Related papers: Light quark mass differences in the $\pi^0 - \eta …
The eta to 3 pion decays are a valuable source of information on low energy QCD. Yet they were not used for an extraction of the chiral symmetry breaking order parameters until now. We use a bayesian approach in the framework of resummed…
We present a calculation of the $\eta$-$\eta'$ mixing in the framework of large-$N_c$ chiral perturbation theory. A general expression for the $\eta$-$\eta'$ mixing at next-to-next-to-leading order (NNLO) is derived, including…
A two mixing angle description of the pseudoscalar decay constants associated to the $\eta$-$\eta^\prime$ system is used to parametrize the theoretical amplitudes of the radiative decays $(\eta,\eta^\prime)\to\gamma\gamma$ and the coupling…
Using the Polyakov--Nambu--Jona-Lasinio model the strange quark chiral phase transition and the effect of its current mass on a hot magnetized three flavor quark matter at zero chemical potential is investigated. The impact of the 't Hooft…
I review to which extent the properties of pseudoscalar mesons can be understood in terms of the underlying quark (and eventually gluon) structure. Special emphasis is put on the progress in our understanding of eta-eta' mixing.…
We report on a first, comprehensive partially quenched study of the eta-eta' problem, based on SESAM configurations on a 16^3x32 lattice at beta=5.6 QCD with two (mass degenerate) active sea quark flavours. By means of the spectral…
The claim that the light quark mass ratio (m_d - m_u)/m_s can be extracted from the decay width ratio Gamma(eta' -> pi^0 pi^+ pi^-)/Gamma(eta' -> eta pi^+ pi^-) is critically investigated within a U(3) chiral unitary framework. The…
We study the flavour singlet pseudoscalar mesons from first principles using lattice QCD. With N_f=2 flavours of light quark, this is the so-called eta_2 meson and we discuss the phenomenological status of this. Using maximally twisted-mass…
The phase diagram of cold dense quark matter is studied using the 't Hooft extended Nambu--Jona-Lasinio Model applied to the light quark sector with a finite current mass for the strange quark (up and down are considered in the chiral…
Flavor mixing is scrutinized at 1-loop in a SU(2)_L gauge theory of massive fermions. The main issue is to cope with kinetic-like, momentum (p^2) dependent effective interactions that arise at this order. They spoil the unitarity of the…
It is shown that the strange quark mass undergoes a first order transition in a generalized 3 flavor Nambu--Jona-Lasinio (NJL) Lagrangian which includes a complete set of explicit chiral symmetry breaking interactions. This transition…
The magnetic and transition magnetic moments of the ground-state baryons are computed in heavy baryon chiral perturbation theory in the large-$N_c$ limit, where N_c is the number of colors. SU(3) symmetry breaking is systematically studied…
We discuss the neutrino mixing, using the texture 0 mass matrices, which work very well for the quarks. The solar mixing angle is directly linked to the mass ratio of the first two neutrinos. The neutrino masses are hierarchical, but the…
We study the mixing of the QCD/QCD-like axion and light-flavor mesons $\pi^0, \eta, \eta'$ within the framework of $U(3)$ chiral perturbation theory up to next-to-leading order in this work. The axion-meson mixing formulas are calculated…
Lattice QCD allows a first-principles study of QCD with the freedom to vary the number and masses of the quarks. I present results on the flavour singlet correlations (this illuminates OZI violating effects) for mesons. Concentrating on the…
In view of the observed strong hierarchy of the quark and lepton masses and of the flavor mixing angles it is argued that the description of flavor mixing must take this into account. One particular interesting way to describe the flavor…
The six-quark instanton induced 't Hooft interaction, which breaks the unwanted U_A (1) symmetry of QCD, is a source of perturbative corrections to the leading order result formed by the four-quark forces with the U_L(3)X U_R(3) chiral…
We consider flavor breaking in the the octet and decuplet baryon masses at second order in large-$N$ chiral perturbation theory, where $N$ is the number of QCD colors. We assume that $1/N \sim 1/N_F \sim m_s / \Lambda \gg m_{u,d}/\Lambda,…
We analyze the structure of quark and lepton mass matrices under the hypothesis that they are determined from a minimum principle applied to a generic potential invariant under the $\left[SU(3)\right]^5\otimes \mathcal O(3)$ flavor…
To explain quark and lepton masses and mixing angles, one has to extend the standard model, and the usual practice is to put the quarks and leptons into irreducible representations of discrete groups. We argue that discrete flavor…