arXiv subjects

Sang-Ho Kim

Publications and source records attributed to Sang-Ho Kim.

At least 19 recordsLinked to original sources

arXiv2026

Kaon-induced $ϕΣ$ production off the proton

We investigate the reaction mechanism of $K^-p \to ϕΣ^0$ within a hybrid Regge approach based on effective Lagrangians. The nonresonant background includes Reggeized $t$-channel $K$ and $K^*$ exchanges, together with ground-state $Σ$ and nucleon exchanges in the $s$ and $u$ channels, respectively. To describe the structures observed at $3.0 \leqslant P_{\rm Lab} \leqslant 4.5$ GeV, we include the high-mass $Σ(2620)$ and $Σ(3000)$ resonances and examine the spin-parity assignments $J^P = 1/2^\pm$, $3/2^\pm$, and $5/2^\pm$. The $K^*$-Reggeon exchange dominates the forward-angle cross sections, whereas the smaller $K$-Reggeon contribution is important for the total cross section at low energies and for the spin-density matrix elements. The nonresonant background alone is not sufficient to reproduce the local structures in the total cross section or the differential cross sections at large $-t'$. Including the two resonances, particularly the $Σ(3000)$, substantially improves the agreement with the available data. The $J^P=5/2^-$ assignment for the $Σ(3000)$ provides a reasonable overall description, although the present data do not permit a definitive determination.

nucl-th↗

arXiv2026

Nonexistence of hidden-charm pentaquarks in $J/ψ$ photoproduction

We investigate $J/ψ$ photoproduction off the proton, $γp \to J/ψp$, to elucidate the nonexistence of hidden-charm pentaquark signals reported by the GlueX and CLAS12 experiments. Within a coupled-channel rescattering mechanism, we employ the transition amplitudes from a previous coupled-channel analysis that dynamically generates the $P_{c\bar{c}}$ states. The kernel amplitudes for the transition to the $J/ψN$ channel include both $t$-channel heavy-meson exchange and $u$-channel heavy-baryon exchange. We find that the rescattering contributions from the $\bar{D}^{(*)}Σ_c$ channels -- indispensable for the formation of the $P_{c\bar{c}}$ resonances -- are about one order of magnitude smaller than those from $\bar{D}^{(*)}Λ_c$, since $g_{\bar{D}^{(*)}NΣ_c}$ is roughly five times smaller than $g_{\bar{D}^{(*)}NΛ_c}$. Since the $P_{c\bar{c}}$ resonances couple to the $J/ψN$ channel predominantly through the $\bar{D}^{(*)}Σ_c$ intermediate states, their suppression prevents the pentaquark signal from appearing in photoproduction. With only a single parameter controlling the overall normalization, the present work describes the GlueX and CLAS12 cross sections well. These results suggest that the null result from photoproduction need not be in conflict with the pentaquark signals observed by the LHCb Collaboration.

hep-ph↗

arXiv2026

Rescattering effects in near-threshold $J/ψ$ photoproduction

We investigate near-threshold $J/ψ$ photoproduction off the nucleon, focusing on hadronic rescattering effects induced by open-charm meson-baryon intermediate states. Beyond the conventional Pomeron-exchange mechanism, the $\bar D^0Λ_c^+$ and $\bar D^{*0} Λ_c^+$ channels are incorporated within an effective Lagrangian framework. The relevant production amplitudes are evaluated at tree level from $t$-, $s$-, and $u$-channel diagrams in a gauge-invariant manner. The resulting total and $t$-dependent differential cross sections are compared with recent near-threshold data from the GlueX, $J/ψ$-007, and CLAS experiments at Jefferson Lab. We find that the open-charm rescattering contributions significantly improve the description of the data, particularly at large momentum transfer, and naturally generate cusp-like structures near the $\bar D^0 Λ_c^+$ and $\bar D^{*0} Λ_c^+$ thresholds in the GlueX data. We further present predictions for the associated open-charm processes $γp \to \bar D^{(*)0} Λ_c^+$, whose cross sections are estimated to be of the order of 5 nb.

