We have searched for second-generation leptoquark (LQ) pairs in the mu mu jets channel using 94 +/- 5 pb(-1) of (p) over bar p collider data collect
ed by the DO experiment at the Fermilab Tevatron during 1993-1996. No evide
nce for a signal is observed. These results are combined with those from th
e mu v + jets and vv + jets channels to obtain 95% confidence level (C.L.)
upper limits on the LQ pair production cross section as a function of mass
and beta, the branching fraction of a LQ decay into a charged lepton and a
quark. Lower limits of 200(180) GeV/c(2) for beta = 1(1/2) are set at the 9
5% C.L. on the mass of scalar LQ. Mass limits are also set on vector leptoq
uarks as a function of beta.