Upper bounds at the weak scale are obtained for all
λijλim type product couplings of the scalar leptoquark
model which may affect K-K(bar), B_d-B_d(bar), and B_s-B_s(bar)$ mixing, as
well as leptonic and semileptonic K and B decays. Constraints are obtained for
both real and imaginary parts of the couplings. We also discuss the role of
leptoquarks in explaining the anomalously large CP-violating phase in
B_s-B_s(bar) mixing.Comment: 16 pages, 5 figures, more constraints analyzed, added a number of
reference