Publications
Publication Information
| Title | A Search for the LHCb Charmed 'Pentaquark' using Photo-Production of $J/¿$ at Threshold in Hall C at Jefferson Lab |
| Authors | Zein-Eddine Meziani, Sylvester Joosten, Michael Paolone, Eugene Chudakov, Mark Jones, Krishna Adhikari, Konrad Aniol, Whitney Armstrong, John Arrington, Arshak Asaturyan, Hamza Atac, S. Bae, Hem Bhatt, Deepak Bhetuwal, Jian-Ping Chen, Xurong Chen, Ho-Meoyng Choi, Seonho Choi, Markus Diefenthaler, James Dunne, Raphael Dupre, Burcu Duran, Dipangkar Dutta, Lamiaa El Fassi, Qiang Fu, Haiyan Gao, H. Go, Chao Gu, J. Ha, Kawtar Hafidi, Jens-Ole Hansen, Mohammad Hattawy, Douglas Higinbotham, Garth Huber, Pete Markowitz, David Meekins, Hamlet Mkrtchyan, R. Nouicer, Li Wenliang, Xiaqing Li, Tianbo Liu, Chao Peng, Lubomir Pentchev, Eric Pooser, Melanie Rehfuss, Nikolaos Sparveris, Vardan Tadevosyan, Renzhuo Wang, Frank Wesselmann, Stephen Wood, Weizhi Xiong, Xuefei Yan, Li Ye, Zhihong Ye, Zafar Ahmed, Yi Zhang, F. Zhao, Zhiwen Zhao, Simon Zhamkochyan |
| JLAB number | JLAB-PHY-16-2358 |
| LANL number | arXiv:1609.00676 |
| Other number | DOE/OR/23177-3954 |
| Document Type(s) | (Other) |
| Associated with EIC: | No |
| Supported by Jefferson Lab LDRD Funding: | No |
| Funding Source: | Nuclear Physics (NP) |
|
Other Submitted to the arXiv: This document is an updated version of the original proposal PR12-16-007, which was approved with an 'A' rating and a 'high-impact' label by the Jefferson Lab PAC 44 in July 2016. The experiment was awarded 11 days of beam time | |
| Publication Abstract: | We propose to measure the photo-production cross section of $J/{\psi}$ near threshold, in search of the recently observed LHCb hidden-charm resonances $P_c$(4380) and $P_c$(4450) consistent with 'pentaquarks'. The observation of these resonances in photo-production will provide strong evidence of the true resonance nature of the LHCb states, distinguishing them from kinematic enhancements. A bremsstrahlung photon beam produced with an 11 GeV electron beam at CEBAF covers the energy range of $J/{\psi}$ production from the threshold photo-production energy of 8.2 GeV, to an energy beyond the presumed $P_c$(4450) resonance. The experiment will be carried out in Hall C at Jefferson Lab using a 50{\mu}A electron beam incident on a 9% copper radiator. The resulting photon beam passes through a 15 cm liquid hydrogen target, producing $J/{\psi}$ mesons through a diffractive process in the $t$-channel, or through a resonant process in the $s$- and $u$-channel. The decay $e^+e^-$ pair of the $J/{\psi}$ will be detected in coincidence using the two high-momentum spectrometers of Hall C. The spectrometer settings have been optimized to distinguish the resonant $s$- and $u$-channel production from the diffractive $t$-channel $J/{\psi}$ production. The $s$- and $u$-channel production of the charmed 5-quark resonance dominates the $t$-distribution at large $t$. The momentum and angular resolution of the spectrometers is sufficient to observe a clear resonance enhancement in the total cross section and $t$-distribution. We request a total of 11 days of beam time with 9 days to carry the main experiment and 2 days to acquire the needed $t$-channel elastic $J/{\psi}$ production data for a calibration measurement. This calibration measurement in itself will greatly enhance our knowledge of $t$-channel elastic $J/{\psi}$ production near threshold. |
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| Group: | Hall C |
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