On the definitions of the gamma*N -> N* helicity amplitudes (2008)
Aznauryan, I. G., Burkert, V. D., Lee, T. -S. H.
We present definitions and formulas that may be useful for a consistent computation of helicity amplitudes for the process gamma* N -> N* in theoretical approaches. Of particular importance is the...
Insights into the pi- p -> eta n reaction mechanism (2008)
Durand, J., Julia-Diaz, B., Lee, T. -S. H., Saghai, B., Sato, T.
A dynamical coupled-channels formalism is used to investigate the $\eta-$meson production mechanism on the proton induced by pions, in the total center-of-mass energy region from threshold up to 2...
Dynamical coupled-channels study of pi N --> pi pi N reactions (2008)
Kamano, H., Julia-Diaz, B., Lee, T. -S. H., Matsuyama, A., Sato, T.
As a step toward performing a complete coupled-channels analysis of the world data of pi N, gamma^* N --> pi N, eta N, pi pi N reactions, the pi N --> pi pi N reactions are investigated starting with...
Extraction of Resonances from Meson-Nucleon Reactions (2008)
Suzuki, N., Sato, T., Lee, T. -S. H.
We present a pedagogical study of the commonly employed Speed-Plot (SP) and Time-delay (TD) methods for extracting the resonance parameters from the data of two particle coupled-channels reactions....
Neutron Structure Functions (2008)
Arrington, J., Coester, F., Holt, R. J., Lee, T. -S. H.
Neutron structure functions can be extracted from proton and deuteron data and a representation of the deuteron structure. This procedure does not require DIS approximations or quark structure...
Coupled-channels study of the $\pi^{-}p \to \eta n$ process (2008)
Durand, J., Juliá-Díaz, B., Lee, T. -S. H., Saghai, B., Sato, T.
The reaction $\pi^{-}p \to \eta n$ is investigated within a dynamical coupled-channels model of meson production reactions in the nucleon resonance region. The meson baryon channels included are $\pi...
Dynamical Coupled-Channels Effects on Pion Photoproduction (2007)
Julia-Diaz, B., Lee, T. -S. H., Matsuyama, A., Sato, T., Smith, L. C.
The electromagnetic pion production reactions are investigated within the dynamical coupled-channels model developed in {\bf Physics Reports, 439, 193 (2007)}. The meson-baryon channels included in...
Dynamical Coupled-Channels Analysis at EBAC (2007)
The status of dynamical coupled-channel analysis at Excited Baryon Analysis Center (EBAC) of Jefferson Laboratory is reported.
The physical meaning of scattering matrix singularities in coupled-channel formalisms (2007)
Capstick, S., Svarc, A., Tiator, L., Gegelia, J., Giannini, M. M., Santopinto, E., ...
The physical meaning of bare and dressed scattering matrix singularities has been investigated. Special attention has been attributed to the role of well known invariance of scattering matrix with...
Regge approach to charged-pion photoproduction at invariant energies above 2 GeV (2007)
Sibirtsev, A., Haidenbauer, J., Krewald, S., Lee, T. -S. H., Thomas, A. W.
A Regge model with absorptive corrections is employed in a global analysis of the world data on positive and negative pion photoproduction for photon energies from 3 to 8 GeV. In this region...
Julia-Diaz, B., Lee, T. -S. H., Matsuyama, A., Sato, T.
As a first step to analyze the electromagnetic meson production reactions in the nucleon resonance region, the parameters of the hadronic interactions of a dynamical coupled-channel model, developed...
On the sign of the pi-rho-omega coupling constant (2006)
Nakayama, K., Oh, Yongseok, Haidenbauer, J., Lee, T. -S. H.
It is shown that the relative sign between the $NN\omega$ and $\pi\rho\omega$ coupling constants can be determined most sensitively from $\omega$ production processes in $NN$ collisions. Recent data...
Extraction and Interpretation of gamma N --> Delta Form Factors within a Dynamical Model (2006)
Julia-Diaz, B., Lee, T. -S. H., Sato, T., Smith, L. C.
Within the dynamical model of Refs. [Phys. Rev. C54, 2660 (1996); C63, 055201 (2001)], we perform an analysis of recent data of pion electroproduction reactions at energies near the Delta(1232)...
