Studying Diquark Structure of Heavy Baryons in Relativistic Heavy Ion Collisions

We propose the enhancement of $\Lambda_c$ yield in heavy ion collisions at RHIC and LHC as a novel signal for the existence of diquarks in the strongly coupled quark-gluon plasma produced in these collisions as well as in the $\Lambda_c$. Assuming that stable bound diquarks can exist in the quark-gluon plasma, we argue that the yield of $\Lambda_c$ would be increased by two-body collisions between $ud$ diquarks and $c$ quarks, in addition to normal three-body collisions among $u$, $d$ and $c$ quarks. A quantitative study of this effect based on the coalescence model shows that including the contribution of diquarks to $\Lambda_c$ production indeed leads to a substantial enhancement of the $\Lambda_c/D$ ratio in heavy ion collisions.Comment: Prepared for Chiral Symmetry in Hadron and Nuclear Physics (Chiral07), Nov. 13-16, 2007, Osaka, Japa

Morphological Characterization of the Radiation Sensitive Cell Line, XRS-5

Morphometric analysis was performed on the radiation sensitive Chinese hamster ovary (CHO) xrs-5 cell line, reverting xrs-5 cells and parental K1 cells. Several ultrastructural parameters (increased nuclear envelope membrane separation, cell and nuclear volume, nuclear to cytoplasmic ratio, and the nuclear surface area per unit volume of the cell) were measured and correlated with radiation sensitivity. A trend in increased cell size and radiosensitivity was observed. However, only the substantially increased nuclear envelope membrane separation in sensitive xrs-5 cells significantly correlated with radiation sensitivity. The maximal nuclear envelope membrane separation in sensitive xrs-5 cells was 270.8 nm. The maximal K1 cell nuclear envelope membrane separation was 134.8 nm, although, on average the K1 cell nuclear envelope membrane separation was 36.8 nm. The reverted xrs-5 cells had a smaller nuclear envelope membrane separation (maximal 83.6 nm), but the measured space did not completely revert to that for K1 cells. Therefore, we conclude that the nuclear envelope membrane separation is correlated with radiation sensitivity of xrs-5 cells, but it cannot be considered as the only defect correlatable with the radiation sensitivity

Theory of vortex lattice effects on STM spectra in d-wave superconductors

Theory of scanning tunneling spectroscopy of low energy quasiparticle (QP) states in vortex lattices of d-wave superconductors is developed taking account of the effects caused by an extremely large extension of QP wavefunctions in the nodal directions and the band structure in the QP spectrum. The oscillatory structures in STM spectra, which correspond to van Hove singularities are analysed. Theoretical calculations carried out for finite temperatures and scattering rates are compared with recent experimental data for high temperature cuprates.Comment: 4 pages, 3 eps figures, M2S-HTSC-VI conference paper, using Elsevier style espcrc2.st

Direct k-space mapping of the electronic structure in an oxide-oxide interface

The interface between LaAlO3 and SrTiO3 hosts a two-dimensional electron system of itinerant carriers, although both oxides are band insulators. Interface ferromagnetism coexisting with superconductivity has been found and attributed to local moments. Experimentally, it has been established that Ti 3d electrons are confined to the interface. Using soft x-ray angle-resolved resonant photoelectron spectroscopy we have directly mapped the interface states in k-space. Our data demonstrate a charge dichotomy. A mobile fraction contributes to Fermi surface sheets, whereas a localized portion at higher binding energies is tentatively attributed to electrons trapped by O-vacancies in the SrTiO3. While photovoltage effects in the polar LaAlO3 layers cannot be excluded, the apparent absence of surface-related Fermi surface sheets could also be fully reconciled in a recently proposed electronic reconstruction picture where the built-in potential in the LaAlO3 is compensated by surface O-vacancies serving also as charge reservoir.Comment: 8 pages, 6 figures, incl. Supplemental Informatio

Management of localized energy in discrete nonlinear transmission lines

The manipulation of locked intrinsic localized modes/discrete breathers is studied experimentally in nonlinear electric transmission line arrays. Introducing a static lattice impurity in the form of a capacitor, resistor or inductor has been used both to seed or destroy and attract or repel these localized excitations. In a nonlinear di-element array counter propagating short electrical pulses traveling in the acoustic branch are used to generate a stationary intrinsic localized mode in the optic branch at any particular lattice site. By changing the pulse polarity the same localized excitation can be eliminated demonstrating that the dynamical impurity associated with the propagating electrical pulse in the acoustic branch can trigger optical localized mode behavior.Comment: submitte

New Universality Class of Quantum Criticality in Ce- and Yb-based Heavy Fermions

A new universality class of quantum criticality emerging in itinerant electron systems with strong local electron correlations is discussed. The quantum criticality of a Ce- or Yb-valence transition gives us a unified explanation for unconventional criticality commonly observed in heavy fermion metals such as YbRh2Si2 and \beta-YbAlB4, YbCu5-xAlx, and CeIrIn5. The key origin is due to the locality of the critical valence fluctuation mode emerging near the quantum critical end point of the first-order valence transition, which is caused by strong electron correlations for f electrons. Wider relevance of this new criticality and important future measurements to uncover its origin are also discussed.Comment: 20 pages, 4 figure

Macroscopic quantum tunneling of two-component Bose-Einstein condensates

We show theoretically the existence of a metastable state and the possibility of decay to the ground state through macroscopic quantum tunneling in two-component Bose-Einstein condensates with repulsive interactions. Numerical analysis of the coupled Gross-Pitaevskii equations clarifies the metastable states whose configuration preserves or breaks the symmetry of the trapping potential, depending on the interspecies interaction and the particle number. We calculate the tunneling decay rate of the metastable state by using the collective coordinate method under the WKB approximation. Then the height of the energy barrier is estimated by the saddle point solution. It is found that macroscopic quantum tunneling is observable in a wide range of particle numbers. Macroscopic quantum coherence between two distinct states is discussed; this might give an additional coherent property of two-component Bose condensed systems. Thermal effects on the decay rate are estimated.Comment: 11 pages, 10 figures, revtex

Absence of anomalous negative lattice-expansion for polycrystalline sample of Tb2Ti2O7

High resolution X-ray powder-diffraction experiments on a well-characterized polycrystalline sample of the spin liquid Tb2Ti2O7 reveal that it shows normal positive thermal-expansion above 4 K, which does not agree with the intriguing anomalous negative thermal-expansion due to a magneto-elastic coupling reported for a single crystal sample below 20 K. We also performed a Rietveld profile refinement of a powder-diffraction pattern taken at a room temperature, and confirmed that it is consistent with the fully ordered cubic pyrochlore structure.Comment: 2 pages, 3 figure

Anti-self-dual Maxwell solutions on hyperk\"ahler manifold and N=2 supersymmetric Ashtekar gravity

Anti-self-dual (ASD) Maxwell solutions on 4-dimensional hyperk\"ahler manifolds are constructed. The N=2 supersymmetric half-flat equations are derived in the context of the Ashtekar formulation of N=2 supergravity. These equations show that the ASD Maxwell solutions have a direct connection with the solutions of the reduced N=2 supersymmetric ASD Yang-Mills equations with a special choice of gauge group. Two examples of the Maxwell solutions are presented.Comment: 9 page