ИСТИНА

Measurements of π+π- electroproduction cross sections represent an important part of the program to study the structure of nucleon resonances with CLAS Ref. [1]. This program extends the study of nucleon resonance transition amplitudes (electrocouplings) to masses up to 1.8 GeV and to photon virtualities (Q2) up to 5.0 GeV2. These data provide access to the active degrees of freedom in the N* structure at different distance scales, and allow the study of non-perturbative strong interaction mechanisms that are responsible for the formation of the ground and excited nucleon states Ref. [2]. In this talk, we will present cross section measurements of the process ep→epπ+π- that continue our previous studies of this exclusive channel using the CLAS detector Ref. [3,4]. Our preliminary data provide complementary kinematical coverage of 1.4 < W < 1.8 GeV and 0.4 < Q2 < 1.1 GeV2, in comparison with previously available measurements, and enable much finer binning in Q2. This kinematical region covers high lying nucleon resonances such as S31(1620), S11(1650), D33(1700), and P13(1720), whose hadronic decay widths into πΔ and ρp can be extracted from the same data set, as these resonances decay preferentially to Nππ final states. Furthermore, electrocouplings of the S11(1650) and F15(1685) resonances previously measured in Nπ electroproduction will be obtained independently from the Nππ data. The analysis of these data within the framework of the JLAB-MSU reaction model (JM) Ref. [5] will improve our knowledge of the Q2 evolution of the γvNN* transition amplitudes considerably, in particular for resonances with masses above 1.6 GeV. 1. I.G. Aznauryan, V.D. Burkert et al. // Prog. Part. Nucl. Phys. 67, 1-54, 2012. 2. I.G. Aznauryan, et al. // Int. J. Mod.Phys. E22, 1330015, 2013. 3. G.V. Fedotov et al. // Phys.Rev. C79, 015204, 2009. 4. M. Ripani et al. // Nucl.Phys. A663, 675-678, 2000. 5. V.I. Mokeev, et al. // Phys. Rev. C 80, 045212, 2009.