Study of nucleon resonances with electromagnetic interactions (2006)
Recent developments in using electromagnetic meson production reactions to study the structure of nucleon resonances are reviewed. Possible future works are discussed.
Neutrino-nucleus reactions in the delta resonance region (2006)
Szczerbinska, B., Sato, T., Kubodera, K., Lee, T. -S. H.
Reliable estimates of neutrino-nucleus reactions in the resonance-excitation region play an important role in many of the on-going and planned neutrino oscillation experiments. We study here...
Search for missing baryon resonances via associated strangeness photoproduction (2006)
Saghai, B., Julia-Diaz, B., Lee, T. -S. H.
Differential cross-section and single polarization observables in the process gamma p --> K^+ Lambda are investigated within a constituent quark model and a dynamical coupled-channel formalism. The...
Dynamical coupled-channel model of meson production reactions in the nucleon resonance region (2006)
Matsuyama, A., Sato, T., Lee, T. -S. H.
A dynamical coupled-channel model is presented for investigating the nucleon resonances in the meson production reactions induced by pions and photons. The model is based on an energy-independent...
Dynamical model of electroweak pion production in the resonance region (2006)
Sato, T., Szczerbinska, B., Kubodera, K., Lee, T. -S. H.
In this report, we will briefly review the dynamical model of pion electroweak production reactions in the $\Delta$ resonance region and report on our study of neutrino-nucleus reactions based on...
Julia-Diaz, B., Saghai, B., Lee, T. -S. H., Tabakin, F.
A dynamical coupled-channel formalism for processes $\pi N \to KY$ and $\gamma N \to KY$ is presented which provides a comprehensive investigation of recent data on the $\gamma p \to K^+ \Lambda$...
Coupled channel study of $K^+\Lambda$ photoproduction (2005)
Julia-Diaz, B., Saghai, B., Lee, T. -S. H., Tabakin, F.
A coupled channel model with $\gamma N$, $KY$ and $\pi N$ channels has been used to analyze the recent data of $\gamma p \to K^+ \Lambda$. The non-resonant interactions within the subspace $KY \oplus...
Photo-excitation of hyperons and exotic baryon in gamma N --> K Anti-K N (2005)
Oh, Yongseok, Nakayama, K., Lee, T. -S. H.
We investigate the reaction of $\gamma N \to K \bar{K} N$ focusing on the photoproduction of $\Lambda(1520)$ and putative exotic $\Theta(1540)$. We consider various background production mechanisms...
Matsui, K., Sato, T., Lee, T. -S. H.
A dynamical model of electroweak pion production reactions in the Delta(1232) region has been extended to include the neutral current contributions for examining the local Quark-Hadron Duality in...
Dynamical coupled-channel study of K+ Lambda photoproduction (2005)
Juliá-Díaz, B., Saghai, B., Tabakin, F., Lee, T. -S. H., Li, Z.
Results for the reaction gamma p --> K+ Lambda, studied within a constituent quark model and a dynamical coupled-channel approach, are presented and compared with recent data. Issues related to the...
Pentaquark Theta^+(1540) production in gamma N --> K Anti-K N (2004)
Oh, Yongseok, Nakayama, K., Lee, T. -S. H.
The recent developments in the search of exotic pentaquark hadrons are briefly reviewed. We then focus on investigating how the exotic pentaquark $\Theta(1540)$ baryon production can be identified in...
Dynamical Model of Electroweak Pion Production Reaction (2004)
The dynamical model of pion electroproduction developed by the authors has been extended to study the pion weak production reaction. The axial vector N-Delta transition form factor G_A^{N\Delta}...
Leading-order Corrections of a Dynamical Model for Electromagnetic Pion Production Reactions (2004)
Sato, T., Lee, T. -S. H., Nakamura, T.
By applying a unitary transformation method, we have derived the leading-order corrections on the effective Hamiltonian of a dynamical model developed in Phys. Rev. C54, 2660 (1996) for...
Electromagnetic Meson Production in the Nucleon Resonance Region (2004)
Burkert, V. D., Lee, T. -S. H.
Recent experimental and theoretical advances in investigating electromagnetic meson production reactions in the nucleon resonance region are reviewed.
