Influence of temperature on ground state energy of bound polaron in asymmetric Gaussian potential quantum well in presence of electromagnetic field

By a combination method of Lee-Low-Pines unitary transformation method and Pekar-type variational method,the ground state energy(GSE)of the bound polaron is studied in the asymmetrical Gaussian potential quantum well considering the temperature and electromagneticfield.The impacts of the temperature and asymmetrical Gaussian potential,electromagnetic field and phonon-electron coupling upon the GSE are obtained.The results show that the GSE of the bound polaron not only oscillates as the temperature changes regardless of the electromagneticfield and asymmetrical Gaussian potential and Coulomb impurity potential(CIP)and electron-phonon coupling but also has different rules with the electromagnetic field and asymmetrical Gaussian potential and CIP and electron-phonon coupling at different temperature zones.

Different production sources of light nuclei in ultra-relativistic heavy-ion collisions

We systematically study different production sources of light nuclei in ultra-relativistic heavy-ion collisions with a new method, an exclusive quark combination model + an inclusive hadron recombination model. We take deuterons and ~3 He produced in Pb-Pb collisions at ■= 2.76 TeV as examples to show the contribution of different production sources by studying their rapidity densities dN/dy, yield ratios and transverse momentum(PT)spectra just after hadronization and at the final kinetic freeze-out. We find that about a half of d and a fourth of ~3 He created just after hadronization can survive after the hadronic evolution process. Nucleons from A resonance decays make a much larger contribution to the regeneration of light nuclei at the hadronic phase stage, and this contribution is about 77% and 90% for d and ~3 He, respectively, calculated at the final kinetic freeze-out. In addition, we give an explanation for the constant behaviors of yield ratios d/p and ~3 He/p as a function of the averaged charged multiplicity in Pb-Pb collisions and also provide a possible explanation for the observation that d/p in Pb-Pb collisions is larger by a factor of about two than in pp collisions at LHC energies.

Production of light-flavor and single-charmed hadrons in pp collisions at√s=5.02 TeV in an equal-velocity quark combination model

We apply an equal-velocity quark combination model to study the production of light-flavor hadrons and single-charmed hadrons at midrapidity in the pp collisions at √s= 5.02 TeV. We find that the experimental data for the pT spectra of Ω and φ exhibit the quark number scaling property, which clearly indicates the quark combination mechanism at hadronization. Experimental data for the pT spectra of p,Λ,Ξ,Ω,φ and K^(+0) are systematically described by the model. The non-monotonic pT dependence of the Ω/φ ratio is naturally explained, and we find that it is closely related to the shape of the logarithm of the strange quark pT distribution. Using the pT spectra of light-flavor quarks obtained from light-flavor hadrons and the pT spectrum of charm quarks, which is consistent with perturbative QCD calculations, the experimental data for differential cross-sections of D^(0,+), D^(+)_s), and Λ^(+)_(c) as functions of p are systematically described. We predict the differential cross-sections of Ξ^(0,+)_(c) and Ω^(0)_(c) . The ratio Ξ^(0,+)_(c) /D^0) in our model is approximately 0.16, and Ω^(0)_(c) /D^(0) is approximately 0.012, owing to the cascade suppression of strangeness.In addition, the predicted Ξ^(0,+)_(c) /D^0) ratios exhibit the non-monotonic dependence on pT in the low pT range.

Constituent quark number scaling from strange hadron spectra in pp collisions at ■=13 TeV

We show that the p_T spectra ofΩ^-andφat midrapidity in the inelastic events in pp collisions at■=13 TeV exhibit a constituent quark number scaling property,which is a clear signal of quark combination mechanism at hadronization.We use a quark combination model with equal velocity combination approximation to systematically study the production of identified hadrons in pp collisions at■=13 TeV.The midrapidity spectra for protons,∧,Ξ^-,Ω^-,φand K~*in the inelastic events are simultaneously fitted by the model.The multiplicity dependence of the yields of these hadrons are also well understood.The strong p_T dependence of the p/φratio is well explained by the model,which further suggests that the production of two hadrons with similar masses is determined by their quark content at hadronization.The p_T spectra of strange hadrons at midrapidity in different multiplicity classes in pp collisions at■=13 TeV are predicted for further tests of the model.The midrapidity p_T spectra of soft(p_T<2 GeV/c)strange quarks and up/down quarks at hadronization in pp collisions at■=13 TeV are extracted.

Statistical method in quark combination model

We present a new method for solving the probability distribution for baryons,antibaryons,and mesons at the hadronization of the constituent quark and antiquark system.The hadronization is governed by the quark combination rule in the quark combination model developed by the Shandong Group.We employ the method of the generating function to derive the outcome of the quark combination rule,which is significantly simpler and easier to generalize than the original method.Furthermore,we use the formula of the quark combination rule and its generalization to study the property of the multiplicity distribution of net-protons.Taking a naive case of quark number fluctuations and correlations at hadronization,we calculate ratios of multiplicity cumulants of final-state net-protons and discuss the potential applicability of the quark combination model by studying hadronic multiplicity fluctuations and the underlying phase transition property in relativistic heavy-ion collisions.