Probing space–time noncommutativity in the top quark pair production at e+e- collider

Abstract

The forward–backward asymmetry observed in the top quark pair production at the Fermilab Tevatron points toward the existence of beyond the standard model physics. We have studied the top quark pair production [Formula: see text] in the TeV energy electron–positron linear collider to the leading order of the noncommutative parameter Θμν in the noncommutative standard model. We have made a detailed laboratory frame analysis of the time-averaged cross-section, polar, azimuthal angular distributions, transverse momentum and rapidity distributions, polar (forward–backward) and azimuthal asymmetries of the top-quark pair production in the presence of earth's rotation. We investigated their dependence on the orientation angle of the noncommutative vector η and the noncommutative scale Λ and found that those deviates from the standard model distributions significantly. The azimuthal distribution which is flat in the standard model deviates largely for η = π/2 and Λ = 700 GeV at the fixed machine energy E com = 1000 GeV . We found that the polar distribution deviates largely from the standard model distribution for η = π/2 and Λ = 500 GeV . The azimuthal asymmetry Aϕ which is zero in the standard model can be as large as 4% for Λ = 500 GeV and η = π/2 at the fixed machine energy E com = 1000 GeV . Assuming that the future TeV linear collider will observe Aϕ = ±0.01 we find Λ≤750(860) GeV corresponding to η = π/2. Similarly, corresponding to polar asymmetry A FBz = 0.5078 (which deviates from the standard model prediction by 1%), we find Λ≤760 GeV at the fixed machine energy E com = 1000 GeV for η = π/2.