A particle of mass \(m\) moves along the \(x\)-axis in a region where its motion is governed solely by a conservative force associated with the potential energy function \(U(x)\). The particle has total mechanical energy \(E\) and moves between the turning points \(x_1\) and \(x_2\), where \(x_1 < x_2\) and \(E > U(x)\) for all \(x_1 < x < x_2\). Which of the following expressions correctly represents the time \(\Delta t\) required for the particle to travel directly from \(x_1\) to \(x_2\)?