70,027 research outputs found

    Chiral field theory of 0−+0^{-+} glueball

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    A chiral field theory of 0−+0^{-+} glueball is presented. By adding a 0−+0^{-+} glueball field to a successful Lagrangian of chiral field theory of pseudoscalar, vector, and axial-vector mesons, the Lagrangian of this theory is constructed. The couplings between the pseodoscalar glueball field and mesons are via U(1) anomaly revealed. Qualitative study of the physical processes of the 0−+0^{-+} glueball of m=1.405GeVm=1.405\textrm{GeV} is presented. The theoretical predictions can be used to identify the 0−+0^{-+} glueball.Comment: 29 page

    Strangeness magnetic form factor of the proton in the extended chiral quark model

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    Background: Unravelling the role played by nonvalence flavors in baryons is crucial in deepening our comprehension of QCD. Strange quark, a component of the higher Fock states in baryons, is an appropriate tool to investigate nonperturbative mechanisms generated by the pure sea quark. Purpose: Study the magnitude and the sign of the strangeness magnetic moment ÎŒs\mu_s and the magnetic form factor (GMsG_M^s) of the proton. Methods: Within an extended chiral constituent quark model, we investigate contributions from all possible five-quark components to ÎŒs\mu_s and GMs(Q2)G_M^s (Q^2) in the four-vector momentum range Q2≀1Q^2 \leq 1 (GeV/c)2^2. Probability of the strangeness component in the proton wave function is calculated employing the 3P0^3 P_0 model. Results: Predictions are obtained without any adjustable parameters. Observables ÎŒs\mu_s and GMs(Q2)G_M^s (Q^2) are found to be small and negative, consistent with the lattice-QCD findings as well as with the latest data released by the PVA4 and HAPPEX Collaborations. Conclusions: Due to sizeable cancelations among different configurations contributing to the strangeness magnetic moment of the proton, it is indispensable to (i) take into account all relevant five-quark components and include both diagonal and non-diagonal terms, (ii) handle with care the oscillator harmonic parameter ω5\omega_5 and the ssˉ{s \bar s} component probability.Comment: References added, typos corrected, accepted for publication by Phys. Rev.

    Intrinsic charm content of the nucleon and charmness-nucleon sigma term

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    In the extended chiral constituent quark model, the intrinsic ccˉc \bar{c} content of the nucleon is investigated. The probabilities of the quark-antiquark components in the nucleon wave functions are calculated by taking the nucleon to be admixtures of three- and five-quark components, with the relevant transitions handled {\it via} the 3^{3}P0_{0} mechanism. Predictions for the probability of the ccˉc \bar{c} in the nucleon wave function and the charmness-nucleon sigma term are presented. Our numerical results turn out to be consistent with the predictions from various other approaches reported in the literature.Comment: Accepted for publication in Phys. Rev.

    Analysis and design of transonic airfoils using streamwise coordinates

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    A new approach is developed for analysis and design of transonic airfoils. A set of full potential equivalent equations in von Mises coordinates is formulated from the Euler equations under the irrotationality and isentropic assumptions. This set is composed of a main equation for the main variable, y, and a secondary equations for the secondary variable, R. The main equation is solved by type dependent differencing combined with a shock point operator. The secondary equation is solved by marching from a non-characteristic boundary. Sample computations on NACA 0012 and biconvex airfoils show that, for the analysis problem, the present approach achieves good agreement with experimental C sub p distributions. For the design problem, the approach leads to a simple numerical algorithm in which the airfoil contour is calculated as part of the flow field solution
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