Study On The Covariant Chiral Effective Field Theory Of Vector Meson

The fundamental theory for strong interaction,the gauge field theory known as QCD with quarks and gluons as its elementary degrees of freedom,is extremely successful in the description of high energy processes.However,to directly use QCD in non-perturbative regime is too difficult,one has to resort to other means like lattice computation,quark models and effective theories instead.Among them,the effective field theory based on QCD's low-energy chiral symmetry makes systematic and analytical studies of hadronic physics feasible in field-theoretical contexts and achieved great successes in light meson sector.Nevertheless,in the processes involving baryons,the loop diagrams would produce components that violate chiral power counting as baryonic masses are close to chiral symmetry breaking scale(1GeV).A number of proposals have been put forward to solve this issue,such as heavy baryon(HB)formalism,infrared regularization.In spite that they work in quite a few cases,each of them is flawed somehow.Especially,HB is not convergent in the processes near some thresholds.In a recent proposal,the issue is treated in fully relativistic formalism with an extended on-mass-shell prescription(EOMS)to remove the obstacles associated with baryonic masses.This proposal has been successfully applied to many physical issues in baryon sector.As vector meson fields are heavy,we also have the same issue of chiral power counting violation.In this thesis,we first employ EOMS in the chiral effective theory of vector fields of spin 1 to probe the applicability of EOMS,and then explore the possibility of simpler prescriptions.For the Goldstone boson self-energy diagram containing vector meson line,our calculation shows that EOMS could indeed kill the chiral power counting violating terms.A closer look at the results then reveals that,the true sources of chiral power counting violation lie actually in the local pieces hidden in the various contributions of loop diagram.This observation in turn motivates us to try the following simpler prescription: On the ground of the mostly employed prescription MS???? in quantum field theory,we make a simple modification by directly extracting the local terms that violate chiral power counting from loop amplitudes and subtracting them together with the divergent pieces so that the finite or renormalized part preserve chiral power counting.We name it as extended MS????,EMS???? for short,and apply it in more diagrams.Comparing to EOMS and other earlier proposals,this prescription incorporates no extra manipulation,no modification of the theory(for instance,heavy field approximation,additional regularizations,etc.)but only the most frequently employed dimensional scheme for regularizing covariant field theories,and then extracts the local pieces that violate chiral power counting to be subtracted via standard local counter-terms,without altering the nonlocal chiral contributions at all.In our view,this feature would bring about better convergence of chiral expansion,and represents a promising step towards a completely satisfactory organization of the chiral effective field theory for heavy hadrons.Of course,testing and developing our proposal in the calculation of more physical problems would be natural next moves.