arXiv subjects

Su Houng Lee

Publications and source records attributed to Su Houng Lee.

At least 19 recordsLinked to original sources

arXiv2026

Production of the $ϕ$ and $Ω$ via recombination of jet parton showers in relativistic heavy ion collisions

We study the production of the $ϕ(1020)$ and $Ω(1672)$ in heavy ion collisions at $\sqrt{s_{NN}} = 5.02$ TeV by employing two complementary approaches. In the first approach, the production of the $ϕ$ and $Ω$ is discussed in the coalescence model. In the second approach, we developed a hybrid framework that combines the recombination of shower and thermal partons with remnant string fragmentation. Thermal partons in the quark-gluon plasma are modeled using a blast-wave parameterization, while the phase space information of medium-modified parton showers is generated from Q-PYTHIA, using unquenched jet partons obtained from HIJING initial inputs. We show that both approaches agree well with the experimental measurements, and demonstrate that this hybrid framework provides deeper insight into the underlying strangeness components in the production of $ϕ$ and $Ω$ in relativistic heavy-ion collisions.

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arXiv2026

Three-body forces in the quark model

We review the connection between constituent-quark Hamiltonians and QCD and investigate the long-standing difficulty of describing meson and baryon spectra with one common two-body interaction. A Hamiltonian calibrated to ground-state mesons leaves systematic baryon mass residuals, largest in the light-quark sector and decreasing toward heavier flavors. We show that a short-range, color-spin-dependent connected three-quark interaction substantially reduces this incompatibility. Mass-scaled finite-range profiles yield high-accuracy baryon spectra, whereas flavor-independent common-range profiles do not remove the residual flavor pattern. The result is tested on additional ground-state baryons outside the calibration set and through meson--baryon compatibility analyses across several alternative quark-model Hamiltonians. We also benchmark radial and orbital excitations to identify the regime in which a static compact valence Hamiltonian remains reliable, and provide explicit color-spin matrix elements for two- and three-body operators in baryons and multiquark configurations. Within the tested valence-space representations, the results indicate that a mass-dependent short-range connected three-quark interaction provides the missing contribution required for a consistent simultaneous description of meson and baryon ground-state spectra.

hep-ph↗

arXiv2026

Multiquark clustering in neutron-star matter from color-spin molecular dynamics

We study the equation of state of neutron-star matter with color-spin molecular dynamics. The calculation includes the internal color and spin degrees of freedom and their time evolution. The matter composition, including strangeness under $β$ equilibrium, is determined by energy minimization. We find two main trends. First, within the present color-spin molecular dynamics framework and under the adopted clustering criterion along the stable neutron-star branch, isolated quarklike configurations do not appear; instead, color-magnetic interactions favor the self-consistent formation of multiquark clusters. Within the same criterion, the cluster-size distribution is concentrated at quark numbers that are multiples of three, corresponding to integer baryon numbers. Second, relative to the conventional no-$K^*$ baseline, the interaction between strange and light quarks has a strong impact on neutron-star radii. This suggests that future radius measurements, together with phenomenological information on the strangeness-onset density, may help constrain flavor-sector interactions involving strangeness.

astro-ph.HE↗

arXiv2026

New nonet scalar mesons and glueballs: the mass spectra and the production yields in relativistic heavy ion collisions

We propose a new nonet scheme for scalar mesons consisting of $f_{0}(980)$, $a_{0}(980)$, $K_{0}^{\ast}(1430)$, and $f_{0}(1770)$, regarding them as quark-antiquark $P$-wave states classified by $\mathrm{SU}(3)$ light flavor symmetry. We investigate their production in relativistic heavy ion collisions, and estimate their yields by applying the statistical model and the quark coalescence model. In contrast to these scalar mesons, we regard $f_{0}(1500)$ as a glueball that is not included in the proposed nonet. We quantify the production yields of $f_{0}(1500)$ by accounting for various internal structures of this state, and compare their yields with those of the new nonet scalar mesons. Given the production yields of these hadrons, our results strongly suggests that $f_{0}(1500)$ is a glueball.