Models of Meson-Baryon Reactions in the Nucleon Resonance Region (2004)
Lee, T. -S. H., Matsuyama, A., Sato, T.
It is shown that most of the models for analyzing meson-baryon reactions in the nucleon resonance region can be derived from a Hamiltonian formulation of the problem. An extension of the...
Dynamical coupled-channel model of kaon-hyperon interactions (2004)
Chiang, Wen-Tai, Saghai, B., Tabakin, F., Lee, T. -S. H.
The pi N --> KY and KY --> KY reactions are studied using a dynamical coupled-channel model of meson-baryon interactions at energies where the baryon resonances are strongly excited. The channels...
Pion electroproduction amplitudes predicted by three theoretical models in the $Q^2 \leq 0.5$ (GeV/c)$^2$ region are compared. The objective is to facilitate the analyses of the data from new...
f_2, sigma, and 2-pi exchanges in rho meson photoproduction (2003)
The $\sigma$ meson exchange model for $\rho$ photoproduction at low energies is re-examined and a new model is developed by considering explicit two-pion exchange and the $f_2$ tensor meson exchange....
Rho meson photoproduction at low energies (2003)
The $\sigma$-exchange and $f_2$-exchange mechanisms for $\rho$ meson photoproduction are re-examined. Then the commonly employed $\sigma$-exchange amplitude is revised by using the recent information...
Spin effects and baryon resonance dynamics in phi-meson photoproduction at few GeV (2003)
The diffractive $\phi$-meson photoproduction amplitude is dominated by the Pomeron exchange process and contains the terms that govern the spin-spin and spin-orbital interactions. We show that these...
Dynamical Model of Weak Pion Production Reactions (2003)
Sato, T., Uno, D., Lee, T. -S. H.
The dynamical model of pion electroproduction has been extended to investigate the weak pion production reactions. The predicted cross sections of neutrino-induced pion production reactions are in...
pi and rho loop corrections to omega photoproduction in the resonance region (2002)
One-loop corrections due to the intermediate $\pi N$ and $\rho N$ states are studied in $\omega$ photoproduction near threshold. Our results show that the coupled-channel effects should be taken into...
Quark-Exchange Mechanism of $\gamma d \to np$ Reaction At 2-6 GeV (2002)
Julia-Diaz, Bruno, Lee, T. -S. H.
Within the constituent quark model, we examine the extent to which the deuteron photo-disintegration at 2-6 GeV can be described by the quark-exchange mechanism. With the parameters constrained by...
One-loop corrections to omega photoproduction near threshold (2002)
One-loop corrections to $\omega$ photoproduction near threshold have been investigated by using the approximation that all relevant transition amplitudes are calculated from the tree diagrams of...
Eta Meson Production in NN Collisions (2002)
Nakayama, K., Speth, J., Lee, T. -S. H.
Eta meson production in both proton-proton and proton-neutron collisions is investigated within a relativistic meson exchange model of hadronic interactions. It is found that the available cross...
Final state interactions in omega photoproduction near threshold (2002)
Vector meson photoproduction and electroproduction have been suggested as a tool to find or confirm the nucleon resonances. In order to extract more reliable informations on the nucleon resonances,...
Study of Nucleon Resonances with Double Polarization Observables of Pion Photoproduction (2001)
Dutta, D., Gao, H., Lee, T. -S. H.
The role of the nucleon resonances in the double polarization observables of pion photoproduction is investigated by using the resonance parameters predicted by Capstick and Roberts. As an example,...
Dynamical Study of the d(e,e' pi+) reaction (2001)
The $d(e,e'\pi^+)$ reaction in the parallel kinematics has been investigated using a dynamical model of pion electroproduction on the nucleon. A unitary $\pi NN$ model has been used in order to...
Coupled-channel study of gamma p --> K+ Lambda (2001)
Chiang, Wen-Tai, Tabakin, F., Lee, T. -S. H., Saghai, B.
A coupled-channel (CC) approach has been developed to investigate kaon photoproduction on the nucleon. In addition to direct K+ Lambda production, our CC approach accounts for strangeness production...
Higher and missing resonances in omega photoproduction (2001)
Oh, Yongseok, Titov, Alexander I., Lee, T. -S. H.
