Very light sbottom and gluino scenario confronting electroweak precision tests

Abstract

The minimal supersymmetric model with light sbottom (∼ m b ) 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 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 δR b safely within the experimental bounds even for heavier sbottom too heavy ( b ̃ 2≳200 GeV) to be produced at LEP2 in association with light sbottom b ̃ 1 .