Vertex Detector System Design

The ILC is designed to explore precision physics produced with low cross sections. A flagship study at the ILC will be the measurements of Higgs couplings to quarks and bosons. These measurements, which will span more than two orders of magnitude in mass and coupling strength, require excellent separation of b, c, and light quark vertices. A related measurement is the self-coupling of the Higgs. Here the signal reaction, e+e− → ZHH → qqbbbb with four b-jets must be separated from backgrounds like tt → bbcscs, ZZZ, and ZZH. Different constraints on the vertex detector come from measurements like heavy quark forwardbackward asymmetry. Here the emphasis is on forward tracking with flavor tagging and determination of the charge of the parent b quark. Whether the ultimate focus is on Higgs, supersymmetry, or other new physics phenomena, it is likely that precise measurements of heavy quark jets and their decay vertices will play a crucial role [2].