แบบจำลองนัมบุ-โจนา-ลาซินิโอในทฤษฎีสนามควอนตัมกรวยแสง / ชาญกิจ คันฉ่อง = Nambu-Jona-Lasinio model in light-cone quantum field theory / Chankit Khanchong
The study of front form field theory is approached by choosing light-cone time coordinates in the formulation of variational principle in terms of functional derivatives. In the formula that shows the variations of the action, the Lagrangian is considered to be a functional of the basic fields when the time derivative of the field is considered to be a functional of the field. Hence this formula can be written in the form of variations of basic fields at the outset. The Euler-Lagrange equations can be written in terms of the Lagrangian as in point mechanics. Front form free Dirac system has non-diagonal light-cone Dirac algebra according to the form of light-cone metric. Therefore the system has constraints that make dependent auxiliary fields appear. The Faddeev-Jackiw procedure can be used to formulate Hamiltonian formulation on independent field and to quantize this system. In finding the field equation of this system, the form of the Lagrangian or Hamiltonian can be changed by integration by parts into the form that functional derivatives with respect to field can be found in the direct way. Quantization of front form free Dirac system is applied to the mean-field approximate Nambu{7f2014}Jona-Lasinio (NJL) model in the front form. The order parameter calculated in this approximate model can be non-zero, while the vacuum of the model is trivial in contrast with the order parameter in the instant form. Solution of the constraints for the auxiliary fields in terms of independent fields is non-trivial. Consequenly, the front form order parameter of the model can be non-zero.
