Related papers: Extracting the chiral anomaly from $e^+e^-\to 3\pi…
We have measured the cross section $\sigma(e^+e^-\to\pi^+\pi^-\gamma(\gamma))$ at DA$\Phi$NE, the Frascati \phi-factory, using events with initial state radiation photons emitted at small angle and inclusive of final state radiation. We…
Light meson ( $\pi,\ \sigma,\ a_0$) properties in the environment with chiral imbalance are analyzed with the help of meson effective Lagrangian associated with QCD. New spatial parity violating decays of scalar mesons arise as a result of…
The in-medium pion properties, {\it i.e.} the temporal pion decay constant $f_t$, the pion mass $m_\pi^*$ and the wave function renormalization, in symmetric nuclear matter are calculated in an in-medium chiral perturbation theory up to the…
We have measured the $\pi^+\to {\rm e}^+\nu\gamma$ branching ratio over a wide region of phase space, based on a total of 65,460 events acquired using the PIBETA detector. Minimum-$\chi^2$ fits to the measured $(E_{e^+},E_\gamma)$ energy…
We present here an extension of our model for the pion, which we used previously to calculate its diagonal structure function, to the off-forward case. The imaginary part of the off-forward gamma^* pi -> gamma^* pi scattering amplitude is…
We use chiral perturbation theory for SU(2) to compute the leading corrections to the thermal mass of the pions and the pion decay constant in the presence of the magnetic field in a low-temperature expansion. The magnetic field gives rise…
We calculate the amplitude of the rare flavour-changing neutral-current decay $B\to \pi\ell^+\ell^-$ at large recoil of the pion. The nonlocal contributions in which the weak effective operators are combined with the electromagnetic…
Recent experimental pion polarizability data are reviewed and analyzed. Data on the radiative \pi^+ meson photoproduction on the proton at MAMI has been used to determine the difference of the electric and magnetic dipole polarizabilities…
We report on two pion-photoproduction measurements in the threshold region conducted in the A2 collaboration at MAMI with the almost 4{\pi} Crystal Ball detector. The first was with a linearly polarized photon beam and unpolarized…
In view of ongoing experimental activities to determine the pion polarizabilities, we have started to recalculate the available two-loop expressions in the framework of chiral perturbation theory, because they have never been checked…
We consider the quadratic scalar radius of the pion, $<r^2_{{\rm S},\pi}>$, and the mixed $K-\pi$ scalar radius, $<r^2_{{\rm S},K\pi}>$. With respect to the second, we point out that the more recent (post-1974) experimental results in…
Generalized Hidden Local Symmetry (GHLS) model as the chiral model of pseudoscalar, vector, and axial vector mesons and their interactions containing also the couplings of strongly interacting particles with electroweak gauge bosons, is…
The COMPASS collaboration at CERN has investigated the \pi^- \gamma -> \pi^- \pi^- \pi^+ reaction at center-of-momentum energy below five pion masses, sqrt(s) < 5 m(\pi), embedded in the Primakoff reaction of 190 GeV pions impinging on a…
The extrapolation of the decay amplitudes of the pseudoscalar mesons into two photons from the soft meson limit where it is obtained from the axial-anomaly to the mass shell involves the contribution of the 0^ - continuum. These chiral…
Large discrepancy of the p-wave phase shift data $\delta_{1}(\nu)$ of the $\pi$-$\pi$ scattering from those of the dispersion calculation is pointed out. In order to determine which is correct, the pion form factor $F_{\pi}(\nu)$, which is…
We review the recent measurements of the rare pion decays: Pi+ -> Pi0 e+ Nu [pion beta, Pi_(e3), or Pi_beta decay], radiative decay Pi+ -> e+ Nu Gamma [Pi_(e2Gamma) or RPD], and Pi+ -> e+ Nu [Pi_(e2)] decay, as well as the radiative muon…
In this report we describe the analysis status of electron-pion inelastic scattering $\pi e \to \pi' e' \gamma$ and $\pi e \to \pi' e' \pi^0$ reaction data, measured in inverse pion-electron scattering at 590 GeV/c at FNAL. The data give…
Pionic beta decay \pi^+ to \pi^0 e^+ \nu_e is analyzed in chiral perturbation theory with virtual photons and leptons. All electromagnetic corrections up to order e^2 p^2 are taken into account. Theoretical results are confronted with…
Taken by itself, the interference with the etaprime appears to strongly affect the amplitude of the transition eta->3 pi. I point out that this effect is fictitious and also occurs in the mass spectrum of the pseudoscalars. Chiral symmetry…
New data are presented on the p(e,e'p)\pi^0 reaction at threshold at a four-momentum transfer of Q^2=0.05 GeV^2/c^2. The data were taken with the three-spectrometer setup of the A1 Collaboration at the Mainz Microtron MAMI. The complete…