hep-ph↗

arXiv2026

Production of $K^* Σ$ and $D^* Σ_c$ in pion-induced reactions off the nucleon

We investigate the mechanisms of strangeness production in the $π^- p \to K^{*0} Σ^0$ and $π^- p \to K^{*+} Σ^-$ reactions within a hybrid Regge framework in which effective Lagrangian vertices are combined with Reggeized exchanges. The nonresonant background consists of $t$-channel $K$- and $K^*$-Reggeon exchanges, $s$-channel nucleon and $Δ$ exchanges, and $u$-channel $Σ$- and $Λ$-Reggeon exchanges, whose roles differ markedly between the two isospin channels. We additionally include several $N^*$ and $Δ^*$ resonances in the $s$ channel and find that the $Δ(2150)1/2^-$ resonance provides the dominant near-threshold contribution. The resulting total and differential cross sections and spin-density matrix elements (SDMEs) are in good agreement with the available data. Additional measurements near threshold ($W \lesssim$ 2.5 GeV) would be valuable for clarifying the role of $s$-channel baryon resonances. Within the same framework, with Regge trajectories and energy-scale parameters fixed by a QGSM-motivated prescription, we also predict the cross sections for the charm-production reactions $π^- p \to D^{*-} Σ_c^+$ and $π^- p \to D^{*0} Σ_c^0$. Their total cross sections are suppressed by approximately $4$--$5$ and $7$--$8$ orders of magnitude, respectively, compared with those of the corresponding strangeness-production reactions. These results may serve as useful guidance for future experiments at facilities such as J-PARC.

hep-ph↗

arXiv2026

Production of $ϕΛ$, $D_s^{*-} Λ_c^+$, and $J/ψΛ$ in kaon-induced reactions off the nucleon

We investigate the reaction mechanism of strangeness production in $K^- p \to ϕΛ$ within a hybrid Regge approach, taking into account $t$-channel $K$- and $K^*$-Reggeon exchanges. We present results for the total cross section, $t$-dependent differential cross sections, and spin-density matrix elements (SDMEs), and compare them with the available experimental data. We find that $K^*$-Reggeon exchange provides the dominant contribution, while $K$-Reggeon exchange remains nonnegligible, particularly in describing the SDMEs. In contrast, the $s$-channel $Λ$ and $u$-channel nucleon exchanges are negligible. To obtain reliable predictions for the open-charm reaction $K^- p \to D_s^{*-} Λ_c^+$, we employ a Quark-Gluon String Model (QGSM)-motivated Regge framework that incorporates both pseudoscalar- and vector-Reggeon exchanges. Within this framework, the Regge trajectories $α(t)$ and energy-scale parameters $s_0$ are determined consistently, thereby constaining the model and reducing theoretical ambiguities. For the hidden-charm reaction $K^- p \to J/ψΛ$, we use the same quark-level diagrammatic correspondence. The total cross sections for $K^- p \to D_s^{*-} Λ_c^+$ and $K^- p \to J/ψΛ$ are suppressed by approximately 5-6 and 8-9 orders of magnitude, respectively, compared with that for $K^- p \to ϕΛ$. We also examine possible $s$-channel contributions from the hidden-charm pentaquark states with strangeness, $P_{cs}(4337)^0$ and $P_{cs}(4459)^0$, to both $D_s^{*-} Λ_c^+$ and $J/ψΛ$ production.

hep-ph↗

arXiv2025

Role of meson exchange and final-state interaction in $J/ψ$-meson photoproduction

