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Fu-Hu Liu

Publications and source records attributed to Fu-Hu Liu.

At least 55 records · Page 3Linked to original sources

A new description of transverse momentum spectra of identified particles produced in proton-proton collisions at high energies

The transverse momentum spectra of identified particles produced in high energy proton-proton ($p+p$) collisions are empirically described by a new method with the framework of participant quark model or the multisource model at the quark level, in which the source itself is exactly the participant quark. Each participant (constituent) quark contributes to the transverse momentum spectrum, which is described by the TP-like function, a revised Tsallis--Pareto-type function. The transverse momentum spectrum of the hadron is the convolution of two or more TP-like functions. For a lepton, the transverse momentum spectrum is the convolution of two TP-like functions due to two participant quarks, e.g. projectile and target quarks, taking part in the collisions. A discussed theoretical approach seems to describe the $p+p$ collisions data at center-of-mass energy $\sqrt{s}=200$ GeV, 2.76 TeV, and 13 TeV very well.

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Effective (kinetic freeze-out) temperature, transverse flow velocity and kinetic freeze-out volume in high energy collisions

The transverse momentum spectra of different types of particles produced in central and peripheral gold-gold (Au-Au) and (inelastic) proton-proton ($pp$) collisions at the Relativistic Heavy Ion Collider (RHIC), as well as in central and peripheral lead-lead (Pb-Pb) and $pp$ collisions at the Large Hadron Collider (LHC) are analyzed by the standard distribution in terms of multi-component. The obtained results from the standard distribution give an approximate agreement with the measured experimental data by the STAR, PHENIX and ALICE Collaborations. The methodical behavior of the effective (kinetic freeze-out) temperature, transverse flow velocity and kinetic freeze-out volume with the mass dependence for different particles is obtained, which observes the early kinetic freeze-out of heavier particles as compared to the lighter particles. The parameters for emissions of different particles are observed to be different, which reveals a direct signature of the mass dependent differential kinetic freeze-out. It is also observed that the peripheral nucleus-nucleus ($AA$) and $pp$ collisions at the same center-of-mass energy per nucleon pair are close in terms of the extracted parameters.

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Excitation function of initial temperature of heavy flavor quarkonium emission source in high energy collisions

The transverse momentum spectra of $J/ψ$, $ψ(2S)$, and $Υ(nS, n=1,2,3)$ produced in proton-proton ($p$+$p$), proton-antiproton ($p$+$\bar{p}$), proton-lead ($p$+Pb), gold-gold (Au+Au), and lead-lead (Pb+Pb) collisions over a wide energy range are analyzed by the (two-component) Erlang distribution, the Hagedorn function (the inverse power-law), and the Tsallis-Levy function. The initial temperature is obtained from the color string percolation model due to the fit by the (two-component) Erlang distribution in the framework of multisource thermal model. The excitation functions of some parameters such as the mean transverse momentum and initial temperature increase from dozens of GeV to above 10 TeV. The mean transverse momentum and initial temperature decrease (increase slightly or do not change obviously) with the increase of rapidity (centrality). Meanwhile, the mean transverse momentum of $Υ(nS, n=1,2,3)$ is larger than that of $J/ψ$ and $ψ(2S)$, and the initial temperature for $Υ(nS, n=1,2,3)$ emission is higher than that for $J/ψ$ and $ψ(2S)$ emission, which shows a mass-dependent behavior.

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Energy scan/dependence of kinetic freeze-out scenarios of multi-strange and other identified particles in central nucleus-nucleus collisions

The transverse momentum (mass) spectra of the multi-strange and non-multi-strange (i.e. other identified) particles in central gold-gold (Au-Au), lead-lead (Pb-Pb), argon-muriate (Ar-KCl) and nickel-nickel (Ni-Ni) collisions over a wide energy range have been studied in this work. The experimental data measured by various collaborations have been analyzed. The blast-wave fit with Tsallis statistics is used to extract the kinetic freeze-out temperature and transverse flow velocity from the experimental data of transverse momentum (mass) spectra. The extracted parameters increase with the increase of collision energy and appear with the trend of saturation at the Beam Energy Scan (BES) energies at the Relativistic Heavy Ion Collider (RHIC). This saturation implies that the onset energy of phase transition of partial deconfinement is 7.7 GeV and that of whole deconfinement is 39 GeV. Furthermore, the energy scan/dependence of kinetic freeze-out scenarios are observed for the multi-strange and other identified particles, though the multiple freeze-out scenarios are also observed for various particles.

