with fixed GG-parity and PP-parity have been constructed . The Amado-Cannata-Dedoder-Locher-Shao formulation(Phys Rev Lett. {\bf 72}, 970 (1994)) is extended to the decays of the X(1860). By this method, the branch-fraction ratios of Br(Xη4π)Br(X\to \eta 4\pi), Br(Xη2π)Br(X\to \eta 2\pi) and Br(X3η)Br(X\to 3\eta) are calculated. It is shown that if the X(1860) is a bound state of (ppˉ)(p\bar{p}), the decay channel (Xη4π)X\to \eta 4\pi) is favored over (Xη2π)(X\to \eta 2\pi). In this way, we develop criteria for distinguishing the baryonium interpretation for the near-threshold enhancement effects in (ppˉ)(p\bar{p})-mass spectrum in J/ψγppˉJ/\psi{\to}\gamma p{\bar p} from other possibilities. Experimental checks are expected. An intuitive picture for our results is discussed.Comment: 19 pages, 3 figure

    Massive Lyman Break Galaxies at z~3 in the Spitzer Extragalactic First Look Survey

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    We investigate the properties of 1088 Lyman Break Galaxies (LBGs) at z~3 selected from a ~2.63deg2subregionoftheFirstLookSurveyfieldusingthegroundbasedmulticolordataandtheSpitzerSpaceTelescopemidinfrareddataat38and24um.Withthewideareaandthebroadwavelengthcoverage,wesamplealargenumberofrareubanddropoutswhicharemassive(M>1011Msun),allowingustoperformastatisticalanalysisofthesesubsetsofLBGsthathavenotbeenstudiedindetail.Opticallybright(R(AB)<24.5mag)LBGsdetectedinmidinfrared(S3.6um>6uJy)resideatthemostmassiveanddustyendoftheLBGpopulation,withrelativelyhighandtight deg2 sub-region of the First Look Survey field using the ground-based multi-color data and the Spitzer Space Telescope mid-infrared data at 3--8 and 24 um. With the wide area and the broad wavelength coverage, we sample a large number of ``rare'' u-band dropouts which are massive (M* > 10^11 Msun), allowing us to perform a statistical analysis of these subsets of LBGs that have not been studied in detail. Optically bright (R(AB) < 24.5 mag) LBGs detected in mid-infrared (S_{3.6um} > 6 uJy) reside at the most massive and dusty end of the LBG population, with relatively high and tight M/L$ in rest-frame near-infrared. Most infrared-luminous LBGs (S_{24um} > 100 uJy) are dusty star-forming galaxies with star formation rates of 100--1000 Msun/yr, total infrared luminosity of > 10^12 Lsun. By constructing the UV luminosity function of massive LBGs, we estimate that the lower limit for the star formation rate density from LBGs more massive than 10^11 Msun at z~3 is > 3.3 x 10^-3 Msun/yr/Mpc^3, showing for the first time that the UV-bright population of massive galaxies alone contributes significantly to the global star formation rate density at z~3. When combined with the star formation rate densities at z < 2, our result reveals a steady increase in the contribution of massive galaxies to the global star formation from z=0 to z=3, providing strong support to the downsizing of galaxy formation.Comment: 15 pages, 13 figures. Accepted for publication in Ap
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