51 research outputs found
Mass of Y(3940) in Bethe-Salpeter equation for quarks
The general form of the Bethe-Salpeter wave functions for the bound states
composed of two vector fields of arbitrary spin and definite parity is
corrected. Using the revised general formalism, we investigate the observed
\emph{Y}(3940) state which is considered as a molecule state consisting of
. Though the attractive potential between and
including one light meson (, , , )
exchange is considered, we find that in our approach the contribution from
one- exchange is equal to zero and consider SU(3) symmetry breaking. The
obtained mass of \emph{Y}(3940) is consistent with the experimental value.Comment: 19 pages, 4 figures, 1 tabl
Mass and width of unstable molecular state in quantum field theory
Applying resonance theory in the framework of relativistic quantum field
theory, we investigate the temporal evolution of molecular state composed of
two vector mesons as determined by the total Hamiltonian. Then exotic meson
resonance is considered as a mixed state of two unstable molecular
states and , and the corrected mass and
width for resonance are calculated. In this actual calculation, we
minutely show how to obtain the corrections for resonance and to exhibit the
key features of dispersion relation in a new Feynman diagram. The numerical
results are consistent with the experimental values
Quark Mass Ratios in ChPT with the Difference of Quark Condensates Considered
The chiral effective Lagrangian for pseudoscalar nonet is constructed in
consideration of isospin breaking. And the difference of quark condensates is
taken accounted. The SU(3) singlet eta0 is not taken as Goldstone-boson. The
mixing with and without isospin symmetry is considered. The quark mass ratios
are obtained through solving the mass equations of mesons. We estimate the
change of quark mass ratios according to the change of the masses of pion+ and
kaon+ to see how the electromagnetic corrections affect our results. It turn
out that massless up quark is possible. The upper limit for mu/md is around
0.39. 2ms/(mu+md)=24.23~25.12. The values for quark condensate ratios and other
constants are limited in narrow ranges.Comment: 10 page
Smoking patterns and sociodemographic factors associated with tobacco use among Chinese rural male residents: a descriptive analysis
<p>Abstract</p> <p>Background</p> <p>Although evidence has shown high prevalence rates of tobacco use in the general urban populations in China, relatively little is known in its rural population. The purposes of this study were to examine smoking patterns and sociodemographic correlates of smoking in a sample of rural Chinese male residents.</p> <p>Methods</p> <p>The study employed a cross-sectional, multi-stage sampling design. Residents (N = 4,414; aged 15 years and older) were recruited from four geographic regions in China. Information on participants' tobacco use (of all forms), including their daily use, and sociodemographic characteristics were collected via survey questionnaires and the resultant data were analyzed using chi-square tests and logistic regression procedures.</p> <p>Results</p> <p>The overall smoking prevalence in the study sample was 66.8% (n = 2,950). Of these, the average use of tobacco products per day was 12.70 (SD = 7.99) and over 60% reported daily smoking of more than 10 cigarettes. Geographic regions of the study areas, age of the participants, marital status, ethnicity, education, occupation, and average personal annual income were found to be significantly associated with an increased likelihood of smoking among rural Chinese male residents.</p> <p>Conclusion</p> <p>There is a high smoking prevalence in the Chinese rural population and smoking behaviors are associated with important sociodemographic factors. Findings suggest the need for tobacco control and intervention policies aimed at reducing tobacco use in Chinese rural smoking populations.</p
Generation and verification of three-dimensional network of fractured rock masses stochastic discontinuities based on digitalization
Development of Bethe-Salpeter theory for dealing with unstable system
In the framework of relativistic quantum field theory, the solution of
homogeneous Bethe-Salpeter equation for two-body bound state can not describe
unstable system, so we develop Bethe-Salpeter theory to investigate resonance
which is regarded as an unstable two-body system. Based on Bethe-Salpeter wave
function, we consider the time evolution of two-body bound state determined by
the total Hamiltonian. The total matrix element for arbitrary decay channel is
expressed in terms of the Heisenberg picture, and Mandelstam's approach is
generalized to calculate the matrix element between bound states with respect
to arbitrary value of the final state energy. Some innovations to Feynman
diagram are made so that the key features of dispersion relation can be more
clearly exhibited. This new resonance theory in quantum field theory is applied
to investigate exotic particle which is considered as an unstable meson-meson
molecular state.Comment: arXiv admin note: text overlap with arXiv:2210.0156
Viscoelastic Boundary Conditions for Multiple Excitation Sources in the Time Domain
Transmitting boundaries are important for modeling the wave propagation in the finite element analysis of dynamic foundation problems. In this study, viscoelastic boundaries for multiple seismic waves or excitations sources were derived for two-dimensional and three-dimensional conditions in the time domain, which were proved to be solid by finite element models. Then, the method for equivalent forces’ input of seismic waves was also described when the proposed artificial boundaries were applied. Comparisons between numerical calculations and analytical results validate this seismic excitation input method. The seismic response of subway station under different seismic loads input methods indicates that asymmetric input seismic loads would cause different deformations from the symmetric input seismic loads, and whether it would increase or decrease the seismic response depends on the parameters of the specific structure and surrounding soil
Hybridising Human Judgment, AHP, Grey Theory, and Fuzzy Expert Systems for Candidate Well Selection in Fractured Reservoirs
The selection of appropriate wells for hydraulic fracturing is one of the most important decisions faced by oilfield engineers. It has significant implications for the future development of an oilfield in terms of its productivity and economics. In this study, we developed a fuzzy model for well selection that combines the major objective criteria with the subjective judgments of decision makers. This was done by fusing the analytic hierarchy process (AHP) method, grey theory and an advanced version of fuzzy logic theory (FLT). The AHP component was used to identify the relevant criteria involved in selecting wells for hydraulic fracturing. Grey theory was used to determine the relative importance of those criteria. Then a fuzzy expert system was applied to fuzzily process the aggregated inputs using a Type-2 fuzzy logic system. This undertakes approximate reasoning and generates recommendations for candidate wells. These techniques and technologies were hybridized by using an intercommunication job-sharing method that integrates human judgment. The proposed method was tested on data from an oilfield in Western China and finally the most appropriate candidate wells for hydraulic fracturing were ranked in order of their projected output after fracturing
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