We study the role of the nucleon resonances ($N^*$) in $\omega$ photoproduction by using the quark model resonance parameters predicted by Capstick and Roberts. The employed $\gamma N \to N^*$ and...
Meson-exchange $\pi N$ Models in Three-Dimensional Bethe-Salpeter Formulation (2000)
Hung, Cheng-Tsung, Yang, Shin Nan, Lee, T. -S. H.
The pion-nucleon scattering is investigated by using several three-dimensional reduction schemes of the Bethe-Salpeter equation for a model Lagrangian involving $\pi$, $N$, $\Delta$, $\rho$, and...
Nucleon resonances in polarized omega photoproduction (2000)
Oh, Yongseok, Titov, Alexander I., Lee, T. -S. H.
The role of the nucleon resonances ($N^*$) in $\omega$ photoproduction is investigated by using the resonance parameters predicted by Capstick and Roberts. The contributions from the nucleon...
Phi^{zero}-N Bound State (2000)
Gao, H., Lee, T. -S. H., Marinov, V.
We show that the QCD van der Waals attractive potential is strong enough to bind a $\phi^{0}$ meson onto a nucleon inside a nucleus to form a bound state. The direct experimental signature for such...
Dynamical Study of the Delta Excitation in N(e,e' pi) Reactions (2000)
The dynamical model developed in [Phys. Rev. C 54, 2660 (1996)] has been applied to investigate the pion electroproduction reactions on the nucleon. It is found that the model can describe to a very...
Nucleon resonances in omega photoproduction (2000)
Oh, Yongseok, Titov, Alexander I., Lee, T. -S. H.
The role of the nucleon resonances ($N^*$) in $\omega$ photoproduction is investigated by using the resonance parameters predicted by Capstick and Roberts [Phys. Rev. D {\bf 46}, 2864 (1992); {\bf...
Quantum Monte Carlo Calculations of Pion Scattering from Li (2000)
Lee, T. -S. H., Wiringa, R. B.
We show that the neutron and proton transition densities predicted by recent quantum Monte Carlo calculations for A=6,7 nuclei are consistent with pion scattering from 6Li and 7Li at energies near...
Pion Production Model - Connection between Dynamics and Quark Models (2000)
We discuss the difficulties in testing the hadron models by using the N^* parameters extracted from the empirical amplitude analyses of the pi-N and gamma-N reaction data. As an alternative or...
Baryon Resonance Extraction from piN Data using a Unitary Multichannel Model (1999)
Vrana, T. P., Dytman, S. A., Lee, T. -S. H.
A unitary multi-channel approach, first developed by the Carnegie-Mellon- Berkeley group, is applied to extract the pole positions, masses, and partial decay widths of nucleon resonances. Input used...
Dynamical Test of Constituent Quark Models with $\pi N$ Reactions (1999)
Yoshimoto, T., Sato, T., Arima, M., Lee, T. -S. H.
A dynamical approach is developed to predict the $\pi N$ scattering amplitudes starting with the constituent quark models. The first step is to apply a variational method to solve the three-quark...
Evidence for the fourth P11 resonance predicted by the constituent quark model (1999)
Capstick, Simon, Lee, T. -S. H., Roberts, W., Svarc, A.
It is pointed out that the third of five low-lying P11 states predicted by a constituent quark model can be identified with the third of four states in a solution from a three-channel analysis by the...
Strange hadron matter and SU(3) symmetry (1999)
Stoks, V. G. J., Lee, T. -S. H.
We calculate saturation curves for strange hadron matter using recently constructed baryon-baryon potentials which are constrained by SU(3) symmetry. All possible interaction channels within the...
An isotopic effect in phi photoproduction at a few GeV (1998)
Titov, A. I., Lee, T. -S. H., Toki, H.
A distinct isotopic effect in phi photoproduction at 2-5 GeV region is identified by examining the production amplitudes due to Pomeron-exchange and meson-exchange mechanisms. This effect is mainly...
Non-perturbative chiral approach to Kp -->gamma Y reactions (1998)
Lee, T. -S. H., Oller, J. A., Oset, E., Ramos, A.
A recently developed nonperturbative chiral approach to describe the S=-1 meson-baryon reactions has been extended to investigate the near threshold $K^- p \to \gamma \Lambda, \gamma \Sigma^0$...
