differential cross section: measured

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Measurement of the differential cross section of photon plus jet production in ppbar collisions at sqrt{s}=1.96 TeV

Measurement of the differential cross section of photon plus jet production in ppbar collisions at sqrt{s}=1.96 TeV

in the tracking system. The tracking system provides a 35 µm vertex resolution along the beam line and 15 µm resolution in the transverse plane near the beam line for charged particles with p T ≈ 10 GeV. The solenoid mag- net is surrounded by the central preshower (CPS) detec- tor located immediately before the inner layer of the elec- tromagnetic calorimeter. The CPS consists of approxi- mately one radiation length of lead absorber surrounded by three layers of scintillating strips. The preshower de- tectors are in turn surrounded by sampling calorimeters constructed of depleted uranium absorbers in an active liquid argon volume. The calorimeter is composed of three sections: a central calorimeter (CC) covering the range of pseudorapidities |η det | < 1.1 [15] and two end calorimeters (EC) with coverage extending to |η det | ≈ 4.2, with all three housed in separate cryostats. The electromagnetic (EM) section of the central calorimeter contains four longitudinal layers of approximately 2, 2, 7, and 10 radiation lengths, and is finely-segmented trans- versely into cells of size ∆η det × ∆φ det = 0.1 × 0.1, with the exception of layer three with 0.05 × 0.05 granular- ity. The calorimeter resolution for measurements of the electron/photon energy at 50 GeV is about 3.6%. The luminosity is measured using plastic scintillator arrays placed in front of the EC cryostats at 2.7 < |η det | < 4.4.
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Measurement of the inclusive differential jet cross section in pp collisions at sqrt{s} = 2.76 TeV

Measurement of the inclusive differential jet cross section in pp collisions at sqrt{s} = 2.76 TeV

and approximately 7% at p T = 40 GeV/c for track class (ii). Charged tracks with p T > 40 GeV/c make negligible contribution to the inclusive jet population considered in this analysis. EMCal clusters are formed by a clustering algorithm that combines signals from adjacent EMCal towers, with cluster size limited by the requirement that each cluster contains only one local energy maximum. A noise suppression threshold of 0.05 GeV is imposed on individual tower energies, and the cluster energy must exceed 0.3 GeV. Noisy towers, identified by their event-averaged characteristics and comprising about 1% of all EMCal towers, are removed from the analysis. Clusters with large apparent energy but anomalously small number of contributing towers are attributed to the interaction of slow neutrons or highly ionizing particles in the avalanche photodiode of the corresponding tower, and are removed from the analysis. EMCal non-linearity was measured with test beam data to be negligible for cluster energy between 3 GeV and 50 GeV, with more energetic clusters making negligible contribution to the inclusive jet population considered in this analysis. A non-linearity correction is applied for clusters with energy below 3 GeV, with value approximately 7% at 0.5 GeV.
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Measurement of the differential cross section d\sigma/dt in elastic $p\bar{p}$ scattering at sqrt(s)=1.96 TeV

Measurement of the differential cross section d\sigma/dt in elastic $p\bar{p}$ scattering at sqrt(s)=1.96 TeV

II. D0 DETECTOR We briefly describe the elements of the detector that are relevant for the measurement reported here. A de- tailed description of the D0 detector can be found in reference [10]. The central tracking system of the D0 detector comprises a silicon microstrip tracker (SMT) and a central fiber tracker (CFT), surrounded by a 2 T superconducting solenoidal magnet. The pseudorapid- ity [14] coverage for the tracking detectors is |η| < 3 for the SMT and |η| < 2.5 for the CFT. Outside of the superconducting magnet, the liquid-argon and uranium calorimeter is composed of three sections housed in sepa- rate cryostats: a central calorimeter section covering the pseudorapidity range |η| < 1.1 and two end calorimeter sections that extend coverage to |η| ≈ 4.2 [15]. A muon system [16], outside of the calorimetry, consists of three layers of tracking detectors and scintillation trigger coun- ters, and large toroidal magnets for muon momentum measurement. The luminosity monitor (LM) consists of plastic scintillator arrays located at z = ±140 cm (where z is measured from the IP along the nominal direction of the proton beam), and covers the pseudorapidity range 2.7 < |η| < 4.4. The LM is used to detect non-diffractive inelastic collisions and to make an accurate determina- tion of the luminosity.
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Investigation of the formaldehyde differential absorption cross section at high and low spectral resolution in the simulation chamber SAPHIR

