Asymmetry sum rule for molecular predissociation

© 2000 American Physical SocietyIn the case of weak diatomic molecular predissociation by noninteracting, optically inactive continuum states, it is demonstrated that the predissociation line shape is more accurately represented by a Beutler-Fano profile than by a Lorentzian. The weak asymmetry that is found to occur is due principally to interactions with neighboring vibrational resonances. For this type of predissociation in the case of multiple continua, a sum rule for the corresponding line-shape asymmetry is derived. This sum rule is verified numerically using single-channel and multichannel coupled Schrödinger-equation calculations for the Schumann-Runge band system of O2. Similar results are presented for the case of optically active continua.F. T. Hawes, L. W. Torop, B. R. Lewis and S. T. Gibso

Reverse Monte Carlo modeling of amorphous silicon

An implementation of the Reverse Monte Carlo algorithm is presented for the study of amorphous tetrahedral semiconductors. By taking into account a number of constraints that describe the tetrahedral bonding geometry along with the radial distribution function, we construct a model of amorphous silicon using the reverse monte carlo technique. Starting from a completely random configuration, we generate a model of amorphous silicon containing 500 atoms closely reproducing the experimental static structure factor and bond angle distribution and in improved agreement with electronic properties. Comparison is made to existing Reverse Monte Carlo models, and the importance of suitable constraints beside experimental data is stressed.Comment: 6 pages, 4 PostScript figure

GENETICS OF RESISTANCE TO GROUNDNUT ROSETTE VIRUS DISEASE

Groundnut Rosette Virus disease (GRD) has long been regarded a major limiting biotic constraint to groundnut production in Sub-Saharan Africa (SSA). The disease is caused by a complex of three viral components that interact in a synergistic fashion resulting into severe crop losses. A study was conducted to better understand the genetics of inheritance of GRD resistance. Nineteen groundnut genotypes among which twelve F2 families populations arising from a 3x4 North Carolina II mating design, were evaluated for their percentage disease severity (PDS) and incidence (PDI). There was significant genetic variability for resistance to GRD among the materials studied with more significant additive gene action as compared to non additive. However, since specific combining ability effects were not so consistent among the F2 family populations, evaluation and testing of progenies alongside with their parents would be more meaningful and selection in the early generations would be the most effective strategy. Further, narrow sense heritability of 53% suggests that prerformance of groundnut progenies could be partly predicted by both parental and individual cross means.La rosette, une maladie virale de l\u2019arachide (GRD) a pendant longtemps \ue9t\ue9 consid\ue9r\ue9e comme une contrainte biotique majeur \ue0 la production de l\u2019arachide en Afrique Sub Saharienne (SSA). La maladie est caus\ue9e par un complexe de trois composants viraux qui interagissent de fa\ue7on synerg\ue9tique causant ainsi de pertes lourdes de la culture. Une \ue9tude \ue9tait men\ue9e afin de mieux comprendre l\u2019acquisition g\ue9n\ue9tique de la r\ue9sistance de GRD. Dix neuf g\ue9notypes d\u2019arachides parmi douze populations de famille F2 provenant de la disposition du mating 3x4 de Nord Caroline II \ue9taient \ue9valu\ue9s sur base de leur pourcentage de s\ue9verit\ue9 (PDS) et incidence maladie (PDI). Une variabilit\ue9 significative de la r\ue9sistance au GRD parmi le mat\ue9riel \ue9tudi\ue9 avec plus d\u2019 action additive significative du g\ue8ne en comparaison \ue0 la non additive. Par ailleurs, du fait que les effets de combinaison des aptitudes n\u2019\ue9taient pas consistants parmi les populations de familles F2, l\u2019\ue9valuation et le test des prog\ue9nies avec leurs parents pourraient \ueatre plus significatif et la s\ue9lection parmi les g\ue9n\ue9rations pr\ue9coces pourrait \ueatre une strat\ue9gie la plus efficace. Aussi, l\u2019heritabilit\ue9 de 53% sugg\ue8re que la performance des prog\ue9nies d\u2019arachide pourrait partiellement \ueatre pr\ue9dit par le moyen de croisements parentaux et individuals

Dialectic tensions in the financial markets: a longitudinal study of pre- and post-crisis regulatory technology

