Variational Monte Carlo study of pentaquark states in a correlated quark model

Accurate numerical solution of the five-body Schrodinger equation is effected via variational Monte Carlo in a correlated quark model. The spectrum is assumed to exhibit a narrow resonance with strangeness S=+1. A fully antisymmetrized and pair-correlated five-quark wave function is obtained for the assumed non-relativistic Hamiltonian which has spin, isospin, and color dependent pair interactions and many-body confining terms which are fixed by the non-exotic spectra. Gauge field dynamics are modeled via flux tube exchange factors. The energy determined for the ground states with spin-parity 1/2- (1/2+) is 2.22 GeV (2.50 GeV). A lower energy negative parity state is consistent with recent lattice results.Comment: 3 pages, PANIC05 conference proceeding

Multiple cerebral infarctions in the context of malignancy

Coagulation disorders are common in patients with malignancy, sometimes leading to arterial and venous thrombosis. Such patients are therefore at increased risk for ischaemic stroke. Though usually occurring in advanced stages of cancers, sometimes stroke can be the first manifestation of a hidden, yet undiagnosed, malignancy. This report presents a case of recurrent strokes secondary to malignancy-related thromboembolism in a 63-year old gentleman.peer-reviewe

Effect of collisions on neutrino flavor inhomogeneity in a dense neutrino gas

We investigate the stability, with respect to spatial inhomogeneity, of a two-dimensional dense neutrino gas. The system exhibits growth of seed inhomogeneity due to nonlinear coherent neutrino self-interactions. In the absence of incoherent collisional effects, we observe a dependence of this instability growth rate on the neutrino mass spectrum: the normal neutrino mass hierarchy exhibits spatial instability over a larger range of neutrino number density compared to that of the inverted case. We further consider the effect of elastic incoherent collisions of the neutrinos with a static background of heavy, nucleon-like scatterers. At small scales, the growth of flavor instability can be suppressed by collisions. At large length scales we find, perhaps surprisingly, that for inverted neutrino mass hierarchy incoherent collisions fail to suppress flavor instabilities, independent of the coupling strength.Comment: 10 pages, 6 figures Version accepted in PLB. Minor changes. Title change

Spin asymmetries for confined Dirac particles

We study the Bjorken `x' (or equivalently Nachtmann `xi') dependence of the virtual photon spin asymmetry in polarized deep inelastic scattering of electrons from hadrons. We use an exactly solved relativistic potential model of the hadron, treating the constituents as independent massless Dirac particles confined to an infinitely massive force center. The importance of including the p-wave components of the Dirac wave function is demonstrated. Comparisons are made to the observed data on the proton by taking into account the observed flavor dependence of the valence quark distribution functions.Comment: 4 pages, 4 figues; submitted to Phys. Lett.