19,199 research outputs found
On determination of the geometric cosmological constant from the OPERA experiment of superluminal neutrinos
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
which is the sum of the quantum zero point energy
and the geometric cosmological constant . The
OPERA experiment can be applied to determine the geometric cosmological
constant . It is the first time to distinguish the contributions of
and 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
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 - Revealed with SDSS, DEEP2, and Keck spectra
We conduct a systematic study of galactic outflows in star-forming galaxies
at - 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
-, 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 (), 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 -; Mg II and C II at
-), 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
to at a given SFR. Moreover, we find that the value of
increases from to by 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 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
in our galaxies that agrees with the
momentum-driven outflow model () within the uncertainty.Comment: 13 pages, 10 figures, ApJ in pres
Proton-Antiproton Annihilation in Baryonium
A possible interpretation of the near-threshold enhancement in the
-mass spectrum in is the of existence
of a narrow baryonium resonance X(1860). Mesonic decays of the
-bound state X(1860) due to the nucleon-antinucleon annihilation
are investigated in this paper. Mesonic coherent states with fixed -parity
and -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 , and are calculated. It is shown
that if the X(1860) is a bound state of , the decay channel ( is favored over . In this way, we develop
criteria for distinguishing the baryonium interpretation for the near-threshold
enhancement effects in -mass spectrum in 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
We investigate the properties of 1088 Lyman Break Galaxies (LBGs) at z~3
selected from a ~2.63M/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
- …