Investigation of the formaldehyde differential absorption cross section at high and low spectral resolution in the simulation chamber SAPHIR

Received: 12 January 2007 – Published in Atmos. Chem. Phys. Discuss.: 26 February 2007 Revised: 11 June 2007 – Accepted: 3 July 2007 – Published: 9 July 2007 Abstract. The results from a simulation chamber study on the formaldehyde (HCHO) absorption cross section in the UV spectral region are presented. We performed 4 ex- periments at ambient HCHO concentrations with simulta- neous measurements of two DOAS instruments in the at- mosphere simulation chamber SAPHIR in J¨ulich. The two instruments differ in their spectral resolution, one work- ing at 0.2 nm (broad-band, BB-DOAS), the other at 2.7 pm (high-resolution, HR-DOAS). Both instruments use dedi- cated multi reflection cells to achieve long light path lengths of 960 m and 2240 m, respectively, inside the chamber. Dur- ing two experiments HCHO was injected into the clean chamber by thermolysis of well defined amounts of para- formaldehyde reaching mixing rations of 30 ppbV at max- imum. The HCHO concentration calculated from the in- jection and the chamber volume agrees with the BB-DOAS measured value when the absorption cross section of Meller and Moortgat (2000) and the temperature coefficient of Cantrell (1990) were used for data evaluation. In two fur- ther experiments we produced HCHO in-situ from the ozone + ethene reaction which was intended to provide an indepen- dent way of HCHO calibration through the measurements of ozone and ethene. However, we found an unexpected devi- ation from the current understanding of the ozone + ethene reaction when CO was added to suppress possible oxidation of ethene by OH radicals. The reaction of the Criegee inter- mediate with CO could be 240 times slower than currently assumed. Based on the BB-DOAS measurements we could deduce a high-resolution cross section for HCHO which was not measured directly so far.
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Measurement of differential cross sections and $W^+/W^-$ cross-section ratios for $W$ boson production in association with jets at $\sqrt{s}=8$ TeV with the ATLAS detector

Measurement of differential cross sections and $W^+/W^-$ cross-section ratios for $W$ boson production in association with jets at $\sqrt{s}=8$ TeV with the ATLAS detector

7.4 Non-perturbative corrections The N jetti , BlackHat+Sherpa, and MCFM results do not include non-perturbative effects from hadronisation and the underlying event. These corrections are computed for each bin with Sherpa 2.2.1 [ 37 ] combining matrix element calculations with up to two parton emissions at LO in pQCD. The calculation uses the NNPDF 3.0 PDF set and dynamic renormalisation and factorisation scales determined by the CKKW scale-setting procedure. The corrections are typically around 2–3% and are applied to the predictions for all measured distributions. Statistical uncertainties in these corrections and the systematic uncertainty, defined by the envelope of variations of the starting scale of the parton shower, the recoil scheme, the mode of shower evolution and the number of emitted partons from the matrix element, are included in the respective theory uncertainties. For the W + /W − predictions, no non-perturbative corrections are required as these effects cancel out in the ratio. The impact of QED radiation, which is considered as part of the dressed-electron definition in the measured cross sections, on the parton-level theoretical predictions is investigated using Sherpa 2.2.1 with the same set-up as the NLO Sherpa predictions described above and found to be very small. No correction for this effect is applied.
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Measurement of the Drell-Yan triple-differential cross section in $pp$ collisions at $\sqrt{s} = 8$ TeV

Measurement of the Drell-Yan triple-differential cross section in $pp$ collisions at $\sqrt{s} = 8$ TeV

7.6.2 Unfolding bias The simulation used as an initial prior in the unfolding process could lead to a potential bias in the measured cross sections. This potential bias is quantified by varying the predictions within theoretical uncertainties. The PDF bias is probed using signal MC events reweighted to each of the 26 different eigenvector variations of the CT10 PDF set in the determination of M. For each variation the change in the unfolded cross section is found to be much smaller than the change in the predicted cross section using each eigenvector PDF set. Changing the PDF set can alter the predicted cross section by up to a few percent but the influence on the unfolded result is less than 0.1%. Furthermore, the change in the unfolded result, using one to five iterations of unfolding, is much smaller than the total uncertainty in the data. This study is repeated by reweighting the signal MC events to different values of the scattering amplitude
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Measurement of the triple-differential dijet cross section in proton-proton collisions at $\sqrt{s}=8\,\text {TeV} $ and constraints on parton distribution functions