This article presents the findings from a longitudinal research study on regulatory technology in the UK financial services industry. The financial crisis with serious corporate and mutual fund scandals raised the profile of compliance as governmental bodies, institutional and private investors introduced a ‘tsunami’ of financial regulations. Adopting a multi-level analysis, this study examines how regulatory technology was used by financial firms to meet their compliance obligations, pre- and post-crisis. Empirical data collected over 12 years examine the deployment of an investment management system in eight financial firms. Interviews with public regulatory bodies, financial institutions and technology providers reveal a culture of compliance with increased transparency, surveillance and accountability. Findings show that dialectic tensions arise as the pursuit of transparency, surveillance and accountability in compliance mandates is simultaneously rationalized, facilitated and obscured by regulatory technology. Responding to these challenges, regulatory bodies continue to impose revised compliance mandates on financial firms to force them to adapt their financial technologies in an ever-changing multi-jurisdictional regulatory landscape

Global Search for New Physics with 2.0/fb at CDF

Data collected in Run II of the Fermilab Tevatron are searched for indications of new electroweak-scale physics. Rather than focusing on particular new physics scenarios, CDF data are analyzed for discrepancies with the standard model prediction. A model-independent approach (Vista) considers gross features of the data, and is sensitive to new large cross-section physics. Further sensitivity to new physics is provided by two additional algorithms: a Bump Hunter searches invariant mass distributions for "bumps" that could indicate resonant production of new particles; and the Sleuth procedure scans for data excesses at large summed transverse momentum. This combined global search for new physics in 2.0/fb of ppbar collisions at sqrt(s)=1.96 TeV reveals no indication of physics beyond the standard model.Comment: 8 pages, 7 figures. Final version which appeared in Physical Review D Rapid Communication

Observation of Orbitally Excited B_s Mesons

We report the first observation of two narrow resonances consistent with states of orbitally excited (L=1) B_s mesons using 1 fb^{-1} of ppbar collisions at sqrt{s} = 1.96 TeV collected with the CDF II detector at the Fermilab Tevatron. We use two-body decays into K^- and B^+ mesons reconstructed as B^+ \to J/\psi K^+, J/\psi \to \mu^+ \mu^- or B^+ \to \bar{D}^0 \pi^+, \bar{D}^0 \to K^+ \pi^-. We deduce the masses of the two states to be m(B_{s1}) = 5829.4 +- 0.7 MeV/c^2 and m(B_{s2}^*) = 5839.7 +- 0.7 MeV/c^2.Comment: Version accepted and published by Phys. Rev. Let

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

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

Measurement of the polarisation of W bosons produced with large transverse momentum in pp collisions at sqrt(s) = 7 TeV with the ATLAS experiment

This paper describes an analysis of the angular distribution of W->enu and W->munu decays, using data from pp collisions at sqrt(s) = 7 TeV recorded with the ATLAS detector at the LHC in 2010, corresponding to an integrated luminosity of about 35 pb^-1. Using the decay lepton transverse momentum and the missing transverse energy, the W decay angular distribution projected onto the transverse plane is obtained and analysed in terms of helicity fractions f0, fL and fR over two ranges of W transverse momentum (ptw): 35 < ptw < 50 GeV and ptw > 50 GeV. Good agreement is found with theoretical predictions. For ptw > 50 GeV, the values of f0 and fL-fR, averaged over charge and lepton flavour, are measured to be : f0 = 0.127 +/- 0.030 +/- 0.108 and fL-fR = 0.252 +/- 0.017 +/- 0.030, where the first uncertainties are statistical, and the second include all systematic effects.Comment: 19 pages plus author list (34 pages total), 9 figures, 11 tables, revised author list, matches European Journal of Physics C versio

Observation of a new chi_b state in radiative transitions to Upsilon(1S) and Upsilon(2S) at ATLAS

The chi_b(nP) quarkonium states are produced in proton-proton collisions at the Large Hadron Collider (LHC) at sqrt(s) = 7 TeV and recorded by the ATLAS detector. Using a data sample corresponding to an integrated luminosity of 4.4 fb^-1, these states are reconstructed through their radiative decays to Upsilon(1S,2S) with Upsilon->mu+mu-. In addition to the mass peaks corresponding to the decay modes chi_b(1P,2P)->Upsilon(1S)gamma, a new structure centered at a mass of 10.530+/-0.005 (stat.)+/-0.009 (syst.) GeV is also observed, in both the Upsilon(1S)gamma and Upsilon(2S)gamma decay modes. This is interpreted as the chi_b(3P) system.Comment: 5 pages plus author list (18 pages total), 2 figures, 1 table, corrected author list, matches final version in Physical Review Letter