2,543 research outputs found
Diquark Representations for Singly Heavy Baryons with Light Staggered Quarks
In the staggered fermion formulation of lattice QCD, we construct diquark
operators which are to be embedded in singly heavy baryons. The group
theoretical connections between continuum and lattice staggered diquark
representations are established.Comment: v1, 13 pages with title "Staggered Diquarks for Singly Heavy
Baryons"; v2, 4 pages in revtex, changed the title to be more specifi
Observational Constraints on Kinetic Gravity Braiding from the Integrated Sachs-Wolfe Effect
The cross-correlation between the integrated Sachs-Wolfe (ISW) effect and the
large scale structure (LSS) is a powerful tool to constrain dark energy and
alternative theories of gravity. In this paper, we obtain observational
constraints on kinetic gravity braiding from the ISW-LSS cross-correlation. We
find that the late-time ISW effect in the kinetic gravity braiding model
anti-correlates with large scale structures in a wide range of parameters,
which clearly demonstrates how one can distinguish modified gravity theories
from the LCDM model using the ISW effect. In addition to the analysis based on
a concrete model, we investigate a future prospect of the ISW-LSS
cross-correlation by using a phenomenological parameterization of modified
gravity models.Comment: 7 pages, 3 figures, accepted for publication in Physical Review
Power Spectrum Analysis of the 2dF QSO Sample Revisited
We revisit the power spectrum analysis of the complete sample of the two
degree field (2dF) QSO redshift (2QZ) survey, as a complementary test of the
work by Outram et al. (2003). A power spectrum consistent with that of the 2QZ
group is obtained. Differently from their approach, fitting of the power
spectrum is investigated incorporating the nonlinear effects, the geometric
distortion and the light-cone effect. It is shown that the QSO power spectrum
is consistent with the cold dark matter (CDM) model with the matter
density parameter . Our constraint on the density
parameter is rather weaker than that of the 2QZ group. We also show that the
constraint slightly depends on the equation of state parameter of the dark
energy. The constraint on from the QSO power spectrum is demonstrated,
though it is not very tight.Comment: 15 pages, 5 figures, accepted for publication in the Astrophysical
Journa
Quantum Larmor radiation in conformally flat universe
We investigate the quantum effect on the Larmor radiation from a moving
charge in an expanding universe based on the framework of the scalar quantum
electrodynamics (SQED). A theoretical formula for the radiation energy is
derived at the lowest order of the perturbation theory with respect to the
coupling constant of the SQED. We evaluate the radiation energy on the
background universe so that the Minkowski spacetime transits to the Milne
universe, in which the equation of motion for the mode function of the free
complex scalar field can be exactly solved in an analytic way. Then, the result
is compared with the WKB approach, in which the equation of motion of the mode
function is constructed with the WKB approximation which is valid as long as
the Compton wavelength is shorter than the Hubble horizon length. This
demonstrates that the quantum effect on the Larmor radiation of the order
e^2\hbar is determined by a non-local integration in time depending on the
background expansion. We also compare our result with a recent work by Higuchi
and Walker [Phys. Rev. D80 105019 (2009)], which investigated the quantum
correction to the Larmor radiation from a charged particle in a
non-relativistic motion in a homogeneous electric field.Comment: 12 pages, 4 figure, accepted for publication in Physical Review
Can Geometric Test Probe the Cosmic Equation of State ?
Feasibility of the geometric test as a probe of the cosmic equation of state
of the dark energy is discussed assuming the future 2dF QSO sample. We examine
sensitivity of the QSO two-point correlation functions, which are theoretically
computed incorporating the light-cone effect and the redshift distortions, as
well as the nonlinear effect, to a bias model whose evolution is
phenomenologically parameterized. It is shown that the correlation functions
are sensitive on a mean amplitude of the bias and not to the speed of the
redshift evolution. We will also demonstrate that an optimistic geometric test
could suffer from confusion that a signal from the cosmological model can be
confused with that from a stochastic character of the bias.Comment: 11 pages, including 3 figures, accepted for publication in ApJ
Linear response calculation using the canonical-basis TDHFB with a schematic pairing functional
A canonical-basis formulation of the time-dependent Hartree-Fock-Bogoliubov
(TDHFB) theory is obtained with an approximation that the pair potential is
assumed to be diagonal in the time-dependent canonical basis. The
canonical-basis formulation significantly reduces the computational cost. We
apply the method to linear-response calculations for even-even nuclei. E1
strength distributions for proton-rich Mg isotopes are systematically
calculated. The calculation suggests strong Landau damping of giant dipole
resonance for drip-line nuclei.Comment: 6 pages, 1 figure, INPC 2010 conference proceding
A generalization of heterochromatic graphs
In 2006, Suzuki, and Akbari & Alipour independently presented a necessary and
sufficient condition for edge-colored graphs to have a heterochromatic spanning
tree, where a heterochromatic spanning tree is a spanning tree whose edges have
distinct colors. In this paper, we propose -chromatic graphs as a
generalization of heterochromatic graphs. An edge-colored graph is
-chromatic if each color appears on at most edges. We also
present a necessary and sufficient condition for edge-colored graphs to have an
-chromatic spanning forest with exactly components. Moreover, using this
criterion, we show that a -chromatic graph of order with
has an -chromatic spanning forest with exactly
() components if for any
color .Comment: 14 pages, 4 figure
Coating thermal noise of a finite-size cylindrical mirror
Thermal noise of a mirror is one of the limiting noise sources in the high
precision measurement such as gravitational-wave detection, and the modeling of
thermal noise has been developed and refined over a decade. In this paper, we
present a derivation of coating thermal noise of a finite-size cylindrical
mirror based on the fluctuation-dissipation theorem. The result agrees to a
previous result with an infinite-size mirror in the limit of large thickness,
and also agrees to an independent result based on the mode expansion with a
thin-mirror approximation. Our study will play an important role not only to
accurately estimate the thermal-noise level of gravitational-wave detectors but
also to help analyzing thermal noise in quantum-measurement experiments with
lighter mirrors.Comment: 13 pages, 4 figure
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