Measurement of the triple-differential dijet cross section in proton-proton collisions at $\sqrt{s}=8\,\text {TeV} $ and constraints on parton distribution functions

The precise data constrain the PDFs, especially in the highly boosted regime that probes the highest fractions x of the proton momentum carried by a parton. The impact of the data on the PDFs is demonstrated by performing a simultaneous fit to cross sections of deep-inelastic scattering obtained by the HERA experiments and the dijet cross sec- tion measured in this analysis. When including the dijet data, an increased gluon PDF at high x is obtained and the over- all uncertainties of the PDFs, especially those of the gluon distribution, are significantly reduced. In contrast to a fit that uses inclusive jet data, this measurement carries more infor- mation on the valence-quark content of the proton such that a more flexible parameterisation is needed to describe the low-x behaviour of the u and d valence quark PDFs. This higher sensitivity is accompanied by slightly larger uncer- tainties in the valence quark distributions as a consequence of the greater flexibility in the parameterisation of the PDFs. In a simultaneous fit the strong coupling constant α S (MZ)
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Measurement of the double-differential high-mass Drell-Yan cross section in pp collisions at $\sqrt{s}$ = 8 TeV with the ATLAS detector

Measurement of the double-differential high-mass Drell-Yan cross section in pp collisions at $\sqrt{s}$ = 8 TeV with the ATLAS detector

7 Systematic uncertainties The systematic uncertainties on the measurements are discussed separately for those sources which arise only in the electron channel, those which arise only in the muon channel, and those which are com- mon to both measurements. In each section the sources are discussed in order of importance, with the largest sources of uncertainty listed first. Each source is classified as being correlated or uncorrel- ated between measurement bins in a single channel. The uncorrelated sources are propagated using the pseudo-experiment method in which the correction factors used to improve the modelling of data by the simulation are randomly shifted in an ensemble of pseudo-experiments according to the mean and standard deviation of the correction factor. The resulting uncertainty on the measured cross section is determined from the variance of the measurements for the ensemble. The correlated contributions are
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Fast calculation of the light differential scattering cross section of optically soft and convex bodies.

Fast calculation of the light differential scattering cross section of optically soft and convex bodies.

photodetector array. The incident light is scattered by the sample, i.e. the suspension. Then, either the light intensity can be recorded at various scattering direction, or the transmitted intensity, i.e. the non-scattered and non-absorbed light. For suspension with identical particles, the scattered intensity is proportional to the concentration and the differential scattering cross section of the particles, whereas the transmitted light intensity is related to the particle concentration and the light extinction cross section. If the particle concentration is known, the extinction cross section is obtained through a turbidity measurement by means of the Beer-Lambert law for diluted suspension. In fact, the suspension consists of particles having different sizes and morphologies. The turbidity spectrum or the angular scattered intensity distribution of such a suspension must be analyzed during the precipitation process. The corresponding data have to be treated to deduce the concentration of each class of particle. Those are characterized by their total or differential scattering or extinction cross sections. For instance, the measured quantity is the turbidity at several wavelengths, the known parameters are the extinction cross sections and the unknown variables are the concentrations. As a consequence, the solving of the inverse problem requires previously the calculation of the optical properties of each class of particle. The exact calculation of any shapely particle is possible by numerical methods [1]. However, the whole analysis needs a too large computational time if these exact methods are used for the calculation of the optical properties. Moreover, rigorous numerical simulations are not mandatory because the particle shape, the agglomerate structure and maybe even the relevant material properties are not available with precision in such reactor. Thus simple and accurate expressions for the optical properties of particles or crystals are useful to solve inverse problems coming from such optical particle sizing techniques.
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Measurement of the Z boson differential cross-section in transverse momentum in the electron-positron channel with the ATLAS detector at LHC.

Measurement of the Z boson differential cross-section in transverse momentum in the electron-positron channel with the ATLAS detector at LHC.