We investigate $J/ψ$ photoproduction off the nucleon using a dynamical model based on a Hamiltonian framework. First, Pomeron exchange is regarded as a background contribution that accounts for the gradual rise of the total cross section with increasing beam energy. Then, the meson-exchange and direct $J/ψ$-radiation contributions are included as part of the Born term. More specifically, we examine the contributions of the light-meson [$π^0(135)$, $η(548)$, $η'(958)$, $f_1(1285)$] and charmonium-meson [$η_c(1S)$, $χ_{c0}(1P)$, $χ_{c1}(1P)$, $η_c(2S)$, $χ_{c1}(3872)$] exchanges in the $t$-channel diagram. Most of the coupling constants are determined from the radiative decays of the $J/ψ$ or other relevant charmonium states. Finally, we consider the $J/ψN$ final-state interaction (FSI) within the leading-order approximation, which includes gluon-exchange and direct $J/ψN$-coupling terms. The model parameters of the Hamiltonian are fitted to the data from the GlueX and $J/ψ$-007 experiments at Jefferson Laboratory (JLab). The light mesons $η(548)$ and $η'(958)$ are found to make the most significant contributions, whereas the charmonium mesons play only a minor role. The direct $J/ψ$-radiation term begins to come into play only in the backward scattering regions. The FSI contribution is suppressed by a factor of $10^1 - 10^2$ in comparison to the Born-term contribution when a Yukawa-type potential is employed for the charmonium-nucleon interaction. Our results agree well with the available JLab data on the total and $t$-dependent differential cross sections. High-precision, angle-dependent data in the threshold region ($E_γ\leqslant 8.9$ GeV) are crucial for confirming the FSI effect.

hep-ph↗

arXiv2025

$J/ψ$-meson photoproduction off the nucleon in a dynamical model

The photoproduction of $J/ψ$ meson off the nucleon is investigated within a dynamical model approach based on a Hamiltonian which describes the reaction mechanisms of the Pomeron exchange, meson exchange, and direct $J/ψ$ radiation terms.To shed light on the low-energy mechanism, we scrutinize the role of light-meson [$π^0(135)$, $η(548)$, $η'(958)$, $f_1(1285)$] and charmonium-meson [$η_c(1S)$, $χ_{c0}(1P)$, $χ_{c1}(1P)$, $η_c(2S)$, $χ_{c1}(3872)$] exchanges in the $t$-channel diagram. The values of the coupling constants are mostly determined by the radiative decays of the $J/ψ$ meson or the relevant charmonium mesons. The final $J/ψ$-$N$ interaction is required by the unitarity condition and is described by the gluon-exchange and direct $J/ψN$ coupling terms. The parameters of the Hamiltonian are determined by the latest GlueX and $J/ψ$-007 experiments at the Jefferson Laboratory (JLab). We find that $η(548)$ and $η'(958)$ light mesons give the most significant contribution to $γp \to J/ψp$ among the meson-exchange terms.Meanwhile, the effect of charmonium mesons turns out to be small compared to that of light mesons.It turns out that the contribution of the FSI term is about 1 - 2 orders of magnitude smaller than that of the Born term and is significant near the threshold when the Yukawa form is used as for the charmonium-nucleon potential. The resulting total and $t$-dependent differential cross sections provide good agreement with the JLab data. The angle-dependent data with high precision near the very threshold ($E_γ\leqslant 8.9$ GeV) are strongly desired to pin down the role of the FSI term more properly.

hep-ph↗

arXiv2024

Effective Lagrangian for strong and electromagnetic interactions of high-spin resonances

Recent experiments of photon-nucleon and meson-nucleon scatterings have accumulated a lot of data for various meson production processes. One of the purposes of those experiments is to search for the missing resonances which are not discovered until now but whose existence was predicted by hadron models. The analyses of the data requires the development of dynamical coupled-channel models. Since several missing resonances are expected to have spin higher than 3/2, we need to include higher-spin resonances in dynamical coupled-channel models, which enable us to determine the couplings of effective Lagrangians of higher-spin baryons with pseudoscalar mesons or vector mesons. However, hadron models, such as quark models, give predictions only of the decay amplitudes of such baryons. Here we demonstrate the formalism of high-spin resonances and construct the relation between the coupling constants of effective Lagrangians and the partial decay widths that can be predicted by hadron models. This allows us to compare the coupling constants to the hadron model predictions not only in magnitude but in sign as well.

