82 research outputs found
Modelling Investment When Relative Prices Are Trending: Theory and Evidence for the UK
No full textThis paper investigates the ability of aggregate and disaggregate equations to account for the boom in UK plant and machinery investment in the second half of the 1990s. We extend previous US research by Tevlin and Whelan (2002) by explaining the failure of the aggregate equations more formally in terms of misspecification when relative prices are trending; and by conducting the econometric analysis in a formal cointegration framework. In line with the US research, we find asset-level equations can explain the UK investment boom over this period, whereas the aggregate equation completely fails.investment, computers, relative prices
Infrared subtraction at next-to-next-to-leading order for gluonic initial states
No full textIn this thesis we describe a procedure for isolating the infrared singularities present in gluonic scattering amplitudes at
next-to-leading and next-to-next-to-leading order. We adopted the
antenna subtraction framework which has been successfully applied to the
calculation of NNLO corrections to the 3-jet cross section and related
event shape distributions in electron-positron annihilation. We consider
processes with coloured particles in the initial state, and in
particular two-jet production in hadron-hadron collisions at
accelerators such as the Large Hadron Collider (LHC). We derive explicit
formulae for subtracting the single and double unresolved contributions
from the double radiation gluonic processes using
antenna functions with initial state partons. We show numerically that
the subtraction term effectively approximates the matrix element in the
various single and double unresolved configurations
The 2001 recession: how was it different and what developments may have caused it?
No full textThe 2001 recession was unique in several respects. For instance, the peak-to-trough decline in real gross domestic product was one of the smallest on record and its duration was slightly shorter than average. This article examines some of the other unique features of the 2001 recession compared with the “average” post-World War II recession. The author also shows that forecasters were surprised by the onset of the recession, perhaps because of incomplete data available to them in real time. Finally, the article examines the errors from a well-known macroeconomic forecast and finds that forecasters were surprised by the declines in real business and household fixed investment, as well as real net exports, before the March 2001 business cycle peak.Recessions ; Economic indicators ; Business cycles
Search for New Particles in Two-Jet Final States in 7 TeV Proton-Proton Collisions with the ATLAS Detector at the LHC
No full textA search for new heavy particles manifested as resonances in two-jet final states is presented. The data were produced in 7 TeV proton-proton collisions by the LHC and correspond to an integrated luminosity of 315 nb(-1) collected by the ATLAS detector. No resonances were observed. Upper limits were set on the product of cross section and signal acceptance for excited-quark (q*) production as a function of q* mass. These exclude at the 95% C. L. the q* mass interval 0: 30< m(q)*< 1:26 TeV, extending the reach of previous experiments
Soil–atmosphere exchange of ammonia in a non-fertilized grassland: measured emission potentials and inferred fluxes
No full textA 50-day field study was carried out in a semi-natural, non-fertilized
grassland in south-western Ontario, Canada during the late summer and early
autumn of 2012. The purpose was to explore surface–atmosphere exchange
processes of ammonia (NH3) with a focus on bi-directional fluxes
between the soil and atmosphere. Measurements of soil pH and ammonium
concentration ([NH4+]) yielded the first direct quantification of
soil emission potential (Γsoil = [NH4+]/[H+])
for this land type, with values ranging from 35 to 1850 (an average of
290). The soil compensation point, the atmospheric NH3 mixing ratio
below which net emission from the soil will occur, exhibited both a seasonal
trend and diurnal trend. Higher daytime and August compensation points were
attributed to higher soil temperature. Soil–atmosphere fluxes were estimated
using NH3 measurements from the Ambient Ion Monitor Ion Chromatograph
(AIM-IC) and a simple resistance model. Vegetative effects were ignored
due to the short canopy height and significant Γsoil. Inferred
fluxes were, on average, 2.6 ± 4.5 ng m−2 s−1 in August
(i.e. net emission) and −5.8 ± 3.0 ng m−2 s−1 in September
(i.e. net deposition). These results are in good agreement with the only
other bi-directional exchange study in a semi-natural, non-fertilized
grassland. A Lagrangian dispersion model (Hybrid Single-Particle Lagrangian Integrated Trajectory – HYSPLIT) was used to calculate air
parcel back-trajectories throughout the campaign and revealed that NH3
mixing ratios had no directional bias throughout the campaign, unlike the
other atmospheric constituents measured. This implies that soil–atmosphere
exchange over a non-fertilized grassland can significantly moderate
near-surface NH3 concentrations. In addition, we provide indirect
evidence that dew and fog evaporation can cause a morning increase of
[NH3]g. Implications of our findings on current NH3
bi-directional exchange modelling efforts are also discussed
Measurement of inclusive jet and dijet cross sections in proton-proton collisions at 7 TeV centre-of-mass energy with the ATLAS detector
No full textJet cross sections have been measured for the first time in proton-proton collisions at a centre-of-mass energy of 7 TeV using the ATLAS detector. The measurement uses an integrated luminosity of 17 nb−1 recorded at the Large Hadron Collider. The anti-k t algorithm is used to identify jets, with two jet resolution parameters, R=0.4 and 0.6. The dominant uncertainty comes from the jet energy scale, which is determined to within 7% for central jets above 60 GeV transverse momentum. Inclusive single-jet differential cross sections are presented as functions of jet transverse momentum and rapidity. Dijet cross sections are presented as functions of dijet mass and the angular variable χ. The results are compared to expectations based on next-to-leading-order QCD, which agree with the data, providing a validation of the theory in a new kinematic regime
Search for supersymmetric particles in events with lepton pairs and large missing transverse momentum in √s = 7 TeV proton-proton collisions
No full textLuminosity Determination in pp Collisions at √(s)=7 TeV Using the ATLAS Detector at the LHC
No full textMeasurements of luminosity obtained using the ATLAS detector during early running of the Large Hadron Collider (LHC) at √s = 7 TeV are presented. The luminosity is independently determined using several detectors and multiple algorithms, each having different acceptances, systematic uncertainties and sensitivity to background. The ratios of the luminosities obtained from these methods are monitored as a function of time and of μ, the average number of inelastic interactions per bunch crossing. Residual time- and μ-dependence between the methods is less than 2% for 0 < μ < 2.5. Absolute luminosity calibrations, performed using beam separation scans, have a common systematic uncertainty of ±11%, dominated by the measurement of the LHC beam currents. After calibration, the luminosities obtained from the different methods differ by at most ±2%. The visible cross sections measured using the beam scans are compared to predictions obtained with the PYTHIA and PHOJET event generators and the ATLAS detector simulation. © CERN for the benefit of the ATLAS collaboration 2011
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