Deciphering the mechanism of near-threshold $$$$J/\psi $$$$ photoproduction
Abstract The photoproduction of the $$$$J/\psi $$$$ off the proton is believed to deepen our understanding of various physics issues. On the one hand, it is proposed to provide access to the origin of the proton mass, based on the QCD multipole expansion. On the other hand, it can be employed in a study of pentaquark states. The process is usually assumed to proceed through vector-meson dominance, that is the photon couples to a $$$$J/\psi $$$$ which rescatters with the proton to give the $$$$J/\psi p$$$$ final state. In this paper, we provide a compelling hint for and propose measurements necessary to confirm a novel production mechanism via the $$$$\varLambda _c \bar{D}^{(*)}$$$$ intermediate states. In particular, there must be cusp structures at the $$$$\varLambda _c \bar{D}^{(*)}$$$$ thresholds in the energy dependence of the $$$$J/\psi $$$$ photoproduction cross section. The same mechanism also implies the $$$$J/\psi $$$$ -nucleon scattering lengths of order 1 mfm. Given this, one expects only a minor contribution of charm quarks to the nucleon mass.
- Research Organization:
- George Washington Univ., Washington, DC (United States)
- Sponsoring Organization:
- USDOE Office of Science (SC), Nuclear Physics (NP); National Natural Science Foundation of China (NSFC); Russian Science Foundation
- Grant/Contract Number:
- SC0016583; 18-12-00226; XDB34030303; QYZDB-SSW-SYS013; 11835015; 11947302; 11961141012
- OSTI ID:
- 1714391
- Alternate ID(s):
- OSTI ID: 1726236
- Journal Information:
- European Physical Journal. C, Particles and Fields, Journal Name: European Physical Journal. C, Particles and Fields Vol. 80 Journal Issue: 11; ISSN 1434-6044
- Publisher:
- SpringerCopyright Statement
- Country of Publication:
- Germany
- Language:
- English
Similar Records
Kaon physics without new physics in $$ \varepsilon _K$$
Impact parameter dependence of color charge correlations in the proton