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Kinetic freeze-out properties from transverse momentum spectra of pions in high energy proton-proton collisions

Transverse momentum spectra of negative and positive pions produced at mid-(pseudo)rapidity in inelastic or non-single-diffractive proton-proton collisions over a center-of-mass energy, $\sqrt{s}$, range from a few GeV to above 10 TeV are analyzed by the blast-wave fit with Boltzmann (Tsallis) distribution. The blast-wave fit results are well fitting to the experimental data measured by several collaborations. In a particular superposition with Hagedorn function, both the excitation functions of kinetic freeze-out temperature ($T_0$) of emission source and transverse flow velocity ($β_T$) of produced particles obtained from a given selection in the blast-wave fit with Boltzmann distribution have a hill at $\sqrt{s}\approx10$ GeV, a drop at dozens of GeV, and then an increase from dozens of GeV to above 10 TeV. However, both the excitation functions of $T_0$ and $β_T$ obtained in the blast-wave fit with Tsallis distribution do not show such a complex structure, but a very low hill. In another selection for the parameters or in the superposition with the usual step function, $T_0$ and $β_T$ increase generally quickly from a few GeV to about 10 GeV and then slightly at above 10 GeV, there is no such the complex structure, when also studying nucleus-nucleus collisions.

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Dependence of temperatures and kinetic freeze-out volume on centrality in Au-Au and Pb-Pb collisions at high energy

Centrality-dependent double-differential transverse momentum spectra of negatively charged particles ($π^-$, $K^-$ and $\bar p$) at mid-(pseudo)rapidity interval in nuclear collisions are analyzed by the standard distribution in terms of multi-component. The experimental data measured in gold-gold (Au-Au) collisions by the PHENIX Collaboration at the Relativistic Heavy Ion Collider (RHIC) and in lead-lead (Pb-Pb) collisions by the ALICE Collaboration at the Large Hadron Collider (LHC) are studied. The effective temperature, initial temperature, kinetic freeze-out temperature, transverse flow velocity and kinetic freeze-out volume are extracted from the fitting to transverse momentum spectra. We observed, that the mentioned five quantities increase with the increase of event centrality due to the fact that the average transverse momentum increases with the increase of event centrality. This renders that larger momentum (energy) transfer and further multiple-scattering had happened in central centrality.

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Excitation functions of related parameters from transverse momentum (mass) spectra in high energy collisions

Transverse momentum (mass) spectra of positively and negatively charged pions, positively and negatively charged kaons, protons and antiprotons produced at mid-(pseudo)rapidity in various collisions at high energies are analyzed in this work. The experimental data measured in central gold-gold, central lead-lead, and inelastic proton-proton collisions by several international collaborations are studied. The (two-component) standard distribution is used to fit the data and extract the excitation function of effective temperature. Then, the excitation functions of kinetic freeze-out temperature, transverse flow velocity, and initial temperature are obtained. In the considered collisions, the four parameters increase with the increase of collision energy in general, and the kinetic freeze-out temperature appears the trend of saturation at the top Relativistic Heavy Ion Collider and the Large Hadron Collider.

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Multiparticle production and initial quasi-temperature from proton induced carbon collisions at $p_{Lab}=31$ GeV/$c$

The momentum spectra of charged pions ($π^+$ and $π^-$) and kaons ($K^+$ and $K^-$), as well as protons ($p$), produced in the beam protons induced collisions in a 90-cm-long graphite target [proton-carbon ($p$-C) collisions] at the beam momentum $p_{Lab}=31$ GeV/$c$ are studied in the framework of a multisource thermal model by using Boltzmann distribution and Monte Carlo method. The theoretical model results are approximately in agreement with the experimental data measured by the NA61/SHINE Collaboration. The related free parameters (effective temperature, rapidity shifts, and fraction of non-leading protons) and derived quantities (average transverse momentum and initial quasi-temperature) under given experimental conditions are obtained. It is shown that the considered free parameters and derived quantities to be strongly dependent on emission angle over a range from 0 to 380 mrad and weakly dependent on longitudinal position (graphite target thickness) over a range from 0 to 90 cm.

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Multisource thermal model to the transverse momentum spectra in pp collisions at RHIC and LHC energies

In this paper, an improved multi-source thermal model is used to analyze the transverse momentum spectra in $pp$ collisions at high energies ranging from $\sqrt{\mathrm{\it s_{NN}}}$ = 62.4 GeV to 7 TeV. We give a detailed comparison between the theoretical results and experimental data at RHIC and LHC energies. It is shown that the excitation factors of emission sources depend linearly on ln$\sqrt{\mathrm{\it s_{NN}}}$ in the framework. Based on the variation regularity of the source-excitation factors, transverse momentum spectra are predicted in $pp$ collisions at higher energies, potential future $pp$ colliders operating at $\sqrt{\mathrm{\it s_{NN}}}$ = 33 and 100 TeV.

