학술논문
Nuclear density dependence of polarization transfer in quasi-elastic ${\rm A}(\vec{e},e' \vec{p})$ reactions
Document Type
Working Paper
Author
Kolar, T.; Cosyn, W.; Giusti, C.; Achenbach, P.; Ashkenazi, A.; Böhm, R.; Bosnar, D.; Brecelj, T.; Christmann, M.; Cohen, E. O.; Distler, M. O.; Doria, L.; Eckert, P.; Esser, A.; Gilman, R.; Geimer, J.; Gülker, P.; Hoek, M.; Izraeli, D.; Kegel, S.; Klag, P.; Kohl, Y.; Korover, I.; Lichtenstadt, J.; Littich, M.; Manoussos, T.; Mardor, I.; Markus, D.; Merkel, H.; Mihovilovič, M.; Müller, J.; Müller, U.; Olivenboim, M.; Pätschke, J.; Paul, S. J.; Piasetzky, E.; Plura, S.; Pochodzalla, J.; Požun, M.; Ron, G.; Schlimme, B. S.; Schoth, M.; Schulz, F.; Sfienti, C.; Stengel, S.; Spreckels, R.; Štajner, S.; Stephan, E.; Strauch, S.; Szyszka, C.; Širca, S.; Thiel, M.; Weber, A.; Wilczek, A.; Yaron, I.
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Subject
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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.