https://doi.org/10.1140/epja/i2008-10609-3
Regular Article — Experimental Physics
A new measurement of the structure functions PLL - PTT/ε and PLT in virtual Compton scattering at Q2 = 0.33 (GeV/c)2
1
Department of Subatomic and Radiation Physics, University of Gent, 9000, Gent, Belgium
2
Institut für Kernphysik, Johannes Gutenberg-Universität, 55099, Mainz, Germany
3
LPC, Universitée Blaise Pascal, IN2P3, 63177, Aubière Cedex, France
4
Department of Physics, University of Zagreb, 10002, Zagreb, Croatia
5
CEA DAPNIA-SPhN, C.E. Saclay, 91191, Gif-sur-Yvette Cedex, France
6
Physik-Department, Technische Universität München, 85748, Garching, Germany
7
Dipartimento di Fisica Nucleare e Teorica, Università degli Studi di Pavia, and INFN, Sezione di Pavia, Pavia, Italy
8
Jožef Stefan Institute, Ljubljana, Slovenia
9
Department of Physics, University of Ljubljana, Ljubljana, Slovenia
10
Institute of Space Science, RO-76900, Bucharest-Magurele, Romania
* e-mail: helene@clermont.in2p3.fr
Received:
7
March
2008
Revised:
16
May
2008
Published online:
16
July
2008
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).
PACS: 13.60.Fz Elastic and Compton scattering – / 14.20.Dh Protons and neutrons – / 25.30.Rw Electroproduction reactions –
© SIF, Springer-Verlag Berlin Heidelberg, 2008
