Measurements of the induced polarization in the quasi-elastic A(e,e′p→) process in non-coplanar kinematics

Autor: Concettina Sfienti, M. Heilig, S. Strauch, M. Hoek, T. Brecelj, Ronald Gilman, T. Kolar, J. Müller, Harald Merkel, S. Širca, Patrick Achenbach, Ivica Friščić, U. Müller, D. Izraeli, S. Kegel, J. Pochodzalla, R. Spreckels, Anselm Esser, Michaela Thiel, L. Debenjak, J. Beričič, D. G. Middleton, J. Lichtenstadt, Guy Ron, D. Bosnar, Adi Ashkenazi, I. Yaron, M. Olivenboim, S. Štajner, M. Schoth, I. Korover, A. Weber, Hartmuth Arenhövel, Carlotta Giusti, B. S. Schlimme, E. Cline, F. Schulz, M. O. Distler, M. Mihovilovič, Eliahu Cohen, E. Piasetzky, R. Böhm, Israel Mardor, S.J. Paul, P. Klag, Y. Kohl, A. Tyukin
Rok vydání: 2020
Předmět:
Zdroj: Physics Letters B. 811:135984
ISSN: 0370-2693
DOI: 10.1016/j.physletb.2020.135984
Popis: We report measurements of the induced polarization P → of protons knocked out from 2H and 12C via the A ( e , e ′ p → ) reaction. We have studied the dependence of P → on two kinematic variables: the missing momentum p miss and the “off-coplanarity” angle ϕ p q between the scattering and reaction planes. For the full 360° range in ϕ p q , both the normal ( P y ) and, for the first time, the transverse ( P x ) components of the induced polarization were measured with respect to the coordinate system associated with the scattering plane. P x vanishes in coplanar kinematics, however in non-coplanar kinematics, it is on the same scale as P y . We find that the dependence on ϕ p q is sine-like for P x and cosine-like for P y . For carbon, the magnitude of the induced polarization is especially large when protons are knocked out from the p 3 / 2 shell at very small p miss . For the deuteron, the induced polarization is near zero at small | p miss | , and its magnitude increases with | p miss | . For both nuclei such behavior is reproduced qualitatively by theoretical results, driven largely by the spin-orbit part of the final-state interactions. However, for both nuclei, sizeable discrepancies exist between experiment and theory.
Databáze: OpenAIRE
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