The factors entering equation ( 3.19 ) depend on the values of the cuts done, and on kinematic variables like E T and η of the electron candidate. The efficiencies can be estimated using MC simulations, however they can be measured more accurately using a data driven method, called “tag and probe”. This method is based on the selection in data of a clean and unbiased sample of electrons, called probes, that can be used to evaluate the efficiency of the different cuts. In order to select this sample, tight requirements are done on other objects of the event, called tags, that are related to the probes by means of a decay or other process. For example, consider the Z → ee process. In order to use this process for tag and probe, one electron is required to pass tight ID cuts, the other one to have opposite charge to the first one (looser selection), and the invariant mass of the pair to be close to the Z resonance peak. This way, the event is “tagged” by the tight selected electron and the requirement on the invariant mass, and the loose selected electrons can be used as probes, just by applying a given cut on them and evaluating the fraction of times the cut is passed.
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Radar Cross Section Measurement within Reverberation Chamber: Stirrer position issues

Radar Cross Section Measurement within Reverberation Chamber: Stirrer position issues

In the last years, Reverberation Chambers (RCs) became a promising alternative testing facility for a wide range of electromagnetic applications including global parameter estimation sucha as absorbing cross section [3] or antenna efficiency [4] and some more detailed feature analysis such as radiation pattern measurement [5]. Recently, the use of an RC as an alternative test environment to perform RCS measurement [6], [9]. This RCS characterization relies on the extraction of the ballistic wave backscattered by the target among the diffuse field backscattered by the RC itself. This approach presents some advantages by using a cheaper measurement setup compared to classical AC measurement. Also, and contrary to the method proposed in [7], no time gating is required, thus avoiding any Fourier Transform.
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Idiosyncratic Consumption Risk and the Cross-Section of Asset Returns

Idiosyncratic Consumption Risk and the Cross-Section of Asset Returns

However, in our opinion it is the best one can do with the CEX. A Þnal issue regarding the construction of this sample of assetholders is that we only con- struct a sample of households who report positive holdings of assets. Interestingly, several studies (Mankiw and Zeldes (1991), Jacobs (1999), Brav, Constantinides and Geczy (1999), Vissing-Jorgensen (2000)) have constructed additional samples containing only households who report holdings above certain positive thresholds (e.g. $1,000, $5,000 etc.). We do not attempt to do this because of two reasons. First, unlike other papers we construct a sample of assetholders using different questions. Therefore, imposing thresholds is less straightfor- ward. Second, our construction of synthetic cohorts described in the next section is only meaningful if the sample size is large enough. By eliminating more and more households due to increasingly stringent asset holding criteria, this exercise becomes problematic.
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Comparative advantage and the cross-section of business cycles

Comparative advantage and the cross-section of business cycles

find that the theory predicts cross-country differences in terms of trade volatility of 0.012 and 0.010 when the elasticity of unskilled labour supply is A.=0 or X=0.35. respectively[r]

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Hedge Fund Returns and Factor Models : A Cross-Section Approach

Hedge Fund Returns and Factor Models : A Cross-Section Approach

standardized data, we renormalize them in order to obtain the same stan- dard deviation as for S&P 500 index. S&P 500 index returns have been centered by their mean in order to facilitate the comparison with the es- timated latent factors. The correlation coefficients between the two latent factors with the S&P 500 index are respectively 0, 85 and 0, 27. The first factor behaves closely with the S&P 500 index, while the second one is less correlated with the equity market. Even if the equity market factor seems to play an important role in explaining the cross-section of equity hedge fund returns, we are yet unable to identify a significant portion of common risk represented by the second latent factor if we use a single factor model.
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Approximation of the scattering cross section for aggregated spherical particles

Approximation of the scattering cross section for aggregated spherical particles

Consider main features of mean scattering cross sections of aggregates like it was done in [8]. Figures 1(a,b) represent R Xu = C Xu,N /(NC Mie,;1 ) against the primary particle size parameter for several N-chains and for the two systems TiO 2 /water and SiO 2 /water. The trends are the same for compact aggregates (the compact configuration means for example a tetrahedron for the case of 4 primary particles, a cube for the case of 8 and so on). The shape of the curves R Xu is similar whatever the material. R Xu is a decreasing

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Time-like observables: differential cross section and angular asymmetry