hep-ph↗

arXiv2024

Exclusive $J/ψ$ photo-production on nuclei

Motivated by the recent experimental developments, the Pom-CQM model of the $γ+ N \to J/ψ+ N$ reaction of Lee et al. [Eur. Phys. J. A. 58, 252 (2022)] and Sakinah et al. [Phys. Rev. C. 109, 065204 (2024)] has been applied to predict the exclusive $J/ψ$ photo-production on nuclei ($A$). Within the multiple scattering theory, the calculations have been performed by including the impulse amplitude $T^{\rm IMP}_{J/ψA,γA}$ and the $J/ψ$-nucleus final state interaction (FSI) amplitude $T^{\rm FSI}_{J/ψA,γA}$. For the deuteron target, $T^{\rm IMP}_{J/ψd,γd}$ is calculated exactly using the wave function generated from the realistic nucleon-nucleon potentials. It is found that, near the threshold region, the $J/ψ$ photo-production cross sections depend sensitively on the $d$-state of the deuteron wave function. The FSI amplitude $T^{\rm FSI}_{J/ψA,γA}$ is calculated using the first-order optical potential constructed from the $J/ψ$-$N$ scattering amplitude generated from the employed Pom-CQM model. It turns out that the FSI has significant effects in the large momentum-transfer region. By using the conventional fixed scatter approximation (FSA) and the nuclear form factors from the variational Monte-Carlo (VMC) calculations of Lonardoni et al. [Phys. Rev.C. 96, 024326 (2017)], the cross sections of the $J/ψ$ photo-production on ${^4\rm He}$, ${^{16}\rm O}$, and ${^{40}\rm Ca}$ are also predicted for future experimental investigations at JLab and EIC.

nucl-th↗

arXiv2024

Intriguing aspects of light baryon resonances

We discuss that some light baryon resonances exhibit properties which cannot be described when attributing a three-valence quark structure to them. Besides pointing out the hadron resonances which clearly require description beyond the quark model, we focus on the third $s_{11},~ N^*$ state and its decay to final states consisting of the lightest hyperon resonances which have a partial width comparable to that for the decay to $πN$. Such properties of the mentioned nucleon resonance get manifested in the cross sections and other observables related to processes producing the lightest hyperon resonances. We show that all these findings arise from the strong association of the baryon resonances to the dynamics among the ground-state hadrons.

hep-ph↗

arXiv2023

Double-strangeness exchange reactions in a hybrid Regge-plus-resonance approach

We investigate double-strangeness exchange reactions, $K^-p\to K^+Ξ^-$ and $K^-p\to K^0Ξ^0$, using an effective Lagrangian approach based on a hybrid Regge-plus-resonance model involving rescattering diagrams. We consider the background processes that include $Λ$, $Σ$, and $Σ(1385)$ Regge trajectories in the $u$ channel and the $s$-channel Born-term diagrams. The $s$-channel hyperon resonances account for the bump structures in the total cross sections. The $s$-channel $Λ(2100,7/2^-)$ and $Σ(2030,7/2^+)$ resonances contribute significantly, and the $Σ(2250)$ resonance favors $J^P = 7/2^-$. The interference pattern between the $Λ(2100,7/2^-)$ and $Σ(2030,7/2^+)$ amplitudes is essential for describing forward differential cross sections in the resonance region $2.07 < \sqrt{s} < 2.15$ GeV. The absence of the $S=-2$ meson leads to the inclusion of the meson-baryon rescattering diagrams to describe the $K^- p \to KΞ$ reaction data, proving the significant contribution of the $(ϕ,ρ,ω)$--$(Λ,Σ)$ rescattering diagrams.

