Non-Perturbative Effects on a Fractional D3-Brane

In this note we study the N=1 abelian gauge theory on the world volume of a single fractional D3-brane. In the limit where gravitational interactions are not completely decoupled we find that a superpotential and a fermionic bilinear condensate are generated by a D-brane instanton effect. A related situation arises for an isolated cycle invariant under an orientifold projection, even in the absence of any gauge theory brane. Moreover, in presence of supersymmetry breaking background fluxes, such instanton configurations induce new couplings in the 4-dimensional effective action, including non-perturbative contributions to the cosmological constant and non-supersymmetric mass terms.Comment: 18 pages, v3: refs adde

Projection Postulate and Atomic Quantum Zeno Effect

The projection postulate has been used to predict a slow-down of the time evolution of the state of a system under rapidly repeated measurements, and ultimately a freezing of the state. To test this so-called quantum Zeno effect an experiment was performed by Itano et al. (Phys. Rev. A 41, 2295 (1990)) in which an atomic-level measurement was realized by means of a short laser pulse. The relevance of the results has given rise to controversies in the literature. In particular the projection postulate and its applicability in this experiment have been cast into doubt. In this paper we show analytically that for a wide range of parameters such a short laser pulse acts as an effective level measurement to which the usual projection postulate applies with high accuracy. The corrections to the ideal reductions and their accumulation over n pulses are calculated. Our conclusion is that the projection postulate is an excellent pragmatic tool for a quick and simple understanding of the slow-down of time evolution in experiments of this type. However, corrections have to be included, and an actual freezing does not seem possible because of the finite duration of measurements.Comment: 25 pages, LaTeX, no figures; to appear in Phys. Rev.

Predictors of Lumbar Spine Degeneration and Low Back Pain in the Community: The Johnston County Osteoarthritis Project

Objective: To determine the incidence and worsening of lumbar spine structure and low back pain (LBP) and whether they are predicted by demographic characteristics or clinical characteristics or appendicular joint osteoarthritis (OA). Methods: Paired baseline (2003–2004) and follow-up (2006–2010) lumbar spine radiographs from the Johnston County Osteoarthritis Project were graded for osteophytes (OST), disc space narrowing (DSN), spondylolisthesis, and presence of facet joint OA (FOA). Spine OA was defined as at least mild OST and mild DSN at the same level for any level of the lumbar spine. LBP, comorbidities, and back injury were self-reported. Weibull models were used to estimate hazard ratios (HRs) and 95% confidence intervals (95% CIs) of spine phenotypes accounting for potential predictors including demographic characteristics, clinical characteristics, comorbidities, obesity, and appendicular OA. Results: Obesity was a consistent and strong predictor of incidence of DSN (HR 1.80 [95% CI 1.09–2.98]), spine OA (HR 1.56 [95% CI 1.01–2.41]), FOA (HR 4.99 [95% CI 1.46–17.10]), spondylolisthesis (HR 1.87 [95% CI 1.02–3.43]), and LBP (HR 1.75 [95% CI 1.19–2.56]), and worsening of DSN (HR 1.51 [95% CI 1.09–2.09]) and LBP (HR 1.51 [95% CI 1.12–2.06]). Knee OA was a predictor of incident FOA (HR 4.18 [95% CI 1.44–12.2]). Spine OA (HR 1.80 [95% CI 1.24–2.63]) and OST (HR 1.85 [95% CI 1.02–3.36]) were predictors of incidence of LBP. Hip OA (HR 1.39 [95% CI 1.04–1.85]) and OST (HR 1.58 [95% CI 1.00–2.49]) were predictors of LBP worsening. Conclusion: Among the multiple predictors of spine phenotypes, obesity was a common predictor for both incidence and worsening of lumbar spine degeneration and LBP

Inflammatory, Structural, and Pain Biochemical Biomarkers May Reflect Radiographic Disc Space Narrowing: The Johnston County Osteoarthritis Project

The purpose of this work is to determine the relationship between biomarkers of inflammation, structure, and pain with radiographic disc space narrowing (DSN) in community-based participants. A total of 74 participants (37 cases and 37 controls) enrolled in the Johnston County Osteoarthritis Project during 2006–2010 were selected. The cases had at least mild radiographic DSN and low back pain (LBP). The controls had neither radiographic evidence of DSN nor LBP. The measured analytes from human serum included N-cadherin, Keratin-19, Lumican, CXCL6, RANTES, IL-17, IL-6, BDNF, OPG, and NPY. A standard dolorimeter measured pressure-pain threshold. The coefficients of variation were used to evaluate inter- and intra-assay reliability. Participants with similar biomarker profiles were grouped together using cluster analysis. The binomial regression models were used to estimate risk ratios (RR) and 95% confidence intervals (CI) in propensity score-matched models. Significant associations were found between radiographic DSN and OPG (RR = 3.90; 95% CI: 1.83, 8.31), IL-6 (RR = 2.54; 95% CI: 1.92, 3.36), and NPY (RR = 2.06 95% CI: 1.62, 2.63). Relative to a cluster with low levels of biomarkers, a cluster representing elevated levels of OPG, RANTES, Lumican, Keratin-19, and NPY (RR = 3.04; 95% CI: 1.22, 7.54) and a cluster representing elevated levels of NPY (RR = 2.91; 95% CI: 1.15, 7.39) were significantly associated with radiographic DSN. Clinical Significance: These findings suggest that individual and combinations of biochemical biomarkers may reflect radiographic DSN. This is just one step toward understanding the relationships between biochemical biomarkers and DSN that may lead to improved intervention delivery

