A new measurement of the structure functions $P_{LL}-P_{TT}/epsilon$ and $P_{LT}$ in virtual Compton scattering at $Q^2=$ 0.33 (GeV/c)$^2$
| Autor: | Collaboration, The MAMI-A1, Janssens, P., Doria, L., Achenbach, P., Gayoso, C. Ayerbe, Baumann, D., Bernauer, J. C., Bensafa, I. K., Böhm, R., Bosnar, D., Burtin, E., D'Hose, N., Defaÿ, X., Ding, M., Distler, M. O., Fonvieille, H., Friedrich, J., Friedrich, J. M., Laveissière, G., Makek, M., Marroncle, J., Merkel, H., Müller, U., Nungesser, L., Pasquini, B., Pochodzalla, J., Postavaru, O., Potokar, M., Ryckbosch, D., Majos, S. Sanchez, Schlimme, B. S., Seimetz, M., Širca, S., Tamas, G., Van de Vyver, R., Van Hoorebeke, L., Van Overloop, A., Walcher, Th., Weinriefer, M. |
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| Rok vydání: | 2008 |
| Předmět: | |
| Zdroj: | Eur.Phys.J.A37:1,2008 |
| Druh dokumentu: | Working Paper |
| DOI: | 10.1140/epja/i2008-10609-3 |
| Popis: | The cross section of the $ep \to e' p' \gamma$ 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 $P_LL}-P_{TT}/epsilon$ and $P_{LT}$ 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 ($\le$ 1 (GeV/c)$^2$). Comment: 9 pages, 10 figures. EPJA version. slight revisions in the text and figures |
| Databáze: | arXiv |
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