Related papers: Charge asymmetry in the process $e^+e^-\to \pi^+\p…
The $e^+e^- \to \omega \pi^0 \to \pi^0 \pi^0 \gamma$ process was investigated in the SND experiment at the VEPP-2M collider. A narrow energy interval near the $\phi$-meson was scanned. The observed cross-section reveals, at the level of…
We present the midrapidity charged pion invariant cross sections and the ratio of $\pi^-$-to-$\pi^+$ production ($5<p_T<13$ GeV/$c$), together with the double-helicity asymmetries ($5<p_T<12$ GeV/$c$) in polarized $p$$+$$p$ collisions at…
The cross section of the $e^+e^-\to\omega\pi^0\to\pi^0\pi^0\gamma$ reaction was measured by the SND detector at VEPP-2M $e^+e^-$ collider in the energy range from threshold up to 1.4 GeV. Results of the cross section fitting by the sum of…
The main experimental works, where dipole polarizabilities of charged pions have been determined, are considered. Possible reasons for the differences between the experimental data are discussed. In particular, it is shown that the account…
The process of $e^+e^-$ annihilation into a $\pi^+\pi^-$ pair with radiation of a photon is considered. The amplitude of the reaction $e^+e^-\to\pi^+\pi^-\gamma$ consists of the model independent initial-state radiation (ISR) and…
The $\Sigma$ beam asymmetry in the photoproduction of negative pions from quasi-free neutrons in a deuterium target was measured at Graal in the energy interval 700 - 1500 MeV and a wide angular range, using polarized and tagged photons.…
With the data samples taken at center-of-mass energies from 2.00 to 3.08 GeV with the BESIII detector at the BEPCII collider, a partial wave analysis on the $e^{+}e^{-}\rightarrow\pi^{+}\pi^{-}\pi^{0}$ process is performed. The Born cross…
The process e+e- --> pi+ pi- pi0 gamma has been studied at a center-of-mass energy near the Y(4S) resonance using a 89.3 fb-1 data sample collected with the BaBar detector at the PEP-II collider. From the measured 3pi mass spectrum we have…
We consider the sin(phi) single target-spin asymmetry in deep-inelastic pi^{+} inclusive electroproduction off a longitudinally polarized target. We show that at larger transverse momentum of the outgoing hadron the evaluated asymmetry…
We calculate the rate of collisional decay of the axial charge in an ultrarelativistic electron-positron plasma, also known as the chirality flipping rate. We find that contrary to the existing estimates, the chirality flipping rate appears…
The pion form factor plays a crucial role in the determination of the contribution of the hadronic vacuum polarisation to the muon anomalous magnetic moment. In order to measure this quantity, energy-scan experiments rely on Monte Carlo…
Charge asymmetries in diffractive electroproduction of two mesons are proportional to the interference of Pomeron and Odderon exchange amplitudes. We calculate in the framework of QCD and in the Born approximation a forward-backward charge…
The background due to the direct diffractive dissociation of the photon into the $\pi^+\pi^-$-pair to the "elastic" diffractive $\rho^0$-meson production in electron-proton collisions is calculated. The amplitude for the background process…
The study of charge asymmetry of pions in the high-energy process gamma p -> pi+ pi- p (e p -> e pi+ pi- p) at very small dipion momenta offers a method to measure the phase of the forward hadronic (quasi)elastic amplitude gamma p -> rho p.…
We present a theoretical study of the $\gamma\gamma^{*} \to \pi^+\pi^-, \pi^0\pi^0$ processes from the threshold through the $f_2(1270)$ region in the $\pi\pi$ invariant mass. We adopt the Omn\`es representation in order to account for…
In this work, the two-photon-exchange (TPE) effects in $e^+e^- \rightarrow \pi^+ \pi^-$ at small $\sqrt{s}$ are discussed within a hadronic model. In the limit $m_e\rightarrow 0$, the TPE contribution to the amplitude can be described by…
We report the first evidence for a non-zero beam-spin azimuthal asymmetry in the electroproduction of positive pions in the deep-inelastic region. Data have been obtained using a polarized electron beam of 4.3 GeV with the CLAS detector at…
We demonstrate that one can use the occurrence of charge symmetry breaking as a tool to explore the eta--nucleus interaction near the eta threshold. Based on indications that the cross section ratio of pi+ and pi0 production on nuclei…
We have measured the cross section $\sigma(e^+e^-\to\pi^+\pi^-\gamma)$ with the KLOE detector at DA$\Phi$NE, at an energy $W=M_\phi=1.02$ GeV. From the dependence of the cross section on $m(\pi^+\pi^-)=\sqrt{W^2-2WE_\gamma}$, where…
We analyse the contributions to the charge asymmetry in $K^\pm\to\pi^\pm\ell^+\ell^-$ decays induced by gluino-exchange diagrams in the context of supersymmetric models with generic flavour couplings. We show that sizeable deviations with…