arXiv subjects

Xiao-Ming Xu

Publications and source records attributed to Xiao-Ming Xu.

At least 19 recordsLinked to original sources

arXiv2025

Production of $ψ(4040)$, $ψ(4160)$, and $ψ(4415)$ mesons in strong interactions

Using the inelastic scattering of charmed strange mesons by open-charm mesons in hadronic matter produced in Pb-Pb collisions at the Large Hadron Collider, we study the production of $ψ(4040)$, $ψ(4160)$, and $ψ(4415)$ mesons. Master rate equations are established for inelastic scattering. The scattering is caused by quark interchange in association with color interactions between all constituent pairs in different mesons. We consider fifty-one reactions between charmed strange and open-charm mesons. Unpolarized cross sections for the reactions are obtained from a temperature-dependent interquark potential. The temperature dependence of the cross sections causes the contributions of the reactions to the production of $ψ(4040)$, $ψ(4160)$, and $ψ(4415)$ to change with decreasing temperature during the evolution of hadronic matter. For central Pb-Pb collisions at $\sqrt{s_{NN}}=5.02$ TeV, the master rate equations reveal that the $ψ(4040)$ number density is larger than the $ψ(4160)$ number density which is larger than the $ψ(4415)$ number density.

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arXiv2024

Dissociation cross sections of $ψ(3770)$, $ψ(4040)$, $ψ(4160)$, and $ψ(4415)$ mesons with nucleons

We study the dissociation of $ψ(3770)$, $ψ(4040)$, $ψ(4160)$, and $ψ(4415)$ mesons in collisions with nucleons, which takes place in high-energy proton-nucleus collisions. Quark interchange between a nucleon and a $c\bar c$ meson leads to the dissociation of the $c\bar c$ meson. We consider the reactions: $pR \to Λ_c^+ \bar{D}^0$, $pR \to Λ_c^+ \bar{D}^{*0}$, $pR \to Σ_c^{++} D^-$, $pR \to Σ_c^{++} D^{*-}$, $pR \to Σ_c^{+} \bar{D}^0$, $pR \to Σ_c^{+} \bar{D}^{*0}$, $pR \to Σ_c^{*++} D^-$, $pR \to Σ_c^{*++} D^{*-}$, $pR \to Σ_c^{*+} \bar{D}^0$, and $pR \to Σ_c^{*+} \bar{D}^{*0}$, where $R$ stands for $ψ(3770)$, $ψ(4040)$, $ψ(4160)$, or $ψ(4415)$. A reaction of a neutron and a $c\bar c$ meson corresponds to a reaction of a proton and the $c\bar c$ meson by replacing the up quark with the down quark and vice versa. Transition-amplitude formulas are derived from the $S$-matrix element. Unpolarized cross sections are calculated with the transition amplitudes for scattering in the prior form and in the post form. The cross sections relate to nodes in the radial wave functions of $ψ(3770)$, $ψ(4040)$, $ψ(4160)$, and $ψ(4415)$ mesons.

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arXiv2023

Cross sections for inelastic $K$+$ϕ$ scattering

In the first Born approximation we study the reactions $Kϕ\toπK$, $ρK$, $πK^*$, and $ρK^*$ with quark-antiquark annihilation and creation. Transition amplitudes are derived with the development in spherical harmonics of the relative-motion wave functions of the two initial mesons and of the two final mesons so that parity is conserved and the total angular momentum of the final mesons equals the one of the initial mesons. Unpolarized cross sections are calculated from the transition amplitudes that also contain mesonic quark-antiquark relative-motion wave functions and transition potentials for quark-antiquark annihilation and creation. Notable temperature dependence of the cross sections is shown. While the cross sections for $Kϕ\toρK$, $Kϕ\toπK^*$, and $Kϕ\toρK^*$ may be of the millibarn scale, the cross section for $Kϕ\toπK$ is very small.

