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Sang-Ho Kim

Publications and source records attributed to Sang-Ho Kim.

At least 37 records · Page 2Linked to original sources
arXiv2019

$K^0Λ$ Photoproduction with Nucleon Resonances

We investigate the reaction mechanism of $K^0 Λ$ photoproduction off the neutron target, i.e., $γn \to K^0 Λ$, in the range of $W\approx 1.6-2.2$ GeV. We employ an effective Lagrangian method at the tree-level Born approximation combining with a Regge approach. As a background, the $K^*$-Reggeon trajectory is taken into account in the $t$ channel and $Λ$ and $Σ$ hyperons in the $u$-channel Feynman diagram. In addition, the role of various nucleon resonances listed in the Particle Data Group (PDG) is carefully scrutinized in the $s$ channel where the resonance parameters are extracted from the experimental data and constituent quark model. We present our numerical results of the total and differential cross sections and compare them with the recent CLAS data. The effect of the narrow nucleon resonance $N(1685,1/2^+)$ on cross sections is studied in detail and it turns out that its existence is essential in $K^0 Λ$ photoproduction to reproduce the CLAS data.

hep-ph↗
arXiv2018

$ηn$ photoproduction and nucleon resonances

We present results of a recent work on the reaction mechanism of $ηn$ photoproduction off the neutron in the range of $ \sqrt{s} \approx 1.5 - 1.9$ GeV and discuss the role of various nucleon resonances listed in the Particle Data Group (PDG). We make use of an effective Lagrangian approach combining with a Regge method. The total and helicity-dependent cross sections $σ_{1/2},\,σ_{3/2}$ are computed and the numerical results are in good agreement with the A2 experimental data.

hep-ph↗
arXiv2018

Effects of nucleon resonances on $η$ photoproduction off the neutron reexamined

We investigate $η$ photoproduction off the neutron target, i.e., $γn \to ηn$, employing an effective Lagrangian method combining with a Regge approach. As a background, we consider nucleon exchange in the $s$-channel diagram and $ρ$- and $ω$-meson Regge trajectories in the $t$ channel. The role of nucleon resonances given in the Review of Particle Data Group in the range of $W \approx 1500 - 2100$ MeV and the narrow nucleon resonance $N(1685,1/2^+)$ is extensively studied. The numerical results of the total and differential cross sections, double polarization observable $E$, and helicity-dependent cross sections $σ_{1/2}$, $σ_{3/2}$ are found to be in qualitative agreement with the recent A2 experimental data. The predictions of the beam asymmetry are also given.

hep-ph↗
arXiv2018

$K^0Λ$ photoproduction off the neutron with nucleon resonances

We investigate kaon photoproduction off the neutron target, i.e., $γn \to K^0 Λ$, focusing on the role of nucleon resonances given in the Review of Particle Data Group in the range of $\sqrt{s} \approx 1600 - 2200$ MeV. We employ an effective Lagrangian method and a Regge approach. The strong couplings of nucleon resonances with $KΛ$ vertices are constrained by quark model predictions. The numerical results of the total and differential cross sections are found to be in qualitative agreement with the recent CLAS and FOREST experimental data. We discuss the effects of the narrow nucleon resonance $N(1685,1/2^+)$ on both the total and differential cross sections near the threshold energy. In addition, we present the results of the beam asymmetry as a prediction.

hep-ph↗
arXiv2017

Photoproduction of the scalar mesons $f_0(500)$ and $f_0(980)$ off the nucleon

We investigate photoproduction of the scalar mesona off the nucleon, using the effective Lagrangians and the Regge approach. We first study $f_0(980)$ photoproduction, replacing the Feynman propagator with the Regge ones for the $ρ$-meson exchange in the $t$-channel. The model parameters are fixed by reproducing the experimental data on the differential cross section. We then apply the same method to $f_0(500)$ or $σ$ photoproduction with the same parameters for the Regge propagator. Since the threshold energy of the $f_0(500)$ production is rather low, $N^*$ resonances, which can decay into the nucleon and two pions in the isoscalar and scalar state, can come into play in the $s$-channel. To examine the effects of the $N^*$ resonances, we set up two models to look into the respective contribution of the $N^*$ resonances. We find that in particular $N^*(1440)$ and $N^*(1680)$ play important roles in $f_0(500)$ photoproduction. We discuss the physical implications of the present results.

