First measurement of polarized spin-density matrix elements and differential cross sections d$σ$/d$t$ in $ω$~photoproduction off the proton for $2.7 < E_γ< 5.2$ GeV using CLAS at Jefferson Lab
T. Hu, Z. Akbar, V. Crede, J. M. Laget, V. Mathieu, M. J. Amaryan, W. R. Armstrong, H. Atac, N. A. Baltzell, L. Barion, M. Battaglieri, I. Bedlinskiy, B. Benkel, F. Benmokhtar, A. Bianconi, L. Biondo, A. Biselli, M. Bondi, F. Bossù, S. Boiarinov, W. J. Briscoe, S. Bueltmann, D. Bulumulla, V. D. Burkert, R. Capobianco, D. S. Carman, J. C. Carvajal, A. Celentano, T. Chetry, G. Ciullo, G. Clash, P. L. Cole, M. Contalbrigo, G. Costantini, A. D'Angelo, N. Dashyan, R. De Vita, M. Defurne, A. Deur, S. Diehl, C. Djalali, R. Dupre, H. Egiyan, A. El Alaoui, L. El Fassi, L. Elouadrhiri, P. Eugenio, S. Fegan, A. Filippi, G. Gavalian, Y. Ghandilyan, G. P. Gilfoyle, F. X. Girod, A. A. Golubenko, G. Gosta, R. W. Gothe, K. A. Griffioen, M. Guidal, K. Hafidi, H. Hakobyan, M. Hattawy, T. B. Hayward, D. Heddle, A. Hobart, M. Holtrop, Y. Ilieva, D. G. Ireland, E. L. Isupov, D. Jenkins, H. S. Jo, K. Joo, S. Joosten, D. Keller, A. Khanal, M. Khandaker, A. Kim, W. Kim, F. J. Klein, V. Klimenko, A. Kripko, V. Kubarovsky, V. Lagerquist, L. Lanza, M. Leali, P. Lenisa, K. Livingston, I. J. D. MacGregor, D. Marchand, L. Marsicano, V. Mascagna, M. E. McCracken, B. McKinnon, Z. E. Meziani, S. Migliorati, R. G. Milner, T. Mineeva, M. Mirazita, V. Mokeev, C. Munoz Camacho, P. Nadel-Turonski, K. Neupane, J. Newton, S. Niccolai, M. Nicol, G. Niculescu, M. Osipenko, A. I. Ostrovidov, P. Pandey, M. Paolone, L. L. Pappalardo, R. Paremuzyan, E. Pasyuk, S. J. Paul, W. Phelps, N. Pilleux, O. Pogorelko, J. W. Price, Y. Prok, B. A. Raue, T. Reed, M. Ripani, J. Ritman, A. Rizzo, G. Rosner, F. Sabatié, C. Salgado, S. Schadmand, A. Schmidt, R. A. Schumacher, E. V. Shirokov, U. Shrestha, P. Simmerling, D. Sokhan, N. Sparveris, S. Stepanyan, I. I. Strakovsky, S. Strauch, R. Tyson, M. Ungaro, L. Venturelli, H. Voskanyan, A. Vossen, E. Voutier, D. P. Watts, X. Wei, M. H. Wood, B. Yale, M. Yurov, N. Zachariou, J. Zhang
We report on the differential cross sections d$σ$/d$t$, the unpolarized spin-density matrix elements $ρ^0_{00}$, $ρ^0_{1-1}$, Re\,$ρ^0_{10}$, and the first extraction of the polarized elements Im\,$ρ^3_{10}$, Im\,$ρ^3_{1-1}$ for the reaction $γp\to pω$ using the CLAS spectrometer at Jefferson Laboratory. The $ω$~mesons were detected in their dominant charged decay mode, $ω\to π^+π^-π^0$, and all $t$-dependent results are presented in a fine binning for incident photon energies between 2.73 and 5.16~GeV (corresponding to the center-of-mass energy range $W \in [\,2.45,3.25\,]$~GeV). All matrix elements are first measurements for $-t > 0.6$~GeV$^2$. Moreover, differential cross sections d$σ$/d(cos\,$Θ_{\rm \,c.m.}^{\,ω}$) and the corresponding angle-dependent unpolarized spin-density matrix elements in the Adair frame are presented for the incident photon energy range 1.56--3.80~GeV (corresponding to $W \in [\,1.95,2.83\,]$~GeV). These new $ω$~photoproduction data are consistent with earlier CLAS results but extend the energy range well beyond the nucleon resonance region into the Regge regime. The comparison with Regge-theory-based model predictions shows that the new data impose more stringent constraints on our understanding of $ω$~photoproduction.
Comments9 pages, 4 figures, accepted for publication by Physics Letters B
