arXiv subjects

Seung-il Nam

Publications and source records attributed to Seung-il Nam.

110 records · Page 7Linked to original sources

arXiv2006

QCD condensates with flavor SU(3) symmetry breaking

We investigate the effects of flavor SU(3)-symmetry breaking on the QCD condensates, based on the nonlocal effective chiral action from the instanton vacuum, focusing on the quark-gluon mixed one. We employ two different parameterizations for the dependence of the momentum-dependent dynamical quark mass on the strange current quark mass. We obtain the ratios of the mixed condensates:$[<\bar{s}σ_{μν}G^{μν}s><\bar{u}\sig ma_{μν}G^{μν}u>]^{1/5}=0.87$. It turns out that the dimensional parameter $m^2_0=<\bar{q} σ_{μν}G^{μν}q>/ <\bar{q}q> =1.60\sim 1.92 {\rm GeV}^2$.

hep-ph↗

arXiv2006

A new $N^*(1675)$ resonance in the $γN\toηN$ reaction

We study the $η$-photoproduction focusing on the new nucleon resonance which was observed at $\sqrt{s}=1675$ MeV with a narrow decay width ($\sim 10$ MeV) in the recent GRAAL experiment. Using an effective Lagrangian approach, we compute differential cross sections for the $η$-photoproduction. In addition to $N^*(1675)$, we employ three other nucleon resonances, i.e. $N^*(1535)$, $N^*(1650)$ and $N^*(1710)$, and vector meson exchanges which are the most relevant ones to this reaction process. As a result, we can reproduce the GRAAL data qualitatively well and observe obvious isospin asymmetry between the transition magnetic moments of $N^*(1675)$: $μ_{γnn^*}\ggμ_{γpp^*}$.

hep-ph↗