hep-ph↗
arXiv2017

Photoproduction of $Λ(1405)$ with the $N^*$ and $t$-channel Regge contributions

We investigate the photoproduction of $Λ(1405)\equivΛ^*$ hyperon resonance, i.e., $γp\to K^+Λ^*$, employing the effective Lagrangian approach with the $t$-channel Regge trajectories at tree level. We extensively explore the effects from the nucleon resonances in the vicinity of the threshold $\sqrt{s}_\mathrm{th}\approx1900$ MeV, i.e., $N(2000)$, $N(2030)$, $N(2055)$, $N(2095)$, and $N(2100)$, and observe that they are of great importance to reproduce the recent CLAS/Jlab experimental data. Total and differential cross sections are given as numerical results and compared with the experimental data, in addition to the $t$-channel momentum transfer and photon-beam asymmetry. The invariant-mass plots for $γp\to K^+π^0Σ^0$ via $Λ^*$ are also extracted from the two-body process results, showing a qualitative agreement with the data. We also discuss the constituent-counting rule for the internal structure of $Λ^*$, resulting in that $Λ^*$ appears to be different from a simple three-quark $(uds)$ state.

hep-ph↗
arXiv2017

Decay angular distributions of $K^*$ and $D^*$ vector mesons in pion-nucleon scattering

The production mechanisms of open strangeness ($K^*$) and open charm ($D^*$) vector mesons in $π^- p$ scattering, namely, $π^- +p \to K^{*0} + Λ$ and $π^- + p \to D^{*-} + Λ_c^+$, are investigated within the modified quark-gluon string model. In order to identify the major reaction mechanisms, we consider the subsequent decays of the produced vector mesons into two pseudoscalar mesons, i.e., $K^* \to K + π$ and $D^* \to D + π$. We found that the decay distributions and density matrix elements are sensitive to the production mechanisms and can be used to disentangle the vector trajectory and pseudoscalar trajectory exchange models. Our results for $K^*$ production are compared with the currently available experimental data and the predictions for $D^*$ production processes are presented as well. Our predictions can be tested at the present or planned experimental facilities.

nucl-th↗
arXiv2016

Heavy pentaquark states $P_c(4380)$ and $P_c(4450)$ in the $J/ψ$ production induced by pion beams off the nucleon

In this study, we investigate the $J/ψ$ production induced by pion beams off the nucleon, particularly the heavy pentaquarks $P_c(4380)$ and $P_c(4450)$ in intermediate states, based on a hybridized Regge model. The process involving $ρ$ and $π$ meson exchange in the $t$ channel is considered as background, and the heavy pentaquark exchange is included in the $s$ channel. The coupling constants such as the $ρNN$ and $πNN$ vertices are taken from the $NN$ potentials, whereas those for the $J/ψρπ$ and $J/ψππ$ vertices are determined by using experimental data based on the branching ratios. In order to estimate the $P_c(4380)$ and $P_c(4450)$ coupling constants, we use the experimental upper limit on the total cross section as a guide for the $πN\to J/ψN$ reaction. The background total cross section is the order of $10^{-4}-10^{-3}$ nb. In the vicinity of the heavy pentaquark masses, the total cross section reaches about $1$ nb.

hep-ph↗
arXiv2016

$K^0 Λ$ and $D^- Λ_c^+$ production induced by pion beams off the nucleon

We present a comparative study of the pion induced production of $K^0 Λ$ and $D^- Λ_c^+$ off the nucleon. A hybrid framework is utilized by combining an effective Lagrangian method with a Regge approach. We consider the $t$-channel process in a plannar diagram by vector-meson Reggeon exchanges and the $u$-channel one in a non-planar diagram by baryon Reggeon exchanges. The present model reproduces the $K^0 Λ$ production data well with a few parameters. Having fixed them, we predict the $D^- Λ_c^+$ production, which turns out to be about $10^4-10^6$ times smaller than the strangeness one, depending on the kinematical regions.

hep-ph↗
arXiv2015

Production of strange and charmed baryons in pion induced reactions

We study the strangeness and charm productions induced by the pion beam, i.e. the $π^-$p $\rightarrow$ $K^{*0}Λ$ and $π^-$p $\rightarrow$ $D^{*-}Λ_c^+$ reactions, based on two different theoretical frameworks: an effective Lagrangian method and a Regge approach. In order to estimate the magnitude of the charm production relative to that of the strangeness production, we assume that the coupling constants for the charmed meson and baryon vertices are the same as those for the strangeness channel. We found that the total cross section for the charm production was about $10^3 - 10^6$ times smaller than that for the strangeness production, depending on theoretical approaches and kinematical regions. We also discuss each contribution to observables for both reactions. In general, the Regge approach explains the experimental data very well over the whole energy region.

hep-ph↗
arXiv2015

Pion Induced Reactions for the Study of Charmed Baryons

In this talk, we report the study of $π^- p \to K^{*0} Λ$ and $π^- p \to D^{*-} Λ_c^+$ reactions by using an effective Lagrangian method and a hybrid Regge model. The total and differential cross sections for the $K^{*0} Λ$ production are first calculated and then those for the $D^{*-} Λ_c^+$ one are estimated. The two models yield different results, each exhibiting specific features. Our prediction for the charm production provides valuable information about the upcoming J-PARC experiment.

