相关论文: The branching ratio $\omega \to \pi^+\pi^-$ revisi…
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 extract the G-parity-violating branching ratio Br(omega->pi^+ pi^-) from the effective rho-omega mixing matrix element Pi_{rho omega}(s), determined from e^+e^- -> pi^+ pi^- data. The omega->pi^+ pi^- partial width can be determined…
We present a determination of the pion charge radius from high precision data on the pion vector form factor from both timelike and spacelike regions, using a novel formalism based on analyticity and unitarity. At low energies, instead of…
We analyze the pion transition form factor using dispersion theory. We calculate the singly-virtual form factor in the time-like region based on data for the $e^+e^-\to 3\pi$ cross section, generalizing previous studies on…
Data samples corresponding to the isospin-violating decay $D_s^{*+}\to D_s^+ \pi^0$ and the decays $D_s^{*+}\to D_s^+\gamma$, $D^{*0}\to D^0\pi^0$ and $D^{*0}\to D^0\gamma$ are reconstructed using 90.4 ${\rm fb}^{-1}$ of data recorded by…
In terms of effective field theory and mixed propagator approach, we show that there is a larger hidden effect of isospin breaking in $\rho^0\to\pi^0\gamma$ decay due to an $\omega$ exchange, $\rho^0\to\omega\to\pi^0\gamma$. The branching…
We have studied radiative pion decays Pi+ -> e+ nu gamma in three broad kinematic regions using the PIBETA detector and a stopped pion beam. Based on Dalitz distributions of 42,209 events we have evaluated absolute Pi -> e nu gamma…
We have used the PIBETA large acceptance detector for a precise measurement of the $\pi^+ \to e^+\nu\gamma$ radiative decay at rest, with broad phase space coverage. Using the CVC value for the pion vector form factor, $F_V = 0.0259(5)$, we…
We study consistently the pion's static observables and the elastic and \gamma*\gamma -> \pi^0 transition form factors within a light-front model. Consistency requires that all calculations are performed within a given model with the same…
We study the implications of several recent high-precision measurements of the pion form factor in the region of the rho-omega interference "shoulder" for (i) the extraction of the rho-omega mixing matrix element, Pi_{\rho\omega}(m_rho^2),…
We propose a dispersive representation of the charged pion vector form factor that is consistent with chiral symmetry and fulfills the constraints imposed by analyticity and unitarity. Unknown parameters are fitted to the very precise data…
We present a dispersive representation of the $\eta'$ transition form factor that allows one to account, in a consistent way, for the effects of $\rho$-$\omega$ mixing in both the isoscalar and the isovector contributions. Using this…
We present the first upper-limit measurement of the branching fractions of the isospin-violating transitions $\chi_{c0,2} \rightarrow \pi^{0} \eta_{c}$. The measurements are performed using $106\times 10^{6}$ $\psi(3686)$ events accumulated…
The (Delta I = 1) decay D_s^* --> Ds pi0 and (\Delta I = 0) decay D_s^* --> Ds gamma have been reconstructed using 90.4 fb^-1 of data recorded by the BaBar detector at the PEP-II asymmetric-energy e^+e^- collider. The relative branching…
Using a sample of $(10087 \pm 44) \times 10^{6}$ $J/\psi$ events collected with the BESIII detector, an improved measurement of the decay $\eta^{\prime}\rightarrow e^{+}e^{-}\omega$, with $\omega\rightarrow\pi^{+}\pi^{-}\pi^{0}$ and…
Based on a sample of 227 million BBbar pairs collected by the BaBar detector at the PEP-II asymmetric-energy B Factory at SLAC, we measure the branching fraction B(B0 -> pi0pi0) = (1.17 +- 0.32 +- 0.10) x 1e-6, and the asymmetry C(pi0pi0) =…
We present measurements of branching fractions and CP-violating asymmetries for neutral B meson decays to two-body final states of charged pions and kaons based on a sample of about 88 million Y(4S)-->BB decays. From a time-independent fit…
Dispersive representations of the pi-pi scattering amplitudes and pion form factors, valid at two-loop accuracy in the low-energy expansion, are constructed in the presence of isospin-breaking effects induced by the difference between the…
Using a large acceptance calorimeter and a stopped pion beam we have made a precise measurement of the rare Pi+ -> Pi0 e+ Nu,(pi_beta) decay branching ratio. We have evaluated the branching ratio by normalizing the number of observed…
A new approach to the parameterization of pion form factors is presented and for illustration applied to the pion vector form factor. It has the correct analytic structure, is at low energies consistent with recent high accuracy analyses of…