Properties of Low-Lying Heavy-Light Mesons

We present preliminary results for the B meson decay constant and masses of low-lying heavy-light mesons in the static limit. Calculations were performed on the lattice in the quenched approximation using multistate smearing functions generated from a Hamiltonian for a spinless relativistic quark. The 2S--1S and 1P--1S mass splittings are measured. Using the 1P--1S charmonium splitting to set the overall scale, the ground state decay constant, f_B, is 319 +- 11 (stat) MeV.Comment: 8 pages, 9 figures, UCLA/92/TEP/4

Masses and Decay Constants of Heavy-Light Mesons Using the Multistate Smearing Technique

We present results for f_B and masses of low-lying heavy-light mesons. Calculations were performed in the quenched approximation using multistate smearing functions generated from a spinless relativistic quark model Hamiltonian. Beta values range from 5.7 to 6.3, and light quark masses corresponding to pion masses as low as 300 MeV are computed at each value. We use the 1P--1S charmonium splitting to set the overall scale.Comment: 9 pages, 13 figures, and 5 tables as a single 193K compressed and uuencoded Postscript file, FERMILAB--CONF--93/376-

First results from the asymmetric O(a) improved Fermilab action

We present first results from calculations using O(a) improved (FNAL) space-time asymmetric action on a 12^3 x 24 quenched lattice at \beta = 5.7 and c_SW = 1.57. The asymmetry parameter is determined non-perturbatively from the energy-momentum dispersion relation. This improvement scheme is mass dependent, and the calculations have been done in the charm and bottom quark mass sectors since it is at these heavier masses that the asymmetry is expected to be relevant.Comment: 3 pp. LaTeX2e, 6PostScript figures, uses espcrc2.sty. Contribution to Lattice99 (Pisa) proceedings (Improvement and Renormalisation

Unquenched QCD with Light Quarks

We present recent results in unquenched lattice QCD with two degenerate light sea quarks using the truncated determinant approximation (TDA). In the TDA the infrared modes contributing to the quark determinant are computed exactly up to some cutoff in quark off-shellness (typically 2$\Lambda_{QCD}$). This approach allows simulations to be performed at much lighter quark masses than possible with conventional hybrid MonteCarlo techniques. Results for the static energy and topological charge distributions are presented using a large ensemble generated on very coarse (6$^4$) but physically large lattices. Preliminary results are also reported for the static energy and meson spectrum on 10$^3$x20 lattices (lattice scale $a^{-1}$=1.15 GeV) at quark masses corresponding to pions of mass $\leq$ 200 MeV. Using multiboson simulation to compute the ultraviolet part of the quark determinant the TDA approach becomes an exact with essentially no increase in computational effort. Some preliminary results using this fully unquenched algorithm are presented.Comment: LateX, 39 pages, 16 eps figures, 1 ps figur

Light Quark Masses with an O(a)-Improved Action

We present the recent Fermilab calculations of the masses of the light quarks, using tadpole-improved Sheikholeslami-Wohlert (SW) quarks. Various sources of systematic errors are studied. Our final result for the average light quark mass in the quenched approximation evaluated in the $\bar{MS}$ scheme is $\bar{m}_q(\mu=2 GeV;n_f=0)= (m_u+m_d)/2=3.6 \pm 0.6 MeV$.Comment: 3 pgs. 3 figures. espcrc2.sty included. Talk presented at LATTICE96(phenomenology

Leptonic Decays of Heavy-Light Systems

Results from recent lattice calculations of the decay constants $f_B$ and $f_D$ are reviewed. A discussion of the methods currently used is presented, together with an outline of the various systematic effects involved.Comment: Plenary talk given at LAT95, Melbourne, July 1995. 12 pages (Two column format), Latex file with 2 postscript figures uuencoded. Requires psfig.sty and espcrc2.sty [Numbers in Table 4 from LANL Collaboration updated slightly.

