Hadronic decay of a scalar B meson from the lattice

We explore the transitions B$(0^+)$ to B $\pi$ and B$_s(0^+)$ to B K from lattice QCD with $N_f=2$ flavours of sea quark, using the static approximation for the heavy quark. We evaluate the effective coupling constants, predicting a B$(0^+)$ to B $\pi$ width of around 160 MeV. Our result for the coupling strength adds to the evidence that the B$_s(0^+)$ meson is not predominantly a molecular state (BK).Comment: 10 pages LATE

Scaling of FLIC Fermions

Hadron masses are calculated in quenched lattice QCD on a variety of lattices in order to probe the scaling behavior of the Fat-Link Irrelevant Clover (FLIC) fermion action, a fat-link clover fermion action in which the purely irrelevant operators of the fermion action are constructed using APE-smeared links. The scaling analysis indicates FLIC fermions provide a new form of nonperturbative O(a) improvement where near-continuum results are obtained at finite lattice spacing.Comment: 4 pages, 1 figure, 2 tables. Figure updated and references added. Accepted for publication in Phys. Rev.

Non-perturbative renormalization of lattice operators in coordinate space

We present the first numerical implementation of a non-perturbative renormalization method for lattice operators, based on the study of correlation functions in coordinate space at short Euclidean distance. The method is applied to compute the renormalization constants of bilinear quark operators for the non-perturbative O(a)-improved Wilson action in the quenched approximation. The matching with perturbative schemes, such as MS-bar, is computed at the next-to-leading order in continuum perturbation theory. A feasibility study of this technique with Neuberger fermions is also presented.Comment: 11 pages and 9 figures, LaTeX2

Boosting Higgs discovery - the forgotten channel

Searches for a heavy Standard Model Higgs boson focus on the 'gold plated mode' where the Higgs decays to two leptonic Z bosons. This channel provides a clean signature, in spite of the small leptonic branching ratios. We show that using fat jets the semi-leptonic ZZ mode significantly increases the number of signal events with a similar statistical significance as the leptonic mode.Comment: 12 pages, 3 figure

Material Property Correlations: Comparisons between FRAPCON-3.4, FRAPTRAN 1.4, and MATPRO

The U.S. Nuclear Regulatory Commission (NRC) uses the computer codes FRAPCON-3 and FRAPTRAN to model steady state and transient fuel behavior, respectively, in regulatory analysis. In order to effectively model fuel behavior, material property correlations must be used for a wide range of operating conditions (e.g. temperature and burnup). In this sense, a 'material property' is a physical characteristic of the material whose quantitative value is necessary in the analysis process. Further, the property may be used to compare the benefits of one material versus another. Generally speaking, the material properties of interest in regulatory analysis of nuclear fuel behavior are mechanical or thermodynamic in nature. The issue of what is and is not a 'material property' will never be universally resolved. In this report, properties such as thermal conductivity are included. Other characteristics of the material (e.g. fission gas release) are considered 'models' rather than properties, and are discussed elsewhere. Still others (e.g., neutron absorption cross-section) are simply not required in this specific analysis. The material property correlations for the FRAPCON-3 and FRAPTRAN computer codes were documented in NUREG/CR-6534 and NUREG/CR-6739, respectively. Some of these have been modified or updated since the original code documentation was published. The primary purpose of this report is to consolidate the current material property correlations used in FRAPCON-3 and FRAPTRAN into a single document. Material property correlations for oxide fuels, including uranium dioxide (UO2) and mixed oxide (MOX) fuels, are described in Section 2. Throughout this document, the term MOX will be used to describe fuels that are blends of uranium and plutonium oxides, (U,Pu)O2. The properties for uranium dioxide with other additives (e.g., gadolinia) are also discussed. Material property correlations for cladding materials and gases are described in Sections 3 and 4, respectively. In addition to describing the material property correlations used in the subroutines of FRAPCON-3 and FRAPTRAN, this report also provides a variety of comparisons between material property correlations and data. Although they are frequently identical, comparisons are made between the material property correlations used in the FRAPCON-3 and FRAPTRAN codes. Comparisons are also made between the material property correlations used in MATPRO, a compilation of fuel and cladding material property correlations with an extensive history of used with various fuel performance and severe accident codes. For a number of reasons, consistency between the material property correlations in FRAPCON-3, FRAPTRAN, and MATPRO has never been complete. However, the current versions of FRAPCON-3 and FRAPTRAN use a relatively consistent set of correlations for the properties that are used by both codes. The material property correlations in the most recent version of MATPRO are documented in Volume 4 of NUREG/CR-6150. In addition to comparison of the various correlations, correlation-to-data comparisons are also made with FRAPCON-3, FRAPTRAN, and MATPRO. All comparisons made in this report are based on the material property correlations used in the most recent version of the FRAPCON-3 and FRAPTRAN codes, FRAPCON-3.4 and FRAPTRAN 1.4. The source code for each material property correlation discussed will be provided for FRAPCON-3.4 and FRAPTRAN 1.4 (see appendix) as well as a range of applicability and an estimate of uncertainty where possible

A First Principles Estimate of Finite Size Effects in Quark-Gluon Plasma Formation

Using lattice simulations of quenched QCD we estimate the finite size effects present when a gluon plasma equilibrates in a slab geometry, i.e., finite width but large transverse dimensions. Significant differences are observed in the free energy density for the slab when compared with bulk behavior. A small shift in the critical temperature is also seen. The free energy required to liberate heavy quarks relative to bulk is measured using Polyakov loops; the additional free energy required is on the order of 30-40 MeV at 2-3 T_c.Comment: 10 pages, 5 figures, RevTeX; revised version includes comparison with the Bjorken model and various small improvement

Developments and new applications of numerical stochastic perturbation theory

A review of new developments in numerical stochastic perturbation theory (NSPT) is presented. In particular, the status of the extension of the method to gauge fixed lattice QCD is reviewed and a first application to compact (scalar) QED is presented. Lacking still a general proof of the convergence of the underlying stochastic processes, a self-consistent method for testing the results is discussed.Comment: 3 pages, 1 figure. Poster presented at the Lattice97 conference, Edinburgh, U

Light Hadron Spectroscopy: Theory and Experiment

Rapporteur talk at the Lepton-Photon Conference, Rome, July 2001: reviewing the evidence and strategies for understanding scalar mesons, glueballs and hybrids, the gluonic Pomeron and the interplay of heavy flavours and light hadron dynamics. Dedicated to the memory of Nathan Isgur, long-time collaborator and friend, whose original ideas in hadron spectroscopy formed the basis for much of the talk.Comment: to be published in "Lepton Photon 2001 Conference Proceedings" (World Scientific Publishing), 19 pages with 6 figure

Topological Charge Evolution in the Markov-Chain of QCD

The topological charge is studied on lattices of large physical volume and fine lattice spacing. We illustrate how a parity transformation on the SU(3) link-variables of lattice gauge configurations reverses the sign of the topological charge and leaves the action invariant. Random applications of the parity transformation are proposed to traverse from one topological charge sign to the other. The transformation provides an improved unbiased estimator of the ensemble average and is essential in improving the ergodicity of the Markov chain process.Comment: 4 pages, 2 figure