Apparent unitarity violation in top quark's mass off-shell region from a new physics at high energy colliders

Perturbative unitarity conditions have been playing an important role by estimating the energy scale of new physics, including the Higgs mass as one of the most important examples. In this letter, we show that there is a possibility to see the hint of a new physics (top quark partner) indirectly by observing an "apparent" unitarity violation in $M_{bw}$ distribution well above top quark mass in a process of a heavy resonance decaying into a pair of top quarks.