hep-ph↗

arXiv2026

The structure of the $X(3915)$ meson and its production in heavy ion collisions

We study the structure of the $X(3915)$ meson in a quark model and explore how its production in heavy ion collisions depends on its internal structure. We first analyze the $X(3915)$ as a $c\bar{c}s\bar{s}$ state and solve the Hamiltonian with color-spin interactions within the quark model. We find that the ground state of the $c\bar{c}s\bar{s}$ with total spin 0 obtained from the quark model analysis favors a separated $D_s \bar{D}_s$ state. To probe its structure further, we study its production in relativistic heavy ion collisions for various proposed configurations. We calculate the transverse momentum distributions and yields for the $X(3915)$ assuming its structure to be either a charmonium, a tetraquark, or a hadronic molecular state. We argue that by measuring the transverse momentum distributions and yields of the $X(3915)$ produced in heavy ion collisions, one can identify the structure of the $X(3915)$.

hep-ph↗

arXiv2026

$f_2(1270)\toπ+π$ as a probe of spin and vorticity in heavy-ion collisions

The correlation between vorticity and spin alignment in heavy-ion collisions can be probed through polarization measurements of hadrons, whose total spin originates from both constituent-quark spins and orbital angular momentum in the quark-model framework. To motivate such experimental studies, we calculate the general angular distribution of produced pion in $f_2(1270)\toπ+π$ using interaction Lagrangian and helicity formalism and check that both methods yield the same result. The distribution is given as a function of angle between pion and initial quantization axis of $f_2$ and the spin density matrix element of $f_2$. Its diagonal entries and $ρ_{20}$ component were computed assuming local thermal equilibrium and blast wave model for different centrality classes, hence given as a function of azimuthal angle with respect to the impact parameter.

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arXiv2026

Role of $Σ^*(1385)$ on $Λ$ hyperon polarization in relativistic heavy ion collisions

The effect of $Σ^*(1385)$ baryon resonance on the time evolution of the $Λ$ hyperon polarization in hadronic matter is studied using a kinetic approach. This approach explicitly includes the production of the $Σ^*$ resonance from the $Λ-π$ and $Σ(1192)-π$ scatterings as well as its decay into $Λ+π$ or $Σ+π$. The resulting coupled kinetic equations governing the time evolution of $Λ$, $Σ$ and $Σ^*$ numbers and polarizations are solved for Au-Au collisions at $\sqrt{s_{NN}}=7.7$ GeV and 20-50\% centrality, using initial values determined by thermal yields and the thermal vorticity at chemical freeze-out temperature. As the hadronic matter expands and cools, the $Λ$ polarization is found to increase slightly during early times and then decreases very slowly afterwards, while the $Σ$ polarization remains nearly constant and the $Σ^*$ polarization continuously decreases. Including feed-down contributions to the $Λ$ polarization from the decays of partially polarized $Σ^0$, $Σ^*$, and $Ξ(1322)$ hyperons, where the $Ξ$ polarization is obtained by solving coupled kinetic equations for the $Ξ$ and $Ξ^*(1532)$ system, the resulting $Λ$ polarization becomes smaller and decreases over time. In both cases, however, the time variation of the $Λ$ polarization is sufficiently small to support the assumption of an early freeze-out of $Λ$ spin degree of freedom in relativistic heavy ion collisions.

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arXiv2026

Exploring bound states and interactions of the nucleon-antinucleon system in a constituent quark model

In this work, we study the nucleon-antinucleon system in a constituent quark model. We first construct the nucleon-antinucleon wave function such that the multiquark and multiantiquark components each satisfy the Pauli exclusion principle, and then investigate the possibility of a bound state using a Hamiltonian that includes color-color, spin-dependent interactions and three-quark potentials. Our results indicate that, in specific channels, the nucleon-antinucleon interaction exhibits significant attraction, suggesting a strong possibility of a bound state.

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arXiv2025

Long-Range $N-J/ψ$ Interaction from an Operator Product Expansion Perspective

A recent lattice QCD study has shown that the $N-J/ψ$ potential is attractive at all distances, and its long-range tail is well described by two-pion exchange. Here, we study to what extent the long-range part of the attraction can be reproduced from the perspective of the operator product expansion (OPE). This is accomplished by extracting the leading-order four-quark operator that couples to two pions and calculating its contribution to the $J/ψ$ mass in nuclear matter, to linear order in density, within the QCD sum rule framework. Using previous estimates of the four-quark operators for the chiral symmetric and breaking parts, we obtain a mass decrease that is smaller in magnitude but qualitatively consistent with the attraction obtained in the lattice QCD calculation. By expressing the interaction in terms of four-quark operators, we can analyze the effects of chiral symmetry restoration in dense matter on the masses of the $J/ψ$ and other mesons composed of heavy quarks.

