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This review addresses the question of the chirality of $b$ quark weak couplings from a theoretical and from a purely phenomenological point of view. Due to their small magnitude $b$ decay couplings are subject to possible large corrections…
We demonstrate that the chiral gauge flavor $SU(3)_f$ dynamics spontaneously generates the chiral symmetry breaking fermion self energies $\Sigma(p^2)$ resulting in wide and wild spectra of lepton and quark masses. The Goldstone theorem…
Employing a symmetry-preserving contact-interaction formulation of the Dyson-Schwinger equations in quantum chromodynamics (QCD), we examine the identity of the $\sigma$ meson and its implications for the gravitational structure of hadrons.…
A nonlinear realization of SU(2) chiral symmetry spontaneous breaking approach is developed in the composite operator formalism. A Lagrangian including quark, gluon and Goldstone boson degrees of freedom of the chiral quark model is…
We calculate the S and P wave phase shifts in $\Lambda - \pi$ scattering at the $\Xi$ mass using the full relativistic $SU(3)_L \times SU(3)_R$ chiral perturbation theory. We get small phase shifts similar to previous calculations using $…
The paper studies a strong coupling constant between {\pi} meson and octet baryon using the hard-wall AdS/QCD model, which considers SU(3)f symmetry-breaking effects. Briefly mentioned are profile functions for pseudoscalar meson and baryon…
Scalar form factor of the nucleon is calculated in the framework of light cone QCD sum rules, using the most general form of the baryon current. Using the result on scalar form factor of the nucleon, the nucleon-scalar "sigma" and "a_0"…
Light-cone QCD sum rules are employed to compute the strong coupling constants: g_{B^* B^* pi}, g_{B_1 B_0 pi} and g_{B_1 B^* pi}, where (B,B^*) and (B_0,B_1) are negative and positive parity (0^-,1^-) and (0^+,1^+) \bar qQ doublets. The…
We study the SU(3)-invariant relevant deformation of D=4 N=4 SU(N) gauge theory at large N using the AdS/CFT correspondence. At low energies, we obtain a nonsupersymmetric gauge theory with three left-handed quarks in the adjoint of SU(N).…
The coupling $g_{B^\ast B \pi}$ is related to the form factor at zero momentum of the axial current between $B^\ast$ and $B$ states. Moreover it is related to the effective coupling between heavy mesons and pions that appear the heavy meson…
The $D^*D\pi$ form factor is evaluated at low and moderate $Q^2$ in a hadronic loop model, for off-shell $D$ mesons. The results contain arbitrary constants, which are fixed so as to match previous QCD sum rule calculations valid at higher…
We calculate the coupling constants, $g_{\pi NS_{11}}$ and $g_{\eta NS_{11}}, using QCD sum rules in the presence of an external meson field. A covariant derivative is introduced within the S_{11} interpolating field so that in the…
New relations between QCD Borel sum rules for strong coupling constants of K-mesons to baryons are derived. It is shown that starting from the sum rule for the coupling constants $g_{\pi\Sigma\Sigma}$ and $g_{\pi\Sigma\Lambda}$ it is…
The leading order strangeness S=-3 and -4 baryon-baryon interactions are analyzed within chiral effective field theory. The chiral potentials consist of contact terms without derivatives and of one-pseudoscalar-meson exchanges. Assuming…
We describe the chiral phase transition for vector-like SU(N) gauge theories as a function of the number of quark flavors Nf by making use of an anomaly-induced effective potential. The potential depends explicitly on the full beta-function…
Baryonic correlation functions are calculated within an effective chiral quark model motivated by the instanton liquid model of QCD. Using a flavour SU(3) symmetry for the local four-quark interaction and taking rotational zero modes for…
We investigate the parity-violating $\pi NN$ Yukawa coupling constant $h^1_{\pi NN}$ within the framework of the SU(2) chiral quark-soliton model, based on the $\Delta S=0$ effective weak Lagrangian derived within the same framework. We…
The form factors and the coupling constant of the $B_s B^* K $ and $B_s B K^*$ vertices are calculated using the QCD sum rules method. Three point correlation functions are computed considering both the heavy and light mesons off-shell in…
We study the low energy evolution of coupling constants of the standard model and show that gauge coupling unification can be achieved at the electroweak scale with a suitable normalization. We choose the grand unification group to be the…
We study chiral symmetry breaking in the Nambu--Jona-Lasinio model regularized in proper-time in arbitrary space-time dimensions through an iterative procedure by writing the gap equation in the form of a discrete dynamical system with the…