Part I Proposed Experimental Tests of the Right-handed Weak Current All possible experiments which test the SU(2)_L x U(1)_R x U(1)_B-L model and SU(2)_L x SU(2)_R x U(1)_B-L model using the LEP e⁺e⁻ collider and HERA e⁻p collider are calculated and the most sensitive experiments are examined. Part II Semi-Phenomenological Theory of (Qq̅) System The (QQ̅) and (Qq̅) mesons are calculated using a QCD motivated potential model. It is discovered that by including a long distance relativistic correction term derived by Grome, the Coulomb + Linear potential works not only for c and b quarks, but s quark as well. The leptonic decay constants of various (Qq̅) mesons together with their masses are predicted. The topponium states are also discussed. / Ph. D.