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arXiv2025

Charm-strange meson production in relativistic heavy ion collisions

We study charm-strange mesons, or $D_s$, $D_s^*$, $D_{s0}^*(2317)$, and $D_{s1}(2460)$ mesons by focusing on their production by coalescence from a quark-gluon plasma in relativistic heavy ion collisions at $\sqrt{s_{NN}}=5.02$ TeV. Starting from the investigation of the transverse momentum distribution of both charm and strange quarks through transverse momentum distributions of $ϕ$ and $D^0$ mesons, we calculate the transverse momentum distributions and yields of $D_s$, $D_s^*$, $D_{s0}^*(2317)$, and $D_{s1}(2460)$ mesons based on the coalescence model. We find that the yield and transverse momentum distribution of the $D_s$ meson agree well with the experimental measurements at $\sqrt{s_{NN}}=5.02$ TeV at LHC. We further evaluate the transverse momentum ratio between $D_s$ and $D^0$ mesons, and investigate the role of light and strange quarks in the production of charmed mesons in heavy ion collisions. Finally, we calculate the transverse momentum distribution and yield of the $D_{s0}^*(2317)$ meson in a four-quark state, and compare to those of $D_{s0}^*(2317)$ meson in a two-quark state.

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arXiv2025

Studying the in-medium $ϕ$ meson spectrum through kaons in proton-nucleus reactions

Exploring the mass modifications of $ϕ$ mesons in nuclei provides insights into the nature of strongly interacting matter. Specifically, $ϕ$ meson mass shifts can be related to the in-medium modification of the strange quark condensate. Therefore, the partial restoration of chiral symmetry can be studied by observing the mass shifts through the decay channels $ϕ\rightarrow e^+e^-$, and $ϕ\rightarrow K^+K^-$. In this paper, we examine the possibility of observing the $ϕ$ meson mass modifications of the $ϕ$ mesons in 30 GeV proton-nucleus (C, Cu, Pb) collisions, to be studied at the J-PARC E88 experiment, through the kaonic decay channel, with the off-shell Budapest Boltzmann-Uehling-Uhlenbeck (BuBUU) transport model. By applying different mean fields to the kaons, we examine their effects on the invariant mass spectra. Our simulations suggest that, although different mean fields for the kaons do affect the spectrum, there is a common observable effect primarily driven by the $ϕ$ mass shift. However, due to the threshold associated with the two kaons, the signal we observe is quite different from the one expected in dilepton spectra. Therefore, to meaningfully constrain the mass shift, it will be useful to include both kaon and dilepton channels in the analysis of the experimental data.

hep-ph↗

arXiv2025

The Electron-Ion Collider as A Prospective Facility for Pentaquark Measurements

The Electron-Ion Collider provides a groundbreaking opportunity to study heavy pentaquarks with unprecedented precision, leveraging its high collision energy and beam spin polarization capabilities. As a representative case, we analyze electroproduction cross sections of Pc (4312) under different spin-parity hypotheses using the vector meson dominance model. To ensure a parameter-free approach and minimize ambiguity, we incorporate results from the LHCb and GlueX experiments. To characterize the spin and the parity of Pc (4312), we propose measuring the beam spin asymmetry and decay kinematic polarization, quantities that can be accurately determined by the ePIC detector. Our approach can be extended to investigate other heavy pentaquarks produced in electron-proton and electron-deuteron collisions, as well as to study their interactions with nuclear matter in electron-heavy ion collisions. We strongly encourage the EIC community to explore this potential and integrate pentaquark studies as a critical element of the scientific mission.

hep-ph↗

arXiv2024

Chiral symmetry breaking, chiral partners, and the $K_1$ and $K^*$ in medium

We clarify the concept of chiral partners. For a vector meson, the isospin-zero and hypercharge-zero state in the flavor octet mixes with the flavor singlet state. Since the flavor singlet vector meson does not have a chiral partner, the mixed $ω$ and $ϕ$ mesons will not have chiral partners. This means that even when chiral symmetry is restored, these mesons will not become degenerate with their corresponding parity partners. On the other hand, the $K_1$ and $K^*$ mesons are chiral partners, and both have widths smaller than 100 MeV. Therefore, we emphasize that studying these mesons in environments where chiral symmetry is restored is particularly important for understanding the effect of chiral symmetry restoration on chiral partners and their masses.

