Journal Article

Measurement of the cross-section ratio σψ(2S)/σJ/ψ(1S) in exclusive photoproduction at HERA

Quintero, A., Bussey, P. J., Stanco, L., Lorkowski, F., Polini, A., Tokushuku, K., Brock, I., Levchenko, B. B., Pidhurskyi, I., Garfagnini, A., Geiser, A., Schörner-Sadenius, T., Aggarwal, R., Onishchuk, Yu, Żarnecki, A. F., Karshon, U., Lohrmann, E., Wan Abdullah, W. A. T., Ciesielski, R., Ruspa, M., Dusini, S., Paul, E., Brook, N. H., Surrow, B., Jomhari, N. Z., Klein, U., Hochman, D., Malka, J., Nagano, K., Aushev, V., Kovalchuk, N., Kuze, M., Grzelak, G., Klanner, R., Tymieniecka, T., Bruni, A., Korzhavina, I. A., Wichmann, K., Shcheglova, L. M., Foster, B., Nam, J. D., Löhr, B., Tomaszewska, J., Trofymov, A., Makarenko, I., Adamus, M., Wing, M., Yamada, S., Rubinsky, I., Shchedrolosiev, M., Skillicorn, I. O., Verbytskyi, A., Stefaniuk, N., Kaur, P., Catterall, C. D., Levy, A., Bloch, I., Gallo, E., Słomiński, W., Cooper-Sarkar, A. M., Gangadharan, D., Corradi, M., Schneekloth, U., Gwenlan, C., Behnke, O., Longhin, A., Chwastowski, J., Selyuzhenkov, I., Abt, I., Masciocchi, S., Dementiev, R. K., Kadenko, I., Solano, A., Brugnera, R., Yamazaki, Y., Turkot, O., Caldwell, A., Przybycień, M., Bertolin, A., Zenaiev, O., Ciborowski, J., Ferrando,

2022

Overview

A bstract The exclusive photoproduction reactions γp → J/ψ (1 S ) p and γp → ψ (2 S ) p have been measured at an ep centre-of-mass energy of 318 GeV with the ZEUS detector at HERA using an integrated luminosity of 373 pb − 1 . The measurement was made in the kinematic range 30 < W < 180 GeV, Q 2 < 1 GeV 2 and | t | < 1 GeV 2 , where W is the photon-proton centre-of-mass energy, Q 2 is the photon virtuality and t is the squared four-momentum transfer at the proton vertex. The decay channels used were J/ψ (1 S ) → μ + μ − , ψ (2 S ) → μ + μ − and ψ (2 S ) → J/ψ (1 S ) π + π − with subsequent decay J/ψ (1 S ) → μ + μ − . The ratio of the production cross sections, R = σ ψ (2 S ) /σ J/ψ (1 S ) , has been measured as a function of W and | t | and compared to previous data in photoproduction and deep inelastic scattering and with predictions of QCD-inspired models of exclusive vector-meson production, which are in reasonable agreement with the data.

• Publisher: Springer Berlin Heidelberg,Springer Nature B.V
• Subject: Center of mass / Classical and Quantum Gravitation / Collaboration / Cross-sections / Decay / Elementary Particles / Energy / High energy physics / Inelastic scattering / Kinematics / Luminosity / Magnetic fields / Momentum transfer / Particle production / Photons / Photoproduction / Physics / Physics and Astronomy / Protons / Quantum Field Theories / Quantum Field Theory / Quantum Physics / Regular Article - Experimental Physics / Relativity Theory / Sensors / String Theory / Vector mesons