Precision Measurements in the Scalar Top Sector of the MSSM at a Linear e+e− Collider

The scalar top discovery potential has been studied for the TESLA project with a full-statistics background simulation at √ s = 500 GeV and L = 500 fb−1. The beam polarization is very important to measure the scalar top mixing angle and to determine its mass. The latest estimation of the beam polarization parameters is applied. This study includes e polarization, which improves the sensitivity. For a 180 GeV scalar top at minimum production cross section, we obtain ∆m = 0.8 GeV and ∆cos θt̃ = 0.008 in the neutralino channel, and ∆m = 0.5 GeV and ∆cos θt̃ = 0.004 in the chargino channel. The MSSM parameters for the Snowmass point 5 at cos θt̃ = 0.513 predict a scalar top of 210 GeV and a neutralino of about 120 GeV. For this parameter choice ∆m = 0.95 GeV and ∆cos θt̃ = 0.0125 is obtained, and a preliminary c-tagging study is presented in the neutralino channel. Presented at the LCWS02, Korea, Aug. 2002 PRECISION MEASUREMENTS IN THE SCALAR TOP SECTOR OF THE MSSM AT A LINEAR e + e − COLLIDER A. FINCH, H. NOWAK and A. SOPCZAK Lancaster University, UK, DESY Zeuthen, Germany Abstract The scalar top discovery potential has been studied for the TESLA project with a full-statistics background simulation at √ s = 500 GeV and L = 500 fb. The beam polarization is very important to measure the scalar top mixing angle and to determine its mass. The latest estimation of the beam polarization parameters is applied. This study includes e polarization, which improves the sensitivity. For a 180 GeV scalar top at minimum production cross section, we obtain ∆m = 0.8 GeV and ∆cos θt̃ = 0.008 in the neutralino channel, and ∆m = 0.5 GeV and ∆cos θt̃ = 0.004 in the chargino channel. The MSSM parameters for the Snowmass point 5 at cos θt̃ = 0.513 predict a scalar top of 210 GeV and a neutralino of about 120 GeV. For this parameter choice ∆m = 0.95 GeV and ∆cos θt̃ = 0.0125 is obtained, and a preliminary c-tagging study is presented in the neutralino channel.The scalar top discovery potential has been studied for the TESLA project with a full-statistics background simulation at √ s = 500 GeV and L = 500 fb. The beam polarization is very important to measure the scalar top mixing angle and to determine its mass. The latest estimation of the beam polarization parameters is applied. This study includes e polarization, which improves the sensitivity. For a 180 GeV scalar top at minimum production cross section, we obtain ∆m = 0.8 GeV and ∆cos θt̃ = 0.008 in the neutralino channel, and ∆m = 0.5 GeV and ∆cos θt̃ = 0.004 in the chargino channel. The MSSM parameters for the Snowmass point 5 at cos θt̃ = 0.513 predict a scalar top of 210 GeV and a neutralino of about 120 GeV. For this parameter choice ∆m = 0.95 GeV and ∆cos θt̃ = 0.0125 is obtained, and a preliminary c-tagging study is presented in the neutralino channel. Introduction The study of the scalar top quarks is of particular interest, since the lighter stop mass eigenstate is likely to be the lightest scalar quark in a supersymmetric theory. The mass eigenstates are mt̃1 and mt̃2 with mt̃1 < mt̃2 , where t̃1 = cos θt̃t̃L+sin θt̃t̃R and t̃2 = −sin θt̃t̃L + cos θt̃t̃R with the mixing angle cos θt̃. We study the experimental possibilities to determine mt̃1 and cos θt̃ at a high-luminosity e e linear collider such as the TESLA project [1] with polarized e and e− beams. The simulated production process is ee → t̃1 ̄̃ t1 with two decay modes t̃1 → χ̃c and t̃1 → χ̃b. A 100% branching fraction in each decay mode is simulated. The first scalar top decay into a c-quark and the lightest neutralino results in a signature of two jets and large missing energy. The second investigated stop decay mode leads