Electromagnetic Charge Radius of the Pion at High Precision
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TLDR
A determination of the pions charge radius from high precision data on the pion vector form factor from both timelike and spacelike regions is presented, using a novel formalism based on analyticity and unitarity.Abstract:
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 the poorly known modulus of the form factor, we use its phase, known with high accuracy from Roy equations for pi pi elastic scattering via the Fermi-Watson theorem. We use also the values of the modulus at several higher timelike energies, where the data from e(+)e(-) annihilation and tau decay are mutually consistent, as well as the most recent measurements at spacelike momenta. The experimental uncertainties are implemented by Monte Carlo simulations. The results, which do not rely on a specific parametrization, are optimal for the given input information and do not depend on the unknown phase of the form factor above the first inelastic threshold. Our prediction for the charge radius of the pion is r(pi) = (0.657 +/- 0.003) fm, which amounts to an increase in precision by a factor of about 2.7 compared to the Particle Data Group average.read more
Citations
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Three-pion contribution to hadronic vacuum polarization
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Two-pion contribution to hadronic vacuum polarization
TL;DR: The contribution of the 3π channel to hadronic vacuum polarization (HVP) using a dispersive representation of the e+e− → 3π amplitude was studied in this paper.
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The branching ratio $\omega \to \pi^+\pi^-$ revisited
TL;DR: In this article, a model-independent approach based on dispersion theory was proposed to analyze the most recent data for the pion vector form factor in the timelike region.
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Pion electromagnetic form factor at high precision with implications to $a_\mu^{\pi\pi}$ and the onset of perturbative QCD
TL;DR: In this article, a parametrization-free formalism based on analyticity and unitarity was used to obtain a determination of the electromagnetic form factor of the pion in several significant kinematical regions, with the inclusion of precise inputs from both timelike and spacelike regions.
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Pion vector form factor from lattice QCD at the physical point
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TL;DR: In this paper, the electromagnetic pion form factor at small values of the four-momentum transfer was investigated at a fixed lattice spacing with pion masses equal to its physical value, 240 MeV and 340 MeV.
References
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The OPAL Collaboration
K. Ackerstaff,Gideon Alexander,John Allison,N. Altekamp,Kelby Anderson,S. B. Anderson,Silvia Arcelli,Shoji Asai,D. Axen,Georges Azuelos,A. H. Ball,E. L. Barberio,Roger Barlow,R. Bartoldus,J. R. Batley,S. Baumann,J. Bechtluft,C.J. Beeston,T. Behnke,A. N. Bell,K. W. Bell,Gideon Bella,Stan Bentvelsen,Siegfried Bethke,Otmar Biebel,A. Biguzzi,S. D. Bird,Volker Blobel,I. J. Bloodworth,J. E. Bloomer,M. Bobinski,P. Bock,D. Bonacorsi,M. Boutemeur,BT Bouwens,S. Braibant,L. Brigliadori,Robert M Brown,Helfried Burckhart,Carsten Daniel Burgard,R. Bürgin,Paolo Capiluppi,R. K. Carnegie,A. A. Carter,J. R. Carter,C. Y. Chang,Dave Charlton,D Chrisman,P. E. L. Clarke,I. Cohen,J. E. Conboy,O. C. Cooke,Marco Cuffiani,Shlomo Dado,C. Dallapiccola,G. M. Dallavalle,R. Davis,S. J. De Jong,L. A. del Pozo,Klaus Kurt Desch,Beatrix Dienes,Mathieu Doucet,Ehud Duchovni,Guenter Duckeck,I. P. Duerdoth,D. Eatough,J. E.G. Edwards,P. G. Estabrooks,H. G. Evans,Meirin Oan Evans,Fabrizio Fabbri,Marcello Fanti,A. A. Faust,Frank Fiedler,M. Fierro,H. Fischer,Ivor Fleck,Ron Folman,D. G. Fong,M. Foucher,A Furtjes,David Futyan,P. Gagnon,J. W. Gary,J. Gascon,S. M. Gascon-Shotkin,N. I. Geddes,Ch. Geich-Gimbel,T. Geralis,G. Giacomelli,Paolo Giacomelli,R. Giacomelli,V. Gibson,W. R. Gibson,Douglas Gingrich,D. Glenzinski,J. Goldberg,M. J. Goodrick,W. Gorn,C. Grandi,Eilam Gross,J. Grunhaus,M. Gruwe,Csaba Hajdu,G. G. Hanson,M. Hansroul,M. Hapke,C. K. Hargrove,P.A. Hart,C. Hartmann,M. Hauschild,Christopher Hawkes,R. J. Hawkings,R. J. Hemingway,Matthew Herndon,Gregor Herten,Rolf-Dieter Heuer,Michael Hildreth,John Hill,S. J. Hillier,Peter R Hobson,R. J. Homer,A. K. Honma,D. Horvath,K. R. Hossain,R. Howard,P. Hüntemeyer,D. E. Hutchcroft,P. Igo-Kemenes,D. C. Imrie,M. R. Ingram,K. Ishii,A. Jawahery,P. W. Jeffreys,H. Jeremie,M. Jimack,A. Joly,C. R. Jones,G. T. Jones,Matthew Jones,U. Jost,P. Jovanovic,T. R. Junk,D. Karlen,V. Kartvelishvili,Kiyotomo Kawagoe,Tatsuo Kawamoto,P. I. Kayal,Richard Keeler,R. G. Kellogg,B. W. Kennedy,Julie Kirk,A. Klier,Stefan Kluth,Takashi Kobayashi,Michael Kobel +155 more
TL;DR: In this paper, the authors present measurements of triple gauge boson coupling parameters using data recorded by the OPAL detector at LEP2 at a centre-of-mass energy of 172 GeV.
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