Measurement of inclusive W and Z cross sections in pp collisions at √s = 7 TeV

Journal of High Energy Physics 2011.1 (2011): 080 reproduced by permission of Scuola Internazionale Superiore di Studi Avanzati (SISSA)Measurements of inclusive W and Z boson production cross sections in pp collisions at √s = 7 TeV are presented, based on 2.9 pb-1 of data recorded by the CMS detector at the LHC. The measurements, performed in the electron and muon decay channels, are combined to give σ(pp → WX) × B(W → lʋ) = 9.95 ± 0.07 (stat.) ± 0.28 (syst.) ± 1.09 (lumi.) nb and σ(pp → ZX) × B(Z → l +l-) = 0.931 ± 0.026 (stat.) ± 0.023 (syst.) ± 0.102 (lumi.) nb, where ℓ stands for either e or μ. Theoretical predictions, calculated at the next-to-next-to-leading order in QCD using recent parton distribution functions, are in agreement with the measured cross sections. Ratios of cross sections, which incur an experimental systematic uncertainty of less than 4%, are also reporte

Urban form and air quality in U.S. metropolitan and megapolitan areas

The spatial form, or morphology, of urban areas may significantly affect the anthropogenic production of air pollutants. This dissertation explores the relationships between air quality and urban form at the metropolitan and megapolitan (multi-metropolitan) scale. Urban form was quantified for 86 metropolitan and 19 megapolitan areas using both pre-existing sprawl indices and multiple spatial metrics derived from remotely sensed landcover data. Air quality was assessed by measuring several key air pollutants, including the ambient concentration of ozone (O3), the non-point source emissions of the two O3 precursors nitrogen oxides (NOx) and volatile organic compounds (VOCs), the ambient concentration and non-point source emissions of fine particulate matter (PM2.5) and coarse particulate matter (PM10), and the mobile emissions of carbon dioxide (CO2). The ambient concentrations of air pollutants were averaged over the 5-year period 1998 to 2002. While controlling for industrial emissions, climate, population and geographic area, multiple linear regression was used to evaluate the degree of association between measures of urban form and air quality. The results suggest that urban form has a measurable impact on both the non-point source emission and ambient concentration of air pollution. Urban areas that exhibited more "sprawl-like" urban forms (i.e. lower residential density, less street network connectivity, less contiguous urban development) generally had higher non-point source emissions and/ or ambient concentrations of air pollution. Pre-existing sprawl indices were most significantly associated with ambient concentrations, while two spatial-metrics based measures of urban structure, urban "continuity" and urban "shape complexity," were most significantly associated with non-point source emissions. The relationships between measures of urban form calculated using spatial metrics and air pollution were most significant at the metropolitan scale. The extent of the urban area (i.e. high versus low urban threshold), however, did not significantly affect the associations between urban form, as assessed using spatial metrics, and air pollution. Understanding the relationships between urban form and air quality is an important step in identifying effective urban land use configurations and developing healthier cities

Modeling nutrient attenuation by riparian buffer zones along headwater streams

"In this study I propose a statistical model, the Riparian Nutrient Attenuation Model (RNAM), designed to quickly and accurately access the nutrient attenuation capability of riparian buffer zones. This information may help land managers evaluate riparian systems in terms of their capacity to retain nutrients. Developed using data available in the literature, RNAM uses three physical properties of the riparian, including vegetation type, slope, and width, to estimate the retention of total N, NO3- and P. Three RNAM sub-models, RNAM-nitrogen, RNAM-nitrate and RNAM-phosphorus, were developed to handle each of the three nutrients. In developing RNAM, the relationships between the predictor variables and nutrient retention were examined. A preliminary test of RNAM indicated that each of the sub-models is capable of producing reasonably accurate estimations of percent nutrient reduction. RNAM-nitrogen, however, produced inconsistent estimates of nitrogen reduction at higher levels. More data is needed to calibrate and validate RNAM."--Abstract from author supplied metadat

SUSY Magnetic Moments Sum Rules and Supersymmetry Breaking

It was recently shown that unbroken N=1 Susy relates, in a model independent way, the magnetic transitions between states of different spin within a given charged massive supermultiplet. We verify explicitly these sum rules for a vector multiplet in the case of massless and massive fermions. The purpose of this analysis is to provide the ground for the broken susy case. We study the modifications of these results when an explicit soft Susy breaking realized through a universal mass for all scalars is present. As a by-product we provide a computation of the $g-2$ of the $W$ boson in the standard model which corrects previous evaluations in the literature.Comment: 16+5 pages, Latex,(feynman.tex to print the figures), DFPD 94/TH/2

