Implications of Results from Z- and WW-Threshold Running

TL;DR

This work assesses the physics reach of a high-luminosity GigaZ run at a future TESLA-like linear collider, projecting measurements of electroweak observables with unprecedented precision ($\Delta M_W = 6$ MeV and $\Delta\sin^2\theta_{\mathrm{eff}} = 0.00001$). By comparing SM and MSSM predictions using full one-loop and leading higher-order corrections, it demonstrates that such precision enables stringent consistency tests and enhanced sensitivity to new physics, including an indirect Higgs mass determination at about $5\%$ accuracy. The study also analyzes the b-physics potential with about $6\times10^8$ $b$ quarks, highlighting flavor-tagging advantages from beam polarization and comparing with LHC-b/BTeV capabilities. Overall, GigaZ could decisively probe SM vs MSSM relations, constrain the unitarity triangle, and expand clean-flavor physics in a lower-background environment. $M_W$ and $\sin^2\theta_{\mathrm{eff}}$ play central roles, with $m_h$ determination and $b$-quark studies forming key complementary facets of the program.

Abstract

One year of Z- and WW-Threshold running of TESLA can provide the possibility to measure electroweak precision observables to an extremely high accuracy. At the Z peak O(10^9) Z bosons and about 6 10^8 b quarks can be collected. We employ the expected uncertainties ΔMW = 6 MeV and Δsin(theta_W,eff) = 0.00001 and demonstrate in this way that very stringent consistency tests of the Standard Model and the Minimal Supersymmetric Standard Model will be possible. The indirect determination of the Higgs-boson mass within the Standard Model can reach an accuracy of about 5 %. The 6 10^8 b quarks can be used to investigate various b physics topics.

Figures (2)

• Figure 1: Theoretical prediction of the SM and the MSSM in the $\sin^2\theta_{\mathrm{eff}}$--$M_W$-plane compared with expected experimental accuracies at LEP2/Tevatron, the LHC and GigaZ.
• Figure 2: The expected accuracy of the LHC and GigaZ is compared with the prediction of the MSSM for $m_h \approx 115 \,\, \mathrm{GeV}$ and $M_{\mathrm{SUSY}} = 300, 600, 1000 \,\, \mathrm{GeV}$.