Critical slowing down of topological modes

We investigate the critical slowing down of the topological modes using local updating algorithms in lattice 2-d CP^(N-1) models. We show that the topological modes experience a critical slowing down that is much more severe than the one of the quasi-Gaussian modes relevant to the magnetic susceptibility, which is characterized by $\tau_{\rm mag} \sim \xi^z$ with $z\approx 2$. We argue that this may be a general feature of Monte Carlo simulations of lattice theories with non-trivial topological properties, such as QCD, as also suggested by recent Monte Carlo simulations of 4-d SU(N) lattice gauge theories.Comment: 16 pages, 4 figure

B decays on the lattice

I review recent developments in lattice calculations of B decay matrix elements and other related quantities.Comment: LATTICE99(plenary), 12 pages, 7 postscript figures, uses espcrc2.sty, references are update

Correlates and outcomes of posttransplant smoking in solid organ transplant recipients : a systematic literature review and meta-analysis

Despite smoking being an absolute or relative contraindication for transplantation, about 11% to 40% of all patients continue or resume smoking posttransplant. This systematic review with meta-analysis investigated the correlates and outcomes associated with smoking after solid organ transplantation.; We searched PubMed, EMBASE, CINAHL, and PsycINFO from inception until January 2016, using state-of-the art methodology. Pooled odds ratios (ORs) with 95% confidence intervals (CIs) were computed for correlates/outcomes investigated 5 times or more.; Seventy-three studies (43 in kidney, 17 in heart, 12 in liver, 1 in lung transplantation) investigated 95 correlates and 24 outcomes, of which 6 correlates and 4 outcomes could be included in the meta-analysis. The odds of smoking posttransplant were 1.33 times higher in men (95% CI, 1.12-1.57). Older individuals were significantly less likely to smoke (OR, 0.48; 95% CI, 0.38-0.62), as were patients with a higher body mass index (OR, 0.68; 95% CI, 0.52-0.89). Hypertension (OR, 1.16; 95% CI, 0.77-1.75), diabetes mellitus (OR, 0.52; 95% CI, 0.15-1.78), and having a history of cardiovascular disease (OR, 0.92; 95% CI, 0.77-1.09) were not significant correlates. Posttransplant smokers had higher odds of newly developed posttransplant cardiovascular disease (OR, 1.41; 95% CI, 1.02-1.95), nonskin malignancies (OR, 2.58; 95% CI, 1.26-5.29), a shorter patient survival time (OR, 0.59; 95% CI, 0.44-0.79), and higher odds of mortality (OR, 1.74; 95% CI, 1.21-2.48).; Posttransplant smoking is associated with poor outcomes. Our results might help clinicians to understand which patients are more likely to smoke posttransplant, guide interventional approaches, and provide recommendations for future research

String Breaking as a Mixing Phenomenon in the SU(2) Higgs Model

We study the potential of a static quark anti-quark pair in the confinement ``phase'' of the SU(2) Higgs model. Around separation r_b, the confining string of the gauge field breaks by formation of a dynamical pair of light quarks. The ground state and first excited state static potentials are determined by a variational technique from a matrix correlation in which suitably smeared gauge and Higgs fields enter. Our results at beta=2.4 clearly show string breaking (r_b ~ 1.9r_0). The investigation of properly defined overlaps confirms the interpretation of string breaking as a level crossing phenomenon between string-type and meson-type states. We study the scaling properties of the static potentials along a line of constant physics, varying the lattice spacing by a factor of 2. Our results show compatibility with scaling within tiny errors.Comment: 21 pages, 9 figure

Quenched divergences in the deconfined phase of SU(2) gauge theory

The spectrum of the overlap Dirac operator in the deconfined phase of quenched gauge theory is known to have three parts: exact zeros arising from topology, small nonzero eigenvalues that result in a non-zero chiral condensate, and the dense bulk of the spectrum, which is separated from the small eigenvalues by a gap. In this paper, we focus on the small nonzero eigenvalues in an SU(2) gauge field background at $\beta=2.4$ and $N_T=4$. This low-lying spectrum is computed on four different spatial lattices ($12^3$, $14^3$, $16^3$, and $18^3$). As the volume increases, the small eigenvalues become increasingly concentrated near zero in such a way as to strongly suggest that the infinite volume condensate diverges.Comment: 12 pages, 3 figures, version to appear in Physical Review

Order a improved renormalization constants

We present non-perturbative results for the constants needed for on-shell $O(a)$ improvement of bilinear operators composed of Wilson fermions. We work at $\beta=6.0$ and 6.2 in the quenched approximation. The calculation is done by imposing axial and vector Ward identities on correlators similar to those used in standard hadron mass calculations. A crucial feature of the calculation is the use of non-degenerate quarks. We also obtain results for the constants needed for off-shell $O(a)$ improvement of bilinears, and for the scale and scheme independent renormalization constants, (Z_A), (Z_V) and (Z_S/Z_P). Several of the constants are determined using a variety of different Ward identities, and we compare their relative efficacies. In this way, we find a method for calculating $c_V$ that gives smaller errors than that used previously. Wherever possible, we compare our results with those of the ALPHA collaboration (who use the Schr\"odinger functional) and with 1-loop tadpole-improved perturbation theory.Comment: 48 pages. Modified "axis" source for figures also included. Typos corrected (version published in Phys. Rev. D

The Schwinger Model with Perfect Staggered Fermions

We construct and test a quasi-perfect lattice action for staggered fermions. The construction starts from free fermions, where we suggest a new blocking scheme, which leads to excellent locality of the perfect action. An adequate truncation preserves a high quality of the free action. An Abelian gauge field is inserted in d=2 by effectively tuning the couplings to a few short-ranged lattice paths, based on the behavior of topological zero modes. We simulate the Schwinger model with this action, applying a new variant of Hybrid Monte Carlo, which damps the computational overhead due to the non-standard couplings. We obtain a tiny ``pion'' mass down to very small \beta, while the ``\eta'' mass follows very closely the prediction of asymptotic scaling. The observation that even short-ranged quasi-perfect actions can yield strong improvement is most relevant in view of QCD.Comment: 30 pages, 16 figures. Following the referee's suggestions, we have incorporated the material of hep-lat/9803018 in this comprehensive pape

Fixed Point Gauge Actions with Fat Links: Scaling and Glueballs

A new parametrization is introduced for the fixed point (FP) action in SU(3) gauge theory using fat links. We investigate its scaling properties by means of the static quark-antiquark potential and the dimensionless quantities $r_0 T_c, T_c/\sqrt{\sigma}$ and $r_0 \sqrt{\sigma}$, where $T_c$ is the critical temperature of the deconfining phase transition, $r_0$ is the hadronic scale and $\sigma$ is the effective string tension. These quantities scale even on lattices as coarse as $a \approx 0.3$ fm. We also measure the glueball spectrum and obtain $m_{0^{++}}=1627(83)$ MeV and $m_{2^{++}}=2354(95)$ MeV for the masses of the scalar and tensor glueballs, respectively.Comment: 45 pages, 12 figures, Late

Strategic responses to global challenges: The case of European banking, 1973–2000

In applying a strategy, structure, ownership and performance (SSOP) framework to three major clearing banks (ABN AMRO, UBS, Barclays), this article debates whether the conclusions generated by Whittington and Mayer about European manufacturing industry can be applied to the financial services sector. While European integration plays a key role in determining strategy, it is clear that global factors were far more important in determining management actions, leading to significant differences in structural adaptation. The article also debates whether this has led to improved performance, given the problems experienced with both geographical dispersion and diversification, bringing into question the quality of decision-making over the long term