Role of system size in freeze-out conditions extracted from transverse momentum spectra of hadrons

The data on hadron transverse momentum spectra in different centrality classes of p + Pb collisions at $\sqrt{{s}_{\mathrm{NN}}}=5.02$ TeV have been analyzed to extract the freeze-out hypersurface within a simultaneous chemical and kinetic freeze-out scenario. The freeze-out hypersurface has been extracted for three freeze-out schemes that differ in the way strangeness is treated: (i) unified freeze-out for all hadrons at complete thermal equilibrium (1FO), (ii) unified freeze-out for all hadrons with an additional parameter ${\ensuremath{\gamma}}_{S}$ which accounts for possible out-of-equilibrium production of strangeness ($1\mathrm{FO}+{\ensuremath{\gamma}}_{S}$), and (iii) separate freeze-out for hadrons with and without strangeness content (2FO). Unlike in heavy-ion collisions where 2FO performs best in describing the mean hadron yields as well as the transverse momentum spectra, with p + Pb we find that $1\mathrm{FO}+{\ensuremath{\gamma}}_{S}$ with one fewer parameter than 2FO performs better. This confirms expectations based on previous analysis of system size dependence in the freeze-out scheme with mean hadron yields: while heavy-ion collisions that are dominated by constituent interactions prefer 2FO, smaller collision systems like proton + nucleus and proton + proton collisions with lesser constituent interaction prefer a unified freeze-out scheme with varying degrees of strangeness equilibration.