Hadron masses and polarizabilities from lattice QCD.

摘要

In this thesis, first, baryon masses in the spin-3/2 sector are computed using a highly-improved anisotropic quark action and Luscher-Weisz (LW) gauge action with tree level tadpole improvement. States with both positive and negative parities are isolated via a parity projection method. Spin projection is used to separate the spin-3/2 states from spin-1/2 states. The extracted masses are compared to experiments where available.; Next, a more challenging calculation is carried out for hadron electro-magnetic polarizabilities in the external field method. An initial calculation using the clover quark action with 17 (14) configurations for electric (magnetic) polarizability is used to establish the feasibility of the method. Then a more extensive calculation is done using the Wilson quark action and 109 (150) configurations in the electric (magnetic) case. For electric polarizability, results are obtained for seven neutral particles (rho, n, Sigma 0, xi0, Λ, Sigma*0, xi *0). For magnetic polarizability, results are obtained for 28 particles covering the entire baryon octet (n, rho, Sigma 0, Sigma-, Sigma+, xi -, xi0, Λ) and decuplet (Delta 0, Delta-, Delta+, Delta ++, Sigma*0, Sigma*-, Sigma *+, xi*0, xi*-, O -), plus selected mesons (pi0, pi +, pi-, K0, K+, K¯0, K¯-, rho0, rho +, rho-). The results are compared with available values from experiments and other theoretical calculations.