The primary purpose of studying quarkonium production in relativistic heavy-ion collisions is to understand the properties of the quark-gluon plasma. At various collision systems, measurements of quarkonium states of different binding energies, such as T(nS), can provide comprehensive information. A model study has been performed to investigate the modification of T(nS) production in Pb-Pb collisions at root sNN = 5.02 TeV and Au-Au collisions at root sNN = 200 GeV. A Monte Carlo simulation study is performed with a publicly available hydrodynamic simulation package for the quark-gluon plasma medium and a theoretical calculation of the temperature-dependent thermal width of T(nS) considering the gluodissociation and inelastic parton scattering for dissociation inside the medium. In addition, we perform a systematic study with different descriptions of initial collision geometry and formation time of T(nS) to investigate their impacts on yield modification. The model calculation with a varied parameter set can describe the experimental data of T(nS) in Pb-Pb collisions at 5.02 TeV and T(2S) in Au-Au collisions at 200 GeV but underestimates the modification of T(1S) at the lower collision energy. The nuclear absorption mechanism is explored to understand the discrepancy between the data and simulation.

Utilizing a quark model characterized by parameters that effectively replicate the masses of ground state hadrons, we illustrate that (us) or (ds) diquarks exhibit greater compactness in comparison to (ud) diquarks. Concretely, the binding energy of the (us) diquark - defined as the diquark's mass minus the combined masses of its individual quarks - is found to be stronger than that of the (ud) diquark. This heightened attraction present in (us) diquarks could lead to enhanced production of Ξc/D particles in high-energy pp or ultrarelativistic heavy-ion collisions.

The primary purpose of studying quarkonium production in relativistic heavy-ion collisions is to understand the properties of the quark-gluon plasma. At various collision systems, measurements of quarkonium states of different binding energies, such as Υ(nS), can provide comprehensive information. A model study has been performed to investigate the modification of Υ(nS) production in Pb-Pb collisions at √(s_NN)= 5.02 TeV and Au-Au collisions at √(s_NN)= 200 GeV. The Monte-Carlo simulation study is performed with a publicly available hydrodynamic simulation package for the quark-gluon plasma medium and a theoretical calculation of temperature-dependent thermal width of Υ(nS) considering the gluo-dissociation and inelastic parton scattering for dissociation inside the medium. In addition, we perform a systematic study with different descriptions of initial collision geometry and formation time of Υ(nS) to investigate their impacts on yield modification. The model calculation with a varied parameter set can describe the experimental data of Υ(nS) in Pb-Pb collisions at 5.02 TeV and Υ(2S) in Au-Au collisions at 200 GeV but underestimates the modification of Υ(1S) at the lower collision energy. The nuclear absorption mechanism is explored to understand the discrepancy between the data and simulation.

We discuss heavy quark diffusion and radiation in an intermediate-momentum regime where finite mass effects can be significant. Diffusion processes are described in the Fokker-Planck approximation for soft momentum transfer, while radiative ones are taken into account by nearly collinear gluon emission from a single scattering in the Boltzmann equation. We also consider radiative corrections to the transverse momentum diffusion coefficient, which are $\mathcal{O}(g^2)$ suppressed than the leading-order diffusion coefficient but logarithmically enhanced. Numerical results show that the heavy quark distribution function depends on the energy loss mechanism so that the momentum dependence of suppression is distinguishable. Employing the heavy quark diffusion coefficient constrained by lattice QCD data, we estimate the nuclear modification factor which exhibits a transition from diffusion at low momentum to radiation at high momentum. The significance of radiative effects at intermediate momentum depends on the diffusion coefficient and running coupling constant.

Quarkonium production has been studied extensively in relativistic heavy-ion collision experiments to understand the properties of the quark gluon plasma. The experimental results on the yield modification in heavy-ion collisions relative to that in $p$+$p$ collisions can be described by several models considering dissociation and regeneration effects. A yield modification beyond initial-state effects has also been observed in small collision systems such as $p$+Au and $p$+Pb collisions, but it is still premature to claim any hot medium effect. A model study in various small collision systems such as $p$+$p$, $p$+Pb, $p$+O, and O+O collisions will help quantitatively understanding nuclear effects on the $Υ(nS)$ production. A theoretical calculation considering the gluo-dissociation and inelastic parton scattering and their inverse reaction reasonably describes the suppression of $Υ(1S)$ in Pb+Pb collisions. Based on this calculation, a Monte-Carlo simulation is developed to more realistically incorporate the medium produced in heavy-ion collisions with event-by-event initial collision geometry and hydrodynamic evolution. We extend this framework to small systems to study the medium effects. In this work, we quantify the nuclear modification factor of $Υ(nS)$ as a function of charged particle multiplicity ($dN_{ch}/dη$) and transverse momentum. We also calculate the elliptic flow of $Υ(nS)$ in small collision systems.

