We measured the ratio Px/Pz of the transverse to longitudinal components of polarization transferred from electrons to bound protons in 12C by the 12C(e,e′p) process at the Mainz Microtron (MAMI). We observed consistent deviations from unity of this ratio normalized to the free-proton ratio, (Px/Pz)12C/(Px/Pz)1H, for both s- and p-shell knocked out protons, even though they are embedded in averaged local densities that differ by about a factor of two. The dependence of the double ratio on proton virtuality is similar to the one for knocked out protons from 2H and 4He, suggesting a universal behavior. It further implies no dependence on average local nuclear density.
@article{arxiv.1711.09680,
title = {Measurement of polarization-transfer to bound protons in carbon and its virtuality dependence},
author = {A1 Collaboration and D. Izraeli and T. Brecelj and P. Achenbach and A. Ashkenazi and R. Böhm and E. O. Cohen and M. O. Distler and A. Esser and R. Gilman and T. Kolar and I. Korover and J. Lichtenstadt and I. Mardor and H. Merkel and M. Mihovilovič and U. Müller and M. Olivenboim and E. Piasetzky and G. Ron and B. S. Schlimme and M. Schoth and C. Sfienti and S. Širca and S. Štajner and S. Strauch and M. Thiel and A. Weber and I. Yaron},
journal= {arXiv preprint arXiv:1711.09680},
year = {2018}
}