The left panel shows the invariant mass distribution of unlike sign $\pi$K pairs from the same and mixed events. The right panel shows the same but after the mixed-event background subtraction. The mixed event background subtracted invariant mass distribution is fitted with a combination of Breit--Wigner function  and second order polynomial distribution. The Breit--Wigner distribution represents the ${\rm K^{*0}}$ signal and the second order polynomial describes the residual background.