相关论文: Remarkable suppression of the $e^{+}e^{-}\to\pi^{+…
We present the up to now most precise evaluation of electroweak and supersymmetric contributions to the anomalous magnetic moment of the muon \amu, describing in detail also the calculational techniques. We calculate the bosonic two-loop…
We review Standard-Model evaluations of hadronic contributions to the muon anomalous magnetic moment $g-2$. Most space is devoted to the hadronic vacuum polarization contribution, in view of the discrepancy between the data-based dispersive…
We provide an in-depth analysis of the $\pi$ distribution amplitude in terms of two different Gegenbauer representations. Detailed predictions for the $\pi-\gamma$ transition form factor are presented, obtained with light-cone sum rules.…
In this letter, we address the question of whether the almost four standard deviations difference between theory and experiment for the muon anomalous magnetic moment $a_\mu$ can be explained as a higher-order Standard Model perturbation…
The electromagnetic form factor of the pion is calculated in a pseudoscalar field theoretical model which constituent quarks. We extract the form factor using the "+" component of the electromagnetic current in the light-cone formalism. For…
The pion electromagnetic form factor at spacelike momentum transfer is calculated in relativistic impulse approximation using the Covariant Spectator Theory. The same dressed quark mass function and the equation for the pion bound-state…
We present a quantitative analysis of the electromagnetic pion form factor in the light-cone sum rule approach, including radiative corrections and higher-twist effects. The comparison to the existing data favors the asymptotic profile of…
The KLOE experiment at the DA$\Phi$NE $\phi$-factory has performed a new precise measurement of the pion form factor using Initial State Radiation events. Results based on an integrated luminosity of 240 pb$^{-1}$ and extraction of the…
The measurement of the $\sigma(e^+e^-\rightarrow \pi^+\pi^-)$ cross section allows to determine the pion form factor $| F_\pi |^2$ and the two pion contribution to the muon anomaly $a_\mu$. Such a measurement has been performed with the…
We comment on the recent calculations of the pion pole part of the light-by-light contribution to the muon anomalous magnetic moment and we point out where the analysis in our previous work was mistaken.
Higher-order hadronic contributions to the anomalous magnetic moment of the electron, muon, and $\tau$ lepton are considered in detail. As a main result we find a reduction by $-11 \times 10^{-11}$ for the g-2 of the muon as compared to…
The vector form factor of the decay $\pi^{+} \rightarrow \gamma + e^{+} + \nu_e$ is calculated by the method for the pseudovector pion-nucleon system. The non-perturbative term is taken into account by using the parameter for the…
A significant discrepancy exists between experiment and calculations of the muon's magnetic moment. We find that standard formulas for the hadronic vacuum polarization term have overlooked pionic states known to exist. Coulomb binding alone…
In the Littlest Higgs model, we comprehensively study the phenomenology of the heavy photon A_H which is lightest, in most of the parameter space, among newly introduced heavy gauge bosons and top-like vector quark. Unexpected behavior is…
The description of the VV'P form factors (V,V' stands for vector particles and P for a pseudoscalar meson) for different particles virtualities remains a challenge for the theory of strong interactions. While their chiral limit is well…
The behaviour of the pion transition form factor for the process $\gamma^\star\gamma \to \pi^0$ and $\gamma^\star\gamma^\star\to \pi^0$ at space-like values of photon momenta is estimated within the nonlocal covariant quark-meson model. The…
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…
We calculate the pion pole term of the light-by-light contribution to the $g-2$ of the muon in the framework of an effective chiral quark model with instanton-like nonlocal quark--quark interaction. The full kinematic dependence of the…
The complete one-loop QED initial state, final state and initial--final state interference corrections to the process e+e- -> pi+pi- are presented. Analytic formulae are given for the virtual and for the real photon corrections. The total…
We reevaluate the hadronic contribution to the running of the QED fine structure constant alpha(s) at s = M_Z^2. We use data from e+e- annihilation and tau decays at low energy and at the qq-bar thresholds, where resonances occur. Using…