Observation of Goos-H\"{a}nchen shifts in metallic reflection

We report the first observation of the Goos-H$\rm \ddot{\textbf{a}}$nchen shift of a light beam incident on a metal surface. This phenomenon is particularly interesting because the Goos-H$\rm \ddot{\textbf{a}}$nchen shift for $p$ polarized light in metals is negative and much bigger than the positive shift for $s$ polarized light. The experimental result for the measured shifts as a function of the angle of incidence is in excellent agreement with theoretical predictions. In an energy-flux interpretation, our measurement shows the existence of a backward energy flow at the bare metal surface when this is excited by a $p$ polarized beam of light.Comment: The parer was published on Optics Express. The new version is modified according to the reviewers suggestion

Probing for Instanton Quarks with epsilon-Cooling

We use epsilon-cooling, adjusting at will the order a^2 corrections to the lattice action, to study the parameter space of instantons in the background of non-trivial holonomy and to determine the presence and nature of constituents with fractional topological charge at finite and zero temperature for SU(2). As an additional tool, zero temperature configurations were generated from those at finite temperature with well-separated constituents. This is achieved by "adiabatically" adjusting the anisotropic coupling used to implement finite temperature on a symmetric lattice. The action and topological charge density, as well as the Polyakov loop and chiral zero-modes are used to analyse these configurations. We also show how cooling histories themselves can reveal the presence of constituents with fractional topological charge. We comment on the interpretation of recent fermion zero-mode studies for thermalized ensembles at small temperatures.Comment: 26 pages, 14 figures in 33 part

On the stability of Dirac sheet configurations

Using cooling for SU(2) lattice configurations, purely Abelian constant magnetic field configurations were left over after the annihilation of constituents that formed metastable Q=0 configurations. These so-called Dirac sheet configurations were found to be stable if emerging from the confined phase, close to the deconfinement phase transition, provided their Polyakov loop was sufficiently non-trivial. Here we show how this is related to the notion of marginal stability of the appropriate constant magnetic field configurations. We find a perfect agreement between the analytic prediction for the dependence of stability on the value of the Polyakov loop (the holonomy) in a finite volume and the numerical results studied on a finite lattice in the context of the Dirac sheet configurations

Time transients in the quantum corrected Newtonian potential induced by a massless nonminimally coupled scalar field

We calculate the one loop graviton vacuum polarization induced by a massless, nonminimally coupled scalar field on Minkowski background. We make use of the Schwinger-Keldysh formalism, which allows us to study time dependent phenomena. As an application we compute the leading quantum correction to the Newtonian potential of a point particle. The novel aspect of the calculation is the use of the Schwinger-Keldysh formalism, within which we calculate the time transients induced by switching on of the graviton-scalar coupling.Comment: 22 pages, 5 figures; detailed calculation of the graviton vacuum polarization moved to the new Appendix; matches published versio

Infinities within graviton scattering amplitudes

We present unitarity as a method for determining the infinities present in graviton scattering amplitudes. The infinities are a combination of IR and UV. By understanding the soft singularities we may extract the UV infinities and relate these to counter-terms in the effective action. As an demonstration of this method we rederive the UV infinities present at one-loop when gravity is coupled to matter.Comment: revised versio

Correlation Between BATSE Hard X-ray Spectral and Timing Properties of Cygnus X-1

We have analyzed approximately 1100 days of Cygnus X-1 hard X-ray data obtained with BATSE to study its rapid variability. We find for the first time correlations between the slope of the spectrum and the hard X-ray intensity, and between the spectral slope and the amplitude of the rapid variations of the hard X-ray flux. We compare our results with expectations from current theories of accretion onto black holes.Comment: 17 pages, 3 Postscript figures, uses aasms4.sty. Accepted for publication in Astrophysical Journal Letter

A chiral model for bar{q}q and bar{q}bar{q}qq$ mesons

We point out that the spectrum of pseudoscalar and scalar mesons exhibits a cuasi-degenerate chiral nonet in the energy region around 1.4 GeV whose scalar component has a slightly inverted spectrum. Based on the empirical linear rising of the mass of a hadron with the number of constituent quarks which yields a mass around $1.4$GeV for tetraquarks, we conjecture that this cuasi-chiral nonet arises from the mixing of a chiral nonet composed of tetraquarks with conventional bar{q}q states. We explore this possibility in the framework of a chiral model assuming a tetraquark chiral nonet around 1.4 GeV with chiral symmetry realized directly. We stress that U_{A}(1) transformations can distinguish bar{q}q from tetraquark states, although it cannot distinguish specific dynamics in the later case. We find that the measured spectrum is consistent with this picture. In general, pseudoscalar states arise as mainly bar{q}q states but scalar states turn out to be strong admixtures of bar{q}q and tetraquark states. We work out also the model predictions for the most relevant couplings and calculate explicitly the strong decays of the a_{0}(1450) and K_{0}^*(1430) mesons. From the comparison of some of the predicted couplings with the experimental ones we conclude that observable for the isovector and isospinor sectors are consistently described within the model. The proper description of couplings in the isoscalar sectors would require the introduction of glueball fields which is an important missing piece in the present model.Comment: 20 pages, 3 figure

Intraductal fully covered self-expandable metal stent versus multiple plastic stents for treating biliary anastomotic strictures after liver transplantation

Background and aims: Fully covered metal stents (FCSEMSs) are increasingly used for treatment of biliary anastomotic strictures (ASs) after liver transplantation (LT), requiring fewer endoscopic interventions than does treatment with multiple plastic stents (MPSs). Previous studies, however, have reported adverse events such as stent migration and pancreatitis. The intraductal FCSEMS (ID-FCSEMS) potentially avoids these disadvantages. This study aimed to assess the efficacy and safety of ID-FCSEMSs compared with MPSs for AS. Methods: The cohorts of LT patients treated for AS with endoscopic stenting between 2010 and 2019 from 2 Dutch liver transplantation centers were retrospectively analyzed. Patients treated with ID-FCSEMSs or MPSs were included. Results: 80 patients (44 with ID-FCSEMSs vs 36 with MPSs) were included, with a median follow-up time of 52 versus 64 months (P = .183). Stricture resolution was 93% in the ID-FCSEMS versus 97% in the MPS group (P = 1.000) after a median of 19 and 26 weeks, respectively (P = .031). The median number of ERCPs was 2 in the ID-FCSEMS group versus 4 in the MPS group (P &lt; .001). Stricture recurrence occurred in 33% of ID-FCSEMS versus 29% of MPS patients (P = .653) after a median of 24 and 55 weeks (P = .403). Stent migration occurred in 16% of ID-FCSEMS versus 39% of MPS patients (P = .020). Post-ERCP fever was observed in 34% of ID-FCSEMS patients compared with 14% of MPS patients (P = .038). No significant differences were found in pancreatitis rate between the groups, being 6.8% for ID-FCSEMSs and 5.6% for MPSs (P = .816). Conclusion: ID-FCSEMSs for the treatment of AS after LT provides similar stricture resolution and recurrence rates as MPSs, though with a significant reduction of procedures needed.</p