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Theoretical Nuclear and Hadron Physics
Department of Physics
Kyungpook National University

About Me


Yongseok Oh

Department of Physics 
Kyungpook National University
Daegu 702-701, Korea

Tel: +82-53-950-7373
Fax: +82-53-952-1739
Email: yohphy at knu.ac.kr

오용석
대구광역시 북구 산격동 1370
경북대학교 자연과학대학 물리학과
(우) 702-701

전화: 053-950-7373
팩스: 053-952-1739
이메일: yohphy@knu.ac.kr

Recent Papers

PHYSICAL REVIEW LETTERS 108, 092001 (2012)

Spin-Density Matrix Elements for γp→K*0Σ+ at Eγ=1.85–3.0  GeV with Evidence for the κ(800) Meson Exchange

S. H. Hwang,1 K. Hicks,2 J. K. Ahn,1 T. Nakano,3 D. S. Ahn,3 W. C. Chang,4 J. Y. Chen,4 S. Date ́,5 H. Ejiri,3,5 H. Fujimura,6 M. Fujiwara,3 S. Fukui,3 W. Gohn,7 T. Hotta,3 K. Imai,8 T. Ishikawa,9 K. Joo,7 Y. Kato,3 H. Kohri,3 Y. Kon,3 H. S. Lee,10 Y. Maeda,11 M. Miyabe,9 T. Mibe,12 Y. Morino,5 N. Muramatsu,3 Y. Nakatsugawa,13 M. Niiyama,14 H. Noumi,3 Y. Oh,15 Y. Ohashi,5 T. Ohta,3 M. Oka,3 J. Parker,14 C. Rangacharyulu,16 S. Y. Ryu,3,13 T. Sawada,3 Y. Sugaya,17 M. Sumihama,18 T. Tsunemi,3 M. Uchida,19 M. Ungaro,7 and M. Yosoi3

(LEPS Collaboration) 

The exclusive reaction γp→K*0Σ+  was measured for the first time using linearly polarized photons at beam energies from 1.85 to 2.96 GeV. Angular distributions in the rest frame of the K\pi system were fitted to extract spin-density matrix elements of the K*0 decay. The measured parity spin asymmetry shows that natural-parity exchange is dominant in this reaction. This result clearly indicates the need for t-channel exchange of the κ(800) scalar meson.    read more


PHYSICAL REVIEW C 85, 042201(R) (2012)

Model-independent determination of the parity of Ξ hyperons

K. Nakayama,1,2 Yongseok Oh,3,4  H. Haberzettl 5

1Department of Physics and Astronomy, University of Georgia, Athens, GA 30602, USA
2Institut fuer Kernphysik and Center for Hadron Physics, Forschungszentrum Juelich, D-52425 Juelich, Germany
3Department of Physics, Kyungpook National University, Daegu 702-701, Korea
4Asia Pacific Center for Theoretical Physics, Pohang, Gyeongbuk 790-784, Korea
5Institute for Nuclear Studies and Department of Physics, The George Washington University, Washington, DC 20052, USA

Based on reflection symmetry in the reaction plane, it is shown that measuring the transverse spin-transfer coefficient Kyy in the K ̄N → KΞ reaction directly determines the parity of the pro- duced cascade hyperon in a model-independent way as πΞ = Kyy, where πΞ = ±1 is the parity. This result based on Bohr’s theorem provides a completely general, universal relationship that applies to the entire hyperon spectrum. A similar expression is obtained for the photoreaction γN → KKΞ by measuring both the double-polarization observable Kyy and the photon-beam asymmetry Σ. Regarding the feasibility of such experiments,  ....         read more

PHYSICAL REVIEW D 85, 016012 (2012)

Axial anomaly and the δLT  puzzle

Nikolai Kochelev
Bogoliubov Laboratory of Theoretical Physics, Joint Institute for Nuclear Research, Dubna, Moscow region, 141980 Russia
Yongseok Oh
Department of Physics, Kyungpook National University, Daegu 702-701, Korea
The axial anomaly contribution to generalized longitudinal-transverse polarizability δLT  is calculated within Regge approach. It is shown that the contribution from the exchange of the a1(1260) Regge trajectory is nontrivial and might have the key role to explain the large difference between the predictions of chiral perturbation theory and the experimental data for the neutron δLT. We also present  ....     read more