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Initial, effective, and kinetic freeze-out temperatures from transverse momentum spectra in high energy proton(deuteron)-nucleus and nucleus-nucleus collisions

The transverse momentum spectra of charged particles produced in proton(deuteron)-nucleus and nucleus-nucleus collisions at high energies are analyzed by the Hagedorn thermal model and the standard distribution in terms of multi-component. The experimental data measured in central and peripheral gold-gold (Au-Au) and deuteron-gold ($d$-Au) collisions by the PHENIX Collaboration at the Relativistic Heavy Ion Collider (RHIC), as well as in central and peripheral lead-lead (Pb-Pb) and proton-lead ($p$-Pb) collisions by the ALICE Collaboration at the Large Hadron Collider (LHC) are fitted by the two models. The initial, effective, and kinetic freeze-out temperatures are then extracted from the fitting to the transverse momentum spectra. It is shown that the initial temperature is larger than the effective temperature, and the effective temperature is larger than the kinetic freeze-out temperature. The three types of temperatures in central collisions are comparable with those in peripheral collisions, and those at the LHC are comparable with those at the RHIC.

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Initial and final state temperatures of antiproton emission sources in high energy collisions

The momentum or transverse momentum spectra of antiprotons produced at mid-rapidity in proton-helium ($p$+He), gold-gold (Au+Au), deuton-gold ($d$+Au), and lead-lead (Pb+Pb) collisions over an energy range from a few GeV to a few TeV are analyzed by the Erlang distribution, the inverse power-law (the Hagedorn function), and the blast-wave fit, or the superposition of two-component step function. The excitation functions of parameters such as the mean transverse momentum, initial state temperature, kinetic freeze-out temperature, and transverse flow velocity increase (slightly) from a few GeV to a few TeV and from peripheral to central collisions. At high energy and in central collisions, large collision energy is deposited in the system, which results in high degrees of excitation and expansion.

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Light particle and quark chemical potentials from negatively to positively charged particle yield ratios corrected by removing strong and weak decays

The yield ratios of negatively to positively charged pions ($π^-/π^+$), negatively to positively charged kaons ($K^-/K^+$), and anti-protons to protons ($\bar p/p$) produced in mid-rapidity interval in central gold-gold (Au-Au) collisions, central lead-lead (Pb-Pb) collisions, and inelastic (INEL) or non-single-diffractive (NSD) proton-proton ($pp$) collisions, as well as in forward rapidity region in INEL $pp$ collisions are analyzed in the present work. Over an energy range from a few GeV to above 10 TeV, the chemical potentials of light flavor particles (pion, kaon, and proton) and quarks (up, down, and strange quarks) are extracted from the mentioned yield ratios in which the contributions of strong decay from high-mass resonance and weak decay from heavy flavor hadrons are removed. Most energy dependent chemical potentials show the maximum at about 4 GeV, while the energy dependent yield ratios do not show such an extremum.

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Quasi-two-body decays $B_{(s)} \to P D_0^*(2400) \to P D π$ in the perturbative QCD approach

We study the quasi-two-body decays $B\to P D^{\ast}_0(2400) \to P Dπ$ with $P=(π, K, η, η^{\prime})$ in the perturbative QCD factorization approach. The predicted branching fractions for the considered decays are in the range of $10^{-9}$-$10^{-4}$. The strong Cabibbo-Kobayashi-Maskawa (CKM) suppression factor $R_{CKM}\approx λ^4 (\barρ^2 + \barη^2) \approx 3\times 10^{-4}$ results in the great difference of the branching ratios for the decays with $D_0^*$ and $\bar{D}_0^*$ as the intermediate states. The ratio $R_{\bar{D}_0^{*0}}$ between the decays $B^0 \to \bar{D}_0^{*0} K^0\to D^-π^+K^0$ and $B^0 \to \bar{D}_0^{*0}π^0 \to D^-π^+π^0$ is about $0.091^{+0.003}_{-0.005}$, consistent with the flavour-$SU$(3) symmetry result. The ratio for the branching fractions is found to be $1.10^{+0.05}_{-0.02}$ between $\mathcal{B}(B_s^0\to D_0^{*+}K^-\to D^0π^+K^-)$ and $\mathcal{B}(B^0\to D_0^{*+} π^-\to D^0π^+ π^-)$ and to be $1.03^{+0.06}_{-0.07}$ between $\mathcal{B}(B_s^0\to\bar{D}_0^{*0} \bar{K}^0\to D^-π^+ \bar{K}^0)$ and $2\mathcal{B}(B^0\to \bar{D}_0^{*0}π^0\to D^-π^+π^0)$. The predictions in this work can be tested by the future experiments.

