Constraints on narrow exotic states from K+p and K0_Lp scattering data

We consider the effect of exotic S=+1 resonances Theta+ and Theta++ on K+p elastic scattering data (total cross section) and the process K0_Lp-->K0_Sp. Data near the observed Theta+(1540) are examined for evidence of additional states. The width limit for a Theta++ state is reconsidered and shown to be much less than 1 MeV.Comment: 4 pages, 3 eps figures; minor corrections, one fig adde

High real-space resolution measurement of the local structure of Ga_1-xIn_xAs using x-ray diffraction

High real-space resolution atomic pair distribution functions (PDF)s from the alloy series Ga_1-xIn_xAs have been obtained using high-energy x-ray diffraction. The first peak in the PDF is resolved as a doublet due to the presence of two nearest neighbor bond lengths, Ga-As and In-As, as previously observed using XAFS. The widths of nearest, and higher, neighbor pairs are analyzed by separating the strain broadening from the thermal motion. The strain broadening is five times larger for distant atomic neighbors as compared to nearest neighbors. The results are in agreement with model calculations.Comment: 4 pages, 5 figure

On the K^+D Interaction at Low Energies

The Kd reactions are considered in the impulse approximation with NN final-state interactions (NN FSI) taken into account. The realistic parameters for the KN phase shifts are used. The "quasi-elastic" energy region, in which the elementary KN interaction is predominantly elastic, is considered. The theoretical predictions are compared with the data on the K^+d->K^+pn, K^+d->K^0pp, K^+d->K^+d and K^+d total cross sections. The NN FSI effect in the reaction K^+d->K^+pn has been found to be large. The predictions for the Kd cross sections are also given for slow kaons, produced from phi(1020) decays, as the functions of the isoscalar KN scattering length a_0. These predictions can be used to extract the value of a_0 from the data.Comment: 22 pages, 5 figure

Superconductivity in ferromagnetic metals and in compounds without inversion centre

The symmetry properties and the general overview of the superconductivity theory in the itinerant ferromagnets and in materials without space parity are presented. The basic notions of unconventional superconductivity are introduced in broad context of multiband superconductivity which is inherent property of ferromagnetic metals or metals without centre of inversion.Comment: 38 pages, no figure

Measurement of Direct Photon Emission in K^+ -> pi^+ pi^0 gamma Decay

We have performed a measurement of the K^+ -> pi^+ pi^0 gamma decay and have observed 2 X 10^4 events. The best fit to the decay spectrum gives a branching ratio for direct photon emission of (4.7\pm0.8\pm0.3) X 10^{-6} in the pi^+ kinetic energy region of 55 to 90 MeV and requires no component due to interference with inner bremsstrahlung.Comment: 9 pages, 3 figures. To be submitted to PR

Identifying the pairing symmetry in the Sr2RuO4 superconductor

We have analyzed heat capacity and thermal conductivity measurements of Sr2RuO4 in the normal and superconducting state and come to the conclusion that an order parameter with nodal lines on the Fermi surface is required to account for the observed low-temperature behavior. A gapped order parameter is inconsistent with the reported thermodynamic and transport data. Guided by a strongly peaked dynamical susceptibility along the diagonals of the Brillouin zone in neutron scattering data, we suggest a spin-fluctuation mechanism that would favor the pairing state with the gap maxima along the zone diagonals (such as for a d_{xy} gap). The most plausible candidates are an odd parity, spin-triplet, f-wave pairing state, or an even parity, spin-singlet, d-wave state. Based on our analysis of possible pairing functions we propose measurements of the ultrasound attenuation and thermal conductivity in the magnetic field to further constrain the list of possible pairing states.Comment: 7 pages, 5 figures; updated list of references and extended introduction; to appear in Phys. Rev. B (Oct. 2000

Risk factors for hepatitis B virus infection in Rio de Janeiro, Brazil

BACKGROUND: Despite international efforts to prevent hepatitis B virus (HBV) infection through global vaccination programs, new cases are still being reported throughout the world. METHODS: To supply data that might assist in improving preventive measures and national surveillance for HBV infection, a cross-sectional study was conducted among individuals referred to the Brazilian National Reference Center for Viral Hepatitis (Rio de Janeiro) during a two-year period. Reported risk factors among infected subjects ("HBV-positive") were compared to those of subjects never exposed ("HBV-negative") to HBV. Two subgroups were further identified within the HBV-positive group, "acute" infection and "non-acute" infection. RESULTS: A total of 1,539 subjects were tested for HBV, of which 616 were HBV-positive (79 acute infection and 537 non-acute infection). HBV-positive subjects were more likely to be of male gender (63% versus 47%); and to report multiple sexual partners (12% versus 6%) and illicit drug use (IDU and/or intranasal cocaine use) (6% versus 3%). Among the HBV-positive subgroups, age differed significantly, with 48% being under 30 years of age in subjects acutely infected compared to 17% in those with non-acute infection. CONCLUSIONS: The association of multiple sexual partners with past HBV infection and the age distribution of currently infected subjects suggest that sexual transmission played a major role in the transmission of HBV in this study population. Thus, vaccination during adolescence should be considered