PHYSICAL REVIEW D 84, 114023 (2011)

Contribution of higher nucleon resonances to K* Lambda photoproduction    

Sang-Ho Kim,1 Seung-il Nam,2 Yongseok Oh,3,2 and Hyun-Chul Kim1,2

1Department of Physics, Inha University, Incheon 402-751, Korea
2School of Physics, Korea Institute for Advanced Study, Seoul 130-722, Korea 
3Department of Physics, Kyungpook National University, Daegu 702-701, Korea 

We investigate K00ð1116Þ photoproduction off the proton and neutron targets using the effective Lagrangian method in the tree-level Born approximation. In addition to the K, K0, and exchanges which are the main contributions to the reaction, we consider the contributions from the higher nucleon resonances D13ð2080Þ and the D15ð2200Þ. We find that the D13ð2080Þ 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  ...                      read more


JOURNAL OF THE KOREAN PHYSICAL SOCIETY 59, 3344-3355 (2011)

Role of nucleon resonances in the πN → ωN reaction 

Yongseok Oh∗

Department of Physics, Kyungpook National University, Daegu 702-701, Korea 

The role of nucleon resonances is studied for the πN → ωN reaction within the effective La- grangian approach. We first confirm that the main background production mechanisms are the ρ-meson exchange and the nucleon terms. With these background production mechanisms, we con- sider the contribution of nucleon resonances of spin up to 7/2 and of a mass below 2.2 GeV. We find that the D13(1520), F15(1680), and G17(2190) resonances have crucial roles in the production mech- anisms of the πN → ωN reaction. ....       read more

JOURNAL OF THE KOREAN PHYSICAL SOCIETY 59, 224-246 (2011)

Combined analysis of eta meson hadro- and photoproduction off nucleons

K. Nakayama,1 Yongseok Oh,2  H. Haberzettl 3

1Department of Physics and Astronomy, University of Georgia, Athens, GA 30602, USA
2Department of Physics, Kyungpook National University, Daegu 702-701, Korea
3Center for Nuclear Studies, Department of Physics, The George Washington University, Washington, DC 20052, USA

The eta-meson photoproduction in photon- and hadron-induced reactions, namely, \gamma p \to p \eta, \pi^- p \to n \eta, p p \to p p \eta, and p n \to p n \eta, are investigated in a combined analysis in order to learn about the relevant production mechanisms and the possible role of nucleon resonances in these reactions. We consider the nucleonic, mesonic, and nucleon resonance currents constructed within an effective Lagrangian approach and compare the results with the available data for cross sections and spin asymmetries for these reactions. We found that the reaction ...   read more

 

PHYSICAL REVIEW C 83, 055201 (2011)

Role of high-spin hyperon resonances in the reaction of γp ---> K^+ K^+ \Xi^-

J. Ka Shing Man,1 Yongseok Oh,2, 3, 4 and K. Nakayama1, 5

1Department of Physics and Astronomy, University of Georgia, Athens, GA 30602, USA
2Department of Physics, Kyungpook National University, Daegu 702-701, Korea
3Excited Baryon Analysis Center, Thomas Jefferson National Accelerator Facility, Newport News, VA 23606, USA
4Asia Pacific Center for Theoretical Physics, POSTECH, Pohang 790-784, Korea
5Institut f¨ur Kernphysik, Forschungszentrum J¨ulich, D-52425 J¨ulich, Germany

The recent data taken by the CLAS Collaboration at the Thomas Jefferson National Accelerator Facility for the reaction of gamma p --> K^+ K^+ Xi.^− are reanalyzed within a relativistic meson-exchange model of hadronic interactions. The present model is an extension of the one developed in an earlier work by Nakayama, Oh, and Haberzettl [Phys. Rev. C 74, 035205 (2006)]. In particular, the role of the spin-5/2 and -7/2 hyperon resonances, which were not included in the previous model, is investigated in the present study. It is shown that the contribution of the Sigma.(2030) hyperon having spin-7/2 and positive parity has a key role ...      read more




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