7,836 research outputs found
Formation of Bicyclic Pyrroles from the Catalytic Coupling Reaction of 2,5-disubstituted Pyrroles with Terminal Alkynes, Involving the Activation of Multiple C-H bonds
Substituted bicyclic pyrroles are produced directly from the coupling reaction of 2,5-disubstituted pyrroles with terminal alkynes, involving the activation of multiple C–H bonds and regioselective cyclisation
Statefinder diagnostic for the modified polytropic Cardassian universe
We apply the Statefinder diagnostic to the Modified Polytropic Cardassian
Universe in this work. We find that the Statefinder diagnostic is quite
effective to distinguish Cardassian models from a series of other cosmological
models. The plane is used to classify the Modified Polytropic Cardassian
models into six cases. The evolutionary trajectories in the plane for the
cases with different and reveal different evolutionary properties
of the universe. In addition, we combine the observational data, the
Cosmic Microwave Background (CMB) data and the Baryonic Acoustic Oscillation
(BAO) data to make a joint analysis. We find that \textbf{Case 2} can be
excluded at the 68.3% confidence level and any case is consistent with the
observations at the 95.4% confidence level.Comment: Comments: Final version for publication in Physical Review D [minor
revision to match the appear version] Journal-ref: Physical Review D 75,
083515 (2007
Search for charmonium and XYZ states in at BESIII
Within the framework of nonrelativistic quantum chromodynamics, we study the
production of charmonium states in at BESIII
with (n=1, 2, 3, and 4), (n=1, 2, and 3), and
(n=1 and 2). The radiative and relativistic corrections are
calculated to next-to-leading order for and wave states. We then argue
that the search for states such as , , ,
and in at BESIII may help clarify the nature
of these states. BESIII can search states through two body process
, where decay to , , or
. This result may be useful in identifying the nature of
states. For completeness, the production of charmonium in at B factories is also discussed.Comment: Comments and suggestions are welcome. References are update
Cosmological constraints from Radial Baryon Acoustic Oscillation measurements and Observational Hubble data
We use the Radial Baryon Acoustic Oscillation (RBAO) measurements, distant
type Ia supernovae (SNe Ia), the observational data (OHD) and the Cosmic
Microwave Background (CMB) shift parameter data to constrain cosmological
parameters of CDM and XCDM cosmologies and further examine the role of
OHD and SNe Ia data in cosmological constraints. We marginalize the likelihood
function over by integrating the probability density to obtain the best fitting results and the confidence regions
in the plane.With the combination analysis for
both of the {\rm }CDM and XCDM models, we find that the confidence
regions of 68.3%, 95.4% and 99.7% levels using OHD+RBAO+CMB data are in good
agreement with that of SNe Ia+RBAO+CMB data which is consistent with the result
of Lin et al's work. With more data of OHD, we can probably constrain the
cosmological parameters using OHD data instead of SNe Ia data in the future.Comment: 8 pages, 6 figures, 2 tables, accepted for publication in Physics
Letters
Thermodynamical properties of dark energy with the equation of state
The thermodynamical properties of dark energy are usually investigated with
the equation of state . Recent observations
show that our universe is accelerating, and the apparent horizon and the event
horizon vary with redshift . When definitions of the temperature and entropy
of a black hole are used to the two horizons of the universe, we examine the
thermodynamical properties of the universe which is enveloped by the apparent
horizon and the event horizon respectively. We show that the first and the
second laws of thermodynamics inside the apparent horizon in any redshift are
satisfied, while they are broken down inside the event horizon in some
redshift. Therefore, the apparent horizon for the universe may be the boundary
of thermodynamical equilibrium for the universe like the event horizon for a
black hole.Comment: 6 pages, 5 figures, Accepted for publication in Physical Review
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