학술논문
The {\eta}'-carbon potential at low meson momenta
Document Type
Working Paper
Author
Nanova, M.; Friedrich, S.; Metag, V.; Paryev, E. Ya.; Afzal, F. N.; Bayadilov, D.; Bantes, B.; Beck, R.; Becker, M.; Böse, S.; Brinkmann, K. -T.; Crede, V.; Drexler, P.; Eberhardt, H.; Elsner, D.; Frommberger, F.; Funke, Ch.; Gottschall, M.; Grüner, M.; Gutz, E.; Hammann, Ch.; Hannappel, J.; Hartmann, J.; Hillert, W.; Hoffmeister, Ph.; Honisch, Ch.; Jude, T.; Kaiser, D.; Kalischewski, F.; Keshelashvili, I.; Klein, F.; Koop, K.; Krusche, B.; Lang, M.; Makonyi, K.; Messi, F.; Müller, J.; Müllers, J.; Piontek, D.; Rostomyan, T.; Schaab, D.; Schmidt, Ch.; Schmieden, H.; Schmitz, R.; Seifen, T.; Sokhoyan, V.; Sowa, C.; Spieker, K.; Thiel, A.; Thoma, U.; Triffterer, T.; Urban, M.; van Pee, H.; Walther, D.; Wendel, Ch.; Werthmüller, D.; Wiedner, U.; Wilson, A.; Witthauer, L.; Wunderlich, Y.; Zaunick, H. -G.
Source
Eur. Phys. J. A, 54 (2018) 182
Subject
Language
Abstract
The production of $\eta^\prime$ mesons in coincidence with forward-going protons has been studied in photon-induced reactions on $^{12}$C and on a liquid hydrogen (LH$_2$) target for incoming photon energies of 1.3-2.6 GeV at the electron accelerator ELSA. The $\eta^\prime$ mesons have been identified via the $\eta^\prime\rightarrow \pi^0 \pi^0\eta \rightarrow 6 \gamma$ decay registered with the CBELSA/TAPS detector system. Coincident protons have been identified in the MiniTAPS BaF$_2$ array at polar angles of $2^{\circ} \le \theta _{p} \le 11^{\circ}$. Under these kinematic constraints the $\eta^\prime$ mesons are produced with relatively low kinetic energy ($\approx$ 150 MeV) since the coincident protons take over most of the momentum of the incident-photon beam. For the C-target this allows the determination of the real part of the $\eta^\prime$-carbon potential at low meson momenta by comparing with collision model calculations of the $\eta^\prime$ kinetic energy distribution and excitation function. Fitting the latter data for $\eta^\prime$ mesons going backwards in the center-of-mass system yields a potential depth of V = $-$(44 $\pm$ 16(stat)$\pm$15(syst)) MeV, consistent with earlier determinations of the potential depth in inclusive measurements for average $\eta^\prime$ momenta of $\approx$ 1.1 GeV/$c$. Within the experimental uncertainties, there is no indication of a momentum dependence of the $\eta^\prime$-carbon potential. The LH$_2$ data, taken as a reference to check the data analysis and the model calculations, provide differential and integral cross sections in good agreement with previous results for $\eta^\prime$ photoproduction off the free proton.
Comment: 9 pages, 13 figures. arXiv admin note: text overlap with arXiv:1608.06074
Comment: 9 pages, 13 figures. arXiv admin note: text overlap with arXiv:1608.06074