We argue why the recently observed Tcc could either be a compact multiquark configuration or a loosely bound molecular configuration composed of charmed mesons, whereas the X (3872) is most likely a molecular configuration. The argument is based on different short range interactions for these tetraquark states coming from the color-color and color-spin interaction in a quark model, and the presence of a common strong D-wave mixing at larger distance similar to the deuteron case, which for the molecular configurations leads to large sizes. Such an analogy at large distance allows us to calculate the transverse momentum dependence of the loosely bound molecular configuration of tetraquarks produced in heavy ion collisions using the coalescence model that successfully reproduces the deuteron data using the proton spectra. The ratio of the integrated X (3872) yield obtained from our method to the psi (2S) yield obtained from the statistical hadronization model method is calculated to be 0.806 +/- 0.234, which is a factor of 2.47 larger than that obtained by using statistical model predictions for both particles and in line with the data from the CMS experiment. As the previously calculated transverse momentum distribution of the Tcc assuming the structure to be a compact multiquark configuration is markedly different, experimental measurements of the transverse distribution of the tetraquark states will discriminate between their two possible structures.

For the Ca-48 and Ra/actinide-based complete fusion reactions, the excitation functions for the production of isotopes of superheavy nuclei with charge numbers 108-116 are calculated and compared to the available experimental data. The calculated production cross sections clearly indicate the border nucleus Ds between the island of stability of superheavy nuclei and the mainland with a relatively large number of neutrons.

We revisit the transport coefficients of heavy quarkonia moving in high-temperature QCD plasmas. The thermal width and mass shift for heavy quarkonia are closely related to the momentum diffusion coefficient and its dispersive counterpart for heavy quarks, respectively. For quarkonium at rest in plasmas the longitudinal gluon part of the color-singlet self-energy diagram is sufficient to determine the leading-order thermal width, whereas the momentum dependence is obtained from the transverse gluon channel. Using the quarkonium-gluon effective vertex based on the dipole interaction of color charges, we discuss the damping rate, the effective rest and kinetic mass shifts of slowly moving quarkonia and compare with the corresponding coefficients of heavy quarks.

Excitation functions are predicted for the production of isotopes of a superheavy nucleus with charge number Z=112 in the (2-5)n -evaporation channels of the complete fusion reactions ^48 Ca+ ^233,235 U for future experiments. The calculated production cross section of the ^277 Cn isotope in the hot fusion reaction ^48 Ca+ ^233 U is compared with the experimental one in the cold fusion reaction ^70 Zn+ ^208 Pb. The strong correlation between the fusion probability and asymmetry in the entrance reaction channel is revealed. The possibility of filling the gap between the isotopes of superheavy nuclei with Z=112 produced in cold and hot fusion reactions is indicated.

We calculate the mass shift and thermal decay width of the J/ψ near the QCD transition temperature Tc by imposing two independent constraints on these variables that can be obtained first by solving the Schrödinger equation and second from the QCD sum rule approach. While the real part of the potential is determined by comparing the QCD sum rule result for charmonium and the D meson to that from the potential model result, the imaginary potential is taken to be proportional to the perturbative form multiplied by a constant factor, which in turn can be determined by applying the two independent constraints. The result shows that the binding energy and the thermal width becomes similar in magnitude at around T=1.09Tc, above which the sum rule analysis also becomes unstable, strongly suggesting that the J/ψ will melt slightly above Tc.

Based on the fact that the mass difference between the chiral partners is an order parameter of chiral phase transition and that the chiral order parameter reduces substantially at the chemical freeze-out point in ultra-relativistic heavy ion collisions, we argue that the production ratio of K1 over K⁎ in such collisions should be substantially larger than that predicted in the statistical hadronization model. We further show that while the enhancement effect might be contaminated by the relatively larger decrease of K1 meson than K⁎ meson during the hadronic phase, the signal will be visible through a systematic study on centrality as the kinetic freeze-out temperature is higher and the hadronic life time shorter in peripheral collisions than in central collisions.

We compute the energy loss of heavy quarkonia in high-temperature QCD plasmas and investigate the energy-loss effects on quarkonium suppression. Based on the effective vertex derived from the Bethe-Salpeter amplitude for quarkonium, the collisional and radiative energy loss are determined by quarkonium-gluon elastic scattering and the associated gluon-bremsstrahlung, respectively. In the energy regime E < m(gamma)(2)/T the collisional energy loss is dominant over the radiative one, and the total energy loss increases with the plasma temperature and the initial energy of quarkonium. Our numerical analysis indicates that the medium-induced energy loss of the Upsilon(1S) results in stronger suppression at higher momentum, although the energy-loss effects are found to be small compared with the previous estimates of quarkonium dissociation in heavy-ion collisions.

