Natural supersymmetry and b→sγ constraints

We investigate constraints from the observed branching ratio for b→sγ and fine-tuning in the framework of natural supersymmetry. The natural supersymmetry requires the large trilinear coupling of the stop sector, light higgsinos (a small μ parameter) and light stops, in order to reduce the fine-tuning in the Higgs sector while avoiding the LEP constraint. It is found that in such a scenario 5% (10%) level of fine-tuning is inevitable due to the b→sγ constraint even if the messenger scale is as low as 105GeV(104GeV), provided that the gaugino masses satisfy the GUT relation.