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arXiv2023

Dissociation Cross Sections of Large-Momentum Charmonia with Light Mesons in Hadronic Matter

Momenta of charmonia created in Pb-Pb collisions at the Large Hadron Collider are so large that three or more mesons may be produced when the charmonia collide with light mesons in hadronic matter. We study the meson-charmonium collision in a mechanism where the collision produces two quarks and two antiquarks, the charm quark then fragmenting into charmed mesons, and the other three constituents as well as quarks and antiquarks created from vacuum give rise to two or more mesons. The absolute square of the transition amplitude for the production of two quarks and two antiquarks is derived from the $S$-matrix element, and cross-section formulas are derived from the absolute square of the transition amplitude and charm-quark fragmentation functions. With a temperature-dependent quark potential, we calculate unpolarized cross sections for inclusive $D^+$, $D^0$, $D^+_s$, or $D^{*+}$ production in scattering of charmonia by $π$, $ρ$, $K$, or $K^\ast$ mesons. At low center-of-mass energies of the charmonium and the light meson, the cross sections are very small. At high energies the cross sections have obvious temperature dependence, and are comparable to peak cross sections of two-to-two meson-charmonium reactions.

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arXiv2022

Production of $ψ(4040)$, $ψ(4160)$, and $ψ(4415)$ mesons in hadronic matter

We present the first study of production of $ψ(4040)$, $ψ(4160)$, and $ψ(4415)$ mesons in hadronic matter. Quark interchange between two colliding charmed mesons leads to the production of the three mesons. We calculate unpolarized cross sections for the reactions, $D\bar{D} \to ρR$, $D\bar{D}^* \to πR$, $D\bar{D}^* \to ρR$, $D^*\bar{D} \to πR$, $D^*\bar{D} \to ρR$, $D^*\bar{D}^* \to πR$, and $D^*\bar{D}^* \to ρR$, where $R$ stands for $ψ(4040)$, $ψ(4160)$, and $ψ(4415)$. In the temperature region covering hadronic matter the peak cross sections of producing $ψ(4040)$ are similar to or larger than the ones of producing $ψ(4415)$, and the latter are generally larger than those of producing $ψ(4160)$. With the cross sections we establish new master rate equations for $ψ(4040)$, $ψ(4160)$, and $ψ(4415)$. The equations are solved for central Pb-Pb collisions at $\sqrt{s_{NN}}=5.02$ TeV at the Large Hadron Collider. Solutions of the equations show that the $ψ(4040)$ number density at kinetic freeze-out of hadronic matter is larger than the $ψ(4415)$ number density which is larger than the $ψ(4160)$ number density.

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arXiv2021

Cross sections for 2-to-1 meson-meson scattering

We study the processes $K\bar{K} \to ϕ$, $πD \to D^\ast$, $π\bar{D} \to \bar{D}^\ast$, and the production of $ψ(3770)$, $ψ(4040)$, $ψ(4160)$, and $ψ(4415)$ mesons in collisions of charmed mesons or charmed strange mesons. The process of 2-to-1 meson-meson scattering involves a quark and an antiquark from the two initial mesons annihilating into a gluon and subsequently the gluon being absorbed by the spectator quark or antiquark. Transition amplitudes for the scattering process derive from the transition potential in conjunction with mesonic quark-antiquark wave functions and the relative-motion wave function of the two initial mesons. We derive these transition amplitudes in the partial wave expansion of the relative-motion wave function of the two initial mesons so that parity and total-angular-momentum conservation are maintained. We calculate flavor and spin matrix elements in accordance with the transition potential and unpolarized cross sections for the reactions using the transition amplitudes. Cross sections for the production of $ψ(4040)$, $ψ(4160)$, and $ψ(4415)$ relate to nodes in their radial wave functions. We suggest the production of $ψ(4040)$, $ψ(4160)$, and $ψ(4415)$ as probes of hadronic matter that results from the quark-gluon plasma created in ultrarelativistic heavy-ion collisions.

