Hyperfine Splitting and the Zeeman Effect in Holographic Heavy-Light Mesons

We inspect the mass spectrum of heavy-light mesons in deformed N=2 super Yang-Mills theory using the AdS/CFT correspondence. We demonstrate how some of the degeneracies of the supersymmetric meson spectrum can be removed upon breaking the supersymmetry, thus leading to the emergence of hyperfine structure. The explicit SUSY breaking scenarios we consider involve on one hand tilting one of the two fundamental D7 branes inside the internal R^6 space, and on the other hand applying an external magnetic field on the (untilted) branes. The latter scenario leads to the well-known Zeeman effect, which we inspect for both weak and strong magnetic fields.Comment: 5 pages, 1 figur

No arbitrage and closure results for trading cones with transaction costs

In this paper, we consider trading with proportional transaction costs as in Schachermayer’s paper (Schachermayer in Math. Finance 14:19–48, 2004). We give a necessary and sufficient condition for ${\mathcal{A}}$ , the cone of claims attainable from zero endowment, to be closed. Then we show how to define a revised set of trading prices in such a way that, firstly, the corresponding cone of claims attainable for zero endowment, ${\tilde{ {\mathcal{A}}}}$ , does obey the fundamental theorem of asset pricing and, secondly, if ${\tilde{ {\mathcal{A}}}}$ is arbitrage-free then it is the closure of ${\mathcal{A}}$ . We then conclude by showing how to represent claims

All purulence is local - epidemiology and management of skin and soft tissue infections in three urban emergency departments

BACKGROUND: Skin and soft tissue infection (SSTIs) are commonly treated in emergency departments (EDs). While the precise role of antibiotics in treating SSTIs remains unclear, most SSTI patients receive empiric antibiotics, often targeted toward methicillin-resistant Staphylococcus aureus (MRSA). The goal of this study was to assess the efficiency with which ED clinicians targeted empiric therapy against MRSA, and to identify factors that may allow ED clinicians to safely target antibiotic use. METHODS: We performed a retrospective analysis of patient visits for community-acquired SSTIs to three urban, academic EDs in one northeastern US city during the first quarter of 2010. We examined microbiologic patterns among cultured SSTIs, and relationships between clinical and demographic factors and management of SSTIs. RESULTS: Antibiotics were prescribed to 86.1% of all patients. Though S. aureus (60% MRSA) was the most common pathogen cultured, antibiotic susceptibility differed between adult and pediatric patients. Susceptibility of S. aureus from ED SSTIs differed from published local antibiograms, with greater trimethoprim resistance and less fluoroquinolone resistance than seen in S. aureus from all hospital sources. Empiric antibiotics covered the resultant pathogen in 85.3% of cases, though coverage was frequently broader than necessary. CONCLUSIONS: Though S. aureus remained the predominant pathogen in community-acquired SSTIs, ED clinicians did not accurately target therapy toward the causative pathogen. Incomplete local epidemiologic data may contribute to this degree of discordance. Future efforts should seek to identify when antibiotic use can be narrowed or withheld. Local, disease-specific antibiotic resistance patterns should be publicized with the goal of improving antibiotic stewardship

Comparison of K-doped and pure cold-rolled tungsten sheets: As-rolled condition and recrystallization behaviour after isochronal annealing at different temperatures

