Light Cone 2021: Physics of Hadrons on the Light Front

Pion to photon transition form factors with basis light-front quantization

1 Dec 2021, 15:10

20m

Emerald Hall B (Jeju Booyoung Hotel)

Contributed talk Parallel Session

Speaker

Chandan Mondal (Institute of Modern Physics, Chinese Academy of Sciences)

Description

We obtain the distribution amplitude (DA) of the pion from its light-front wave functions in the basis light-front quantization framework. This light-front wave function of the pion is given by the lowest eigenvector of a light-front effective Hamiltonian consisting a three-dimensional confinement potential and the color singlet Nambu--Jona-Lasinion interaction both between the constituent quark and antiquark. The quantum chromodynamics (QCD) evolution of the DA is subsequently given by the perturbative Efremov-Radyushkin-Brodsky-Lepage evolution equation. Based on this DA, we then evaluate the singly and doubly virtual transition form factors in the space-like region for ${\pi }^0\to {\gamma }^{\ast }\gamma$ and ${\pi }^0\to {\gamma }^{\ast }{\gamma }^{\ast }$ processes using the hard-scattering formalism. Our prediction for the pion-photon transition form factor agrees well with data reported by the Belle Collaboration. However, in the large $Q^2$ region it deviates from the rapid growth reported by the BaBar Collaboration. Meanwhile, our result on the ${\pi }^0\to {\gamma }^{\ast }{\gamma }^{\ast }$ transition form factor is also consistent with other theoretical approaches and agrees with the scaling behavior predicted by perturbative QCD.

Presentation materials

Chandan_LC2021.pdf