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arXiv2020

Inelastic Meson-Meson Scattering in Hadronic Matter

We review studies of inelastic meson-meson scattering. In nonperturbative schemes with chiral-perturbation-theory Lagrangians and in models based on effective meson Lagrangians, inelastic meson-meson scattering leads to the successful identification of resonances in meson-meson reactions, adequate inclusion of final state interactions in particle decays, and so on. For mesons of which each consists of a quark and an antiquark, inelastic meson-meson scattering may be caused by quark-antiquark annihilation, quark-antiquark creation, quark interchange, and quark-antiquark annihilation and creation. In transition amplitudes for meson-meson scattering mesonic quark-antiquark relative-motion wave functions depend on hadronic matter, and transition potentials are given in perturbative quantum chromodynamics. Via transition amplitudes the cross sections for inelastic meson-meson scattering depend on the temperature of hadronic matter. Some prominent temperature dependence of the cross sections has been found. Inelastic meson-meson scattering becomes even more significant in proton-proton collisions and lead-lead collisions at the Large Hadron Collider.

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arXiv2020

Cross sections for 2-to-3 meson-meson scattering

We study 2-to-3 meson-meson scattering based on the process that a gluon is created from a constituent quark or antiquark and subsequently the gluon creates a quark-antiquark pair. The transition potential for the process is derived in QCD. Eight Feynman diagrams at tree level are involved in the 2-to-3 meson-meson scattering. Starting from the $S$-matrix element, we derive the unpolarized cross section from the eight transition amplitudes corresponding to the eight Feynman diagrams. The transition amplitudes contain color, spin, and flavor matrix elements. The 2-to-3 meson-meson scattering includes $ππ\to πK\bar{K}$, $πK \to ππK$, $πK \to KK\bar{K}$, $KK \to πKK$, and $K\bar{K} \to πK\bar{K}$. Cross sections for the reactions are calculated. The cross sections depend on temperature obviously, and the cross section for $πK \to ππK$ for total isospin $I=3/2$ at zero temperature is compared to experimental data. By comparison with inelastic 2-to-2 meson-meson scattering, we find that 2-to-3 meson-meson scattering may be as important as inelastic 2-to-2 meson-meson scattering.

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arXiv2019

Cross Sections for Inelastic 2-to-2 Meson-Meson Scattering in Hadronic Matter

With quark-antiquark annihilation and creation in the first Born approximation, we study the reactions: $K \bar {K} \to K \bar {K}^\ast, ~K \bar{K} \to K^* \bar{K}, ~πK \to πK^\ast, ~πK \to ρK, ~ππ\to K \bar{K}^\ast, ~ππ\to K^\ast \bar{K}, ~ππ\to K^\ast \bar{K}^\ast, ~πρ\to K \bar{K}, ~πρ\to K^\ast \bar{K}^\ast, ~ρρ\to K^\ast \bar{K}^\ast, ~K \bar{K}^\ast \to ρρ$, and $K^* \bar{K} \to ρρ$. Unpolarized cross sections for the reactions are obtained from transition amplitudes that are composed of mesonic quark-antiquark relative-motion wave functions and the transition potential for quark-antiquark annihilation and creation. From a quark-antiquark potential that is equivalent to the transition potential, we prove that the total spin of the two final mesons may not equal the total spin of the two initial mesons. Based on flavor matrix elements, cross sections for some isospin channels of reactions can be obtained from the other isospin channels of reactions. Remarkable temperature dependence of the cross sections is found.