hep-ph↗

arXiv2024

Separating the transverse and longitudinal modes of $ϕ$, $ρ$, $K^*$ and $K_1$ mesons through their angular-dependent two-body decay modes

The mass shift a spin-1 particle moving in the nuclear medium will depend on its polarization direction. To study polarization-independent mass shifts in the medium, we explore methods to isolate each polarization direction of spin-1 mesons through the angular-dependent two-body decay modes. Specifically, we study $ϕ\to K^{+}K^{-}$, $ρ\toππ$, $K^{*}\to Kπ$, $ϕ\to e^{+}e^{-}$ and $K_{1}\toρK(K^{*}π)$ decays. While each polarization mode can be isolated through angular dependencies, accomplishing the decomposition for the $K_1$ meson further requires measuring the polarization of the $ρ(K^*)$ meson. Concerning $K^{*}$ and $K_1$ mesons, since both particles have vacuum widths smaller than 100 MeV, they are ideal candidates for experimentally measuring chiral partners. The simultaneous observation of mass shifts of these chiral partners would provide valuable insights into the contribution of chiral symmetry breaking to the generation of hadron masses.

hep-ph↗

arXiv2024

The Inevitable Quark Three-Body Force and its Implications for Exotic States

Three-body nuclear forces are essential for explaining the properties of light nuclei with a nucleon number greater than three. Building on insights from nuclear physics, we extract the form of quark three-body interactions and demonstrate that these terms are crucial for extending the quark model fit of the meson spectrum to include baryons using the same parameter set. We then discuss the implications of our findings for exotic configurations involving more than three quarks, such as the $T_{cc}$ and $χ_{c1}(3872)$. We find that the quark three-body interactions provide additional repulsion on the order of 10 MeV for the compact configurations of both the $T_{cc}$ and $χ_{c1}(3872)$. This result, combined with previous calculations, strongly suggests that these tetraquark states are molecular rather than compact states.

hep-ph↗

arXiv2024

Hadronic scattering effects on $Λ$ polarization in relativistic heavy ion collisions

The $Λ$ hyperon spin flip and non-flip cross sections are calculated in a simple hadronic model by including both the $s$-channel process involving the spin 3/2, positive parity $Σ^*(1358)$ resonance and the $t$-channel process via the exchange of a scalar $σ$ meson. Because of its large mass, the $Λ$ spin flip to non-flip cross sections is negligibly small in the $t$-channel process compared to the constant value of 1/3.5 in the $s$-channel process. With the $s-$channel $Λ-π$ spin-dependent cross sections included in a schematic kinetic model, the effects of hadronic scatterings on the $Λ$ spin polarization in Au-Au collisions at $\sqrt{s_{NN}}=7.7$ GeV are studied. It is found that the $Λ$ spin polarization only decreases by 7-12\% during the hadronic stage of these collisions, which justifies the assumption in theoretical studies that compare the $Λ$ polarization calculated at the chemical freezeout to the measured one at the kinetic freezeout.

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arXiv2024

An AI-Inspired Numerical Method in the Quark Model: Application to Finding the Wave Functions for Heavy Tetraquark States

The current ongoing advancements in AI have shed light on the landscape of numerical analysis in science. Inspired by the path of achievement of AI, we have developed a method to construct accurate ground state wave functions of multiquark configurations within a quark model. We successfully tested our method through comparisons with meson-type two-body systems with analytic and numerical solutions. We then applied our method to find the ground-state solutions of $T_{cc}$($ud\bar{c}\bar{c}$) and $T_{bb}$($ud\bar{b}\bar{b}$) states. Our findings indicate that our approach outperforms existing methods, achieving greater accuracy in reproducing highly intricate configurations. Within the model parameters, we find that the $T_{cc}$ is a compact multiquark configuration.

hep-ph↗

arXiv2024

Investigation of suppression of $Υ(nS)$ in relativistic heavy-ion collisions at RHIC and LHC energies

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 $\sqrt{s_{\mathrm{NN}}}=$ 5.02 TeV and Au-Au collisions at $\sqrt{s_{\mathrm{NN}}}=$ 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.

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