ABSTRACT
This Letter presents the first lattice QCD computation of the coupled channel πΣ-K[over ¯]N scattering amplitudes at energies near 1405 MeV. These amplitudes contain the resonance Λ(1405) with strangeness S=-1 and isospin, spin, and parity quantum numbers I(J^{P})=0(1/2^{-}). However, whether there is a single resonance or two nearby resonance poles in this region is controversial theoretically and experimentally. Using single-baryon and meson-baryon operators to extract the finite-volume stationary-state energies to obtain the scattering amplitudes at slightly unphysical quark masses corresponding to m_{π}≈200 MeV and m_{K}≈487 MeV, this study finds the amplitudes exhibit a virtual bound state below the πΣ threshold in addition to the established resonance pole just below the K[over ¯]N threshold. Several parametrizations of the two-channel K matrix are employed to fit the lattice QCD results, all of which support the two-pole picture suggested by SU(3) chiral symmetry and unitarity.
ABSTRACT
A novel cyclic flow photobioreactor, designed for the capture and recycle of CO2 using microalgae, was deployed at a coal-fired power plant. Scenedesmus acutus was cultured continuously for a four-month period, during which a biomass productivity of 0.1-0.2â¯g L-1 day-1 was observed. Samples taken for DNA sequencing showed a strong correlation between the composition of the culture and environmental conditions. Dry and liquid biomass samples and the industrial fertilizers used for preparation of the nutrient medium were analyzed to determine the presence of heavy metals (As, Cd, Hg, Se) and results were compared with standardized and/or regulated maximum contaminant levels (MCLs) for metals in several possible algae derived products. Concentrations of the metals in dry algae biomass were consistent with the incorporation of metals from the supplied nutrients.
Subject(s)
Microalgae , Scenedesmus , Biomass , Carbon Dioxide , PhotobioreactorsABSTRACT
The scalar meson D*(s0)(2317) is found 37(17) MeV below the DK threshold in a lattice simulation of the J(P)=0(+) channel using, for the first time, both DK as well as s¯c interpolating fields. The simulation is done on N(f)=2+1 gauge configurations with m(π) is approximately equal to 156 MeV, and the resulting M(D*(s0))-1/4(M(D(s))+3M(D*(s)))=266(16) MeV is close to the experimental value 241.5(0.8) MeV. The energy level related to the scalar meson is accompanied by additional discrete levels due to DK scattering states. The levels near threshold lead to the negative DK scattering length a(0)=-1.33(20) fm that indicates the presence of a state below threshold.