nucl-th↗

arXiv2023

Towards Voice Reconstruction from EEG during Imagined Speech

Translating imagined speech from human brain activity into voice is a challenging and absorbing research issue that can provide new means of human communication via brain signals. Endeavors toward reconstructing speech from brain activity have shown their potential using invasive measures of spoken speech data, however, have faced challenges in reconstructing imagined speech. In this paper, we propose NeuroTalk, which converts non-invasive brain signals of imagined speech into the user's own voice. Our model was trained with spoken speech EEG which was generalized to adapt to the domain of imagined speech, thus allowing natural correspondence between the imagined speech and the voice as a ground truth. In our framework, automatic speech recognition decoder contributed to decomposing the phonemes of generated speech, thereby displaying the potential of voice reconstruction from unseen words. Our results imply the potential of speech synthesis from human EEG signals, not only from spoken speech but also from the brain signals of imagined speech.

eess.AS↗

arXiv2022

Exotic properties of N^*(1895) and its impact on photoproduction of light hyperons

In this work, we outline the findings of our recent study of the properties of $N^*(1895)$ and its consequential impacts on the cross sections of the photoproduction of $Λ(1405)$. Further, we discuss the possibility of the existence of an isovector state, with the mass similar to $Λ(1405)$, which we refer to as $Σ(1400)$. With the idea of motivating experimental investigations of $Σ(1400)$, we have studied its photoproduction process and determined the respective cross sections and polarization observables. We have studied also the coupling of $N^*(1895)$ to $KΣ(1400)$ and found that it gives an important contribution to the cross sections near the threshold. In the process, we have determined the branching ratios of the decay of $N^*(1895)$, to the final states involving $Λ(1405)$ and $Σ(1400)$, to be in the range of 6-7 MeV. Our findings can motivate consideration of alternative processes in partial wave analyses of experimental data, when studying the properties of $N^*(1895)$.

nucl-th↗

arXiv2022

The decay of $N^*$(1895) to light hyperon resonances

In this talk I review the findings of our recent works where we have studied the decay of $N^*(1895)$ and the implications of such properties on the photoproduction of light hyperons. I discuss that meson-baryon interactions play an essential role in describing the nature of $N^*(1895)$ and report the details of our investigation of its decays to different meson-baryon systems and to final states involving $Λ(1405)$ and a proposed $Σ(1400)$. We find that the width of $N^*(1895)$ gets important contributions from the decay to light hyperon resonances. Such an information can be used to look for alternative processes to study $N^*(1895)$ in experimental data.

hep-ph↗

arXiv2021

Dynamical model of $ϕ$ meson photoproduction on the nucleon and $^4He$

We investigate $ϕ$ meson photoproduction on the nucleon and the \nuclide[4]{He} targets within a dynamical model approach based on a Hamiltonian which describes the production mechanisms by the Pomeron-exchange, meson-exchanges, $ϕ$ radiations, and nucleon resonance excitations mechanisms. The final $ϕN$ interactions are included being described by the gluon-exchange, direct $ϕN$ couplings, and the box-diagrams arising from the couplings with $πN$, $ρN$, $KΛ$, and $KΣ$ channels. The parameters of the Hamiltonian are determined by the experimental data of $γp \to ϕp$ from the CLAS Collaboration. The resulting Hamiltonian is then used to predict the coherent $ϕ$-meson production on the \nuclide[4]{He} targets by using the distorted-wave impulse approximation. For the proton target, the final $ϕN$ rescattering effects, as required by the unitarity condition, are found to be very weak, which supports the earlier calculations in the literature. For the \nuclide[4]{He} targets, the predicted differential cross sections are in good agreement with the data obtained by the LEPS Collaboration. The role of each mechanism in this reaction is discussed and predictions for a wide range of scattering angles are presented, which can be tested in future experiments.

