Research in Theoretical Hadronic Physics and Related Topics

理论强子物理及相关课题研究

• 批准号: 0245056
• 负责人: Carl Carlson
• 金额: $ 22.5万
• 依托单位: College of William and Mary
• 依托单位国家: 美国
• 项目类别: Continuing Grant
• 财政年份: 2003
• 资助国家: 美国
• 起止时间: 2003-06-15 至 2007-05-31
• 项目状态: 已结题
• 来源: https://www.nsf.gov/awardsearch/showAward?AWD_ID=0245056&HistoricalAwards=false
• 关键词: Research; Theoretical; Hadronic; Physics; Related

We propose to investigate a n mber of topics,including:Hard Pion Electroproduction. We will calculate high transverse momentum semi-exclusivepion electroproduction,considering especially the higher twist process where the pions are pro-duced directly and appear kinematically isolated,but including leading twist (where the pionsare produced by parton fragmentation and appear as part of a jet)and estimates of soft pro-cesses.The direct and leading twist processes allow data to yield information about the quarkand gluon distributions in the target.Two particular new items are to do electroproductionrather than photoproduction and to include initial state parton transverse momentum.An ap-plication is to see if the higher twist process are relevant to data from HERMES,and possiblyHall B data from Je .erson Lab,where there is considerable interest in the result.Dipions and the Polarization of Gluons. HERMES has measured dipions photoproducedwith polarized photons o .polarized targets,which has given the .rst determination of the po-larization of gluons in the proton.The published result depends heavily upon the theoreticalanalysis,in turn heavily based on program packages that are tuned to higher energies.Wepropose what we believe is a necessary independent calculation the contributions of the vari-ous processes (photon-gluon fusion,QCD Compton,and vector meson dominance (VMD)),inparticular to see the sensitivity of the results to di .ering fragmentation models,initial statetransverse momentum,and di .ering estimates of the VMD contribution.The Deuteron Form Factor. The only perturbative QCD calculation of the asymptoticdeuteron form factor lies well below the data,but strikingly omits the short range wave functionsthat provide for hidden color states.We have recently developed ways to manipulate 6-quarkcluster wave functions that model these components.We propose to calculate the asymptoticform factor with wave functions including a hidden color component,to see the e .ect of thehidden color components upon the magnitude of the result.Bringing Perturbative QCD to Lower Momentum Transfers. We will study formal andapplied aspects of relations between the Breit and light-front helicity amplitudes,next-to-leadingpower corrections to the high momentum transfer behavior of those amplitudes,and applicationof discrete symmetries to light-front amplitudes.The formal results can allow s,for example,to.nd constraints that approximations to the subdominant helicity amplitudes must obey (whichare not always realized in the literature).More positively,we can se the formal results to guideinvestigation of how non-leading powers can be parameterized and see,again for example,howand where the N .(1232)transition may approach the perturbative QCD results.Phenomenology of Noncommutative Field Theory. Following up on an earlier researchpath,we would like to complete the set of Feynman rules for the Lorentz conserving noncom-mutative .eld theory and .nd the signatures of noncommutative spacetime for a selection ofprocesses in addition to fAfA elastic scattering.Also we would like to consider ways to do Lorentzconserving noncommutative .eld theory with operator algebras in addition to the contractedSnyder algebra we have worked out so far.NSF Review Criteria. Intellectual merit of the proposed activity:Most of the activity is atthe forefront of modern hadronic physics,and the rest is at the forefront of the phenomenologyof an interesting direction in particle physics.The projects will lead to many publicationsin the leading refereed journals.Broader impacts of the proposed activity:The projects willhelp bridge the gap between hadronic theory and observed phenomena,and lead to greaterunderstanding of the mechanisms of hadronic reactions.They will also train new students,including undergraduates.The PI has had two successful women Ph.D.students,and thepresent project may extend opportunities for women entering the .eld.The PI is regularly atthe Je .erson Laboratory and bridging the gap between university and national lab as well asbetween data and theory.

我们建议研究一系列主题，包括：硬质子电生成。我们将计算高横向动量半排他子电产生，特别是考虑到更高的扭转过程，其中介子是直接产生的，看起来是运动学上孤立的，但包括引导扭转(其中的点是由部分子碎裂产生的，看起来是喷流的一部分)和软过程的估计。直接和引导扭转过程允许数据提供关于靶中夸克和胶子分布的信息。两个特殊的新项目是进行电产生而不是光产生，并包括初始态部分子横向动量。一个应用是看看更高扭转过程是否与Hermes的数据相关，以及Je.erson Lab的可能的Hall B数据其中有相当大的兴趣的结果。双离子和胶子的极化。Hermes测量了由偏振光子与偏振靶产生的双子，首次确定了胶子在质子中的极化。已发表的结果在很大程度上依赖于理论分析，而很大程度上基于调谐到更高能量的程序包。我们提出了一个我们认为是必要的独立计算各种过程(光子-胶子聚变、QCD康普顿和矢量介子优势(VMD))的贡献，特别是考察了结果对不同碎裂模型、初始态横动量和VMD贡献的不同估计的敏感性。我们最近发展了一些方法来处理6夸克团簇的波函数来模拟这些成分。我们建议用包含隐藏颜色成分的波函数来计算渐近形式因子，以了解隐藏颜色成分对结果的影响。将微扰QCD引入低动量传递。我们将研究Breit和光波前螺旋度振幅之间关系的形式和应用方面，对这些振幅的高动量传递行为的次导功率修正，以及离散对称对光波前振幅的应用。例如，形式结果可以允许S遵守次优螺旋度振幅的近似必须遵守的约束(文献中并不总是实现)。更积极的是，我们可以利用形式结果来指导研究如何将非主导功率参数化，并再次看到例如，N。(1232)跃迁可能如何以及在哪里接近微扰QCD结果。非对易场论的现象学。在前面的研究基础上，我们想要完成Lorentz守恒非对易.eld理论的Feynman规则集和一些过程的非对易时空的签名.除了Fafa弹性散射.我们还想考虑用算子代数和我们到目前为止已经计算出的压缩Snyder代数来做Lorentz守恒非对易.eld理论的方法.拟议活动的智力价值：大部分活动处于现代强子物理的前沿，其余的处于粒子物理一个有趣方向的现象学前沿。这些项目将导致许多重要的评论期刊发表文章。拟议活动的广泛影响：这些项目将有助于弥合强子理论和观察到的现象之间的差距，并有助于更好地理解强子反应的机制。他们还将培训新学生，包括本科生。PI已经有两名成功的女博士生，目前的项目可能会扩大女性进入老年人的机会。PI定期在杰耶森实验室工作，弥合大学和国家实验室之间以及数据和理论之间的鸿沟。