1201.0903 (Kijun Park et al.)

Measurement of the generalized form factors near threshold via $γ^*
p \to nπ^+$ at high $Q^2$    [PDF]

Kijun Park, Ralf Gothe, Krishna Adhikari, Dasuni Adikaram-Mudiyanselage, Marco Anghinolfi, Hovhannes Baghdasaryan, Jacques Ball, Marco Battaglieri, Vitaly Baturin, Ivan Bedlinskiy, Robert Bennett, Angela Biselli, Craig Bookwalter, Sergey Boyarinov, Derek Branford, William Briscoe, William Brooks, Volker Burkert, Daniel Carman, Andrea Celentano, Shloka Chandavar, Gabriel Charles, Philip Cole, Marco Contalbrigo, Volker Crede, Annalisa D'Angelo, Aji Daniel, Natalya Dashyan, Raffaella De Vita, Enzo De Sanctis, Alexandre Deur, Chaden Djalali, David Doughty, Raphael Dupre, Ahmed El Alaoui, Lamiaa Elfassi, Paul Eugenio, Gleb Fedotov, Ahmed Fradi, Marianna Gabrielyan, Nerses Gevorgyan, Gerard Gilfoyle, Kevin Giovanetti, Francois-Xavier Girod, John Goetz, Wesley Gohn, Evgeny Golovach, Lewis Graham, Keith Griffioen, Michel Guidal, Lei Guo, Kawtar Hafidi, Hayk Hakobyan, Charles Hanretty, David Heddle, Kenneth Hicks, Maurik Holtrop, Yordanka Ilieva, David Ireland, Boris Ishkhanov, Evgeny Isupov, David Jenkins, Hyon-Suk Jo, Kyungseon Joo, Mahbubul Khandaker, Puneet Khetarpal, Andrey Kim, Wooyoung Kim, Andreas Klein, Franz Klein, A. Kubarovsky, Valery Kubarovsky, Sebastian Kuhn, Sergey Kuleshov, Nicholas Kvaltine, Kenneth Livingston, Haiyun Lu, Ian MacGregor, Nikolai Markov, Michael Mayer, Bryan McKinnon, Mac Mestayer, Curtis Meyer, Taisiya Mineeva, Marco Mirazita, Viktor Mokeev, Herve Moutarde, Edwin Munevar Espitia, Pawel Nadel-Turonski, Rakhsha Nasseripour, Silvia Niccolai, Gabriel Niculescu, Maria-Ioana Niculescu, Mikhail Osipenko, Alexander Ostrovidov, Michael Paolone, Luciano Pappalardo, Rafayel Paremuzyan, Seungkyung Park, Sergio Pereira, Evan Phelps, Silvia Pisano, Oleg Pogorelko, Sergey Pozdnyakov, John Price, Sebastien Procureur, Yelena Prok, Giovanni Ricco, Dipak Rimal, Marco Ripani, Barry Ritchie, Guenther Rosner, Patrizia Rossi, Franck Sabatie, Mukesh Saini, Carlos Salgado, Diane Schott, Reinhard Schumacher, Heghine Seraydaryan, Youri Sharabian, Elton Smith, Gregory Smith, Daniel Sober, Daria Sokhan, Samuel Stepanyan, Stepan Stepanyan, Paul Stoler, Igor Strakovski, Steffen Strauch, Mauro Taiuti, Wei Tang, Charles Taylor, Ye Tian, Svyatoslav Tkachenko, Arjun Trivedi, Maurizio Ungaro, Brian Vernarsky, Alexander Vlasov, Eric Voutier, Daniel Watts, Dennis Weygand, Michael Wood, Nicholas Zachariou, Bo Zhao, Zhiwen Zhao, N. Kalantarians, C. E. Hyde

We report the first extraction of the pion-nucleon multipoles near the
production threshold for the $n\pi^+$ channel at relatively high momentum
transfer ($Q^2$ up to 4.2 $\rm{GeV^2}$). The dominance of the s-wave transverse
multipole ($E_{0+}$), expected in this region, allowed us to access the
generalized form factor $G_1$ within the light-cone sum rule (LCSR) framework
as well as the axial form factor $G_A$. The data analyzed in this work were
collected by the nearly $4\pi$ CEBAF Large Acceptance Spectrometer (CLAS) using
a 5.754 $\rm{GeV}$ electron beam on a proton target. The differential cross
section and the $\pi-N$-multipole $E_{0+}/G_D$ were measured using two
different methods, the LCSR and a direct multipole fit. The results from the
two methods are found to be consistent and almost $Q^2$ independent.

View original: http://arxiv.org/abs/1201.0903