The domain of soft hadrons in transverse momentum space in high energy collisions

Abstract

By studying experimental data for invariant transverse momentum distribution $f(p_T)$ of hadrons in high energy $pp$, $p$A and AA collisions, we find two characteristic $p_T$ points relating to the behavior of ${\left[\ln f(p_T)\right]}^{{}^{\prime \prime }}$, i.e., the second derivative of the logarithm of hadronic $p_T$ spectrum with respect to $p_T$. One point is $p_0$ at which ${\left[\ln f(p_T)\right]}^{{}^{\prime \prime }}$ is zero and another point is $p_1$ at which ${\left[\ln f(p_T)\right]}^{{}^{\prime \prime }}$ reaches maximum. \bz{The hadronic distribution can be classified into three kinetic regions, i.e., soft region $0<p_T<p_0$ dominated by hadrons from soft parton system, hard region $p_T>p_1$ dominated by hadrons from high energy partonic jet, and the transition region $p_0<p_T<p_1$ of above two sources of hadron production.} Using rich data of hadronic $p_T$ spectra at RHIC and LHC, we carry out a systematical analysis for $p_0$ and $p_1$ of kaon, $K^{\ast }$, $\varphi$ and baryons such as $p$, $\Lambda$, $\Xi$, $\Omega$ in $pp$, $p$-Pb and heavy-ion collisions, and show their dependence on hadron species, collision energy, collision centrality and/or charged-particle multiplicity. We also study the correlation between $p_0$ of hadrons and their average transverse momentum $⟨p_T⟩$, and find a difference between $p_0$-$⟨p_T⟩$ correlation of baryons and that of mesons which can be understood by quark combination mechanism at hadronization. The systematic comparison for $p_0$-$⟨p_T⟩$ correlation of kaon, $\varphi$, $p$ and $\Lambda$ in $pp$, $p$-Pb, Pb-Pb and Au+Au collisions at RHIC and LHC energies indicates that $p_0$ is a sensitive physical quantity of reflecting the production property of soft hadrons in high energy collisions.

22 pages, 14 figures

References in corpus (16)

• Systematic Measurements of Identified Particle Spectra in pp, d+Au and Au+Au Collisions from STAR
• Measurements of Strange Particle Production in $p+p$ Collisions at $\sqrt{s}$= 200 GeV
• Hydrodynamic Models for Heavy Ion Collisions
• Global Analysis of Fragmentation Functions for Protons and Charged Hadrons
• Multiplicity dependence of $\pi$, K, and p production in pp collisions at $\sqrt{s}=13$ TeV
• Production of light-flavor hadrons in pp collisions at $\sqrt{s}$ = 7 and $\sqrt{s}$ = 13 TeV
• Hydrodynamic radial and elliptic flow in heavy-ion collisions from AGS to LHC energies
• Production of K${}^{\ast }(892{)}^0$ and $\varphi (1020)$ in pp and Pb-Pb collisions at $\sqrt{s_{\mathrm{NN}}}=5.02$ TeV
• A hybrid model approach for strange and multi-strange hadrons in 2.76 A TeV Pb+Pb collisions
• Quark number scaling of hadronic $p_T$ spectra and constituent quark degree of freedom in $p$-Pb collisions at $\sqrt{s_{NN}}=5.02$ TeV
• New insights into hadron production mechanism from $p_T$ spectra in $pp$ collisions at $\sqrt{s}=7$ TeV
• Production of light flavor and single-charmed hadrons in $pp$ collisions at $\sqrt{s}=5.02$ TeV in an equal-velocity quark combination model
• Strange hadron production in a quark combination model in Au+Au collisions at RHIC energies
• Signals of quark combination at hadronization in $pp$ collisions at $\sqrt{s}=200$ GeV
• Multiplicity-dependent production of $\Sigma (1385{)}^{\pm }$ and $\Xi (1530{)}^0$ in pp collisions at $\sqrt{s}=13$ TeV
• Transverse momentum and multiplicity dependence of ${\Lambda }_c^{+}/D^0$ ratio in $pp$ collisions at $\sqrt{s}=13$ TeV