Determining tan β with Neutral and Charged Higgs Bosons at a Future e + e − Linear Collider

The ratio of neutral Higgs field vacuum expectation values, tan β, is one of the most important parameters to determine in either the Minimal Supersymmetric Standard Model (MSSM) or a general type-II Two-Higgs Doublet Model (2HDM). Assuming an energy and integrated luminosity of √ s = 500 GeV and L = 2000 fb at a future linear collider (LC), we show that a very accurate determination of tan β will be possible for low and high tan β values by measuring the production rates of Higgs bosons and reconstructing Higgs boson decays. In particular, based on a TESLA simulation, and assuming no other light Higgs bosons and 100 ≤ mA ≤ 200 GeV, we find that the rate for the process ee → bbA → bbbb provides a good determination of tanβ at high tanβ. In the MSSM Higgs sector, in the sample case of mA = 200 GeV, we find that the rates for e e → bbA + bbH → bbbb and for ee → HA → bbbb provide a good determination of tan β at high and low tanβ, respectively. We also show that the direct measurement of the average total widths of the H and A in ee → HA → bbbb events provides an excellent determination of tanβ at large values. In addition, the charged Higgs boson process ee → HH → tbtb has been studied. The sensitivity to tan β at the LHC obtained directly from heavy Higgs boson production is briefly compared to the LC results.