A new measurement of the structure functions PLL - PTT/ε and PLT in virtual Compton scattering at Q2 = 0.33 (GeV/c)2
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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).
PACS13.60.Fz Elastic and Compton scattering 14.20.Dh Protons and neutrons 25.30.Rw Electroproduction reactions
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