Related papers: eta and eta' Physics at MAMI
Transition form factors of pi^0, eta, eta' mesons are investigated by means of the anomaly sum rule -- an exact nonperturbative relation which follows from the dispersive representation of the axial anomaly. Considering the problem of…
Metallic seals are crucial machine elements in many important applications, e.g., in ultrahigh vacuum systems. Due to the high elastic modulus of metals, and the surface roughness which exists on all solid surfaces, if no plastic…
We report a search for $B$ decays to selected final states with the $\eta_c$ meson: $B^{\pm}\to K^{\pm}\eta_c\pi^+\pi^-$, $B^{\pm}\to K^{\pm}\eta_c\omega$, $B^{\pm}\to K^{\pm}\eta_c\eta$ and $B^{\pm}\to K^{\pm}\eta_c\pi^0$. The analysis is…
We include the $\eta_c$ meson into the $\eta$-$\eta'$-$G$ mixing formalism constructed in our previous work, where $G$ represents the pseudoscalar gluball. The mixing angles in this tetramixing matrix are constrained by theoretical and…
The gp-->etap reaction has been measured with the Crystal Ball and TAPS multiphoton spectrometers in the energy range from the production threshold of 707 MeV to 1.4 GeV (1.49 =< W >= 1.87 GeV). Bremsstrahlung photons produced by the…
We review recent important progresses at the B factories and discuss the future prospects. We also comment on how we might proceed to search for new physics.
The branching ratio of the electromagnetic rare decays $\eta\to\pi^0\gamma\gamma$ and $\eta^\prime\to (\pi^0,\eta)\gamma\gamma$ are analysed in terms of scalar and vector meson exchange contributions using the frameworks of the Linear Sigma…
A detailed simple model is applied to study a metallic cluster. It is assumed that the ions and delocalized electrons are distributed randomly throughout the cluster. The delocalized electrons are assumed to be degenerate. A spherical ball…
A study of $B^0$~and $B^0_s$ meson decays into $J/\psi\eta$~and $J/\psi\eta^{\prime}$ final states is performed using a data set of proton-proton collisions at centre-of-mass energies of 7 and 8TeV, collected by the LHCb experiment and…
This pedagogical review presents the Shell Correction Method (SCM) and variants thereof, appropriate for describing shape deformations and electronic shell effects, energetics and decay pathways of metal-cluster fragmentation processes…
We calculated the form factors of $B_{c}$ transitions into $\eta^{(')}$ meson and pseudoscalar Glueball, where the $B_{c}$ meson is a bound state of two different heavy flavors and is treated as a nonrelativistic state, while the mesons…
Using 58 million $J/\psi$ events taken with the BESII detector, a search for $eta_{c}$ CP violating decays into $\pi\pi$ and $\bar{K}K$ has been performed. No clear $eta_{c}$ is observed, and upper limits for $B(eta_{c}->\pi \pi)$and…
We show that the newly discovered scalar meson $f_0(1500)$ at LEAR has properties compatible with the lightest scalar glueball predicted by lattice QCD and incompatible with a $\qqbar$ state. We suggest that decays of glueballs are into…
We study the $\eta \to 2 \gamma$ decay using an extended three-flavor Nambu-Jona-Lasinio model that includes the 't~Hooft instanton induced interaction. The $\eta$ meson mass and the $\eta \to 2 \gamma$ decay width are reproduced…
The decay $\eta'\rightarrow\pi^0\gamma\gamma$ is studied theoretically in the framework of the Vector Meson Dominance model (VMD). We find theoretically a significant contribution of the interference of $\omega-\rho$ and provide theoretical…
In-medium modification of the eta' mass is discussed in the context of partial restoration of chiral symmetry in nuclear medium. We emphasize that the U_A(1) anomaly effects causes the eta'-eta mass difference necessarily through the chiral…
We obtain explicit expressions for the \eta and \eta' masses and decay constants using U_L(3) x U_R(3) chiral perturbation theory at next-to-leading order in a combined expansion in p^2 and 1/Nc. A numerical fit of the parameters appearing…
Decay channels of the eta meson with at least one lepton pair in the final state are discussed. Preliminary results on electron-positron pair production from the pd->He eta reaction from the WASA experiment at CELSIUS are presented.
Recently, time-dependent current-density functional theory has been extended to include the dynamical interaction of quantum systems with external environments [Phys. Rev. Lett. {\bf 98}, 226403 (2007)]. Here we show that such a theory…
Using psi(2S) --> pi+ pi- J/psi, J/psi --> gamma eta' events acquired with the CLEO-c detector at the CESR e+e- collider, we make the first observations of the decays eta' --> pi+ pi- pi0 and eta' --> pi+ pi- e+ e-, measuring absolute…