Near infrared lasing transitions in Ar, Kr, and Xe atoms pumped by a coaxial e-beam

Optimizations of gas composition and input energy were performed for gas mixtures containing a buffer gas and either Ar, Kr or Xe as the lasing gas. The total gas pressure was varied between 1 and 14 bar and the input energy from 0.03 to 0.7 J/cm3. The excitation source was a small coaxial electron beam with a pumping length of 20 cm and a pulse length of 30 ns (FWHM). From an active volume of 13.3 cm3 a maximum output energy of 12 mJ was obtained from a gas mixture containing 0.3% Xe in Ar at a total gas pressure of 10 bar. The intrinsic efficiency was 0.9%

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