Related papers: $\eta'$-$\eta_c$-mixing with improved stochastic e…

We study $\eta$ and $\eta'$ mesons and their mixing angle in a mixed action approach with so-called Osterwalder-Seiler valence quarks on a Wilson twisted mass sea. The gauge configurations have been generated by ETMC for $N_f=2+1+1$…

We study the flavour singlet pseudoscalar mesons from first principles using lattice QCD. We explore the quark content of the $\eta$ and $\eta'$ mesons and we discuss their decay constants.

We perform an eta' mass analysis based on a total of 1130 dynamical gauge field configurations, with 5 different quark mass values on lattices of size 16^3*32 (SESAM) and 24^3*40 (TkL) at beta = 5.6. We employ the stochastic estimator…

Disconnected diagrams give crucial contributions to the physics of flavor singlet hadrons and to scalar form factors of non-singlet hadrons. Naive lattice calculation of the disconnected diagrams, however, requires a huge number of fermion…

By fitting the two-point correlation functions of topological charge density operators calculated on two $2+1$-flavor gauge ensembles with physical pion mass, we determine both the $\eta$ and $\eta'$ masses and also the mixing angle to be…

The possible range of $\eta-\eta'$ mixing angle is determined from the transition form factors $F_{\eta \gamma}(Q^2)$ and $F_{\eta' \gamma}(Q^2)$ with the help of the present experimental data. For such purpose, the quark-flavor mixing…

We explore flavor singlet pseudoscalar meson, eta', spectrum in two-flavor (Nf=2) lattice QCD. The continuum-like relation between the topology of the QCD vacuum and the U(1)_A anomaly, that prevents eta' meson from being a would-be…

For the flavor-singlet heavy quark system of charmonia in the pseudoscalar ($\eta_c(1S)$) channel, we calculate the elastic (EFF) and transition form factors (TFF) ($\eta_c(1S) \rightarrow \gamma \gamma^*$) for a wide range of photon…

We report on a high statistics lattice QCD calculation of the mass of the eta and eta' mesons using ASQTAD improved staggered fermions. The calculation used two ensembles with different lattice spacings and pion masses. We also report…

We investigate the masses and mixing of $\eta$, $\eta'$ mesons in the framework of twisted mass lattice QCD with $N_f=2+1+1$ dynamical quark flavors. For the first time we perform a controlled chiral and continuum extrapolation to obtain…

Although eta-eta' mixing is qualitatively well understood as a consequence of the U(1)_A anomaly in QCD together with a broken SU(3) flavor symmetry, until recently the values of decay and mixing parameters of the eta and eta' were only…

We reanalyze the eta-gamma and eta'-gamma transition form factors within the modified hard scattering approach on the basis of new experimental data from CLEO and L3. Our approach perfectly describes the experimental data over a wide range…

We present further tests and applications of the new eta-eta' mixing scheme recently proposed by us. The particle states are decomposed into orthonormal basis vectors in a light-cone Fock representation. Because of flavor symmetry breaking…

Masses of the eta and eta-prime mesons are estimated in Nf=2+1 lattice QCD with the non-perturbatively O(a) improved Wilson quark action and the Iwasaki RG-improved gluon action, using CP-PACS/JLQCD configurations on a 16^3 x 32 lattice at…

We present results for the mass of the flavor singlet meson calculated on two-flavor full QCD configurations generated by the CP-PACS full QCD project. We also investigate topological charge fluctuations and their dependence on the sea…

An analysis of various decay processes is performed using the two mixing angle description of the $\eta$-$\eta^\prime$ system, incorporating the link to the gluonic sector through anomalies. The agreement is excellent. For comparison with…

A generalized 3 flavor Nambu-Jona--Lasinio Lagrangian including the explicit chiral symmetry breaking interactions which contribute at the same order in the large $1/N_c$ counting as the $U_A(1)$ 't Hooft flavor determinant is considered to…

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…

Eta bound states in nuclei are sensitive to the flavour-singlet component in the eta. The bigger the singlet component, the more attraction and the greater the binding. eta-etaprime mixing plays an important role in understanding the value…

We determine mass and mixing angles of eta and eta' states using Nf=2+1+1 Wilson twisted mass lattice QCD. We describe how those flavour singlet states need to be treated in this lattice formulation. Results are presented for three values…