Severely deformed cold-rolled tungsten is a promising structural material for future fusion reactor applications due to high melting temperature and excellent mechanical properties. However, the fine-grained microstructure after deformation is not stable at temperatures above 800 °C, leading to brittle material behaviour. In this study, we utilize potassium-doping to inhibit recrystallization of tungsten sheets, a mechanism well known from incandescent lamp wires. We produced K-doped tungsten sheets by warm-rolling and subsequent cold-rolling with five different logarithmic strains up to 4.6, and equivalently rolled pure tungsten sheets. Both sets of materials are compared using EBSD and microhardness testing. In both materials, the hardness increases and the grain size along normal direction decreases with strain; the densities of low and high angle boundaries increase in particular during cold-rolling. The K-doped W sheet reaches the highest hardness with 772 ± 8 HV0.1, compared to the pure W sheet with 711 ± 14 HV0.1. All boundaries taken into account, a Hall-Petch relation describes the hardness evolution nicely, except a deviation of the K-doped tungsten sheet rolled to highest strain with its much higher hardness. The similar structural and mechanical properties of both materials in the as-rolled condition allow further studies of recrystallization behaviour of the new K-doped material with a benchmark against the equivalent pure tungsten sheets. Isochronal annealing for 1 h was performed at different temperatures between 700 °C and 2200 °C. A sharp decrease in hardness to intermediate values is observed at around 900 °C for both materials, presumably reflecting extended recovery. A second decrease is observed at 1400 °C for pure tungsten, approaching the hardness of a single crystal and indicating recrystallization and severe growth of grains. For K-doped tungsten, however, the occurrence of the second decrease is shifted to higher temperatures from 1400 °C to 1800 °C with increasing strain and an intermediate hardness is maintained up to 1800 °C. We refer this dependence of the recrystallization resistance on strain in the K-doped material to the dispersion of K-bubbles, resulting in increased Zener pinning forces retarding boundary motion

Cross-verification of independent quantum devices

Quantum computers are on the brink of surpassing the capabilities of even the most powerful classical computers. This naturally raises the question of how one can trust the results of a quantum computer when they cannot be compared to classical simulation. Here we present a verification technique that exploits the principles of measurement-based quantum computation to link quantum circuits of different input size, depth, and structure. Our approach enables consistency checks of quantum computations within a device, as well as between independent devices. We showcase our protocol by applying it to five state-of-the-art quantum processors, based on four distinct physical architectures: nuclear magnetic resonance, superconducting circuits, trapped ions, and photonics, with up to 6 qubits and 200 distinct circuits

Pion-nucleus optical potential valid up to the DELTA-resonance region

We present in this article an optical potential for the $\pi$-nucleus interaction that can be used in various studies involving $\pi$-nucleus channels. Based on earlier treatments of the low energy $\pi$-nucleus optical potential, we have derived a potential expression applicable from threshold up to the $\Delta$-resonance region. We extracted the impulse approximation form for this potential from the $\pi-N$ scattering amplitude and then added to it kinematical and physical corrections. The kinematic corrections arise from transforming the impulse approximation expression from the $\pi-N$ center of mass frame to the $\pi$-nucleus center of mass frame, while the physical corrections arise mostly from the many-body nature of the $\pi$-nucleus interaction. By taking advantage of the experimental progress in our knowledge of the $\pi-N$ process, we have updated earlier treatments with parameters calculated from state-of-the-art experimental measurements.Comment: 23 pages, 12 figures. Accepted for publication in Physical Review

Na2IrO3 as a spin-orbit-assisted antiferromagnetic insulator with a 340 meV gap

We study Na2IrO3 by ARPES, optics, and band structure calculations in the local-density approximation (LDA). The weak dispersion of the Ir 5d-t2g manifold highlights the importance of structural distortions and spin-orbit coupling (SO) in driving the system closer to a Mott transition. We detect an insulating gap {\Delta}_gap = 340 meV which, at variance with a Slater-type description, is already open at 300 K and does not show significant temperature dependence even across T_N ~ 15 K. An LDA analysis with the inclusion of SO and Coulomb repulsion U reveals that, while the prodromes of an underlying insulating state are already found in LDA+SO, the correct gap magnitude can only be reproduced by LDA+SO+U, with U = 3 eV. This establishes Na2IrO3 as a novel type of Mott-like correlated insulator in which Coulomb and relativistic effects have to be treated on an equal footing.Comment: Accepted in Physical Review Letters. Auxiliary and related material can be found at: http://www.phas.ubc.ca/~quantmat/ARPES/PUBLICATIONS/articles.htm