Related papers: Improved Standard-Model prediction for $\pi^0\to e…
The NLO Brodsky-Lepage-Mackenzie (BLM) scale for the pion transition form factor has been determined. To achieve that, a consistent calculation up to nf-proportional NNLO contributions to both the hard-scattering amplitude and the…
In this paper, the dilepton electromagnetic decays $\chi_{cJ}(1P) \to J/\psi e^+e^-$ and $\chi_{cJ}(1P) \to J\psi \mu^+\mu^-$, where $\chi_{cJ}$ denotes $\chi_{c0}$, $\chi_{c1}$ and $\chi_{c2}$, are calculated systematically in the improved…
We discuss the possibility of performing precise tests of $\mu/e$ universality in $B \to\pi \ell^+\ell^-$ decays. We show that in wide regions of the dilepton invariant mass spectrum the ratio between muonic and electronic decay widths can…
We study dispersive representations of nonlocal form factors in $K^+ \to \pi^+ \ell^+ \ell^-$ and $K^+ \to \pi^+ \nu \bar{\nu}$ decays, with an aim of improving the theoretical description of the spectrum and decay rate of the neutrino…
We calculate the pion decay constant near the critical temperature of the $O(N)$ nonlinear sigma model in the large $N$ limit. Making use of the known low temperature behavior, we construct a Pad\'{e} approximant to obtain the behavior of…
Recently, important updates were made for the hadronic contribution to the theoretical prediction of g-2. The isospin-breaking-corrections, needed in the comparison of the two pion spectral functions from tau decays and e+e- annihilations,…
A global fit of parameters allows us to pin down the Hidden Local Symmetry (HLS) effective Lagrangian, which we apply for the prediction of the leading hadronic vacuum polarization contribution to the muon g-2. The latter is dominated by…
The PIBETA collaboration has used a non-magnetic pure CsI calorimeter operating at the Paul Scherrer Institute to collect the world's largest sample of rare pion and muon decays. We have extracted the absolute pi+ -> pi0 e+ nu decay…
We employ a dispersion relation that allows to recover the phase of the electromagnetic form factor of the pion from its absolute value above threshold. Compared to alternative approaches building on the phase, this approach builds on…
We review the isospin-breaking and electromagnetic corrections to the $\tau^- \to \pi^- \pi^0 \nu_\tau$ decays, which are used as an input to the two-pion contributions to the hadronic vacuum polarization (at LO) of the anomalous magnetic…
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…
We revisit the isospin-breaking corrections relating the $e^+e^-$ hadronic cross-section and the tau decay spectral function, focusing on the di-pion channel, that gives the dominant contribution to the hadronic vacuum polarization piece of…
The study of processes involving the weak decays of the charm quark offers unique possibilities to test the Standard Model from the up-type sector and to probe different New Physics scenarios. In here we focus on the rare decays…
The decay K- -> pi0 e- nu is studied using in-flight decays detected with the ISTRA+ spectrometer. About 920K events are collected for the analysis. The lambda+ slope parameter of the decay form-factor f+(t) in the linear approximation…
The invariant mass spectrum of the $e^{+}e^{-}$ and $\mu ^{+}\mu ^{-}$ pairs from decays of light unflavored mesons with masses below the $\phi (1020)$-meson mass to final states containing along with a dilepton pair one photon, one meson,…
We study transitions between Upsilon states with the emission of charged pions using 604.6/fb of data collected with the Belle detector at the KEKB asymmetric-energy e+e- collider. The measured product branching fraction is B(Upsilon(4S) ->…
We extend the application of lattice QCD to the two-photon-mediated, order $\alpha^2$ rare decay $\pi^0\rightarrow e^+ e^-$. By combining Minkowski- and Euclidean-space methods we are able to calculate the complex amplitude describing this…
A cross section of the process $e^+e^- \to \pipi\pipi$ has been measured using 6798$\pm$93 signal events from a data sample corresponding to an integrated luminosity of 9.8 pb$^{-1}$ collected with the CMD-3 detector in the center-of-mass…
Within the framework provided by quantum chromodynamics's Schwinger-Dyson equations (SDEs), the pion's electromagnetic form factor is computed using solutions of the Bethe-Salpeter equation (BSE) that have finite spacial momentum, and…
The decay $\eta \to \pi^0 \gamma \gamma$ is discussed in the framework of SU(3) chiral perturbation theory. The process is dominated by the ${\cal{O}}(p^6)$ in the momentum expansion where tree-level amplitudes from the effective Lagrangian…