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The pion pair production in $e^+ e^-$ annihilation at flavour factories plays a crucial role in the determination of the hadronic contribution to the muon anomalous magnetic moment. The recent CMD-3 measurement of the pion form factor via…

High Energy Physics - Phenomenology · Physics 2025-06-03 E. Budassi , C. M. Carloni Calame , M. Ghilardi , A. Gurgone , G. Montagna , M. Moretti , O. Nicrosini , F. Piccinini , F. P. Ucci

Radiative corrections due to pair production in process of electron-positron annihilation are considered. The main attention is paid to the corrections of the third order. Simultaneous emission of photons and pairs is taken into account.…

High Energy Physics - Phenomenology · Physics 2009-10-31 A. B. Arbuzov

The leptonic tensor for the process $e^+ e^- \to \gamma+\gamma^*$, which describes the next-to-leading order virtual and soft QED corrections to initial state radiation in $e^+ e^-$ annihilation with emission of an extra virtual photon…

High Energy Physics - Phenomenology · Physics 2009-01-07 German Rodrigo , Aude Gehrmann-De Ridder , Marc Guilleaume , Johann H. Kuhn

The excitation curve of e+e- annihilation into four charged pions in the rho(770) region is calculated using three existing models with rho mesons and pions in intermediate states supplemented by Feynman diagrams with the a_1(1260)pi…

High Energy Physics - Phenomenology · Physics 2008-11-26 Peter Lichard , Josef Juran

In the $e^+e^-$ annihilation processes $e^+e^-\to D^0\bar{D}^0, D^+D^-$ near or above the threshold of $D\bar{D}$, there are not only the resonance contribution $e^+e^-\to \psi (3770)\to D^0\bar{D}^0, D^+D^-$, but also the continuum…

High Energy Physics - Phenomenology · Physics 2008-12-25 Mao-Zhi Yang

In this paper, a coherent study of the $e^+e^-$ annihilation into $K^+K^-\pi^0$, $K^0_SK^0_L\pi^0$ and $K^0_SK^\pm\pi^\mp$ is carried out within the framework of resonance chiral theory. The amplitudes are fixed by fitting to the…

High Energy Physics - Phenomenology · Physics 2025-02-13 Bing-Hai Qin , Wen Qin , Ling-Yun Dai

It is well known that in the presence of strong external electromagnetic fields many processes forbidden in standard QED become possible. One example is the one-photon annihilation process considered recently by the present authors in the…

Plasma Physics · Physics 2011-02-01 D. B. Blaschke , G. Roepke , V. V. Dmitriev , S. A. Smolyansky , A. V. Tarakanov

In this dissertation, a complete calculation of QED radiative corrections is presented for total cross sections and forward- backward asymmetries for s-channel fermion pair production in e+e- annihilation with kinematical cuts to the final…

High Energy Physics - Phenomenology · Physics 2007-05-23 M. A. Jack

We study the annihilation process $p\bar{p} \to \pi^0 e^+ e^-$ within a Regge framework, as a means to provide constraints on timelike nucleon form factors. We present results for the $e^+e^-$ angular distributions and the differential…

High Energy Physics - Phenomenology · Physics 2013-03-11 J. Guttmann , M. Vanderhaeghen

We study the process $e^+e^- \to \pi^+\pi^-\eta \gamma$, where the photon is radiated from the initial state. About 8000 fully reconstructed events of this process are selected from the BaBar data sample with an integrated luminosity of…

High Energy Physics - Experiment · Physics 2018-03-28 The BABAR Collaboration

We study QCD correction to the pair production of colored scalar particles in electron-positron annihilation with an emphasis on gluon emission in the final state. We discuss the usefulness of working in a ``quasi-two-body'' frame and…

High Energy Physics - Phenomenology · Physics 2009-10-28 Ken-ichi Hikasa , Junji Hisano

We present a complete calculation of the K_{l3} decays K^+ --> pi^0 l^+ nu_l and K^0 --> pi^- l^+ nu_l to O(p^4, (m_d-m_u) p^2, e^2 p^2) in chiral perturbation theory with virtual photons and leptons. We introduce the concept of generalized…

High Energy Physics - Phenomenology · Physics 2008-11-26 V. Cirigliano , M. Knecht , H. Neufeld , H. Rupertsberger , P. Talavera

A quark model calculation of the processes gamma gamma -> pi+ pi- and gamma gamma -> pi0 pi0 is performed. At tree level, only charged pions couple to the initial state photons and neutral pions are not expected in the final state. However,…

High Energy Physics - Phenomenology · Physics 2008-11-26 H. G. Blundell , S. Godfrey , G. Hay , E. S. Swanson

Analytic calculation are presented of the contribution to the anomalous magnetic moment of a muon from the channels of annihilation of an electron-positron pair to a pair of charged pi-mesons with radiative correction connected with the…

High Energy Physics - Phenomenology · Physics 2013-08-14 A. I. Ahmadov , E. A. Kuraev , M. K. Volkov , O. O. Voskresenskaya , E. V. Zemlyanaya

In this paper, we employ chiral effective field theory to study the process of electron-positron annihilation into four pions in the low energy region within $E_{c.m.}\leq 0.6$ GeV. The prediction of the cross section is obtained through…

High Energy Physics - Phenomenology · Physics 2026-05-19 Jia-Yu Zhou , Hao-Xiang Pan , Ling-Yun Dai

The annihilation into axion $e^+ e^- \to a$ is investigated in a plasma and an external magnetic field. This process via a plasmon intermediate state has a resonant character at a particular energy of the emitted axion. The emissivity by…

High Energy Physics - Phenomenology · Physics 2009-10-31 N. V. Mikheev , A. Ya. Parkhomenko , L. A. Vassilevskaya

We investigate radiative corrections to K --> 3 pi decays. In particular, we extend the non-relativistic framework developed recently to include real and virtual photons and show that, in a well-defined power counting scheme, the results…

High Energy Physics - Phenomenology · Physics 2008-11-26 M. Bissegger , A. Fuhrer , J. Gasser , B. Kubis , A. Rusetsky

We study, at leading order in the large number of colours expansion and within the Resonance Chiral Theory framework, the odd-intrinsic-parity $e^+ e^- \rightarrow \pi^+ \pi^- (\pi^0, \eta)$ cross-sections in the energy regime populated by…

High Energy Physics - Phenomenology · Physics 2015-06-16 L. Y. Dai , J. Portoles , O. Shekhovtsova

We present a calculation of the $C$-odd radiative corrections to $e^+e^-\to \pi^+\pi^-$ in a dispersive formalism, concentrating on the leading pion-pole contribution in the virtual box diagrams. In particular, we show how the effect of a…

High Energy Physics - Phenomenology · Physics 2025-02-27 Gilberto Colangelo , Martin Hoferichter , Joachim Monnard , Jacobo Ruiz de Elvira

The e+e- --> pi+pi-pi0pi0 reaction cross section as a function of the incident energy is calculated using a model that is an extension of our recently published model of the e+e- annihilation into four charged pions. The latter considered…

High Energy Physics - Phenomenology · Physics 2008-11-26 Josef Juran , Peter Lichard