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arXiv2018

Cross sections for inelastic meson-meson scattering

We study two kinds of inelastic meson-meson scattering. The first kind is inelastic 2-to-2 meson-meson scattering that is governed by quark interchange as well as quark-antiquark annihilation and creation. Cross-section formulas are provided to get unpolarized cross sections for $πK \to ρK^\ast$ for $I=1/2$, $πK^\ast \to ρK$ for $I=1/2$, $πK^\ast \to ρK^\ast$ for $I=1/2$, and $ρK \to ρK^\ast$ for $I=1/2$. Near threshold, quark interchange dominates the reactions near the critical temperature. The second kind is 2-to-1 meson-meson scattering with the process that a quark in an initial meson and an antiquark in another initial meson annihilate into a gluon and subsequently the gluon is absorbed by the other antiquark or quark. The transition potential for the process is derived. Four Feynman diagrams at tree level contribute to the 2-to-1 meson-meson scattering. Starting from the $S$-matrix element, the isospin-averaged unpolarized cross section with transition amplitudes is derived. The cross sections for $ππ\to ρ$ and $πK \to K^*$ decrease with increasing temperature.

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arXiv2017

Dissociation of large transverse-momentum prompt J/psi produced in Pb-Pb collisions at the LHC

A collision of a light meson and a charmonium produces quarks and antiquarks first, then the charm quark fragments into a charmed hadron, and finally three or more mesons are produced. This is the mechanism that we consider and propose to understand the prompt-J/psi nuclear modification factor in the range of J/psi transverse momentum from 10 GeV/c to 18 GeV/c, as measured by the CMS Collaboration and the ATLAS Collaboration. Unpolarized cross sections are derived and calculated for the reactions pion+charmonium ->H_c+X with H_c being a charmed meson. Numerical cross sections are parametrized and used to calculate the dissociation rate of charmonium in the interaction with pions in hadronic matter. The momentum dependence of the rate obtained is so as to lead to a decreasing charmonium nuclear modification factor with increasing transverse momentum.

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arXiv2016

Charmonium dissociation in collision with phi meson in hadronic matter

The phi-charmonium dissociation reactions in hadronic matter are studied. Unpolarised cross sections for 12 reactions are calculated in the Born approximation, in the quark-interchange mechanism and with a temperature-dependent quark potential. The potential leads to remarkable temperature dependence of the cross sections. With the cross sections and the phi distribution function we calculate the dissociation rates of the charmonia in the interactions with the phi meson in hadronic matter. The dependence of the rates on temperature and charmonium momentum is meaningful to the influence of phi mesons on charmonium suppression.

nucl-th↗

arXiv2016

Charmonium dissociation cross sections and charmonium dissociation rates in hadronic matter

K*-charmonium dissociation reactions in hadronic matter are studied in the Born approximation, in the quark-interchange mechanism, and with a temperature-dependent quark potential. We obtain the temperature dependence of unpolarized cross sections for K*-charmonium dissociation reactions which produce charmed mesons and charmed strange mesons. We use the cross sections for charmonium dissociation in collisions with pion, rho meson, kaon, vector kaon, and eta meson to calculate dissociation rates of charmonium with the five types of mesons. Because of the temperature dependence of the meson masses, dissociation cross sections, and meson distribution functions, the charmonium dissociation rates generally increase with the increase of temperature and decrease with the increase of charmonium momentum from 2.2 GeV/c. We find that the first derivative of the dissociation rate with respect to the charmonium momentum is zero when the charmonium is at rest. While the eta + psi' and eta + chi_c dissociation reactions can be neglected, the J/psi, psi', and chi_c dissociation are caused by the collisions with pion, rho meson, kaon, vector kaon, and eta meson.

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arXiv2015

Cross sections for inelastic meson-meson scattering via quark-antiquark annihilation

We study inelastic meson-meson scattering that is governed by quark-antiquark annihilation and creation involving a quark and an antiquark annihilating into a gluon, and subsequently the gluon creating another quark-antiquark pair. The resultant hadronic reactions include for I=1: pion + pion to rho + rho, kaon + antikaon to kaon* + antikaon*, kaon + antikaon* to kaon* + antikaon*, kaon* + antikaon to kaon* + antikaon*, as well as pion + pion to kaon + antikaon, pion + rho to kaon + antikaon*, pion + rho to kaon* + antikaon, and kaon + antikaon to rho + rho. In each reaction, one or two Feynman diagrams are involved in the Born approximation. We derive formulas for the unpolarized cross section, the transition amplitude, and the transition potential for quark-antiquark annihilation and creation. The unpolarized cross sections for the reactions are calculated at six temperatures, and prominent temperature dependence is found. It is due to differences among mesonic temperature dependence in hadronic matter.

