Abstract
The cross-section of the ep → e′p′γ reaction has been measured at Q 2 = 0.33 (GeV/c)2. The experiment was performed using the electron beam of the MAMI accelerator and the standard detector setup of the A1 Collaboration. The cross-section is analyzed using the low-energy theorem for virtual Compton scattering, yielding a new determination of the two structure functions PLL - PTT/ε and PLT which are linear combinations of the generalized polarizabilities of the proton. We find somewhat larger values than in the previous investigation at the same Q 2. This difference, however, is purely due to our more refined analysis of the data. The results tend to confirm the non-trivial Q 2-evolution of the generalized polarizabilities and call for more measurements in the low-Q 2 region (≤ 1 (GeV/c)2).
This is a preview of subscription content, log in via an institution to check access.
Similar content being viewed by others
References
H. Arenhövel, D. Drechsel, Nucl. Phys. A 233, 153 (1974).
P.A.M. Guichon, G.Q. Liu, A.W. Thomas, Nucl. Phys. A 591, 606 (1995).
M. Vanderhaeghen, Phys. Lett. B 402, 243 (1997).
P.A.M. Guichon, M. Vanderhaeghen, Prog. Part. Nucl. Phys. 41, 125 (1998).
A.I. L’vov, S. Scherer, B. Pasquini, C. Unkmeir, D. Drechsel, Phys. Rev. C 64, 015203 (2001).
V. Olmos de Leon et al., Eur. Phys. J. A 10, 207 (2001).
N. d’Hose, H. Merkel, Double Polarization Virtual Compton Scattering in the threshold regime at MAMI, MAMI proposal A1-1/00 (2001).
P. Janssens, Double-polarized virtual Compton scattering as a probe of the proton structure, PhD Thesis, Universiteit Gent (2007).
L. Doria, Polarization observables in virtual Compton scattering, PhD Thesis, Universität Mainz (2008).
P. Bourgeois et al., Phys. Rev. Lett. 97, 212001 (2006).
J. Roche et al., Phys. Rev. Lett. 85, 708 (2000).
G. Laveissière et al., Phys. Rev. Lett. 93, 122001 (2004).
K.I. Blomqvist et al., Nucl. Instrum. Methods A 403, 263 (1998).
P. Janssens et al., Nucl. Instrum. Methods A 566, 675 (2006).
M. Vanderhaeghen et al., Phys. Rev. C 62, 025501 (2000).
J. Friedrich, T. Walcher, Eur. Phys. J. A 17, 607 (2003).
P. Mergell, U. G. Meissner, D. Drechsel, Nucl. Phys. A 596, 367 (1996).
H.W. Hammer, U.-G. Meissner, Eur. Phys. J. A 20, 469 (2004).
M.A. Belushkin, H.W. Hammer, U.G. Meissner, Phys. Rev. C 75, 035202 (2007).
G. Höhler et al., Nucl. Phys. B 114, 505 (1976).
J.J. Kelly, Phys. Rev. C 70, 068202 (2004).
J. Arrington, W. Melnitchouk, J.A. Tjon, Phys. Rev. C 76, 035205 (2007).
C.E. Hyde-Wright, K. de Jager, Annu. Rev. Nucl. Part. Sci. 54, 217 (2004).
T.R. Hemmert, B.R. Holstein, G. Knochlein, D. Drechsel, Phys. Rev. D 62, 014013 (2000).
C.W. Kao, M. Vanderhaeghen, Phys. Rev. Lett. 89, 272002 (2002).
C.-W. Kao, B. Pasquini, M. Vanderhaeghen, Phys. Rev. D 70, 114004 (2004).
B. Pasquini, M. Gorchtein, D. Drechsel, A. Metz, M. Vanderhaeghen, Eur. Phys. J. A 11, 185 (2001).
D. Drechsel, B. Pasquini, M. Vanderhaeghen, Phys. Rep. 378, 99 (2003).
N. d’Hose, Eur. Phys. J. A 28, 117 (2006).
R. Gilman et al., Proposal, JLab PR-07-004 (2006).
M.O. Distler, MAMI A1-2/05 proposal (2005).
Author information
Authors and Affiliations
Corresponding author
Additional information
Communicated by Z.-E. Meziani
Rights and permissions
About this article
Cite this article
Janssens, P., Doria, L., Achenbach, P. et al. A new measurement of the structure functions PLL - PTT/ε and PLT in virtual Compton scattering at Q2 = 0.33 (GeV/c)2 . Eur. Phys. J. A 37, 1–8 (2008). https://doi.org/10.1140/epja/i2008-10609-3
Received:
Revised:
Published:
Issue Date:
DOI: https://doi.org/10.1140/epja/i2008-10609-3