Can we understand an auxetic pion-photon transition form factor within QCD? BaBar faces Belle

Abstract

A state-of-the-art analysis of the pion-photon transition form factor is presented based on an improved theoretical calculation that includes the effect of a finite virtuality of the quasi-real photon in the method of light-cone sum rules. We carry out a detailed statistical analysis of the existing experimental data using this method and by employing pion distribution amplitudes with up to three Gegenbauer coefficients $a_2,a_4,a_6$. Allowing for an error range in the coefficient $a_6\approx 0$, the theoretical predictions for ${\gamma }^{\ast }\gamma \to {\pi }^0$ obtained with nonlocal QCD sum rules are found to be in good agreement with all data that support a scaling behavior of the transition form factor at higher $Q^2$, like those of the Belle Collaboration. The data on ${\gamma }^{\ast }\gamma \to \eta /{\eta }^{\prime }$ from CLEO and \babar are also reproduced, while there is a strong conflict with the auxetic trend of the \babar data above 10 GeV${}^2$. The broader implications of these findings are discussed.

v4: 13 pages, 1 table, 8 figures. Paper body radically redesigned and extended to include Belle data. Contains statistical data analysis and photon small virtuality. Conclusions and references updated. V5 matches version to appear in Physical Review D

References in corpus (21)

• Measurement of gamma gamma* --> pi0 transition form factor at Belle
• Abelian anomaly and neutral pion production
• Light Cone Sum Rules for the pi0-gamma*-gamma Form Factor Revisited
• On the Pion Distribution Amplitude Shape
• Comparing antithetic trends of data for the pion-photon transition form factor
• Pion transition form factor in k_T factorization
• BELLE Data on the ${\pi }^0\gamma \ast \gamma$ Form Factor: A Game Changer?
• Pion in the Holographic Model with 5D Yang-Mills Fields
• Two-photon form factors of the pi0, eta and eta-prime mesons in the chiral theory with resonances
• Puzzles in Hadronic Physics and Novel Quantum Chromodynamics Phenomenology
• Transition Form Factors and Mixing of Pseudoscalar Mesons from Anomaly Sum Rule
• Pion elastic and $({\pi }^0,\eta ,{\eta }^{\prime })\to \gamma {\gamma }^{\ast }$ transition form factors in a broad range of momentum transfers
• The eta-photon transition form factor
• Vector meson dominance and the pi^0 transition form factor
• ${\pi }^0\to {\gamma }^{\ast }\gamma$ transition form factor within Light Front Quark Model
• Quark-hadron duality, axial anomaly and mixing
• Pion-photon transition form factor using light-cone sum rules: theoretical results, expectations, and a global-data fit
• Pion-photon transition form factor in light-cone sum rules
• Pion-Photon Transition Form Factor and Pion Distribution Amplitude in QCD: Facing the Enigmatic Behavior of the BaBar Data
• Novel insights into the $\gamma {\gamma }^{\ast }\to {\pi }^0$ transition form factor
• Axial Anomaly and Light Cone Distributions

Cited by in corpus (42)

• QCD and strongly coupled gauge theories: challenges and perspectives
• Insights into the Emergence of Mass from Studies of Pion and Kaon Structure
• The pion: an enigma within the Standard Model
• Structure of the neutral pion and its electromagnetic transition form factor
• ${\gamma }^{\ast }\gamma \to \eta ,{\eta }^{\prime }$ transition form factors
• Transition form factors ${\gamma }^{\ast }\gamma \to \eta$ and ${\gamma }^{\ast }\gamma \to {\eta }^{\prime }$ in QCD
• Asymptotic behavior of meson transition form factors
• Partonic structure of neutral pseudoscalars via two photon transition form factors
• Pseudoscalar pole light-by-light contributions to the muon $(g-2)$ in Resonance Chiral Theory
• Systematic estimation of theoretical uncertainties in the calculation of the pion-photon transition form factor using light-cone sum rules
• Modeling interactions of photons with pseudoscalar and vector mesons
• Distribution amplitudes of radially-excited pi- and K-mesons
• Subleading power corrections to the pion-photon transition form factor in QCD
• Determination of the pion distribution amplitude
• Chimera distribution amplitudes for the pion and the longitudinally polarized $\rho$-meson
• Pion-photon transition form factor in LCSR and tests of asymptotics
• Spacelike and timelike form factors for the $({\pi }^0,\eta ,{\eta }^{\prime })\to {\gamma }^{\ast }\gamma$ transitions in the light-front quark model
• What binds quarks together at different momentum scales? A conceptual scenario
• Improved ${\pi }^0,\eta ,{\eta }^{\prime }$ transition form factors in resonance chiral theory and their $a_{\mu }^{\mathrm{HLbL}}$ contribution
• Dispersion relation for hadronic light-by-light scattering: $\eta$ and ${\eta }^{\prime }$ poles
• Pion to photon transition form factors with basis light-front quantization
• Axial anomaly and vector meson dominance model
• Heavy and light meson wavefunctions
• Rho meson distribution amplitudes from QCD sum rules with nonlocal condensates
• The pion distribution amplitude and the pion-photon transition form factor in a nonlocal chiral quark model
• Pion transition form factor in the constituent quark model
• On the pion distribution amplitude. Derivation, properties, predictions
• Matching lightcone- and anomaly-sum-rule predictions for the pion-photon transition form factor
• Systematic twist expansion of $({\eta }_c,{\eta }_b)\to {\gamma }^{\ast }\gamma$ transition form factors in light-front quark model
• Power Corrections to Pion Transition Form Factor in Perturbative QCD Approach
• Calculation of the pion-photon transition form factor using dispersion relations and renormalization-group summation
• The longitudinal and transverse distributions of the pion wavefunction from the present experimental data on the pion-photon transition form factor
• Non-Abelian axial anomaly, axial-vector duality, and the pseudoscalar glueball
• Power corrections to the pion transition form factor from higher-twist distribution amplitudes of photon
• Dispersive approach to non-Abelian axial anomaly
• $\eta$-$\gamma$ and ${\eta }^{\prime }$-$\gamma$ transition form factors in a nonlocal NJL model
• Theoretical description and measurement of the pion-photon transition form factor
• Limit on the pion distribution amplitude
• Radial excitation of light mesons and the $\gamma {\gamma }^{\ast }\to {\pi }^0$ transition form factor
• Improved estimates of the pion-photon transition form factor in the $(1\le {\mathbf{Q}}^2\le 5)$~GeV${}^2$ range and their theoretical uncertainties
• Transition form factors of ${\pi }^0$, $\eta$ and ${\eta }^{\prime }$ mesons: What can be learned from anomaly sum rule?
• Pion observables calculated in Minkowski and Euclidean spaces with Ansätze for quark propagators