hep-ph↗

arXiv2015

Temperature-dependent cross sections for charmonium dissociation in collisions with kaons and eta mesons in hadronic matter

We study kaon-charmonium and eta-charmonium dissociation reactions. The K-charmonium dissociation and the eta-charmonium dissociation include 27 reactions. Cross sections for the reactions are calculated in the Born approximation, in the quark-interchange mechanism and with a temperature-dependent quark potential. The temperature dependence of peak cross sections of endothermic reactions is linked to the temperature dependence of quark-antiquark relative-motion wave functions, meson masses and the quark potential. Although the eta meson and kaon have similar masses, the energy and temperature dependence of the eta-charmonium dissociation cross sections are quite different from those of the K-charmonium dissociation cross sections. Using the eta-charmonium and pion-charmonium dissociation cross sections, we calculate the ratio of the corresponding dissociation rates in hadronic matter and we find that such rates are comparable at low J/psi momenta.

hep-ph↗

arXiv2015

Relation between quark-antiquark potential and quark-antiquark free energy in hadronic matter

In the high-temperature quark-gluon plasma and its subsequent hadronic matter created in a high-energy nucleus-nucleus collision, the quark-antiquark potential depends on the temperature. The temperature-dependent potential is expected to be derived from the free energy obtained in lattice gauge theory calculations. This requires one to study the relation between the quark-antiquark potential and the quark-antiquark free energy. When the system's temperature is above the critical temperature, the potential of a heavy quark and a heavy antiquark almost equals the free energy, but the potential of a light quark and a light antiquark, of a heavy quark and a light antiquark and of a light quark and a heavy antiquark is substantially larger than the free energy. When the system's temperature is below the critical temperature, the quark-antiquark free energy can be taken as the quark-antiquark potential. This allows one to apply the quark-antiquark free energy to study hadron properties and hadron-hadron reactions in hadronic matter.

hep-ph↗

arXiv2015

Origin of Temperature of Quark-Gluon Plasma in Heavy Ion Collisions

Initially produced quark-gluon matter at RHIC and LHC does not have a temperature. A quark-gluon plasma has a high temperature. From this quark-gluon matter to the quark-gluon plasma is the early thermalization or the rapid creation of temperature. Elastic three-parton scattering plays a key role in the process. The temperature originates from the two-parton scattering, the three-parton scattering, the four-parton scattering and so forth in quark-gluon matter.

nucl-th↗

arXiv2014

Temperature dependence of cross sections for meson-meson nonresonant reactions in hadronic matter

We study unpolarized cross sections for the endothermic nonresonant reactions: pion pion to rho rho for I=2, KK to K*K* for I=1, KK* to K*K* for I=1, pion K to rho K* for I=3/2, pion K* to rho K* for I=3/2, rho K to rho K* for I=3/2, and pion K* to rho K for I=3/2, which take place in hadronic matter. We provide a potential that is given by perturbative QCD with loop corrections at short distances, becomes a distance-independent and temperature-dependent value at long distances, and has a spin-spin interaction with relativistic modifications. The Schrodinger equation with the potential yields temperature-dependent meson masses and mesonic quark-antiquark relative-motion wave functions. In the first Born approximation with the quark-interchange mechanism, the temperature dependence of the potential, meson masses and wave functions brings about temperature dependence of unpolarized cross sections for the seven nonresonant reactions. Noticeably, rapid changes of pion and K radii cause an increase in peak cross sections while the temperature approaches the critical temperature. Parametrizations of the numerical cross sections are given for their future applications in heavy ion collisions.

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