Toward a more realistic holographic QCD model

By matching the $Dp-Dq$ system in type II superstring theory with the Regge trajectories of vector and axial-vector meson spectra, a possible 5-dimension metric of a $Dp-Dq$ soft-wall model has been determined. The dependence of the metric parameters on Regge trajectory parameters has been demonstrated. It is shown that the models defined in $Dp$ brane background for $p=3$ or 4 can be consistent with experimental data.Comment: 8 pages, proceedings for the YITP International Symposium "Fundamental Problems in Hot and/or Dense QCD", March 3-6, 2008, Kyoto, Japa

Sigma meson and lowest possible glueball candidate in an extended linear σ\sigma model

We formulate an extended linear $\sigma$ model of a quarkonia nonet and a tetraquark nonet as well as a complex iso-singlet (glueball) field to study the low-lying scalar meson. Chiral symmetry and $U_A(1)$ symmetry and their breaking play important role to shape the scalar meson spectrum in our work. Based on our study we will comment on what may be the mass of the lowest possible scalar and pseudoscalar glueball states. We will also discuss on what may be the nature of the sigma or $f_0(600)$ meson.Comment: Contribution to the Proceedings of QCD@work 2012, Lecce, Italy, 18-21 June 2012, 5 pages, 2 figure

Logarithmic correction in the deformed AdS5{\rm AdS}_5 model to produce the heavy quark potential and QCD beta function

We stude the \textit{holographic} QCD model which contains a quadratic term $-\sigma z^2$ and a logarithmic term $-c_0\log[(z_{IR}-z)/z_{IR}]$ with an explicit infrared cut-off $z_{IR}$ in the deformed ${\rm AdS}_5$ warp factor. We investigate the heavy quark potential for three cases, i.e, with only quadratic correction, with both quadratic and logarithmic corrections and with only logarithmic correction. We solve the dilaton field and dilation potential from the Einstein equation, and investigate the corresponding beta function in the G{\"u}rsoy -Kiritsis-Nitti (GKN) framework. Our studies show that in the case with only quadratic correction, a negative $\sigma$ or the Andreev-Zakharov model is favored to fit the heavy quark potential and to produce the QCD beta-function at 2-loop level, however, the dilaton potential is unbounded in infrared regime. One interesting observing for the case of positive $\sigma$, or the soft-wall ${\rm AdS}_5$ model is that the corresponding beta-function exists an infrared fixed point. In the case with only logarithmic correction, the heavy quark Cornell potential can be fitted very well, the corresponding beta-function agrees with the QCD beta-function at 2-loop level reasonably well, and the dilaton potential is bounded from below in infrared. At the end, we propose a more compact model which has only logarithmic correction in the deformed warp factor and has less free parameters.Comment: 24 pages, 16 figure

1-(2,6-Difluoro­benzo­yl)-3-(2,3,5-tri­chloro­phen­yl)urea

The asymmetric unit of the title compound, C14H7Cl3F2N2O2, contains two unique molecules. The 2,3,5-trichloro­phenyl ring is almost coplanar with the urea group in both molecules, whereas the 2,6-difluoro­phenyl ring is twisted from the urea plane by 54.83 (10)° in one molecule and 60.58 (10)° in the other. An intra­molecular N—H—O hydrogen bond stabilizes the mol­ecular conformation. The crystal packing is formed by inter­molecular N—H—O hydrogen bonds and F⋯F inter­actions [2.841 (2) Å]