The isoscalar S-wave pi-N scattering length a+ from pi-deuteron scattering (1997)
Beane, S. R., Bernard, V., Lee, T. -S. H., Meißner, Ulf-G.
We consider constraints on the isoscalar S-wave pi-N scattering length a+ from pi-deuteron scattering, to third order in small momenta and pion masses in chiral perturbation theory. To this order,...
Chiral Perturbation Theory and the pp -> pp pi0 Reaction Near Threshold (1997)
Sato, T., Lee, T. -S. H., Myhrer, F., Kubodera, K.
A chiral-perturbative consideration of the near-threshold pp -> pp pi0 reaction indicates that the pion-rescattering term has a substantial energy and momentum dependence. The existing calculations...
Update of the pi N --> eta N and eta N --> eta N partial-wave amplitudes (1997)
Batinic, Mijo, Dadic, Ivan, Slaus, Ivo, Svarc, Alfred, Nefkens, B. M. K., Lee, T. -S. H.
A three-channel, multi-resonance, unitary model developed in 1995 is used to determine the $\pi N \rightarrow \eta N$ and $\eta N \rightarrow \eta N$ amplitudes using as input the latest data for the...
Neutral pion photoproduction on deuterium in baryon chiral perturbation theory to order q^4 (1997)
Beane, S. R., Bernard, V., Lee, T. -S. H., Meißner, Ulf-G., Van Kolck, U.
Threshold neutral pion photoproduction on the deuteron is studied in the framework of baryon chiral perturbation theory beyond next-to--leading order in the chiral expansion. To fourth order in small...
Kamada, H., Locher, M. P., Lee, T. -S. H., Golak, J., Markushin, V. E., Glöckle, W., ...
The absorption of \pi^+ on ^3He in the $\Delta$-region is evaluated with exact inclusion of the final state interaction among the three emerging protons. The absorption is described by a $\pi N \to...
Exclusive diffractive processes and the quark substructure of mesons (1996)
Pichowsky, M. A., Lee, T. -S. H.
Exclusive diffractive processes on the nucleon are investigated within a model in which the quark-nucleon interaction is mediated by Pomeron exchange and the quark substructure of mesons is described...
Near threshold eta production in proton-proton collisions (1996)
Batinic, M., Svarc, A., Lee, T. -S. H.
The total cross section for the near threshold eta production in proton-proton collisions has been investigated with the assumption that the production mechanism is due to the emission of a meson x...
Medium Effects on Binary Collisions with the Delta Resonance (1996)
To facilitate the relativistic heavy-ion calculations based on transport equations, the binary collisions involving a $\Delta$ resonance in either the entrance channel or the exit channel are...
Pomeron exchange and exclusive electroproduction of rho-mesons in QCD (1996)
Pichowsky, M. A., Lee, T. -S. H.
A Pomeron-exchange model of exclusive electroproduction of $\rho$-mesons is examined using a dressed-quark propagator. It is shown that by representing the photon-$\rho$-meson-Pomeron coupling by a...
It is shown that the threshold productions of $\pi^0 pp$, $\pi^+ np$ and $\pi^+ d$ from $pp$ collisions can be consistently described by a model consisting of a pion s-wave rescattering and $N\bar N$...
De Jong, F., Nakayama, K., Lee, T. -S. H.
The proton-proton bremsstrahlung is investigated within a coupled-channel model with the $\Delta$ degree of freedom. The model is consistent with the $NN$ scattering up to 1 GeV and the $\gamma...
Two-body Pion Absorption on $^3He$ at Threshold (1994)
Kiang, L. L., Lee, T. -S. H., Riska, D. O.
It is shown that a satisfactory explanation of the ratio of the rates of the reactions $^3He(\pi^-,nn)$ and $^3He(\pi^-,np)$ for stopped pions is obtained once the effect of the short range...
Threshold Pion Electroproduction in Chiral Perturbation Theory (1993)
Bernard, V., Kaiser, N., Lee, T. -S. H., Meißner, Ulf-G.
Electroproduction of pions on the nucleon near the threshold is analyzed within the framework of baryon chiral perturbation theory. We give a thorough discussion of the low--energy theorems related...