Charm mass dependence of the weak Hamiltonian in chiral perturbation theory

Suppose that the weak interaction Hamiltonian of four-flavour SU(4) chiral effective theory is known, for a small charm quark mass m_c. We study how the weak Hamiltonian changes as the charm quark mass increases, by integrating it out within chiral perturbation theory to obtain a three-flavour SU(3) chiral theory. We find that the ratio of the SU(3) low-energy constants which mediate Delta I=1/2 and Delta I=3/2 transitions, increases rather rapidly with m_c, as \sim m_c ln (1/m_c). The logarithmic effect originates from "penguin-type" charm loops, and could represent one of the reasons for the Delta I=1/2 rule.Comment: 20 pages. v2: references and clarifications added, published versio

Robust implications on Dark Matter from the first FERMI sky gamma map

We derive robust model-independent bounds on DM annihilations and decays from the first year of FERMI gamma-ray observations of the whole sky. These bounds only have a mild dependence on the DM density profile and allow the following DM interpretations of the PAMELA and FERMI electron/positron excesses: primary channels mu+ mu-, mu+ mu-mu+mu- or e+ e- e+ e-. An isothermal-like density profile is needed for annihilating DM. In all such cases, FERMI gamma spectra must contain a significant DM component, that may be probed in the future.Comment: 16 pages, 8 figures. Final versio

ZZ--Z′Z' mixing and oblique corrections in an SU(3)×U(1){\rm SU(3) \times U(1)} model

A global fit for experiments is included in this revised version.Comment: IFP-460-UNC, TRI-PP-93-11, 20 pages, 2 figures are appende

The Higgs intense--coupling regime in constrained SUSY models and its astrophysical implications

We analyze the Higgs intense--coupling regime, in which all Higgs particles of the Minimal Supersymmetric Standard Model are light with masses of the same order and the value of \tb the ratio of vacuum expectation values of the two Higgs fields is large, in the framework of Supergravity scenarios with non--universal soft Supersymmetry breaking scalar masses in the Higgs sector. In particular, we calculate the relic density abundance of the lightest neutralino candidate for cold dark matter and the rates in direct and indirect detection at present and future experiments. We first show that while in the mSUGRA model this regime is disfavored by present data, there are regions in the parameter space of models with non--universal Higgs masses where it can occur. We then show that because of the large value of $\tan\beta$ and the relatively low values of the neutral Higgs boson masses, the cross section for neutralino--nucleon scattering is strongly enhanced in this regime and would allow for the observation of a signal in direct detection experiments such as CDMS--Soudan. The expected sensitivity of gamma--ray detectors like GLAST might be also sufficient to observe the annihilation of neutralinos in such a regime.Comment: 19 pages, 5 figure

NLO corrections to ultra-high energy neutrino-nucleon scattering, shadowing and small x

We reconsider the Standard Model interactions of ultra-high energy neutrinos with matter. The next to leading order QCD corrections are presented for charged-current and neutral-current processes. Contrary to popular expectations, these corrections are found to be quite substantial, especially for very large (anti-) neutrino energies. Hence, they need to be taken into account in any search for new physics effects in high-energy neutrino interactions. In our extrapolation of the parton densities to kinematical regions as yet unexplored directly in terrestrial accelerators, we are guided by double asymptotic scaling in the large Q^2 and small Bjorken x region and to models of saturation in the low Q^2 and low x regime. The sizes of the consequent uncertainties are commented upon. We also briefly discuss some variables which are insensitive to higher order QCD corrections and are hence suitable in any search for new physics.Comment: 21 pages, LaTeX2e, uses JHEP3.cls (included), 8 ps files for figures published versio

Emergent Electroweak Symmetry Breaking with Composite W, Z Bosons

We present a model of electroweak symmetry breaking in a warped extra dimension where electroweak symmetry is broken at the UV (or Planck) scale. An underlying conformal symmetry is broken at the IR (or TeV) scale generating masses for the electroweak gauge bosons without invoking a Higgs mechanism. By the AdS/CFT correspondence the W,Z bosons are identified as composite states of a strongly-coupled gauge theory, suggesting that electroweak symmetry breaking is an emergent phenomenon at the IR scale. The model satisfies electroweak precision tests with reasonable fits to the S and T parameter. In particular the T parameter is sufficiently suppressed since the model naturally admits a custodial SU(2) symmetry. The composite nature of the W,Z-bosons provide a novel possibility of unitarizing WW scattering via form factor suppression. Constraints from LEP and the Tevatron as well as discovery opportunities at the LHC are discussed for these composite electroweak gauge bosons.Comment: 39 pages, 4 figure