nucl-th↗

arXiv2021

Photoproduction of $Λ^$ and $Σ^$ resonances with $J^P=1/2^-$ off the proton

We study the photoproduction of the $Λ(1405)$ and $Σ(1400)$ hyperon resonances, the latter of which is not a well established state. We evaluate the $s$-, $t$- and $u$-channel diagrams in the Born approximation by employing the effective Lagrangians. A new ingredient is the inclusion of a nucleon resonance $N^*(1895)$ that is dynamically generated with predictions for its coupling to the $KΛ(1405)$ and $KΣ(1400)$ channels. To extend the applicability of the model to energies beyond the threshold region, we consider a Regge model for the $t$-channel $K$- and $K^*$-exchanges. Our results are in good agreement with the CLAS data available on $Λ(1405)$, while for $Σ(1400)$ we predict observables for its production. We also provide polarization observables for both hyperon productions, which can be useful in future experimental investigations. The present study provides new information on the nucleon resonance $N^*(1895)$ which can be an alternative source for generating the hyperon resonances $Λ(1405)$ and $Σ(1400)$.

hep-ph↗

arXiv2020

Investigation of electroproduction of $ϕ$ mesons off protons

We investigate $ϕ$-meson electroproduction off the proton target, i.e., $γ^* p \to ϕp$, by employing a tree-level effective Lagrangian approach in the kinematical ranges of $Q^2$ = (0$-$4) $\mathrm{GeV}^2$, $W$ = (2$-$5) GeV, and $|t| \leq 2\,\mathrm{GeV}^2$. In addition to the universally accepted Pomeron exchange, we consider various meson exchanges in the $t$ channel with the Regge method. Direct $ϕ$-meson radiations in the $s$- and $u$-channels are also taken into account. We find that the $Q^2$ dependence of the transverse ($σ_{\mathrm{T}}$) and longitudinal ($σ_{\mathrm{L}}$) cross sections are governed by Pomeron and $(a_0,f_0)$ scalar meson exchanges, respectively. Meanwhile, the contributions of $(π,η)$ pseudoscalar- and $f_1(1285)$ axial-vector-meson exchanges are much more suppressed. The results of the interference cross sections ($σ_{\mathrm{LT}}, σ_{\mathrm{LT}}$) and the spin-density matrix elements indicate that $s$-channel helicity conservation holds at $Q^2$ = (1$-$4) $\mathrm{GeV}^2$. The result of the parity asymmetry yield $P \simeq 0.95$ at $W$ = 2.5 GeV, meaning that natural-parity exchange dominates the reaction process. Our numerical results are in fair agreement with the experimental data and thus the use of our effective Reggeized model is justified over the considered kinematical ranges of $Q^2$, $W$, and $t$.

hep-ph↗

arXiv2019

Pomeron, nucleon-resonance, and $(0^+,0^-,1^+)$-meson contributions in $ϕ$-meson photoproduction

We investigate the reaction mechanism of the $ϕ$-meson photoproduction off the proton target, i.e., $γp\toϕp$, up to $\sqrt{s}=2.8$ GeV. For this purpose, we employ an effective Lagrangian approach in the tree-level Born approximation, and we employ various experimental and theoretical inputs. As a theoretical setup, the vectorlike Pomeron ($C=+1$) is taken into account as a parameterized two-gluon exchange contribution. We also consider $f_1(1285)$ axial-vector-meson, ($π,η$) pseudoscalar-meson, and ($a_0,f_0$) scalar-meson exchanges in the $t$ channel, in addition to the experimentally confirmed nucleon resonances, such as $N^*(2000,5/2^+)$ and $N^*(2300,1/2^+)$, for the direct $ϕ$-meson radiations in the $s$ and $u$ channels. We provide numerical results for the total and differential cross sections as well as the spin-density matrices in the Gottfried-Jackson, Adair, and helicity frames. We observe that, together with the universally accepted pomeron contribution, the considered meson and nucleon-resonance contributions play significant roles in reproducing the experimental data for the forward and backward $ϕ$-meson scattering-angle regions, respectively, indicating the nontrivial interferences between mesonic and baryonic contributions.

hep-ph↗