We present recent investigations on the vector and axial-vector transitions of the baryon antidecuplet within the framework of the self-consistent SU(3) chiral quark-soliton model, taking into account the 1/N_c rotational and linear m_s corrections. The main contribution to the electric-like transition form factor comes from the wave-function corrections. This is a consequence of the generalized Ademollo-Gatto theorem. It is also found that in general the leading-order contributions are almost canceled by the rotational 1/N_c corrections. The results are summarized as follows: the vector and tensor K^*-N-Theta coupling constants, g_{K^*-N-Theta}=0.74 - 0.87 and f_{K^*-N-Theta}=0.53 - 1.16, respectively, and Gamma_{Theta->KN}=0.71 MeV, based on the result of the K-N-Theta coupling constant g_{K-n-Theta}=0.83. We also show the differential cross sections and beam asymmetries, based on the present results. We also discuss the connection of present results with the original work by Diakonov, Petrov, and Polyakov.
Suppression of Theta^+(J^P=3/2^(+,-)) photoproduction from the proton
我们研究了质子和中子光生Theta^+的情况，γ N -> Kbar Theta^+。假设θ ^+的自旋和宇称为J^P = 3/2^（+，-），结果表明，与中子相比，质子的产生受到强烈抑制。这可能为CLAS实验通过反应γ p -> Kbar ^0 Theta^+发现Theta ^+的无效结果提供了一个可能的解释。
Photoproduction of Theta^+(1540,1/2^+) reexamined with new theoretical information
考虑到手征夸克-孤子模型（chiQSM）给出的K-N-Theta和K*-N-Theta耦合强度的新理论信息，我们利用有效拉格朗日方法重新研究了γ N -> Kbar Theta^+反应过程中奇异五夸克态重子Theta^+（1540，1/2^+）的光生.我们还考虑了交叉对称强子形状因子，也满足在壳条件。由于矢量K介子、g_{K* N Theta}和f_{K* N Theta}具有相当大的矢量和张量耦合，与赝标K介子的矢量耦合g_{K N Theta} ~ 0.8几乎相同，因此K* 交换贡献在光子束不对称性中起关键作用。
Exclusive photoproduction of a $γ\,π^\pm$ pair in the kinematics where the pair has a large invariant mass and the final nucleon has a small transverse momentum is described in the collinear factorization framework. The scattering amplitude is calculated at leading order in $α_s$ and the differential cross sections for the process are estimated in the kinematics of the JLab~12-GeV experiments. The order of magnitude of the predicted cross-sections seems sufficient for a dedicated experiment to be performed. The process turns out to be very sensitive to the axial generalized parton distribution…
We investigate photoproduction of axial vector meson $f_1(1285)$ based on the CLAS experiment $γp\to pf_1(1285)\to pηπ^+π^-$ using the Regge model for $ρ^0+ω$ exchanges. The combined analysis of $γp\to pη'\to pηπ^+π^-$ reaction including $η(1295)$ is accompanied to evaluate the decay mode $η(1295)\to ηπ^+π^-$ from the potential overlap with the $f_1$ reaction. The predominance of $ρ^0(770)$ exchange over the $ω(782)$ with the coupling constant $γρ^0f_1$ extracted from the CLAS experiment leads to a good description of the measured cross sections for $f_1$, while the scale of the cross section …
We present a new version of the EtaMAID model for $η$ and $η'$ photoproduction on nucleons. The model includes 23 nucleon resonances parameterized with Breit-Wigner shapes. The background is described by vector and axial-vector meson exchanges in the $t$ channel using the Regge cut phenomenology. Parameters of the resonances were obtained from a fit to available experimental data for $η$ and $η'$ photoproduction on protons and neutrons. The nature of the most interesting observations in the data is discussed.
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 confi…
Gamow-Teller transitions in nuclei tell us that the nucleon's axial charge $g_A^{(3)}$ is quenched in large nuclei by about 20%. This result tells us that the spin structure of the nucleon is modified in nuclei and disfavours models of the medium dependence of parton structure based only on nucleon short range correlations in nuclei. For polarized photoproduction the Gerasimov-Drell-Hearn integral is expected to be strongly enhanced in medium.