We investigate the hadron production from the vortical quark-gluon plasma created in heavy-ion collisions. Based on the quark-coalescence and statistical hadronization models, we show that total hadron yields summed over the spin components are enhanced by the local vorticity with quadratic dependence. The enhancement factor amounts to be a few percent and may be detectable within current experimental sensitivities. We also show that the effect is stronger for hadrons with larger spin, and thus propose a new signature of the local vorticity, which may be detected by the yield ratio of distinct hadron species having different spins such as $\phi$ and $\eta'$. The vorticity dependence of hadron yields seems robust, with consistent predictions in both of the hadron production mechanisms for reasonable values of the vorticity strength estimated for heavy-ion collisions.

We calculate the transition between a quarkonium state and an unbound heavy quark-antiquark pair through gluo-dissociation and inelastic parton scattering using a partonic picture that interpolates between the formal limits based on potential nonrelativistic QCD (pNRQCD) at different temperatures. While the thermal width increases with momentum and temperature, the quarkonium regeneration is affected by the heavy quark distribution function which depends on the diffusion constant. By solving the Boltzmann equation with the dissociation and regeneration terms, we investigate the medium modifications of quarkonium momentum spectra. Our numerical results indicate that the ϒ(1S) RAA at high transverse momentum are influenced by the regeneration effects depending on the heavy quark diffusion. In this picture, the published CMS data that show an almost transverse momentum independence can be explained by the interplay between the suppression by dissociation and enhancement by regeneration at low and high transverse momenta, respectively. With the same input, we also calculate the transverse momentum dependence of the ϒ(1S) v2 and show that it lies within the limits of the available data.

The excitation functions of the production of new heaviest isotopes of superheavy nuclei with charge numbers 112–118 are predicted in the 1n− and 2n−evaporation channels of the 48Ca-induced actinide-based complete fusion reactions for future experiments.

For weakly bound quarkonia, we rederive the next-to-leading order cross sections of quarkonium dissociation by partons that include the hard thermal loop (HTL) resummation. Our results calculated with an effective vertex from the Bethe-Salpeter amplitude reduce to those obtained by potential nonrelativistic QCD (pNRQCD) in the relevant kinematical limit, and they can be used in a wide temperature range applicable to heavy quark systems in heavy ion collisions. Based on the lattice computation of the temperature-dependent binding energy, our numerical analysis on $\Upsilon(1S)$ indicates that at high temperature the dominant mechanism for quarkonium dissociation is inelastic parton scattering as expected in the quasifree approximation, while it is the gluo-dissociation at low temperature. By comparing with the momentum diffusion coefficient of a heavy quark, we discuss possible O(g) corrections to the next-to-leading order thermal width.

We study the hadronic effects on the cc tetraquark state by focusing on the T-cc(1(+))meson during the hadronic stage of relativistic heavy ion collisions. We evaluate the absorption cross section of the T-cc meson by pions in the quasifree approximation, and investigate the time evolution of the T-cc abundance in the hadronic medium based on the effective volume and temperature of the hadronic phase at both the BNL Relativistic Heavy Ion Collider (RHIC) and the CERN Large Hadron Collider (LHC) modeled by hydrodynamic calculations with the lattice equation of state. We probe two possible scenarios for the structure of the T-cc, where it is assumed to be either a compact multiquark state or a larger sized molecular configuration composed of DD*. Our numerical results suggest that the hadronic effects on the T-cc, production are insignificant, and its final abundance depends on the initial yield of the T-cc, produced from the quark-gluon plasma phase, which will depend on the assumed structure of the state.

The excitation functions of the production of new heaviest isotopes of superheavy nuclei with charge numbers 111–117 in the pxn and αxn evaporation channels of the 48Ca-induced hot fusion reactions are predicted for the first time for future experiments.

The possibilities of direct production of new isotopes of transfermium nuclei $^{261,263,264}\mathrm{No}$, $^{263,264}\mathrm{Lr}$, $^{263,264,266,268}\mathrm{Rf}$, $^{264,265}\mathrm{Db}$, and $^{267,268,270,272}\mathrm{Sg}$ are studied in various asymmetric hot fusion-evaporation reactions with radioactive beams. The optimal reaction partners and conditions for the synthesis of new isotopes are suggested. The products of the suggested reactions can fill a gap of unknown isotopes between the isotopes of heaviest nuclei obtained in the $xn$ evaporation channels of the cold and hot complete fusion reactions with the stable beams.