Spatial relationships between entomopathogenic nematodes and nematophagous fungi in Florida citrus orchards

Relationships between entomopathogenic nematodes (EPNs), nematophagous fungi (NF) and soil physical and chemical properties were studied in a survey of 53 citrus orchards in central ridge and flatwoods ecoregions of Florida. Seven species of NF associated with nematodes were quantified directly using a real time qPCR assay. All nematophagous fungi studied except Arthrobotrys musiformis and Hirsutella rhossiliensis were frequently detected (24-56%) in both regions. Paecilomyces lilacinus and Gamsylella gephyropagum were encountered more frequently in the flatwoods (P = 0.03) and on the ridge (P = 0.02), respectively. Redundancy analysis revealed seven abiotic and biotic factors as significantly related to the NF occurrence. Multiple regression of fungi on these variables explained 78%, 66%, 48%, 36%, 23% and 4% of the variation in Catenaria sp., A. musiformis, A dactyloides, P. lilacinus, A. oligospora and G. gepharopagum, respectively. When the data from citrus were pooled with those reported previously from natural areas and subjected to principle component analysis, the first two principle components explained 43% of the variation in NF communities. The surveys (citrus vs natural areas) were discriminated by PC2 (P < 0.001) and the ecoregion by PC1 (P < 0.002), and all but one NF species were related (P < 0.01) to one or both components. NF communities tended to have more species and greater diversity in the flatwoods, where EPN richness and diversity were the least. However, the strength of associations between individual EPN and NF species as measured by SADIE reflected the associations between each species and ground water depth, suggesting that ecoregion preferences affected the species associations. Within each ecoregion, significant relationships between the individual NF and EPN species measured by stepwise regression tended to be positive. The results did not support the hypothesis that NF modulate the spatial patterns of EPN species between or within these two ecoregions. (C) 2017 Elsevier Inc. All rights reserved.USDA-CSREES Special Grant (TSTAR)U.S-Egypt Science and Technology Joint Fund [338]Ramon Areces Spanish FoundationMarie Curie International Outgoing Fellowship within the 7th European Community Framework Programme [FP7-PEOPLE-2009-IOF-252980

Anomalous Chiral Behavior in Quenched Lattice QCD

A study of the chiral behavior of pseudoscalar masses and decay constants is carried out in quenched lattice QCD with Wilson fermions. Using the modified quenched approximation (MQA) to cure the exceptional configuration problem, accurate results are obtained for pion masses as low as $\approx$ 200 MeV. The anomalous chiral log effect associated with quenched $\eta'$ loops is studied in both the relation between $m_{\pi}^2$ vs. $m_q$ and in the light-mass behavior of the pseudoscalar and axial vector matrix elements. The size of these effects agrees quantitatively with a direct measurement of the $\eta'$ hairpin graph, as well as with a measurement of the topological susceptibility, thus providing several independent and quantitatively consistent determinations of the quenched chiral log parameter $\delta$. For $\beta=5.7$ with clover-improved fermions $(C_{sw} =1.57)$ all results are consistent with $\delta=0.065\pm 0.013$ .Comment: 51 pages, 20 figures, Late

Semileptonic form factors - a model-independent approach

We demonstrate that the B->D(*) l nu form factors can be accurately predicted given the slope parameter rho^2 of the Isgur-Wise function. Only weak assumptions, consistent with lattice results, on the wavefunction for the light degrees of freedom are required to establish this result. We observe that the QCD and 1/m_Q corrections can be systematically represented by an effective Isgur-Wise function of shifted slope. This greatly simplifies the analysis of semileptonic B decay. We also investigate what the available semileptonic data can tell us about lattice QCD and Heavy Quark Effective Theory. A rigorous identity relating the form factor slope difference rho_D^2-rho_A1^2 to a combination of form factor intercepts is found. The identity provides a means of checking theoretically evaluated intercepts with experiment.Comment: 18 pages, Revtex, 4 postscript figures, uses epsfig.st