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We study the reactions $gammagammarightarrow pi^0pi^0$, $pi^+pi^-$, $K^0bar{K}^0$, $K^+K^-$, $eta eta$ and $pi^0eta$ based on a chiral Lagrangian with dynamical light vector mesons as formulated within the hadrogenesis conjecture. At present our chiral Lagrangian contains 5 unknown parameters that are relevant for the photon fusion reactions. They parameterize the strength of interaction terms involving two vector meson fields. These parameters are fitted to photon fusion data $gammagammarightarrow pi^0pi^0$, $pi^+pi^-, pi^0eta$ and to the decay $etarightarrowpi^0gammagamma$. In order to derive gauge invariant reaction amplitudes in the resonance region constraints from micro-causality and exact coupled-channel unitarity are used. Our results are in good agreement with the existing experimental data from threshold up to about 0.9 GeV for the two-pion final states. The $a_0$ meson in the $pi^0eta$ channel is dynamically generated and an accurate reproduction of the $gammagammarightarrow pi^0eta$ data is achieved up to 1.2 GeV. Based on our parameter sets we predict the $gammagammarightarrow $ $K^0bar{K}^0$, $K^+K^-$, $eta eta$ cross sections.
We consider the chiral Lagrangian with a nonet of Goldstone bosons and a nonet of light vector mesons. The mixing between the pseudoscalar mesons eta and eta-prime is taken into account. A novel counting scheme is suggested that is based on hadrogene
A previous formal derivation of the effective chiral Lagrangian for low-lying pseudoscalar mesons from first-principles QCD without approximations [Wang et al., Phys. Rev. D61, (2000) 54011] is generalized to further include scalar, vector, and axial
We obtain the light meson mass spectroscopy from the light-front quantum chromodynamics (QCD) Hamiltonian, determined for their constituent quark-antiquark and quark-antiquark-gluon Fock components, together with a three-dimensional confinement. The
We derive the chiral effective Lagrangian for excited heavy-light mesons from QCD under proper approximations. We focus on the chiral partners with $j_l^P=frac{3}{2}^+$ and $j_l^P=frac{3}{2}^-$ which amounts to ($1^+,2^+$) and ($1^-,2^-$) states resp
An intrinsic parity violating hadronic tau lepton decay is investigated. $tau to pi pi eta u$ is the process in which the dominant contribution to the amplitude is due to the intrinsic parity violation. To predict the hadronic invariant mass spectra