Excited nucleon spectrum from lattice QCD with maximum entropy method

We study excited states of the nucleon in quenched lattice QCD with the spectral analysis using the maximum entropy method. Our simulations are performed on three lattice sizes $16^3\times 32$, $24^3\times 32$ and $32^3\times 32$, at $\beta=6.0$ to address the finite volume issue. We find a significant finite volume effect on the mass of the Roper resonance for light quark masses. After removing this systematic error, its mass becomes considerably reduced toward the direction to solve the level order puzzle between the Roper resonance $N'(1440)$ and the negative-parity nucleon $N^*(1535)$.Comment: Lattice2003(spectrum), 3 pages, 4 figure

Polarization Switching Dynamics Governed by Thermodynamic Nucleation Process in Ultrathin Ferroelectric Films

A long standing problem of domain switching process - how domains nucleate - is examined in ultrathin ferroelectric films. We demonstrate that the large depolarization fields in ultrathin films could significantly lower the nucleation energy barrier (U*) to a level comparable to thermal energy (kBT), resulting in power-law like polarization decay behaviors. The "Landauer's paradox": U* is thermally insurmountable is not a critical issue in the polarization switching of ultrathin ferroelectric films. We empirically find a universal relation between the polarization decay behavior and U*/kBT.Comment: 5 pages, 4 figure

Plasmoid-Induced-Reconnection and Fractal Reconnection

As a key to undertanding the basic mechanism for fast reconnection in solar flares, plasmoid-induced-reconnection and fractal reconnection are proposed and examined. We first briefly summarize recent solar observations that give us hints on the role of plasmoid (flux rope) ejections in flare energy release. We then discuss the plasmoid-induced-reconnection model, which is an extention of the classical two-ribbon-flare model which we refer to as the CSHKP model. An essential ingredient of the new model is the formation and ejection of a plasmoid which play an essential role in the storage of magnetic energy (by inhibiting reconnection) and the induction of a strong inflow into reconnection region. Using a simple analytical model, we show that the plasmoid ejection and acceleration are closely coupled with the reconnection process, leading to a nonlinear instability for the whole dynamics that determines the macroscopic reconnection rate uniquely. Next we show that the current sheet tends to have a fractal structure via the following process path: tearing, sheet thinning, Sweet- Parker sheet, secondary tearing, further sheet thinning... These processes occur repeatedly at smaller scales until a microscopic plasma scale (either the ion Larmor radius or the ion inertial length) is reached where anomalous resistivity or collisionless reconnection can occur. The current sheet eventually has a fractal structure with many plasmoids (magnetic islands) of different sizes. When these plasmoids are ejected out of the current sheets, fast reconnection occurs at various different scales in a highly time dependent manner. Finally, a scenario is presented for fast reconnection in the solar corona on the basis of above plasmoid-induced-reconnection in a fractal current sheet.Comment: 9 pages, 11 figures, with using eps.sty; Earth, Planets and Space in press; ps-file is also available at http://stesun8.stelab.nagoya-u.ac.jp/~tanuma/study/shibata2001

Sustainability of multi-field inflation and bound on string scale

We study the effects of the interaction terms between the inflaton fields on the inflationary dynamics in multi-field models. With power law type potential and interactions, the total number of e-folds may get considerably reduced and can lead to unacceptably short period of inflation. Also we point out that this can place a bound on the characteristic scale of the underlying theory such as string theory. Using a simple multi-field chaotic inflation model from string theory, the string scale is constrained to be larger than the scale of grand unified theory.Comment: (v1) 9 pages, 1 figure;(v2) 10 pages, references added; (v3) 15 pages, 4 figures, more discussions about parameters and observable quantities, references added, to appear in Modern Physics Letters

The continuum limit of quark number susceptibilities

We report the continuum limit of quark number susceptibilities in quenched QCD. Deviations from ideal gas behaviour at temperature T increase as the lattice spacing is decreased from T/4 to T/6, but a further decrease seems to have very little effect. The measured susceptibilities are 20% lower than the ideal gas values, and also 10% below the hard thermal loop (HTL) results. The off-diagonal susceptibility is several orders of magnitude smaller than the HTL results. We verify a strong correlation between the lowest screening mass and the susceptibility. We also show that the quark number susceptibilities give a reasonable account of the Wroblewski parameter, which measures the strangeness yield in a heavy-ion collision.Comment: 8 pages, 5 figure

Purification and recovery of 100MoO3 in crystal production for AMoRE experiment

The AMoRE collaboration searches for the neutrinoless double-beta decay of 100Mo with ultra-radiopure molybdate crystals operated as low-temperature scintillating bolometers. For such a rare event search experiment, the techniques for investigating and reducing radioactive background contaminants in detector materials are extremely crucial. This paper discusses techniques for deep purification of enriched molybdenum for growing the crystals and the recovery of 100MoO3 from the residual melt left after growing lithium molybdate crystals. The purities of enriched molybdenum trioxide powders before and after the purification and that of the recovered powder were tested with ICP-MS; results of these tests are presented.Comment: 7 pages, 2 tables, proceeding of the INSTR20 conference in JINS