Finite Theories and the SUSY Flavor Problem

We study a finite SU(5) grand unified model based on the non-Abelian discrete symmetry A_4. This model leads to the democratic structure of the mass matrices for the quarks and leptons. In the soft supersymmetry breaking sector, the scalar trilinear couplings are aligned and the soft scalar masses are degenerate, thus solving the SUSY flavor problem.Comment: 17 pages, LaTeX, 1 figur

Can we live in a self-tuning universe?

The self-tuning brane scenario is an attempt to solve the cosmological constant problem in the context of extra dimensions. Rather than making the vacuum energy small, this approach proceeds by removing the gravitational effect of vacuum energy on the expansion of the universe. Such behavior is only possible through changing the Friedmann equation of conventional cosmology, and we discuss difficulties in obtaining cosmological evolution compatible with observation in this context. Specific models considered include a bulk scalar field coupling to the brane via a conformal transformation of the brane metric, and via a rescaling of the brane volume element

Superconductivity in the ternary ZrVGe compound

We report bulk superconductivity in ZrVGe withTc=6K determined by magnetization, electronic transport and specific heat measurements. From the analysis of magnetization and resistivity data we obtain the thermodynamic critical fieldsμ0Hc1andμ0Hc2, respectively. The heat capacity data deviate from conventional BCS theory suggesting possible unconventional superconducting behavior

Jet size dependence of single jet suppression in lead-lead collisions at sqrt(s(NN)) = 2.76 TeV with the ATLAS detector at the LHC

Measurements of inclusive jet suppression in heavy ion collisions at the LHC provide direct sensitivity to the physics of jet quenching. In a sample of lead-lead collisions at sqrt(s) = 2.76 TeV corresponding to an integrated luminosity of approximately 7 inverse microbarns, ATLAS has measured jets with a calorimeter over the pseudorapidity interval |eta| < 2.1 and over the transverse momentum range 38 < pT < 210 GeV. Jets were reconstructed using the anti-kt algorithm with values for the distance parameter that determines the nominal jet radius of R = 0.2, 0.3, 0.4 and 0.5. The centrality dependence of the jet yield is characterized by the jet "central-to-peripheral ratio," Rcp. Jet production is found to be suppressed by approximately a factor of two in the 10% most central collisions relative to peripheral collisions. Rcp varies smoothly with centrality as characterized by the number of participating nucleons. The observed suppression is only weakly dependent on jet radius and transverse momentum. These results provide the first direct measurement of inclusive jet suppression in heavy ion collisions and complement previous measurements of dijet transverse energy imbalance at the LHC.Comment: 15 pages plus author list (30 pages total), 8 figures, 2 tables, submitted to Physics Letters B. All figures including auxiliary figures are available at http://atlas.web.cern.ch/Atlas/GROUPS/PHYSICS/PAPERS/HION-2011-02

Search for direct production of charginos and neutralinos in events with three leptons and missing transverse momentum in √s = 7 TeV pp collisions with the ATLAS detector

A search for the direct production of charginos and neutralinos in final states with three electrons or muons and missing transverse momentum is presented. The analysis is based on 4.7 fb−1 of proton–proton collision data delivered by the Large Hadron Collider and recorded with the ATLAS detector. Observations are consistent with Standard Model expectations in three signal regions that are either depleted or enriched in Z-boson decays. Upper limits at 95% confidence level are set in R-parity conserving phenomenological minimal supersymmetric models and in simplified models, significantly extending previous results

Measurement of the View the tt production cross-section using eμ events with b-tagged jets in pp collisions at √s = 13 TeV with the ATLAS detector

This paper describes a measurement of the inclusive top quark pair production cross-section (σtt¯) with a data sample of 3.2 fb−1 of proton–proton collisions at a centre-of-mass energy of √s = 13 TeV, collected in 2015 by the ATLAS detector at the LHC. This measurement uses events with an opposite-charge electron–muon pair in the final state. Jets containing b-quarks are tagged using an algorithm based on track impact parameters and reconstructed secondary vertices. The numbers of events with exactly one and exactly two b-tagged jets are counted and used to determine simultaneously σtt¯ and the efficiency to reconstruct and b-tag a jet from a top quark decay, thereby minimising the associated systematic uncertainties. The cross-section is measured to be: σtt¯ = 818 ± 8 (stat) ± 27 (syst) ± 19 (lumi) ± 12 (beam) pb, where the four uncertainties arise from data statistics, experimental and theoretical systematic effects, the integrated luminosity and the LHC beam energy, giving a total relative uncertainty of 4.4%. The result is consistent with theoretical QCD calculations at next-to-next-to-leading order. A fiducial measurement corresponding to the experimental acceptance of the leptons is also presented