Study of Multiplicity Dependencies of Midrapidity p_T Spectra of Identified Charged Particles in Proton-Proton Collisions at the LHC Using a Two-Component Model

The recently proposed two-component Tsallis-Hagedorn Model with Transverse Flow (THMTF) function, which is the sum of thermodynamically consistent Tsallis function with embedded transverse flow and inverse power-law function (which is asymptotic of Hagedorn function at high p_T values), has described quite well simultaneously the experimental midrapidity p_T spectra of the charged pions and kaons, protons and antiprotons in the whole measured p_T range up to 20 GeV/c at all ten multiplicity classes in proton-proton collisions at sqrt(s)=7 and 13 TeV at the LHC. Dependencies of non-extensivity parameter, q, kinetic freeze-out temperature parameter, T₀, momentum scale parameter, P₀, and power-index n of the two-component THMTF function on <dN_ch/dη> in proton-proton collisions at sqrt(s)=7 and 13 TeV have been analyzed and interpreted. Analyzing <dN_ch/dη> dependencies of parameters T₀ and <β_T>, the border <dN_ch/dη> values of transition towards plateau region of kinetic freeze-out temperature (T₀) (and simultaneous emergence of transverse flow) and probable onset of deconfinement phase transition (towards QGP-like state) have been estimated to be <dN_ch/dη>≈ 7.6±0.9 and <dN_ch/dη>≈ 9.0±1.0 in proton-proton collisions at sqrt(s)= 7 and 13 TeV, respectively. These estimates made using THMTF function in present work have been above but close to the corresponding <dN_ch/dη> ≈6.1±0.3 and <dN_ch/dη> ≈7.1±0.2 estimates of possible onset of deconfinement phase transition in proton-proton collisions at sqrt(s)= 7 and 13 TeV, respectively, made in our earlier works using Hagedorn function with embedded transverse flow. Our estimates are consistent with and complement the corresponding early result ((dN_ch/dη) ≈ 6±1) of Campanini and Ferri for probable onset of deconfinement phase transition, obtained from analyses of the experimental <p_T> versus <dN_ch/dη> curves and extracted experimental EOSs, and squared speed of sound in proton-proton and proton-antiproton collisions in wide energy, sqrt(s)= 31-7000 GeV, interval. The mean number of partons participating in a scattering, n_α=5, has been estimated from extracted average value of power-index n in the analyzed proton-proton collisions. This suggests that g+q→meson+q and g+g→meson+g gluon fragmentation reactions are the main mechanisms for high p_T meson production in proton-proton collisions at the LHC. The obtained significant differences in <dN_ch/dη> dependencies of parameters q and n for pions and kaons, on the one hand, and for (anti)protons, on the other hand, can imply that pions and kaons demonstrate features of local thermalization in proton-proton collisions at the LHC with high enough multiplicity, whereas (anti)protons show significant deviations due to non-thermal production mechanisms. The Pearson coefficients of linear correlation have been calculated between various parameters of the two-component THMTF function in proton-proton collisions at sqrt(s)= 7 and 13 TeV and compared with those obtained recently in Xe+Xe and Pb+Pb collisions at the LHC.