Very light sbottom and gluino scenario confronting electroweak precision tests

The minimal supersymmetric model with light sbottom (similar tom(b)) and light gluino (12 similar to 16 GeV) can explain the excess of bottom quark production cross section at hadron colliders and has drawn much attention. We calculate one-loop contribution to Z-pole observable R-b in this scenario when large CP-violating phases are allowed in the gluino mass and/or sbottom sector. We show that these large CP-violating phases can suppress the new contribution deltaR(b) safely within the experimental bounds even for heavier sbottom too heavy ((b) over tilde (2) greater than or equal to 200 GeV) to be produced at LEP2 in association with light sbottom (b) over tilde (1). (C) 2002 Elsevier Science B.V. All rights reserved.