Eccentricity fluctuations from the Color Glass Condensate at RHIC and LHC

In this brief note, we determine the fluctuations of the initial eccentricity in heavy-ion collisions caused by fluctuations of the nucleon configurations. This is done via a Monte-Carlo implementation of a Color Glass Condensate $k_t$-factorization approach. The eccentricity fluctuations are found to nearly saturate elliptic flow fluctuations measured recently at RHIC. Extrapolations to LHC energies are shown.Comment: 2 pages, 2 figure

Exchange between deep donors in semiconductors: a quantum defect approach

Exchange interactions among defects in semiconductors are commonly treated within effective-mass theory using a scaled hydrogenic wave-function. However such a wave-function is only applicable to shallow impurities; here we present a simple but robust generalization to treat deep donors, in which we treat the long-range part of the wavefunction using the well established quantum defect theory, and include a model central-cell correction to fix the bound-state eigenvalue at the experimentally observed value. This allows us to compute the effect of binding energy on exchange interactions as a function of donor distance; this is a significant quantity given recent proposals to carry out quantum information processing using deep donors. As expected, exchange interactions are suppressed (or increased), compared to the hydrogenic case, by the greater localization (or delocalization) of the wavefunctions of deep donors (or `super-shallow' donors with binding energy less then the hydrogenic value). The calculated results are compared with a simple scaling of the Heitler-London hydrogenic exchange; the scaled hydrogenic results give the correct order of magnitude but fail to reproduce quantitatively our calculations. We calculate the donor exchange in silicon including inter-valley interference terms for donor pairs along the $\{100\}$ direction, and also show the influence of the donor type on the distribution of nearest-neighbour exchange constants at different concentrations. Our methods can be used to compute the exchange interactions between two donor electrons with arbitrary binding energy.Comment: 11 pages, 10 figures, RevTeX

Forward particle productions at RHIC and the LHC from CGC within local rcBK evolution

In order to describe forward hadron productions in high-energy nuclear collisions, we propose a Monte-Carlo implementation of Dumitru-Hayashigaki-Jalilian-Marian formula with the unintegrated gluon distribution obtained numerically from the running-coupling BK equation. We discuss influence of initial conditions for the BK equation by comparing a model constrained by global fit of small-x HERA data and a newly proposed one from the running coupling MV model.Comment: Talk given at conference Quark Matter 2011, 4 page

Diurnal changes in shoot water dynamics are synchronized with hypocotyl elongation in Arabidopsis thaliana

We recently demonstrated the circadian clock modulated water dynamics in the roots of a small model plant, Arabidopsis thaliana, by the Nuclear Magnetic Resonance (NMR) microimaging technique. Our developed technique was able to visualize the water distribution that depended on differences in the 1H signal among region in the shoot, such as the shoot apex, the hypocotyl and the root shoot junction. Water content in the shoot increased during periods of light in comparison with dark periods, and continued through the early stage of seedling growth until the dark period. When the water content changed, elongation and/or movement occurred in the hypocotyl, and these events were synchronized. The water dynamics of the shoot also displayed an opposite phase with the root water dynamics

Branching ratio change in K- absorption at rest and the nature of the Lambda(1405)

We investigate in-medium corrections to the branching ratio in K- absorption at rest and their effect on the (positively and negatively) charged pion spectrum. The in-medium corrections are due to Pauli blocking, which arises if the Lambda(1405) is assumed to be a $\bar{K}$-nucleon bound state and leads to a density and momentum dependent mass shift of the Lambda(1405). Requiring that the optical potential as well as the branching ratio are derived from the same elementary T-matrix, we find that the in-medium corrected, density dependent T-matrix gives a better description of the K- absorption reaction than the free, density-independent one. This result suggests that the dominant component of the Lambda(1405) wave function is the $\bar{K}N$ bound state.Comment: 8 Pages, Revtex with epsf, and embedded 8 ps figure

Re-Hardening of Hadron Transverse Mass Spectra in Relativistic Heavy-Ion Collisions

We analyze the spectra of pions and protons in heavy-ion collisions at relativistic energies from 2 A GeV to 65+65 A GeV by using a jet-implemented hadron-string cascade model. In this energy region, hadron transverse mass spectra first show softening until SPS energies, and re-hardening may emerge at RHIC energies. Since hadronic matter is expected to show only softening at higher energy densities, this re-hardening of spectra can be interpreted as a good signature of the quark-gluon plasma formation.Comment: 10 pages, 3 figures, 1 table, Poster presentation at QM2001, Revised to correct latex error in citation on April 6, 200

Precise determination of the hyperfine parameters of europium in multifluorite perovskites by 151Eu Mössbauer spectroscopy

The hyperfine interactions at the europium lattice sites in samples of the homologous (Fe,Cu)Sr2(Eu,Ce)nCu2O4+2n+z (n=2,3) series were studied by Eu151 Mössbauer spectroscopy. The work was motivated by the search for new superconducting phases. This homologous series is based on the YBa2Cu3O7−δ (1:2:3) structure. The samples used in the Mössbauer measurements consisted of crystallites with random orientation and grain oriented crystallites. The texture of oriented samples was analyzed by x-ray diffraction. The complete quadrupole Hamiltonian of the 21.5-keV γ-transition of Eu151 was successfully applied in the analyses of all the Mössbauer spectra. In samples having n≤2 the europium atoms occupy a single lattice site, whereas the spectra of the n=3 samples exhibit hyperfine interactions of the two different europium sites. Analyzing the hyperfine parameters of the latter samples was made possible by simultaneous fitting of three spectra, corresponding to three different crystal orientations of the same specimen. This fitting scheme also enables more precise determination of the hyperfine parameters in the n=2 samples. In these samples an electric field gradient (EFG), with a large negative-valued main component (Vzz) parallel with the crystal c axis, was found. In the n=3 samples, the two EFG’s of the europium sites were found to have Vzz components of opposite signs. The negative Vzz value was attributed to the rare-earth site adjacent to the CuO layer. This site, found in all samples of the series, corresponds to the rare-earth site of the 1:2:3 system.Peer reviewe