377 research outputs found
Study of f_0(980) and f_0(1500) from B_s \to f_0(980)K, f_0(1500)K Decays
In this paper, we calculate the branching ratios and CP-violating asymmetries
for \bar B^0_s \to f_0(980)K, f_0(1500)K within Perturbative QCD approach based
on k_T factorization. If the mixing angle falls into the range of
25^\circ<\theta<40^\circ, the branching ratio of \bar B^0_s\to f_0(980)K is
2.0\times 10^{-6}<{\cal B}(\bar B^0_s\to f_0(980)K)<2.6\times 10^{-6}, while
lies in the range of 140^\circ<\theta<165^\circ, {\cal B}(\bar
B^0_s\to f_0(980)K) is about 6.5\times 10^{-7}. As to the decay {\cal B}(\bar
B^0_s\to f_0(1500)K), when the mixing scheme \mid f_0(1500)>=0.84\mid s\bar
s>-0.54\mid n\bar n> for f_0(1500) is used, it is difficult to determine which
scenario is more preferable than the other one from the branching ratios for
these two scenarios, because they are both close to 1.0\times10^{-6}. But there
exists large difference in the form factor F^{\bar B_s^0\to f_0(1500)} for two
scenarios.Comment: 14 pages, 3 figures, submitted to J. Phys.
Nonleptonic charmless two-body B decays involving tensor mesons in the covariant light-front approach
We reanalyzed nonleptonic charmless two-body B decays involving tensor mesons
in final state motivated by the disagreement between current experimental
information and theoretical predictions obtained in ISGW2 model for some
(where , and denote a pseudoscalar, a
vector and a tensor meson, respectively). We have calculated branching ratios
of charmless and modes, using form factors
obtained in the covariant light-front (CLF) approach and the full effective
Hamiltonian. We have considered the two-mixing angle
formalism for channels, which increases branching
ratios for these processes. Our predictions obtained in the CLF approach are,
in general, greater than those computed in the framework of the ISGW2 model and
more favorable with the available experimental data. Specifically, our results
for exclusive channels and are in agreement with recent experimental information.Comment: 10 page
Nonleptonic charmless two-body decays
In this work we have studied hadronic charmless two-body B decays involving
p-wave mesons in final state. We have calculated branching ratios of
decays (where and denotes a axial-vector and a tensor meson,
respectively), using form factors obtained in the covariant
light-front (CLF) approach, and the full effective Hamiltonian. We have
obtained that ,
,
(with ) for ,
with
, for
where . It seems that these decays can be measured
in experiments at factories. Additionally, we have found that
and
ratios could be useful to determine numerical values of mixing angles
and , respectively.Comment: 12 page
Study of and from and Decays
We use the decay modes and to
study the scalar mesons and within perturbative QCD
framework. For , we perform our calculation in two
scenarios of the scalar meson spectrum. The results indicate that scenario II
is more favored by experimental data than scenario I. The important
contribution from annihilation diagrams can enhance the branching ratios about
50% in scenario I, and about 30% in scenario II. The predicted branching ratio
of in scenario I is also less favored by the experiments.
The direct CP asymmetries in are small, which are
consistent with the present experiments.Comment: More references are added. Published Versio
The DArk Matter Particle Explorer mission
The DArk Matter Particle Explorer (DAMPE), one of the four scientific space
science missions within the framework of the Strategic Pioneer Program on Space
Science of the Chinese Academy of Sciences, is a general purpose high energy
cosmic-ray and gamma-ray observatory, which was successfully launched on
December 17th, 2015 from the Jiuquan Satellite Launch Center. The DAMPE
scientific objectives include the study of galactic cosmic rays up to
TeV and hundreds of TeV for electrons/gammas and nuclei respectively, and the
search for dark matter signatures in their spectra. In this paper we illustrate
the layout of the DAMPE instrument, and discuss the results of beam tests and
calibrations performed on ground. Finally we present the expected performance
in space and give an overview of the mission key scientific goals.Comment: 45 pages, including 29 figures and 6 tables. Published in Astropart.
Phy
Exclusive Semileptonic Decays of Bc Meson
We present a detailed analysis of exclusive semileptonic decays of Bc meson
involving pseudoscalar and vector mesons in the BSW framework, by investigating
the effects of the flavor dependence on the average transverse quark momentum
inside a meson. Branching ratios of exclusive semileptonic decays of Bc meson
are predicted.Comment: 15 pages, 2 figure
Observation of a ppb mass threshoud enhancement in \psi^\prime\to\pi^+\pi^-J/\psi(J/\psi\to\gamma p\bar{p}) decay
The decay channel
is studied using a sample of events collected
by the BESIII experiment at BEPCII. A strong enhancement at threshold is
observed in the invariant mass spectrum. The enhancement can be fit
with an -wave Breit-Wigner resonance function with a resulting peak mass of
and a
narrow width that is at the 90% confidence level.
These results are consistent with published BESII results. These mass and width
values do not match with those of any known meson resonance.Comment: 5 pages, 3 figures, submitted to Chinese Physics
Measurement of the quasi-elastic axial vector mass in neutrino-oxygen interactions
The weak nucleon axial-vector form factor for quasi-elastic interactions is
determined using neutrino interaction data from the K2K Scintillating Fiber
detector in the neutrino beam at KEK. More than 12,000 events are analyzed, of
which half are charged-current quasi-elastic interactions nu-mu n to mu- p
occurring primarily in oxygen nuclei. We use a relativistic Fermi gas model for
oxygen and assume the form factor is approximately a dipole with one parameter,
the axial vector mass M_A, and fit to the shape of the distribution of the
square of the momentum transfer from the nucleon to the nucleus. Our best fit
result for M_A = 1.20 \pm 0.12 GeV. Furthermore, this analysis includes updated
vector form factors from recent electron scattering experiments and a
discussion of the effects of the nucleon momentum on the shape of the fitted
distributions.Comment: 14 pages, 10 figures, 6 table
A brief review of graphene-based material synthesis and its application in environmental pollution management
The Evolution of Compact Binary Star Systems
We review the formation and evolution of compact binary stars consisting of
white dwarfs (WDs), neutron stars (NSs), and black holes (BHs). Binary NSs and
BHs are thought to be the primary astrophysical sources of gravitational waves
(GWs) within the frequency band of ground-based detectors, while compact
binaries of WDs are important sources of GWs at lower frequencies to be covered
by space interferometers (LISA). Major uncertainties in the current
understanding of properties of NSs and BHs most relevant to the GW studies are
discussed, including the treatment of the natal kicks which compact stellar
remnants acquire during the core collapse of massive stars and the common
envelope phase of binary evolution. We discuss the coalescence rates of binary
NSs and BHs and prospects for their detections, the formation and evolution of
binary WDs and their observational manifestations. Special attention is given
to AM CVn-stars -- compact binaries in which the Roche lobe is filled by
another WD or a low-mass partially degenerate helium-star, as these stars are
thought to be the best LISA verification binary GW sources.Comment: 105 pages, 18 figure
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