Meson-Baryon Couplings from QCD Sum Rules

Coupling constants of the pseudoscalar mesons to the octet baryons are calculated in the QCD sum rule approach. Two-point correlation function of the baryons are evaluated in a single meson state and the vacuum, which yields the designated coupling. The emphasis is on the flavor SU(3) structure of the coupling constants and reliability in extracting the coupling constants from the two-point correlation functions. We first calculate the baryon-diagonal couplings and study the reliability of the sum rule. The F/D ratio of the coupling is determined in the SU(3) limit. We further formulate the baryon-off-diagonal couplings using the projected correlation functions and the vertex functions, so that the unwanted excited states do not contaminate the sum rule. As an example, the (\pi - \Lambda - \Sigma) coupling constant is calculated and the flavor SU(3) breaking effect is studied. We find that the effect of SU(3) breaking on the (\pi - \Lambda - \Sigma) coupling constant is small.Comment: 33 pages, REVTeX4, 6 figure

ppK- bound states from Skyrmions

The bound kaon approach to the strangeness in the Skyrme model is applied to investigating the possibility of deeply bound $ppK^-$ states. We describe the $ppK^-$ system as two-Skyrmion around which a kaon field fluctuates. Each Skyrmion is rotated in the space of SU(2) collective coordinate. The rotational motions are quantized to be projected onto the spin-singlet proton-proton state. We derive the equation of motion for the kaon in the background field of two Skyrmions at fixed positions. From the numerical solution of the equation of motion, it is found that the energy of $K^-$ can be considerably small, and that the distribution of $K^-$ shows molecular nature of the $ppK^-$ system. For this deep binding, the Wess-Zumino-Witten term plays an important role. The total energy of the $ppK^-$ system is estimated in the Born-Oppenheimer approximation. The binding energy of the $ppK^-$ state is $B.E.\simeq 126$ MeV. The mean square radius of the $pp$ subsystem is $\sqrt{}\simeq 1.6$ fm.Comment: Oct 2007, 15 pages, 8 figures; added references, corrected typo

Spin-3/2 pentaquark in the QCD sum rule

We study $IJ^P=0{3/2}^\pm$ and $1{3/2}^\pm$ pentaquark states with $S=+1$ in the QCD sum rule approach. The QCD sum rule for positive parity states and that for negative parity are independently derived. The sum rule suggests that there exist the $0{3/2}^-$ and the $1{3/2}^-$ states. These states may be observed as extremely narrow peaks since they can be much below the $S$-wave threshold and since the only allowed decay channels are $NK$ in $D$-wave, whose centrifugal barriers are so large that the widths are strongly suppressed. The $0{3/2}^-$ state may be assigned to the observed $\Theta^+(1540)$ and the $1{3/2}^-$ state can be a candidate for $\Theta^{++}$.Comment: 27 pages, 14 figure

On the Heaving Motion of Circular Peripheral Jet Ground Effect Machines

The heaving motion of peripheral jet ground effect machines with circular planform has been studied and the simple expressions of the equation of motion are formulated. The analysis is separated into two parts, i.e. the original peripheral jet configuration and the modified configuration equipped with the stability jets. In both cases, the behavior of the jets is quantitatively treated as the “underfed” and the “modified overfed” operation and after some simplification, second order nonlinear differential equations are derived as the equations of heaving motion. Those equations are still valid for a large amplitude heaving oscillation or for a large initial hover height. Furthermore, the frequency and damping characteristics of the small amplitude heaving oscillation can be predicted by the linearized equations of motion which are derived by the use of the approximation of small amplitude. The agreement between the analytical and experimental results is found to be comparatively good

The F/D Ratio and Meson-Baryon Couplings from QCD Sum Rules

Coupling constants of the pseudoscalar mesons to the octet baryons are computed in the QCD sum rule approach. The pi-NN, eta-NN, pi-XiXi, eta-XiXi, pi-SigmaSigma, eta-SigmaSigma as well as pi-Lambda-Sigma couplings are studied. Determining the pertinent Dirac structure in the correlation function, we analyze the couplings in the SU(3) limit. We find the F/D ratio to be \sim 0.6-0.8 that is consistent with the SU(6) value. We also estimate the SU(3) breaking effect using a projected correlation function method.Comment: 4 pages, Talk given at XVI International Conference on Particles and Nuclei (PANIC02), Osaka, Japan, Sep.30 - Oct.4, 200

Model-independent study of the QCD sum rule for the pi NN coupling constant

We reinvestigate the QCD sum rule for the pi NN coupling constant, g, starting from the vacuum-to-pion matrix element of the correlation function of the interpolating fields of two nucleons. We study in detail the physical content of the correlation function without referring to the effective theory. We consider the invariant correlation functions by splitting the correlation function into different Dirac structures. We show that the coefficients of the double-pole terms are proportional to g but that the coefficients of the single-pole terms are not determined by g. In the chiral limit the single-pole terms as well as the continuum terms are ill defined in the dispersion integral. Therefore, the use of naive QCD sum rules obtained from the invariant correlation functions is not justified. A possible procedure to avoid this difficulty is discussed.Comment: 20 pages, 2 figure