We report on the feasibility of the direct measurement of the top Yukawa coupling gt at the International Linear Collider during its first phase of operation with a center-of-mass energy of 500 GeV. The signal and background models incorporate the nonrelativistic QCD corrections which enhance the production cross section near the tt̄ threshold. The e +e-→tt̄H signal is reconstructed in the 6-jet+lepton and the 8-jet modes. The results from the two channels are combined. The background processes considered are e+e -→tb̄W-/t̄bW+ (which includes e+e-→tt̄), e+e -→tt̄Z, and e+e-→tt̄g *→tt̄bb̄. We use a realistic fast Monte Carlo detector simulation. Signal events are selected using event shape variables, through jet clustering, and by identifying heavy flavor jets. Assuming a Higgs mass of 120 GeV, polarized electron and positron beams with (Pe -,Pe+)=(-0.8,+0.3), and an integrated luminosity of 1ab-1, we estimate that the e+e-→tt̄H events can be seen with a statistical significance of 5.2σ, corresponding to the relative top Yukawa coupling measurement accuracy of |Δg t/gt|=10%.
|Journal||Physical Review D - Particles, Fields, Gravitation and Cosmology|
|Publication status||Published - 2011 Jul 26|
ASJC Scopus subject areas
- Nuclear and High Energy Physics
- Physics and Astronomy (miscellaneous)