Determination of $\tan \beta$ at a Future $e^{+}{e}^{-}$ Linear Collider

Abstract

It is widely stated that the ratio of neutral Higgs field vacuum expectation values, $\text{tanb}$, is one of the most difficult 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 $\text{rts}=500\text{gev}$ and $\text{call}=2000\text{fbi}$, we show that a very accurate determination of $\text{tanb}$ will often be possible using Higgs production rates and/or Higgs decays. Based on a TESLA simulation, and assuming no other light Higgs bosons and $100\le m_A\le 200\text{gev}$, we find that the rate for the process $\text{epem}\to b\text{anti}bA\to b\text{anti}bb\text{anti}b$ provides an excellent determination of $\text{tanb}$ at high $\text{tanb}$. In the MSSM Higgs sector, the rate for $\text{epem}\to b\text{anti}bA+b\text{anti}bH\to b\text{anti}bb\text{anti}b$ ($\text{epem}\to HA\to b\text{anti}bb\text{anti}b$) provides a good determination of $\text{tanb}$ at high (low) $\text{tanb}$, respectively, at moderate $m_A$ values. We also show that direct measurement of the average total width of the $H$ and $A$ in $\text{epem}\to HA\to b\text{anti}bb\text{anti}b$ events provides an excellent determination of $\text{tanb}$ at large $\text{tanb}$.

Comments: 7 pages, 3 figures. Contribution to the Snowmass 2001 Workshop on ``The Future of Particle Physics'', Snowmass, CO, USA, July 2001. Revised to include several improvements and additional references