294 research outputs found
The Process \gamma^{*}_L+ q \to q\bar{q}g + q: Real Corrections to the Virtual Photon Impact Factor
We calculate, for the longitudinally polarized virtual photon, the cross
section of the process \gamma^{*}+q\to (q\bar{q}g)+q at high energies with a
large rapidity gap between the fragmentation system q\bar{q}g and the other
quark. This process provides the real corrections of the virtual photon impact
factor in the next-to leading order. Evidence is given for the appearance of a
new q\bar{q}g Fock-component of the photon state.Comment: 17 pages, 4 figures, revte
Spray nozzle designs for agricultural aviation applications
Techniques of generating monodisperse sprays and information concerning chemical liquids used in agricultural aviation are surveyed. The periodic dispersion of liquid jet, the spinning disk method, and ultrasonic atomization are the techniques discussed. Conceptually designed spray nozzles for generating monodisperse sprays are assessed. These are based on the classification of the drops using centrifugal force, on using two opposing liquid laden air jets, and on operating a spinning disk at an overloaded flow. Performance requirements for the designs are described and estimates of the operational characteristics are presented
NLO corrections to the photon impact factor: Combining real and virtual corrections.
In this third part of our calculation of the QCD NLO corrections to the
photon impact factor we combine our previous results for the real corrections
with the singular pieces of the virtual corrections and present finite analytic
expressions for the quark-antiquark-gluon intermediate state inside the photon
impact factor. We begin with a list of the infrared singular pieces of the
virtual correction, obtained in the first step of our program. We then list the
complete results for the real corrections (longitudinal and transverse photon
polarization). In the next step we define, for the real corrections, the collinear
and soft singular regions and calculate their contributions to the impact factor.
We then subtract the contribution due to the central region. Finally, we
combine the real corrections with the singular pieces of the virtual corrections
and obtain our finite results
Implications of non-linearities between cumulative CO2 emissions and CO2-induced warming for assessing the remaining carbon budget
To determine the remaining carbon budget, a new framework was introduced in the Intergovernmental Panel on Climate Change's Special Report on Global Warming of 1.5 °C (SR1.5). We refer to this as a 'segmented' framework because it considers the various components of the carbon budget derivation independently from one another. Whilst implementing this segmented framework, in SR1.5 the assumption was that there is a strictly linear relationship between cumulative CO2 emissions and CO2-induced warming i.e. the TCRE is constant and can be applied to a range of emissions scenarios. Here we test whether such an approach is able to replicate results from model simulations that take the climate system's internal feedbacks and non-linearities into account. Within our modelling framework, following the SR1.5's choices leads to smaller carbon budgets than using simulations with interacting climate components. For 1.5 °C and 2 °C warming targets, the differences are 50 GtCO2 (or 10%) and 260 GtCO2 (or 17%), respectively. However, by relaxing the assumption of strict linearity, we find that this difference can be reduced to around 0 GtCO2 for 1.5 °C of warming and 80 GtCO2 (or 5%) for 2.0 °C of warming (for middle of the range estimates of the carbon cycle and warming response to anthropogenic emissions). We propose an updated implementation of the segmented framework that allows for the consideration of non-linearities between cumulative CO2 emissions and CO2-induced warming
Spacetime colour reconnection in Herwig 7
We present a model for generating spacetime coordinates in the Monte Carlo event generator Herwig 7, and perform colour reconnection by minimizing a boost-invariant distance measure of the system. We compare the model to a series of soft physics observables. We find reasonable agreement with the data, suggesting that pp-collider colour reconnection may be able to be applied in larger systems
The aT distribution of the Z boson at hadron colliders
We provide the first theoretical study of a novel variable, , proposed
in Ref.[1] as a more accurate probe of the region of low transverse momentum
, for the boson distribution at hadron colliders. The is
the component of transverse to a suitably defined axis. Our study
involves resummation of large logarithms in up to the next-to--leading
logarithmic accuracy and we compare the results to those for the well-known
distribution, identifying important physical differences between the two
cases. We also test our resummed result at the two-loop level by comparing its
expansion to order with the corresponding fixed-order results and
find agreement with our expectations.Comment: 30 pages, 3 figures, JHEP class included. Final version published in
JHE
Packaging and preservation of space-vehicle hardware Final report, 9 Jun. 1966 - 8 Jun. 1967
Packaging and preservation of space vehicle hardwar
Colour reconnections in Herwig++
We describe the implementation details of the colour reconnection model in
the event generator Herwig++. We study the impact on final-state observables in
detail and confirm the model idea from colour preconfinement on the basis of
studies within the cluster hadronization model. Moreover, we show that the
description of minimum bias and underlying event data at the LHC is improved
with this model and present results of a tune to available data.Comment: 19 pages, 21 figures, 2 tables. Matches with published versio
Multi-Parton Interactions at the LHC
We review the recent progress in the theoretical description and experimental
observation of multiple parton interactions. Subjects covered include
experimental measurements of minimum bias interactions and of the underlying
event, models of soft physics implemented in Monte Carlo generators,
developments in the theoretical description of multiple parton interactions and
phenomenological studies of double parton scattering. This article stems from
contributions presented at the Helmholtz Alliance workshop on "Multi-Parton
Interactions at the LHC", DESY Hamburg, 13-15 September 2010.Comment: 68 page
Jet vetoing and Herwig++
We investigate the simulation of events with gaps between jets with a veto on
additional radiation in the gap in Herwig++. We discover that the
currently-used random treatment of radiation in the parton shower is generating
some unphysical behaviour for wide-angle gluon emission in QCD 2 to 2
scatterings. We explore this behaviour quantitatively by making the same
assumptions as the parton shower in the analytical calculation. We then modify
the parton shower algorithm in order to correct the simulation of QCD
radiation.Comment: 18 pages, 11 figure
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