https://scholars.lib.ntu.edu.tw/handle/123456789/31976
Title: | 雙光子交換對電子核子碰撞的貢獻 Two-Photon Exchange Effect in the Elastic Electron-Nucleon Scattering |
Authors: | 陳佑駿 Chen, Yu-Chun |
Keywords: | 核子波行因子,雙光子交換,彈性核子碰撞,部分子,質子,中子;nucleon form factors, two-photon exchange, elastic scattering, partonic, proton | Issue Date: | 2007 | Abstract: | 對於核子波形因子的量測,近代的極化實驗所得的結果,和以前非極化實驗所得的結果對比時,雖在低動量交換時能夠一致,但在高動量交換時卻有巨大的不同。為要解決這個迷題,雙光子交換在彈性電子質子碰撞中的效應開始被注重起來。我們透過部份子的模型,計算雙光子交換的貢獻。我們發現,當加入雙光子交換的貢獻後,能很好的解決之前兩種實驗所得結果嚴重衝突的問題。如今我們明白,雙光子交換的效應,在量測核子的波形因子時伴演了很重要的角色。 When measuring the nucleon form factors, recent polarization experiments at the Thomas Jefferson Laboratory (JLab) have confirmed the earlier Rosenbluth measurements from SLAC at small Q2. However, at large Q2, a huge discrepancy appear between them. To solve this puzzle, the two-photon exchange contribution to elastic electron-proton scattering at large momentum transfer by using a quark-parton representation of virtual Compton scattering was estimated. And then we thus can relate the two-photon exchange amplitude to the generalized parton distributions which also enter in other wide angle scattering processes. We find that the interference of one- and two-photon exchange contribution is able to substantially resolve the difference between electric form factor measurements from Rosenbluth and polarization transfer experiments. Now we know higher-order QED effects can play an important role in precision measurements of nucleon elastic form factors in electron scattering. |
URI: | http://ntur.lib.ntu.edu.tw//handle/246246/54498 | Other Identifiers: | en-US |
Appears in Collections: | 物理學系 |
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ntu-96-D91222006-1.pdf | 23.53 kB | Adobe PDF | View/Open |
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