Constraining the Charged Higgs Mass in the MSSM: A Low-Energy Approach

We examine the current lower bound on the charged Higgs boson mass in the Minimal Supersymmetric Standard Model. By applying direct search constraints on the neutral Higgs bosons and other supersymmetric states, as well as a number of indirect constraints (b -> s gamma, B_s -> mu mu, B -> tau nu, B -> D tau nu), we find that it is possible to push the charged Higgs boson mass as low as 140 GeV. We work in a completely low-energy approach with no assumptions about scalar mass unification, examining two of the most popular limits for neutral Higgs boson searches: the Max-Mixing and No-Mixing scenarios. While both scenarios allow light charged Higgs bosons, they do so for completely different ranges of tan(beta). In either case, one expects light top squarks to accompany a light charged Higgs.