hep-ph↗
arXiv2014

Effects of $N(2000)\, 5/2^+$, $N(2060)\,5/2^-$, $N(2120)\,3/2^-$, and $N(2190)\,7/2^-$ on $K^*Λ$ photoproduction

We reinvestigate $K^*Λ(1116)$ photoproduction off the nucleon target, based on an effective Lagrangian approach. We include higher nucleon resonances such as $N(2000)\, 5/2^+$, $N(2060)\,5/2^-$, $N(2120)\,3/2^-$, and $N(2190)\,7/2^-$, of which the data are taken from the 2012 edition of Review of Paritcle Physics, in addition to the $t$-channel diagrams ($K$, $K^*$, and $κ$), the $s$-channel nucleon, and $u$-channel hyperon($Λ$, $Σ$, and $Σ^*$) contributions. We find that the $N(2120)\,3/2^-$ and $N(2190)\,7/2^-$ resonances are essential in describing the new CLAS data for charged $K^*$ photoproduction. On the other hand, they rarely affect for neutral $K^*$ photoproduction.

hep-ph↗
arXiv2014

Pion induced Reactions for Charmed Baryons

We study pion induced reactions for charmed baryons $B$, $π$ + N $\rightarrow$ $D^*$ + $B$. First we estimate charm production rates in comparison with strangeness production using a Regge model which is dominated by vector ($D^*$ or $K^*$ ) Reggeon exchange. Then we examine the production rates of various charmed baryons $B$ in a quark-diquark model. We find that the production of excited states are not necessarily suppressed, a sharp contrast to strangeness production, which is a unique feature of the charm production with a large momentum transfer.

hep-ph↗
arXiv2013

Study of Baryon Resonances in the Photoproduction gamma p ---> K* Sigma(1190)

In this talk, we report the theoretical studies of baryon resonances for the gamma p ---> K*0 Sigma+ and gamma p ---> K*+ Sigma0 reaction processes by making use of the effective Lagrangian method in the tree-level Born approximation. The numerical results for the total and differential cross sections are shown with the presently available data. It turns out that the contributions from the N* and Delta* resonances are almost negligible near the threshold energy. On the other hand, the effects of the K exchange in the t channel and Delta(1232) in the s channel are considerably larger than other ones in the scattering process, being in good agreement with the experimental data.

hep-ph↗
arXiv2013

K*Sigma photoproduction off the proton target with baryon resonances

We investigate the photoproduction of K*0Sigma+ and K*+Sigma0 off the proton target, employing the effective Lagrangian approach at the tree-level Born approximation. In addition to the (s, t, u)-channel Born diagrams, we take into account various baryon-resonance contributions such as F15(2000), D13(2080), G17(2190), D15(2200), F35(2000), G37(2200), F37(2390), and Sigma*(1385, 3/2+) in a fully covariant manner. We present the numerical results for the energy and angular dependences for the cross sections in comparison to available experimental data. The single-polarization observables, i.e. the photon-beam, recoil and target baryon polarization asymmetries are computed as well for future experiments. We observe from the numerical results that the resonance contributions play a minor role in producing the strength of the cross sections, being different from the K*Lambda photoproduction. In contrast, it turns out that the Delta(1232)-pole contribution and strange-meson exchanges in the t-channel dominate the scattering process. On the other hand, the higher resonances influence the polarization observables such as the recoil and target asymmetries.

hep-ph↗
arXiv2012

Contribution of N* and Delta* resonances in K* Sigma(1190) photoproduction

In this talk, we report theoretical studies on the K*0 Sigma+(1190) photoproduction in the tree-level Born approximation, employing the effective Lagrangian method. We present the energy and angular dependences of the cross sections. It turns out that the N* and Delta* resonance contributions are negligible in the vicinity of the threshold. On the contrary, we observe that the kappa and K exchanges in the t channel and Delta(1232) in the s channel dominate the scattering process, reproducing the experimental data qualitatively well.

hep-ph↗
arXiv2011

Contribution of higher nucleon resonances to K*Λ photoproduction

We investigate K*Λ(1116) photoproduction off the proton and neutron targets in the effective Lagrangian method in the tree-level Born approximation. In addition to the K, K*, and κ exchanges which are the main contributions to the reaction, we consider the contributions from the higher nucleon resonances D13(2080) and the D15(2200). We find that the D13(2080) plays a crucial role in explaining the enhancement of the near-threshold production rate, which results in a good agreement with the experimental data for the proton targets, while the contribution of the D15(2200) is rather small. A similar conclusion is drawn for K* photoproduction off the neutron targets. In addition to the energy and angular dependence of the cross sections, we present the predictions on the photon-beam asymmetry.

hep-ph↗