QCD sum rule analysis of baryon masses

The masses of low-lying baryon states are calculated using the QCD sum rule method. Both octet and decuplet baryon states are studied via the conventional sum rule method and the new parity-projected sum rule method. Firstly, the low-lying N* channels of octets are studied via the conventional sum rule method. Using generalized interpolating fields, three independent sets of QCD sum rules are derived which allow the extraction of the spin$12\pm$, and $32\pm$ states in both the non-strange and strange channels. Thereafter, we explored a new technique which exactly projects out the parities that are mixed in the conventional sum rules. One advantage of the new parity-project sum rules is to be able to study the origin of mass splittings between positive and negative-parity baryon pairs in a direct manner in relation to the chiral-symmetry breaking of QCD as manifested via the vacuum condensates. At last, we re-visited the spin $32\pm$ decuplet states in both the conventional and the parity-projected QCD sum rule methods. These states have not been well-studied in this context in the literature. The uncertainties of our mass predictions are explored by taking into account all the uncertainties in the QCD condensate parameters using a Monte-Carlo based method. The results represent a comprehensive and improved understanding of octet and decuplet baryons from the non-perturbative QCD perspective.