Energy Dependent Chemical Potentials of Light Particles and Quarks from Yield Ratios of Antiparticles to Particles in High Energy Collisions

Abstract

We collect the yields of negatively and positively charged pions (π − and π + ), negatively and positively charged kaons (K − and K + ), as well as anti-protons (p) and protons (p) produced in mid-rapidity interval (in most cases) in central gold-gold (Au-Au), central lead-lead (Pb-Pb), and inelastic or non-single-diffractive proton-proton (pp) collisions at different collision energies. The chemical potentials of light particles and quarks are extracted from the yield ratios, π − /π + , K − /K + , andp/p, of negative to positive particles over an energy range from a few GeV to more than 10 TeV. At a few GeV (∼ 4 GeV), the chemical potentials show and the yield ratios do not show different behaviors comparing with those at other energies, though the limiting values of the chemical potentials and the yield ratios at very high energy are zero and one respectively.

Energy-Dependent Chemical Potentials of Light Hadrons and Quarks Based on Transverse Momentum Spectra and Yield Ratios of Negative to Positive Particles

“…Assuming that μ u , μ d , and μ s represent the chemical potentials of u, d, and s quarks, respectively, and according to Equation (5) and references [12,57,60] under the same value of chemical freeze-out temperature, the yield ratios in terms of quark chemical potentials can be written as…”

“…The critical energy of phase transition [1][2][3][4] is important for studying the quantum chromodynamics (QCD) phase diagram [5,6] and the properties of quark-gluon plasma (QGP) [7][8][9], so more and more scientists devote to finding the critical energy. The experiments performed on the Relativistic Heavy Ion Collider (RHIC) and the Large Hadron Collider (LHC), especially the beam energy scan program at the RHIC, deal with a collision energy range from a few to several tens of GeV [1,7,10,11], which may contain the energy of the critical end point of hadron-quark phase tran-sition [1][2][3][4]12]. The STAR Collaboration found that the critical energy may be or below 19.6 GeV (unless otherwise noted, the energy values presented in this paper are in the center-of-mass coordinate system) [1].…”

“…The STAR Collaboration found that the critical energy may be or below 19.6 GeV (unless otherwise noted, the energy values presented in this paper are in the center-of-mass coordinate system) [1]. One study based on yield ratio (the yield ratio of negative to positive particles) and the correlation between collision energy and transverse momentum indicated that the critical energy maybe range from 11.5 GeV to 19.6 GeV [1,[13][14][15], while another study based on yield ratio showed that the critical energy may be about 4 GeV [12]. Studies about a striking pattern of viscous damping and an excitation function for (R 2 out − R 2 side ) extracted for central collisions indicated the critical energy may be close to 62.4 GeV [16][17][18].…”

“…So it is important to study baryon chemical potential for finding the CEP on QCD phase diagram. When collisions occur at high energy, especially at RHIC and LHC, the collision system probably creates the QGP matter [24][25][26] where the partonic interactions play an important role, and the baryon chemical potential is small, even close to 1 MeV or zero [12,[27][28][29]. While when energy is not very high, the transition from hadron to quark has not yet taken place in the collision system, where the hadronic interactions play an important role [1,[13][14][15], and the value of baryon chemical potential is larger.…”

Energy dependent chemical potentials of light hadrons and quarks based on transverse momentum spectra and yield ratios of negative to positive particles

“…The critical energy of phase transition [1][2][3][4] is important for studying the quantum chromodynamics (QCD) phase diagram [5,6] and the properties of quark-gluon plasma (QGP) [7][8][9], so more and more scientists devote to finding the critical energy. The experiments performed on the Relativistic Heavy Ion Collider (RHIC) and the Large Hadron Collider (LHC), especially the beam energy scan program at the RHIC, deal with a collision energy range from a few to several tens of GeV [1,7,10,11], which may contain the energy of the critical end point of hadron-quark phase transition [1][2][3][4]12]. The STAR Collaboration found that the critical energy may be or below 19.6 GeV [1].…”