A review of regional and global estimates of unconventional gas resources

This Research Report assesses the currently available evidence on the size of unconventional gas resources at the regional and global level. Focusing in particular on shale gas, it provides a comprehensive summary and comparison of the estimates that have been produced to date. It also examines the methods by which these resource estimates have been produced the strengths and weaknesses of those methods, the range of uncertainty in the results and the factors that are relevant to their interpretation

Light hadron spectrum---MILC results with the Kogut-Susskind and Wilson actions

We present the current status of our ongoing calculations of the light hadron spectrum with both Kogut-Susskind (KS) and Wilson quarks in the valence or quenched approximation. We discuss KS quarks first and find that the chiral extrapolation is potentially the biggest source of systematic error. For the Wilson case, we focus on finite volume and source size effects at 6/g^2=5.7. We find no evidence to support the claim that there is a finite volume effect between N_s=16 and 24 of approximately 5%.Comment: 11 pages, 11 figures, LaTeX, uses espcrs2, epsf, Invited talk presented by S. Gottlieb at Lattice QCD on Parallel Computers, University of Tsukuba, March, 1997, to appear in the proceeding

Properties of B-Mesons in Lattice QCD

The results of an extensive study of B-meson properties in quenched lattice QCD are presented. The studies are carried out in the static quark limit where the b-quark is taken to be infinitely massive. Our computations rely on a multistate smearing method introduced previously, with smearing functions generated from a relativistic lattice quark model. Systematic errors arising from excited state contamination, finite volume effects, and the chiral extrapolation for the light quarks are estimated. We obtain continuum results for the mass splitting M_{B_s}- M_{B_u} = 86 (+/-)12(stat) {+7/-9}(syst) MeV, the ratio of decay constants f_{B_s}/f_{B_u} = 1.22 (+/-)0.04(stat) (+/-)0.02 (syst). For the B-meson decay constant we separately exhibit the sizable uncertainties in the extrapolation to the continuum limit a -> 0 and higher order perturbative matching. We obtain f_{B} = 188 (+/-)23(stat) (+/-)15(syst) {+26/-0}(extrap) (+/-)14 (pert) MeV. ----- [Postscript version of paper available by anonymous ftp at fncrd6.fnal.gov. The file is fb.ps in subdirectory theory.]Comment: 75 pages, FERMILAB-PUB-94/164-

Does reject inference really improve the performance of application scoring models?

The voter model on Zd is a particle system that serves as a rough model for changes of opinions among social agents or, alternatively, competition between biological species occupying space. When d≥3, the set of (extremal) stationary distributions is a family of measures μα, for α between 0 and 1. A configuration sampled from μα is a strongly correlated field of 0's and 1's on Zd in which the density of 1's is α. We consider such a configuration as a site percolation model on Zd. We prove that if d≥5, the probability of existence of an infinite percolation cluster of 1's exhibits a phase transition in α. If the voter model is allowed to have sufficiently spread-out interactions, we prove the same result for d≥3

Maximal variance reduction for stochastic propagators with applications to the static quark spectrum

We study a new method -- maximal variance reduction -- for reducing the variance of stochastic estimators for quark propagators. We find that while this method is comparable to usual iterative inversion for light-light mesons, a considerable improvement is achieved for systems containing at least one infinitely heavy quark. Such systems are needed for heavy quark effective theory. As an illustration of the effectiveness of the method we present results for the masses of the ground state and excited states of $\bar{Q}q$ mesons and $\bar{Q}qq$ baryons. We compare these results with the experimental spectra involving $b$ quarks.Comment: 31 pages with 7 postscript file

A lattice determination of moments of unpolarised nucleon structure functions using improved Wilson fermions

Within the framework of quenched lattice QCD and using O(a) improved Wilson fermions and non-perturbative renormalisation, a high statistics computation of low moments of the unpolarised nucleon structure functions is given. Particular attention is paid to the chiral and continuum extrapolations.Comment: LaTeX, 66 pages, 22 figure