Damped sin(beta-alpha) of Higgs couplings and the lightest Higgs boson production at gamma gamma colliders in the minimal supersymmetric standard model

In the decoupling limit M-A(0)2>>M-Z(2), the heavy CP-even, CP-odd, and charged Higgs boson masses are nearly degenerate, sin(beta-alpha) approaches 1, and the lightest CP-even Higgs boson almost displays the same properties as the standard model Higgs boson. But the top and bottom squark sectors can change this pattern through radiative corrections. We find that there are parameter regions at small and moderate tan beta in the minimal supersymmetry standard model under experimental constraints of (g-2)(mu), b-->sgamma, and lower bounds of Higgs boson and sparticle masses, where sin(2)(beta-alpha) is damped (say below 0.8), which has a significant effect on Higgs couplings g(h)(VV)(0)(V=W+/-,Z(0)) and g(h0gammagamma). We discuss its impact on the lightest CP-even Higgs boson production at gammagamma colliders.