Quark gluon plasma and multiplicity dependence of transverse momentum in hadronic collisions

Multiplicity Dependencies of Midrapidity Transverse Momentum Distributions of Identified Charged Particles in Proton-Proton Collisions at (s)1/2 = 7 TeV at the LHC

“…We have estimated, analyzing T 0 and β t versus <dN ch /dη> dependencies, extracted employing the Hagedorn function with included transverse flow, that the probable onset of deconfinement phase transition in proton-proton collisions at (s) 1/2 = 7 TeV takes place at <dN ch /dη> ≈ 6.1 ± 0.3, which is close to the corresponding estimate (<dN ch /dη> ≈ 7.1 ± 0.2) obtained recently in collisions of protons at (s) 1/2 = 13 TeV in [21]. The critical values <dN ch /dη> ≈ 6.1 ± 0.3 and <dN ch /dη> ≈ 7.1 ± 0.2 [21] for the probable onset of deconfinement phase transition in collisions of protons at (s) 1/2 = 7 and 13 TeV, respectively, estimated by us from the analysis of T 0 and β t versus <dN ch /dη> dependencies, proved to be consistent and in good agreement with the respective estimates of Campanini et al in [61][62][63] and theory predictions [63] in case of crossover from hadronic gas to quark gluon plasma starting at (dN ch /dη) ≈ 6. We have also estimated the corresponding critical energy densities for the probable onset of deconfinement phase transitions in proton-proton collisions at (s) 1/2 = 7 and 13 TeV at the LHC to be 0.67 ± 0.03 and 0.76 ± 0.02 GeV/fm 3 , respectively, being significantly lower than the critical QCD energy density (1 GeV/fm 3 ).…”

“…The obtained results [63] proved to be consistent with theory predictions in case of crossover from hadronic gas to quark gluon plasma, starting at (dN ch /dη) ≈ 6 and ending at (dN ch /dη) ≈ 24. Hence, the critical values <dN ch /dη> ≈ 6.1 ± 0.3 and <dN ch /dη> ≈ 7.1 ± 0.2 [21] for the probable onset of deconfinement phase transition in collisions of protons at (s) 1/2 = 7 and 13 TeV, respectively, estimated from the analysis of the dependency of T 0 and β t on <dN ch /dη>, are consistent and in good agreement with the respective estimates of Campanini, deduced from detailed analyses of the average p t (<p t >) versus charged-particle (pseudo)rapidity density dependencies in [61][62][63].…”

“…Here, it is worth mentioning the results of relevant works [61][62][63] of Campanini et al In an early paper [61], the available experimental data on average p t (<p t >) versus chargedparticle rapidity density, dn/dy, dependencies in proton-proton and proton-antiproton collisions at SPS collider and ISR have been examined. It has been suggested [61] that evidence may already be available of high-temperature phase transition to quark-gluon plasma in hadronic collision events at SPS and ISR with central rapidity density dn/dy within one or two units around 6.…”

“…Here, it is worth mentioning the results of relevant works [61][62][63] of Campanini et al In an early paper [61], the available experimental data on average p t (<p t >) versus chargedparticle rapidity density, dn/dy, dependencies in proton-proton and proton-antiproton collisions at SPS collider and ISR have been examined. It has been suggested [61] that evidence may already be available of high-temperature phase transition to quark-gluon plasma in hadronic collision events at SPS and ISR with central rapidity density dn/dy within one or two units around 6. In [62], it has been shown that in various experiments in proton-proton and proton-antiproton collisions at (s) 1/2 energies ranging from 22 GeV to 7 TeV, there is a well-defined slope change in <p t > versus charged-particle rapidity density, which may indicate a phase transition to a new production mechanism of particles at dn/dη = 5.5 ± 1.2.…”

Experimental equation of state in proton-proton and proton-antiproton collisions and phase transition to quark gluon plasma

“…Signals related to these slope changes may indicate transition to a new mechanism of particle production. Many years ago, in [16], we pointed out that pp at ISR and pp data at CERN collider showed a kind of jump at dN ch dη = 6 and that it had to be investigated as a possible phase transition signal [17]. In 2002, Alexopoulos et al [18] assumed that the system produced in pp at √ s = 1800 GeV for dN ch dη > 6.75 was above the deconfinement transition to explain their experimental results.…”