1. Pion to photon transition form factor: Beyond valence quarks
- Author
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Wu, Xiaoyi, Zhu, Zhimin, Lin, Ziyang, Mondal, Chandan, Lan, Jiangshan, Zhao, Xingbo, and Vary, James P.
- Subjects
High Energy Physics - Phenomenology ,Nuclear Theory - Abstract
We investigate the singly virtual transition form factor (TFF) for the $\pi^0\to\gamma^*\gamma$ process in the space-like region using the hard-scattering formalism within the Basis Light-Front Quantization (BLFQ) framework. This form factor is expressed in terms of the perturbatively calculable hard-scattering amplitudes (HSAs) and the light-front wave functions (LFWFs) of the pion. We obtain the pion LFWFs by diagonalizing the light-front QCD Hamiltonian, which is determined for its constituent quark-antiquark and quark-antiquark-gluon Fock sectors with a three-dimensional confinement. We employ the HSAs up to next-to-leading order (NLO) in the quark-antiquark Fock sector and leading order (LO) in the quark-antiquark-gluon Fock sector. The NLO correction to the TFF in the quark-antiquark Fock sector is of the same order as the LO contribution to the TFF in the quark-antiquark-gluon Fock sector. We find that while the quark-antiquark-gluon Fock sector has minimal effect in the large momentum transfer ($Q^2$) region, it has a noteworthy impact in the low-$Q^2$ region. Our results show that, after accounting for both Fock sectors, the TFF within the BLFQ framework aligns well with existing experimental data, particularly in the low $Q^2$ region., Comment: The manuscript consists of 9 pages, 1 table, and 3 figures
- Published
- 2024