Selected Topics in Light Front Field Theory and Applications to the High Energy Phenomena

摘要

In this thesis, we have presented some of the aspects of light-front (LF)field theory through their successful application in the Deep InelasticScattering (DIS). We have developed a LFQCD Hamiltonian description of the DISstructure functions starting from Bjorken-Johnson-Low limit of virtual forwardCompton scattering amplitude and using LF current commutators. We worked in theLF gauge $A^+=0$ and used the old-fashioned LFQCD perturbation theory in ourcalculations. The importance of our work are summarized below. Our approach shares the intution of parton model and addresses directly thestructure functions, which are experimental objects, instead of its moments asin OPE method. Moreover, it can potentially incorporate the non-perturbativecontents of the structure functions as we have demonstrated by introducing anew factorization scheme. In the context of nucleonic helicity structure, the well known gauge fixed LFhelicity operator is shown to provide consistent physical information and helpsus defining new relevant structure functions. The anomalous dimensions relevantfor the $Q^2$-evolution of such structure functions are calculated. Our study is important in establishing the equivalance of LF field theory andthe usual equal-time one through perturbative calculations of the dressedparton structure functions reproducing the well known results. Also theimportance of Gallilean boost symmetry in understanding the correctness of anyhigher order calculation using ($x^+$)-ordered LFQCD perturbation theory areemphasized.