Measurement of the Higgs boson mass and e+e- → ZH cross section using Z → μ+μ- and Z → e+e- at the ILC

This paper presents a full simulation study of the measurement of the production cross section (sigma(ZH)) of the Higgsstrahlung process e(+)e(-) -> ZH and the Higgs boson mass (M-H) at the International Linear Collider (ILC), using events in which a Higgs boson recoils against a Z boson decaying into a pair of muons or electrons. The analysis is carried out for three center-of-mass energies root s = 250, 350, and 500 GeV, and two beam polarizations e(L)(-)e(R)(+) and e(R)(-)e(L)(+), for which the polarizations of e(-) and e(+) are (Pe(-), Pe(+)) = (-80%, +30%) and (+80%, -30%), respectively. Assuming an integrated luminosity of 250 fb(-1) for each beam polarization at root s = 250 GeV, where the best lepton momentum resolution is obtainable, sZH and M-H can be determined with a precision of 2.5% and 37 MeV for e(L)(-)e(R)(+) and 2.9% and 41 MeV for e(R)(-)e(L)(+), respectively. Regarding a 20 year ILC physics program, the expected precisions for the HZZ coupling and M-H are estimated to be 0.4% and 14 MeV, respectively. The event selection is designed to optimize the precisions of sZH and MH while minimizing the bias on the measured sZH due to discrepancy in signal efficiencies among Higgs decay modes. For the first time, model independence has been demonstrated to a sub-percent level for the sigma(ZH) measurement at each of the three center-of-mass energies. The results presented show the impact of center-of-mass energy and beam polarization on the evaluated precisions and serve as a benchmark for the planning of the ILC run scenario.