Bosonic decays of (t)over-tilde2 and (b)over-tilde2

We perform a detailed study of the decays of the heavier top and bottom squarks ((t) over tilde(2) and (b) over tilde(2)) in the Minimal Supersymmetric Standard Model (MSSM). We show that the decays into Higgs or gauge bosons, i.e. (t) over tilde(2) --> (t) over tilde(1) + (h(0),H-0,A(0) or Z(0)), (t) over tilde(2) --> (b) over tilde(1,2) + (H+ or W+), and the analogous (b) over tilde(2) decays, can be dominant in a wide range of the model parameters due to the large Yukawa couplings and mixings of t and b. Compared to the conventional decays into fermions, such as (t) over tilde(2) --> t + (<(chi)over tilde>(0)(i) or (g) over tilde) and (t) over tilde(2) --> b + <(chi)over tilde>(+)(j), these bosonic decay modes can have significantly different decay structures and distributions. This could have an important impact on the search for (t) over tilde(2) and (b) over tilde(2) and the determination of the MSSM parameters at future colliders. (C) 1998 Elsevier Science B.V. All rights reserved.