Fig. 5: Invariant mass fit.
The invariant mass spectrum of opposite-sign pion pairs after the combinatorial background subtraction, for the pair transverse momentum 4 < pT < 6 GeV/c and the azimuthal angle 0 < ϕ–ψ2 < π/12, in high-multiplicity pPb collisions. The solid blue curve is the fit result within the fit range marked with vertical blue dashed lines; the orange dashed curve represents the residual background. The solid red curve represents the f0(980) signal, while the dashed dark-violet and light-green curves correspond to the background contributions from the ρ (770)0 and f2 (1270) resonances, respectively. The ratio between data and the fit result is shown in the lower panel, with the error bars representing statistical uncertainties only. The low-mass region exhibits a nontrivial turn-on behavior and is not included in the fit.