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Energy dependent chemical potentials of light particles and quarks from yield ratios of antiparticles to particles in high energy collisions

We collect the yields of charged pions ($π^-$ and $π^+$), charged kaons ($K^-$ and $K^+$), anti-protons ($\bar p$), 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, $π^-/π^+$, $K^-/K^+$, and $\bar p/p$, of antiparticles to particles over an energy range from a few GeV to above 10 TeV. At a few GeV ($\sim4$ GeV), the chemical potentials show, and the yield ratios do not show, different trends comparing with those at other energies, though the limiting values of the chemical potentials and the yield ratios at very high energy are 0 and 1 respectively.

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Mutual derivation between arbitrary distribution forms of momenta and momentum components

The mutual derivation between arbitrary distribution forms of momenta and momentum components of particles produced in an isotropic emission source are systematically studied in terms of probability theory and mathematical statistics. The distributions of rapidities and pseudorapidities are expediently studied. As an example, the classical and relativistic ideal gas models are used to show these distributions by the analytic and Monte Carlo methods. As an application, the experimental rapidity and transverse momentum spectra of light flavor particles produced in high energy collisions are analyzed by a multi-component relativistic ideal gas model in which the single model can be replaced by other models and distributions.

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Rapidity dependent transverse momentum spectra of heavy quarkonia produced in small collision systems at the LHC

The rapidity dependent transverse momentum spectra of heavy quarkonia (J/psi and Upsilon mesons) produced in small collision systems such as proton-proton (pp) and proton-lead (p-Pb) collisions at center-of-mass energy (per nucleon pair) 5-13 TeV are described by a two-component statistical model which is based on the Tsallis statistics and inverse power-law. The experimental data measured by the LHCb Collaboration at the Large Hadron Collider (LHC) are well fitted by the model results. The related parameters are obtained and the dependences of parameters on rapidity are analyzed.

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Chemical potentials of light hadrons and quarks from yield ratios of negative to positive particles in high energy $pp$ collisions

We describe the transverse momentum spectra of $π^\pm$, $K^\pm$, $p$, and $\bar{p}$ produced in proton-proton ($pp$) collisions at different collision energies by using a Tsallis-Pareto-type function, and obtain the yield ratios, $k_π$, $k_{K}$, and $k_{p}$, of negative to positive particles from the fitting results of transverse momentum spectra and the extracted normalization constants. The transverse momentum dependent and energy dependent chemical potentials of light hadrons ($π$, $K$, and $p$) and quarks ($u$, $d$, and $s$) in $pp$ collisions are then extracted successively from the yield ratios. The six types of transverse momentum dependent chemical potentials show the trend of being close to zero in low-$p_T$ region and away from zero in high-$p_T$ region. Meanwhile, the energy dependent chemical potentials seem to decrease slightly with the increase of the collision energy, and the limiting values of the six types of chemical potentials are zero at very high energy in $pp$ collisions, which confirms that the partonic interactions possibly play an important role at RHIC and LHC, especially at LHC.

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Possible scenarios for single, double, or multiple kinetic freeze-out in high energy collisions

Transverse momentum spectra of different types of particles produced in mid-rapidity interval in central and peripheral gold-gold (Au-Au) collisions, central and peripheral deuteron-gold ($d$-Au) collisions, and inelastic (INEL) or non-single-diffractive (NSD) proton-proton ($pp$) collisions at the Relativistic Heavy Ion Collider (RHIC), as well as in central and peripheral lead-lead (Pb-Pb) collisions, central and peripheral proton-lead ($p$-Pb) collisions, and INEL or NSD $pp$ collisions at the Large Hadron Collider (LHC) are analyzed by the blast-wave model with Boltzmann-Gibbs statistics. The model results are largely consist with the experimental data in special transverse momentum ranges measured by the PHENIX, STAR, ALICE, and CMS Collaborations. It is showed that the kinetic freeze-out temperature of emission source is dependent on particle mass, which reveals the scenario for multiple kinetic freeze-out in collisions at the RHIC and LHC. The scenario for single or double kinetic freeze-out is not observed in this study.

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