Regge exchange contribution to deeply virtual compton scattering

Thumbnail Image
Official URL
Full text at PDC
Publication Date
Advisors (or tutors)
Journal Title
Journal ISSN
Volume Title
Polish Acad Sciences Inst Physics
Google Scholar
Research Projects
Organizational Units
Journal Issue
Recently we have shown that exclusive QCD photon-induced reactions at low Mandelstam-t are best described by Regge exchanges in the entire scaling region, and not only for low values of Bjorken- x. In this paper we explore this crucial Regge behavior in Deeply Virtual Compton Scattering from the point of view of collinear factorization, with the proton tensor written in terms of Generalized Parton Distributions, and we reproduce this feature. Thus it appears that in the Bjorken limit, a large class of hard, low-t exclusive processes are more sensitive to the meson cloud of the proton than to its fundamental quark structure. These process will then be described most efficiently by process- dependent Regge Exclusive Amplitudes rather than by universal Generalized Parton Distributions. We introduce such Regge Exclusive Amplitudes for Deeply Virtual Compton Scattering.
We would like to thank S. Brodsky, P. Hoyer, JM. Laget, P. Kroll, D. Muller, A. Radyushkin and M. Strikman for useful discussions and comments. This work was supported in part by the US Department of Energy grant under contract DE FG0287ER40365, by the US National Science Foundation under grant PHY- 0555232, and by grants FPA 2004-02602, 2005-02327 (Spain). FJLE thanks also the Nuclear Theory Center at Indiana University and the Institute for Theoretical Physics at Graz University for their hospitality during the preparation of this work
Unesco subjects
[1] X. D. Ji, J. Phys. G 24, 1181 (1998) [2] A. V. Radyushkin, Phys. Rev. D 56, 5524 (1997) [3] K. Goeke, M. V. Polyakov and M. Vanderhaeghen, Prog. Part. Nucl. Phys. 47, 401 (2001) [4] A. V. Belitsky, D. Mueller and A. Kirchner, Nucl. Phys. B 629, 323 (2002) [5] M. Diehl, Phys. Rept. 388, 41 (2003). [6] X. D. Ji, Phys. Rev. D 55, 7114 (1997). [7] A. V. Radyushkin, Phys. Lett. B 380, 417 (1996). [8] J. C. Collins and A. Freund, Phys. Rev. D 59, 074009 (1999). [9] J. C. Collins, L. Frankfurt and M. Strikman, Phys. Rev. D 56, 2982 (1997). [10] M. Burkardt, Int. J. Mod. Phys. A 18, 173 (2003). [11] X. D. Ji, W. Melnitchouk and X. Song, Phys. Rev. D56, 5511 (1997). [12] M. Vanderhaeghen, P. A. M. Guichon and M. Guidal, Phys. Rev. D 60, 094017 (1999). [13] L. Morand et al. [CLAS Collaboration], Eur. Phys. J. A 24, 445 (2005). [14] R. Fabbri Exclusive Photon and Meson Production at HERMES, in 12th International Conference on Elastic and Diffractive Scattering, DESY, Hamburg, Germany, May 2007 [15] A. Airapetian et al. [HERMES Collaboration], Eur. Phys. J. C 17, 389 (2000). [16] C. Munoz Camacho et al. [Jefferson Lab Hall A Collab- [17] M. Vanderhaeghen, P. A. M. Guichon and M. Guidal, Phys. Rev. Lett. 80, 5064 (1998). [18] V.Kubarovsky, Deep virtual meson production, in Exclusive Reactions at High Momentum Transfer,JLab, Newport News, VA May, 2007 ( [19] A. Donnachie and P. V. Landshoff, Phys. Lett. B 437, 408 (1998). [20] S. Ahmad, H. Honkanen, S. Liuti and S. K. Taneja, Phys. Rev. D 75, 094003 (2007). [21] V. Guzey and M. V. Polyakov, Eur. Phys. J. C 46, 151 (2006). [22] K. Kumericki, D. Muller and K. Passek-Kumericki, arXiv:hep-ph/0703179. [23] L. Jenkovszky, Phys. Rev. D 74, 114026 (2006). [24] A. P. Szczepaniak and J. T. Londergan, Phys. Lett. B 643, 17 (2006). 25] P. V. Landshoff, J. C. Polkinghorne and R. D. Short, Nucl. Phys. B 28, 225 (1971). [26] P. V. Landshoff and J. C. Polkinghorne, Phys. Rep. 5, 1 (1972). [27] S. J. Brodsky, F. E. Close and J. F. Gunion, Phys. Rev. D 5, 1384 (1972). [28] S. J. Brodsky, F. E. Close and J. F. Gunion, Phys. Rev. D 6, 177 (1972). [29] S.J. Brodsky, F.E. Close, and J.F. Gunion, Phys. Rev. D8, 3678 (1973). [30] Recently similar amplitudes (e.g. gluon and quark prop- agators in Landau gauge) were explored [31] and they were found to have usual threshold branch points associ- ated with the production of colored quasiparticles (such as additional gluons or ghost pairs). [31] R. Alkofer, W. Detmold, C. S. Fischer and P. Maris, Phys. Rev. D 70, 014014 (2004). [32] M. Diehl and T. Gousset, Phys. Lett. B 428, 359 (1998). [33] S. J. Brodsky and F. J. Llanes-Estrada, Eur. Phys. J. C 46, 751 (2006). [34] For positive (negative) k+ singularities of the integrand in the complex k− plane are all in the lower (upper) half- plane and the k− integral vanishes. If k+ = 0 the integrand is k− independent and k− integration is divergent. Thus the result has to be proportional to δ(k+). The coefficient can be determined by integrating over k+ and comparing with the covariant result. [35] S. D. Drell and T. M. Yan, Phys. Rev. Lett. 24, 181 1970). [36] S. J. Brodsky, M. Diehl and D.S. Hwang, Nucl. Phys. B 596, 99 (2001). [37] J. Kuti and V. F.Weisskopf, Phys. Rev. D 4, 3418 (1971). [38] S. J. Brodsky, F. Llanes-Estrada and A. Szczepaniak, in preparation.