Nuclear density dependence of polarization transfer in quasi-elastic ${\rm A}(\vec{e},e' \vec{p})$ reactions

Author:

T. Kolar, W. Cosyn, C. Giusti, P. Achenbach, A. Ashkenazi, R. Böhm, D. Bosnar, T. Brecelj, M. Christmann, E. O. Cohen, M. O. Distler, L. Doria, P. Eckert, A. Esser, R. Gilman, J. Geimer, P. Gülker, M. Hoek, D. Izraeli, S. Kegel, P. Klag, Y. Kohl, I. Korover, J. Lichtenstadt, M. Littich, T. Manoussos, I. Mardor, D. Markus, H. Merkel, M. Mihovilovič, J. Müller, U. Müller, M. Olivenboim, J. Pätschke, S. J. Paul, E. Piasetzky, S. Plura, J. Pochodzalla, M. Požun, G. Ron, B. S. Schlimme, M. Schoth, F. Schulz, C. Sfienti, S. Stengel, R. Spreckels, S. Štajner, E. Stephan, S. Strauch, C. Szyszka, S. Širca, M. Thiel, A. Weber, A. Wilczek, I. Yaron

Keyword:

Nuclear Experiment, Nuclear Experiment (nucl-ex), Nuclear Theory (nucl-th)

journal:

date:

2023-11-02 16:00:00

Abstract

The ratio of the transverse and longitudinal component of polarization transfer to protons in quasi-elastic $(\vec{e}, e^{\prime} \vec{p}\,)$ reaction, $P^{\prime}_x/P^{\prime}_z$, is sensitive to the proton's electromagnetic form factor ratio, $G_E/G_M$. To explore density-dependent in-medium modifications, a comparison of polarization transfer ratios involving protons from distinct nuclear shells, each with different local nuclear densities, has been proposed. In this study, we present such comparisons between four shells, $1s_{1/2}$, $1p_{3/2}$ in $^{12}\mathrm{C}$ and $1d_{3/2}$, $2s_{1/2}$ in $^{40}\mathrm{Ca}$. In an effort to account for other many-body effects that may differ between shells, we use state-of-the-art relativistic distorted-wave impulse-approximation (RDWIA) calculation and present the double ratios, $(P^{\prime}_x/P^{\prime}_z)_{\rm Data}/(P^{\prime}_x/P^{\prime}_z)_{\rm RDWIA}$ as well as the super ratios, $\left[(P^{\prime}_x/P^{\prime}_z)_{\rm A}/(P^{\prime}_x/P^{\prime}_z)_{\rm B}\right]_{\rm Data}/\left[(P^{\prime}_x/P^{\prime}_z)_{\rm A}/(P^{\prime}_x/P^{\prime}_z)_{\rm B}\right]_{\rm RDWIA}$, for chosen shells A and B, as a function of effective local nuclear densities. We find that double ratios for individual shells show a dependence on the probed effective nuclear densities. Studying the ratios, we observed a systematic variation between pairs of higher- and lower-density shells.

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