Form factors of pseudoscalar mesons

Guo, Peng; Szczepaniak, Adam P.

doi:10.1103/physrevc.86.015205

Cited by 22 publications

(22 citation statements)

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“…Hence, our representation will be matched to f (ω) to fully take into account the entire domain of space-like virtualities, instead of just two particular limits (5.5) and (5.6). Beyond the leading expansion (5.1), calculations including α s corrections [154,155], higher terms in the Gegenbauer-polynomial expansion of φ π (u) [147,156] within QCD sum rules [148][149][150]157], Dyson-Schwinger equations [158,159], and Regge theory [160][161][162] could be considered, but a consistent treatment of all subleading corrections becomes very complicated with little numerical impact on (g − 2) µ . As an explicit example we will consider α s corrections in Sect.…”

Section: Leading-order Perturbative Qcdmentioning

confidence: 99%

Dispersion relation for hadronic light-by-light scattering: pion pole

Hoferichter¹,

Hoid²,

Kubis³

et al. 2018

J. High Energ. Phys.

373

223

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The pion-pole contribution to hadronic light-by-light scattering in the anomalous magnetic moment of the muon (g − 2) µ is fully determined by the doubly-virtual pion transition form factor. Although this crucial input quantity is, in principle, directly accessible in experiment, a complete measurement covering all kinematic regions relevant for (g − 2) µ is not realistic in the foreseeable future. Here, we report in detail on a reconstruction from available data, both space-and time-like, using a dispersive representation that accounts for all the low-lying singularities, reproduces the correct high-and low-energy limits, and proves convenient for the evaluation of the (g − 2) µ loop integral. We concentrate on the systematics of the fit to e + e − → 3π data, which are key in constraining the isoscalar dependence, as well as the matching to the asymptotic limits. In particular, we provide a detailed account of the pion transition form factor at low energies in the time-and space-like region, including the error estimates underlying our final result for the pion-pole contribution, a π 0 -pole µ = 62.6 +3.0 −2.5 × 10 −11 , and demonstrate how forthcoming singly-virtual measurements will further reduce its uncertainty.

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Section: Leading-order Perturbative Qcdmentioning

confidence: 99%

Dispersion relation for hadronic light-by-light scattering: pion pole

Hoferichter¹,

Hoid²,

Kubis³

et al. 2018

J. High Energ. Phys.

373

223

View full text Add to dashboard Cite

show abstract

“…We note that there are several theoretical studies [27][28][29][30][31][32][33][34][35][36] trying to reproduce the BABAR data for the pion TFF, apart from those using the 'flat' form for the pion DA [13][14][15]26].…”

Section: Higher Order and Higher Fock State Contributions And Depementioning

confidence: 99%

“…The Regge approach was employed in [29,30] to explain the BABAR data. On the other hand, there are also theoretical calculations suggesting that the BABAR data are not compatible with QCD calculations [37][38][39][40].…”

Section: Higher Order and Higher Fock State Contributions And Depementioning

confidence: 99%

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Evolved QCD predictions for the meson-photon transition form factors

2011

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The QCD evolution of the pion distribution amplitude (DA) φ π (x, Q 2 ) is computed for several commonly used models. Our analysis includes the nonperturbative form predicted by light-front holographic QCD, thus combining the nonperturbative bound state dynamics of the pion with the perturbative ERBL evolution of the pion DA. We calculate the meson-photon transition form factors for the π 0 , η and η using the hard-scattering formalism. We point out that a widely-used approximation of replacing φ (x, (1 − x)Q) with φ(x, Q) in the calculations will unjustifiably reduce the predictions for the meson-photon transition form factors. It is found that the four models of the pion DA discussed give very different predictions for the Q 2 dependence of the meson-photon transition form factors in the region of Q 2 > 30 GeV 2 . More accurate measurements of these transition form factors at the large Q 2 region will be able to distinguish different models of the pion DA. The rapid growth of the large Q 2 data for the pion-photon transition form factor reported by the BABAR Collaboration is difficult to explain within the current framework of QCD. If the BABAR data for the meson-photon transition form factor is confirmed, it could indicate physics beyondthe-standard model, such as a weakly-coupled elementary C = + axial vector or pseudoscalar z 0 in the few GeV domain, an elementary field which would provide the coupling γ * γ → z 0 → π 0 at leading twist. Our analysis thus indicates the importance of additional measurements of the pion-photon transition form factor at large Q 2 .

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“…A rigorous dispersive implementation of this theorem can be achieved via the MuskhelishviliOmnès (MO) method [113,114], where the amplitude is expressed in terms of an Omnès factor uniquely determined by the phase of the scattering process of the final state. This method is particularly well-suited for the study of meson form factors, not only of pions, kaons, but charmed D mesons as well, see for instance [115][116][117][118][119][120][121][122] and references therein. In addition to the right-hand cut accounted for by the MO method, the description of production amplitudes involves a left-hand cut.…”

Section: Amplitude Analysismentioning

confidence: 99%

Analysis Tools for Next-Generation Hadron Spectroscopy Experiments

Battaglieri¹,

Briscoe²,

Celentano³

et al. 2015

Acta Phys. Pol. B

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The series of workshops on New Partial-Wave Analysis Tools for Next-Generation Hadron Spectroscopy Experiments was initiated with the ATHOS 2012 meeting, which took place in Camogli, Italy, June 20-22, 2012. It was followed by ATHOS 2013 in Kloster Seeon near Munich, Germany, May 21-24, 2013. The third, ATHOS3, meeting is planned for April 13-17, 2015 at The George Washington University Virginia Science and Technology Campus, USA. The workshops focus on the development of amplitude analysis tools for meson and baryon spectroscopy, and complement other programs in hadron spectroscopy organized in the recent past including the INT-JLab Workshop on Hadron Spectroscopy in Seattle in 2009, the International Workshop on Amplitude Analysis in Hadron Spectroscopy at the ECT*-Trento in 2011, the School on Amplitude Analysis in Modern Physics in Bad Honnef in 2011, the Jefferson Lab Advanced Study Institute Summer School in 2012, and the School on Concepts of Modern Amplitude Analysis Techniques in Flecken-Zechlin near Berlin in September 2013. The aim of this document is to summarize the discussions that took place at the ATHOS 2012 and ATHOS 2013 meetings. We do not attempt a comprehensive review of the field of amplitude analysis, but offer a collection of thoughts that we hope may lay the ground for such a document.Comment: 28 pages, 11 figures, proceedings of the ATHOS 2012 and ATHOS 2013 meeting

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Form factors of pseudoscalar mesons

Cited by 22 publications

References 50 publications

Dispersion relation for hadronic light-by-light scattering: pion pole

Dispersion relation for hadronic light-by-light scattering: pion pole

Evolved QCD predictions for the meson-photon transition form factors

Analysis Tools for Next-Generation Hadron Spectroscopy Experiments

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