Regular Article - Theoretical Physics
transition form factors in perturbative QCD
Department of Physics and Institute of Theoretical Physics, Nanjing Normal University, 210023, Nanjing, People’s Republic of China
2 School of Nuclear Science and Technology, Frontiers Science Center for Rare Isotopes, Lanzhou University, 730000, Lanzhou, People’s Republic of China
3 Department of Physics, College of Sciences, Nanjing Agricultural University, 210095, Nanjing, People’s Republic of China
4 Institute of Physics, Academia Sinica, 115, Taipei, Taiwan ROC
5 College of Physics and Photoelectric Engineering, Ocean University of China, 266100, Qingdao, People’s Republic of China
6 Key Laboratory of Theoretical Physics of Gansu Province, Lanzhou Center for Theoretical Physics, Lanzhou University, 730000, Lanzhou, People’s Republic of China
7 Center for High Energy Physics, Peking University, 100871, Beijing, People’s Republic of China
Accepted: 26 July 2022
Published online: 6 August 2022
We reanalyze the transition form factors in the perturbative QCD (PQCD) approach by including higher-twist light-cone distribution amplitudes (LCDAs) of a baryon and a proton. The previous PQCD evaluation performed decades ago with only the leading-twist baryon and proton LCDAs gave the form factors, which are two orders of magnitude smaller than indicated by experimental data. We find that the twist-4 baryon LCDAs and the twist-4 and -5 proton LCDAs contribute dominantly, and the enhanced form factors become consistent with those from lattice QCD and other nonperturbative methods. The estimated branching ratios of the semileptonic decays and the hadronic decay are also close to the data. It implies that the b quark mass is not really heavy enough, and higher-power contributions play a crucial role, similar to the observation made in analyses of B meson transition form factors. With the formalism established in this work, we are ready to study various exclusive heavy baryon decays systematically in the PQCD approach.
© The Author(s) 2022
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