; Elschenbroich, U. ; Fabbri, R. ; Fantoni, A. ; Fechtchenko, A. ; Felawka, L. ; Frullani, S. ; Gapienko, G. ; Gapienko, V. ; Garibaldi, F. ; Garrow, K. ; Garutti, E. ; Gavrilov, G. ; Gharibyan, V. ; Graw, G. ; Grebeniouk, O. ; Greeniaus, L.G. ; Gregor, I.M. ; Griffioen, K.A. ; Hafidi, K. ; Hartig, M. ; Hasch, D. ; Heesbeen, D. ; Henoch, M. ; Hertenberger, R. ; Hesselink, W.H.A. ; Hillenbrand, A. ; Hoek, M.
; Holler, Y. ; Hommez, B. ; Iarygin, G. ; Ivanilov, A. ; Izotov, A. ; Jackson, H.E. ; Jgoun, A. ; Kaiser, R. ; Kinney, E. ; Kisselev, A. ; Kopytin, M. ; Korotkov, V. ; Kozlov, V. ; Krauss, B. ; Krivokhijine, V.G. ; Lagamba, L.
; Lapikás, L. ; Laziev, A. ; Lenisa, P. ; Liebing, P. ; Linden-Levy, L.A. ; Lipka, K. ; Lorenzon, W. ; Lu, H. ; Lu, J. ; Lu, S. ; Ma, B.-Q. ; Maiheu, B. ; Makins, N.C.R. ; Mao, Y. ; Marianski, B. ; Marukyan, H. ; Masoli, F. ; Mexner, V. ; Meyners, N. ; Mikloukho, O. ; Miller, C.A. ; Miyachi, Y. ; Muccifora, V. ; Nagaitsev, A. ; Nappi, E. ; Naryshkin, Y. ; Nass, A. ; Negodaev, M. ; Nowak, W.-D. ; Oganessyan, K. ; Ohsuga, H. ; Osborne, A. ; Pickert, N. ; Potashov, S. ; Potterveld, D.H. ; Raithel, M. ; Reggiani, D. ; Reimer, P.E.
; Reischl, A. ; Reolon, A.R. ; Riedl, C. ; Rith, K. ; Rosner, G. ; Rostomyan, A. ; Rubacek, L. ; Rubin, J. ; Ryckbosch, D. ; Salomatin, Y. ; Sanjiev, I. ; Savin, I. ; Schäfer, A. ; Schill, C. ; Schnell, G. ; Schüler, K.P. ; Seele, J. ; Seidl, R. ; Seitz, B. ; Shanidze, R. ; Shearer, C. ; Shibata, T.-A. ; Shutov, V. ; Sinram, K. ; Sommer, W. ; Stancari, M. ; Statera, M. ; Steffens, E. ; Steijger, J.J.M. ; Stenzel, H. ; Stewart, J. ; Stinzing, F. ; Tait, P. ; Tanaka, H. ; Taroian, S. ; Tchuiko, B. ; Terkulov, A.
; Tkabladze, A. ; Trzcinski, A. ; Tytgat, M.
; Vandenbroucke, A. ; van der Nat, P. ; van der Steenhoven, G. ; van Haarlem, Y. ; Vetterli, M.C.
; Vikhrov, V. ; Vincter, M.G.
; Vogel, C. ; Vogt, M. ; Volmer, J. ; Weiskopf, C. ; Wendland, J. ; Wilbert, J. ; Ybeles Smit, G. ; Ye, Y. ; Ye, Z. ; Yen, S. ; Zihlmann, B. ; Zupranski, P. | Item type: | Article | ||||
|---|---|---|---|---|---|
| Journal or Publication Title: | Physics Letters B | ||||
| Publisher: | ELSEVIER SCIENCE BV | ||||
| Place of Publication: | AMSTERDAM | ||||
| Volume: | 599 | ||||
| Number of Issue or Book Chapter: | 3-4 | ||||
| Page Range: | pp. 212-222 | ||||
| Date: | 2004 | ||||
| Institutions: | Physics > Institute of Theroretical Physics > Chair Professor Schäfer > Group Andreas Schäfer | ||||
| Identification Number: |
| ||||
| Keywords: | GENERALIZED PARTON DISTRIBUTIONS; VECTOR-MESON PRODUCTION; MONTE-CARLO GENERATOR; DENSITY MATRIX; P(0) MESONS; 2 PIONS; SCATTERING; QCD; | ||||
| Dewey Decimal Classification: | 500 Science > 530 Physics | ||||
| Status: | Published | ||||
| Refereed: | Yes, this version has been refereed | ||||
| Created at the University of Regensburg: | Yes | ||||
| Item ID: | 71248 |
Abstract
Hard exclusive electroproduction of pi(+) pi(-) pairs off hydrogen and deuterium targets has been studied by the HERMES experiment at DESY Legendre moments (P-1) and (P-3) of the angular distributions of pi(+) mesons in the center-of-mass frame of the pair have been measured for the first time. Their dependence on the pi(+) pi(-) invariant mass can be understood as being due to the interference ...

Abstract
Hard exclusive electroproduction of pi(+) pi(-) pairs off hydrogen and deuterium targets has been studied by the HERMES experiment at DESY Legendre moments (P-1) and (P-3) of the angular distributions of pi(+) mesons in the center-of-mass frame of the pair have been measured for the first time. Their dependence on the pi(+) pi(-) invariant mass can be understood as being due to the interference between relative P-wave (isovector) and S-, D-wave (isoscalar) states of the two pions. The increase in magnitude of (P-1) as Bjorken x increases is interpreted in the framework of generalized parton distributions as an enhancement of flavour non-singlet qq exchange for larger values of x, which leads to a sizable admixture of isoscalar and isovector pion pairs. In addition, the interference between P-wave and D-wave states separately for transverse and longitudinal pion pairs has been studied. The data indicate that in the f(2)(1270) region at <Q(2)> = 3 GeV2 higher-twist effects can be as large as the leading-twist longitudinal component. (C) 2004 Published by Elsevier B.V.
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