Nuclear transparency in a relativistic quark model |
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| Institution: | 1. College of Environmental Science and Engineering, Taiyuan University of Technology, Taiyuan, 030024, China;2. Innovation Center for Postgraduate Education in Municipal Engineering of Shanxi Province, Taiyuan, 030024, China;3. National Engineering Laboratory for Advanced Municipal Wastewater Treatment and Reuse Technology, Key Laboratory of Beijing for Water Quality Science and Water Environment Recovery Engineering, Beijing University of Technology, Beijing, 100124, China;4. School of Civil and Environmental Engineering, Nanyang Technological University, 637819, Singapore;5. Advanced Environmental Biotechnology Centre, NEWRI, Nanyang Technological University, 637141, Singapore;1. British Geological Survey, Keyworth, Nottingham NG12 5GG, UK;2. Department of Geology, College of Sciences, University of Baghdad, Al-Jadriyah, Al-Karadah St. No. 18, Baghdad, Iraq;1. Joint Institute for Nuclear Research (JINR), Dubna, Russia;2. State Scientific Center \"Institute of High Energy Physics\" (IHEP), Protvino, Russia;3. Institute of Space Research, Magurele, Romania;4. P.N. Lebedev Physical Institute of the Russian Academy of Sciences (LPI RAS), Moscow, Russia;5. Southwestern University, Blagoevgrad, Bulgaria;6. Institute for Nuclear Research and Nuclear Energy, Sofia, Bulgaria |
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| Abstract: | We examine the nuclear transparency for the quasi-elastic (e,e′p) process at large momentum transfers in a relativistic quantum-mechanical model for the internal structure of the proton, using a relativistic harmonic oscillator model. A proton in a nuclear target is struck by the incident electron and then propagates through the residual nucleus suffering from soft interactions with other nucleons. We call the proton “dynamical” when we take into account of internal excitations, and “inert” when we freeze it to the ground state. When the dynamical proton is struck with a hard (large-momentum transfer) interaction, it shrinks, i.e. small-sized configuration dominates the process. It the travels through nuclear medium as a time-dependent mixture of nitrinsic excited states and thus changing its size. Its absorption due to the soft interactions with nuclear medium depends on its transverse-size. Since the nuclear transparency is a measure of the absorption strength, we calculate it in our model for the dynamical case, and compare the results with those for the inert case. The effect of the internal dynamics is observed, which is in accord with the idea of the “color transparency”. We also compare our results with the experimental data in regard of q2-dependence as well as A-dependence, and find that the A-dependence may reveal the color-transparency effect more clearly. Similar effects of the internal dynamics in the other semi-exclusive hard processes are briefly discussed. |
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