1,466 research outputs found
Dynamically generated 1^+ heavy mesons
By using a heavy chiral unitary approach, we study the wave interactions
between heavy vector meson and light pseudoscalar meson. By searching for poles
of the unitary scattering amplitudes in the appropriate Riemann sheets, several
heavy states are found. In particular, a bound state with a mass
of GeV which should be associated with the recently observed
state is obtained. In the same way, a bound state
() with mass of GeV in the bottom sector is predicted.
The spectra of the dynamically generated and states in the
channel are also calculated. One broad state and one narrow state are found in
both the charmed and bottom sectors. The coupling constants and decay widths of
the predicted states are further investigated.Comment: 17 pages, 3 figures. Version accepted for publication in Phys. Lett.
Is the first radial excitation of ?
We present a quantitative analysis of the observed by
SELEX mainly focusing on the assumption that is the first
radial excitation of the ground state . By solving the
instantaneous Bethe-Salpeter equation, we obtain the mass MeV for
the first excited state, which is about 26 MeV heavier than the experimental
value MeV. By means of PCAC and low-energy theorem we calculate
the transition matrix elements and obtain the decay widths:
MeV, MeV, and
the ratio as well. This ratio is quite different from the
SELEX data . The summed decay width of those three channels is
approximately 21.7 MeV, already larger than the observed bound for the full
width ( MeV). Furthermore, assuming is state,
we also explore the possibility of wave mixing to explain the SELEX
observation. Based on our analysis, we suspect that it is too early to conclude
that is the first radial excitation of the ground
state . More precise measurements of the relative ratios and
the total decay width are urgently required especially for wave mixing.Comment: 12 pages, 8 figure
Defect Categorization: Making Use of a Decade of Widely Varying Historical Data
This paper describes our experience in aggregating a number of historical datasets containing inspection defect data using different categorizing schemes. Our goal was to make use of the historical data by creating models to guide future development projects. We describe our approach to reconciling the different choices used in the historical datasets to categorize defects, and the challenges we faced. We also present a set of recommendations for others involved in classifying defects
Foreword
Little information exists about the loss of all one’s teeth (edentulism) among older adults in low- and middle-income countries. This study examines the prevalence of edentulism and associated factors among older adults in a cross-sectional study across six such countries. Data from the World Health Organization (WHO’s) Study on global AGEing and adult health (SAGE) Wave 1 was used for this study with adults aged 50-plus from China (N = 13,367), Ghana (N = 4724), India (N = 7150), Mexico (N = 2315), Russian Federation (N = 3938) and South Africa (N = 3840). Multivariate regression was used to assess predictors of edentulism. The overall prevalence of edentulism was 11.7% in the six countries, with India, Mexico, and Russia has higher prevalence rates (16.3%–21.7%) than China, Ghana, and South Africa (3.0%–9.0%). In multivariate logistic analysis sociodemographic factors (older age, lower education), chronic conditions (arthritis, asthma), health risk behaviour (former daily tobacco use, inadequate fruits and vegetable consumption) and other health related variables (functional disability and low social cohesion) were associated with edentulism. The national estimates and identified factors associated with edentulism among older adults across the six countries helps to identify areas for further exploration and targets for intervention
Annihilation Rate of Heavy 0^{++} P-wave Quarkonium in Relativistic Salpeter Method
Two-photon and two-gluon annihilation rates of P-wave scalar charmonium and
bottomonium up to third radial excited states are estimated in the relativistic
Salpeter method. We solved the full Salpeter equation with a well defined
relativistic wave function and calculated the transition amplitude using the
Mandelstam formalism. Our model dependent estimates for the decay widths:
keV,
keV, eV and eV. We also give estimates of total widths by the two-gluon
decay rates: MeV,
MeV, MeV and
MeV.Comment: 8 pages, 1 figure, 4 table
Evidence that the Y(4660) is a f_0(980)psi' bound state
We demonstrate that the experimental information currently available for the
Y(4660) is consistent with its being a f_0(980)psi' molecule. Possible
experimental tests of our hypothesis are presented.Comment: 4 pages, 3 figure
Hadronic-loop induced mass shifts in scalar heavy-light mesons
We calculate the mass shifts of heavy-light scalar mesons due to hadronic
loops under the assumption that these vanish for the groundstate heavy-light
mesons. The results show that the masses calculated in quark models can be
reduced significantly. We stress that the mass alone is not a signal for a
molecular interpretation. Both the resulting mass and the width suggest the
observed state could be a dressed state. We give further
predictions for the bottom scalar mesons which can be used to test the dressing
mechanism.Comment: 14 pages, 2 figures. Version accepted for publication in Phys. Lett.
Single-Particle Model for a Lithium-Ion Cell: Thermal Behavior
The single-particle model presented by Santhanagopalan et al. [ J. Power Sources , 156 , 620 (2006)] is extended to include an energy balance. The temperature dependence of the solid phase diffusion coefficient of the lithium in the intercalation particles, the electrochemical reaction rate constants, and the open circuit potentials (OCPs) of the positive and negative electrodes are included in the model. The solution phase polarization is approximated using a nonlinear resistance, which is a function of current and temperature. The model is used to predict the temperature and voltage profiles in a lithium-ion cell during galvanostatic operations. The single-particle thermal model is validated by comparing the simulated voltage and temperature profiles to the results obtained using a distributed porous electrode model. The simulation results from the single-particle thermal model also show good agreement with experimental voltage data obtained from lithium-ion pouch cells under different discharge rates (C/33, C/2 and C) at different temperatures (15, 25, 35, and 45°C )
Axial Resonances in the Open and Hidden Charm Sectors
A SU(4) flavor symmetrical Lagrangian is constructed for the interaction of
the pseudo-scalar mesons with the vector mesons. SU(4) symmetry is broken to
SU(3) by suppression of terms in the Lagrangian where the interaction should be
driven by charmed mesons. Chiral symmetry can be restored by setting this new
SU(4) symmetry breaking parameters to zero. Unitarization in coupled channels
leads to the dynamical generation of resonances. Many known axial resonances
can be identified including the new controversial X(3872) and the structure
found recently by Belle around 3875 MeV in the hidden charm sector. Also new
resonances are predicted, some of them with exotic quantum numbers.Comment: Final published versio
Strong Decays of the Radial Excited States and
The strong OZI allowed decays of the first radial excited states and
are studied in the instantaneous Bethe-Salpeter method, and by using
these OZI allowed channels we estimate the full decay widths:
MeV, MeV,
MeV and MeV.
We also predict the masses of them: GeV,
GeV, GeV and GeV.Comment: 6 pages, 1 figur
- …