Lattice QCD Study of the Pentaquark Baryons

We study the spin $\frac12$ hadronic state in quenched lattice QCD to search for a possible $S=+1$ pentaquark resonance. Simulations are carried out on $8^3\times 24$, $10^3\times 24$, $12^3\times 24$ and $16^3\times 24$ lattices at $\beta$=5.7 at the quenched level with the standard plaquette gauge action and Wilson quark action. We adopt two independent operators with I=0 and $J^P=\frac12$ to construct a $2\times 2$ correlation matrix. After the diagonalization of the correlation matrix, we successfully obtain the energies of the ground-state and the 1st excited-state in this channel. The volume dependence of the energies suggests the existence of a possible resonance state slightly above the NK threshold in I=0 and $J^P=\frac12^-$ channel.Comment: Talk given at the International Workshop on PENTAQUARK04, SPring-8, Japan, 20-23 July 2004; 7 pages, 3 figure

Perturbative Confinement

A Procedure is outlined that may be used as a starting point for a perturbative treatment of theories with permanent confinement. By using a counter term in the Lagrangian that renormalizes the infrared divergence in the Coulomb potential, it is achieved that the perturbation expansion at a finite value of the strong coupling constant may yield reasonably accurate properties of hadrons, and an expression for the string constant as a function of the QCD Lambda parameter.Comment: Presented at QCD'02, Montpellier, July 2002. 12 pages LaTeX, 8 Figures PostScript, uses gthstyle.sty Reprt-no: ITF-2002/39; SPIN-2002/2

Exact one-loop results for li→ljγl_i \to l_j\gamma in 3-3-1 models

We investigate the decays $l_i\rightarrow l_j \gamma$, with $l_i=e,\mu,\tau$ in a general class of 3-3-1 models with heavy exotic leptons with arbitrary electric charges. We present full and exact analytical results keeping external lepton masses. As a by product, we perform numerical comparisons between exact results and approximate ones where the external lepton masses are neglected. As expected, we found that branching fractions can reach the current experimental limits if mixings and mass differences of the exotic leptons are large enough. We also found unexpectedly that, depending on the parameter values, there can be huge destructive interference between the gauge and Higgs contributions when the gauge bosons connecting the Standard Model leptons to the exotic leptons are light enough. This mechanism should be taken into account when using experimental constraints on the branching fractions to exclude the parameter space of the model.Comment: 27 pages, 5 figures, 4 tables; additional explanation on input parameters; matches journal versio

Aspects of warm-flat directions

Considering the mechanism of dissipative slow-roll that has been used in warm inflation scenario, we show that dissipation may alter usual cosmological scenarios associated with SUSY-flat directions. We mainly consider SUSY-flat directions that have strong interactions with non-flat directions and may cause strong dissipation both in thermal and non-thermal backgrounds. An example is the Affleck-Dine mechanism in which dissipation may create significant (both qualitative and quantitative) discrepancies between the conventional scenario and the dissipative one. We also discuss several mechanisms of generating curvature perturbations in which the dissipative field, which is distinguished from the inflaton field, can be used as the source of cosmological perturbations. Considering the Morikawa-Sasaki dissipative coefficient, the damping caused by the dissipation may be significant for many MSSM flat directions even if the dissipation is far from thermal equilibrium.Comment: 22 pages, accepted for publication in International Journal of Modern Physics

Computer-aided design of large-scale integrated circuits - A concept

Circuit design and mask development sequence are improved by using general purpose computer with interactive graphics capability establishing efficient two way communications link between design engineer and system. Interactive graphics capability places design engineer in direct control of circuit development