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Hee-Jin Kim

Publications and source records attributed to Hee-Jin Kim.

6 recordsLinked to original sources
arXiv2026

Dynamical generation of charmonium-like tetraquarks in an off-shell coupled-channel formalism

We investigate the dynamical generation of charmonium-like ($I=0$) with spin-parity $J^{PC}=0^{++}, 1^{++}, 2^{++}$, and $3^{--}$ in the mass range of $3.6$ to $4.3$ GeV. We employ the off-shell coupled-channel formalism, constructing kernel amplitudes from effective Lagrangians that respect heavy-quark spin-flavor and chiral symmetries. To focus solely on dynamically generated states, we explicitly exclude $s$-channel pole diagrams and include only $t$- and $u$-channel meson exchanges. Solving the integral equations, we identify six poles in the complex energy plane. In the scalar ($0^{++}$) sector, we find a bound state below the $D\bar{D}$ threshold and a resonance at $\sqrt{s_R}=(3861-i\,23)\,\mathrm{MeV}$. For the axial-vector ($1^{++}$) sector, the experimentally observed $χ_{c1}(3872)$ is reproduced as a bound state near the $D\bar{D}^*$ threshold, alongside a broader resonance at $(3961-i\,32)\,\mathrm{MeV}$, which is a plausible candidate for the $X(3940)$. Furthermore, we find a narrow tensor ($2^{++}$) state at $4005\,\mathrm{MeV}$ and a vector ($3^{--}$) state at $4030\,\mathrm{MeV}$. The present results demonstrate that coupled-channel dynamics, particularly involving the $D^*\bar{D}^*$ channel, play a crucial role in the formation of these charmonium-like exotic states.

hep-ph↗
arXiv2025

Production mechanism of doubly charmed exotic mesons $T_{cc}$

We investigate the production mechanism for doubly charmed tetraquark mesons within a coupled-channel formalism. The two-body Feynman kernel amplitudes are constructed using effective Lagrangians that respect heavy quark symmetry, chiral symmetry, SU(3) flavor symmetry, and hidden local symmetry. The fully off-shell coupled scattering equations are solved within the Blankenbecler-Sugar (BbS) reduction scheme. We find three positive-parity and one negative-parity tetraquark states with total spin $J=1$. Among them, two positive-parity states appear as bound states in the isoscalar and isovector $DD^*$ channels, while another appears as a resonance in the $D^*D^*$ channel. A negative-parity resonance is also predicted in the isoscalar channel. We analyze the coupling strengths of these tetraquark states to various channels. The dependence of the results on the reduced cutoff mass $Λ_0$ is examined. The most significant tetraquark state remains stable within the range of $Λ_0=(600-700)$ MeV.

hep-ph↗
arXiv2024

$D_{s0}^*(2317)$ and $B_{s0}^*$ as molecular states

We investigate the dynamical generation of the $D_{s0}^*(2317)$ and $B_{s0}^*$ mesons using a meson-exchange model with a coupled-channelformalism. Our primary focus is on the $D_s^+π^0$ channel below the $DK$ threshold. First, we construct the invariant kernel amplitudes, incorporating effective Lagrangians based on heavy-quark symmetry, flavor SU(3) symmetry, and hidden local symmetry. Since the $D_{s0}^*(2317)$ state implies isospin symmetry breaking, we introduce $π^0-η$ isospin mixing. We subsequently solve the coupled-channel integral equations, which include four different channels, i.e., $D_s^+π^0$, $D^0 K^+$, $D^+ K^0$, and $D_s^+η$. We carefully analyze how the pole corresponding to the $D_{s0}^*(2317)$ state emerges from the coupled channels. Our findings reveal that the pole positions of the $D_{s0}^*(2317)$ meson are at $\sqrt{s_R}=(2317.9 - i 0.0593)$ MeV and the $\bar{B}_{s0}^*$ meson at $(5756.43-i0.0215)$ MeV, respectively. We also discuss their decay widths and destructive interference of the two sources. In conclusion, our current results provide a clear indication supporting the interpretation of the $D_{s0}^*(2317)$ meson as a $DK$ molecular state within the present coupled-channel formalism. In addition, we discuss a possible existence of $\bar{B}_{s0}^{*}$.

hep-ph↗
arXiv2022

Triple Regge exchange and transverse single-spin asymmetries of the very forward neutral pion production in polarized $p+p$ collisions

Recently, the RHICf Collaboration measured the transverse single-spin asymmetries of the very forward neutral pion in polarized $p+p$ collisions at $\sqrt{s}=510$ GeV, produced at large pseudorapidity ($η\gtrsim 6$). The data show large asymmetries both in longitudinal momentum fraction $x_F$ and transverse momentum $p_T$ at $p_T<1\,\mathrm{GeV}/c$. Employing baryonic triple Regge exchanges, we describe the complete RHICf data for the first time and show that the neutral pion production at low $p_T$ can be interpreted as a diffractive one.

hep-ph↗
arXiv2021

Production of hidden-charm strange pentaquarks $P_{cs}$ from the $K^- \,p \to J/ψ\,Λ$ reaction

We investigate the production of the hidden-charm pentaquark $P_{cs}^0(4459)$ with strangeness in the $K^- p \to J/ψΛ$ reaction, employing two different theoretical frameworks, i.e., the effective Lagrangian method and the Regge approach. Having determined all relevant coupling constants, we are able to compute the total and differential cross sections for the $K^- p \to J/ψΛ$ reaction. We examine the contributions of $P_{cs}$ with different sets of spin-parity quantum number assigned. The present results may give a guide for possible future experiments.

hep-ph↗
arXiv2020

The $σ$ and $ρ$ coupling constants for the charmed and beauty mesons

We investigate the $σ$ and $ρ$ coupling constants for the $DD$ and $D^*D^*$ interactions, based on correlated $2π$ exchange in the $DD$ and $D^*D^*$ interactions. Starting from the $D\bar{D}\to ππ$ and $D^*\bar{D}^*\to ππ$ amplitudes derived in the pseudophysical region ($4m_π^2\le t \le 52m_π^2$) with the $S$- and $P$-wave $2π$ correlations considered, we obtain the spectral functions for the $DD\to DD$ and $D^*D^*\to D^*D^*$ amplitude with correlated $S$- and $P$-wave $2π$ exchanges. Using the pole approximation, we estimate the $DDσ$, $DDρ$, $D^*D^*σ$, and $D^*D^*ρ$ coupling constants. We extended phenomenologically the present results to the region in $t\le 0$ and compare them with those from lattice QCD. The results are also compared with those of other models. We also present the results of the $BBσ$, $BBρ$, $B^*B^*σ$, and $B^*B^*ρ$ coupling constants. We observe that it is unlikely that the $σ$ and $ρ$ coupling constants for the $B$ and $B^*$ mesons are the same as those for the $D$ and $D^*$ mesons. On the contrary, they are quite larger than those for the charmed mesons.

hep-ph↗