Very light sbottom and gluino scenario confronting electroweak precision tests

The minimal supersymmetric model with light sbottom (∼mb) and light gluino (12∼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 Rb 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 δRb safely within the experimental bounds even for heavier sbottom too heavy (b̃2≳200 GeV) to be produced at LEP2 in association with light sbottom b̃1.