Time-like observables: differential cross section and angular asymmetry

• A summary and a few comments will be given in Conclusions. The Appendix collects different spectra, which may be useful for further studies. II. PARAMETRIZATIONS OF TL FFS The form factors, in particular |G M |, depend in principle only on the four momentum squared of the virtual photon, q 2 , which corresponds to the total energy s where the mea- surement is performed. The cross section is usually integrated over a limited angular range. Attempts of determining the ratio R = |G E |/|G M | can be found in Refs. [12] (LEAR) and more recently in Ref. [2] through the reaction e + + e − → p + p + γ (BABAR Collaboration), corrected by the initial state radiation. The results, although affected by large errors, are not in agreement, giving, in the second case a value for the ratio larger than unity, in a wide q 2 range above threshold.
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The Total Cross Section at the LHC: Models and Experimental Consequences

The Total Cross Section at the LHC: Models and Experimental Consequences

The total cross section is a highly non-perturbative object that we cannot predict from QCD. In fact, we have to rely on theoretical ideas that were developed before QCD, in the context of the analytic S matrix, such as analyticity, or the unitarity of partial waves. The natural place to discuss these ideas is the complex-j plane, where the singularities of the amplitudes determine their behaviour with s. But we do not know these singularities. The simplest ones, which correspond to the exchange of bound states, are simple poles. Accounting for the exchange of meson trajectories is not too hard, as we know their spectrum. But as their contribution falls with s, they will not matter at the LHC. One must thus model the pomeron, for which there is little spectroscopic guidance. Again, the simplest idea is to use a simple pole at j = 1 + ǫ. But we know that if there are simple poles, there must be cuts, which correspond to multiple exchanges. We do not know how to calculate these: we only know general properties of the two-pomeron cut. This means that there are many possibilities, such as eikonal models, U -matrix unitarisation, extended eikonal/U -matrix models, or multi-channel eikonals. These cuts will be needed at the LHC to restore partial-wave unitarity. It is also possible that the pomeron is not an exchange of bound states, so that one should not start from a simple pole, but rather consider multiple poles (double or triple) at j = 1, which automatically obey unitarity.
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Measurement of the ratio of the $p\bar{p}\to W$+$c$-jet cross section to the inclusive $p\bar{p}\to W$+jets cross section

Measurement of the ratio of the $p\bar{p}\to W$+$c$-jet cross section to the inclusive $p\bar{p}\to W$+jets cross section

significance. PACS numbers: 12.15.Ji, 12.38.Qk, 13.85.Ni, 13.85.Qk, 14.70.Fm, 14.65.Dw In hadron-hadron collisions, the W/Z+b- or c-jet fi- nal state can signal the presence of new physics; how- ever, only a few measurements [1, 2, 3] of cross sec- tions for these standard model processes exist. Charm quark production in association with a W boson can be a significant background, for example, to top quark pair, single top quark and Higgs boson productions, and to supersymmetric top quark (stop) pair produc- tion when only the ˜ t → c ˜ χ 0

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Route to chaos on a dragonfly wing cross section in gliding flight

Route to chaos on a dragonfly wing cross section in gliding flight

ing in the same low Reynolds number range. The exper- imental study from Okamoto et al. [9] has shown that a corrugation or a sinusoidal pattern of surface roughness may be beneficial for aerodynamic characteristics. Kesel [10] also studied corrugated airfoils to understand how to reach the high maximum lift coefficient measured in wind-tunnel tests, concluding that a symmetric corruga- tion will not be optimal for lift generation. Vargas et al. [11] has made a CFD comparisons of a corrugated airfoil geometry from [10] with a flat plate and a profiled air- foil. A higher aerodynamic performance on lift-to-drag ratio is mentioned at the highest Reynolds number tested (Re = 1000) and moderate angle of attack (α = 5 ◦ ). Over a large range of Reynolds numbers [140 − 10000], the corrugation effect which increases lift with low drag penalty is not Reynolds number dependent [12]. Finally, numerical and experimental studies [13, 14] revealed that corrugations may also reduce the lift and drag fluctua- tions because of decreasing the vortex shedding magni- tude. However, at lower Reynolds number, corrugations may have negative effects [15] when not accompanied by a rear arc. This scientific debate dealing with the posi- tive and negative effects of corrugations on low-Reynolds aerodynamic performances is still open [16]. To answer this question will require more studies on the unsteady complex flow around dragonfly wings to describe in de- tails the various regimes that can arise depending on the geometry and flow conditions. This is one motivation for the present study.
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Front blocking and propagation in cylinders with varying cross section

Front blocking and propagation in cylinders with varying cross section

5 Blocking by a narrow passage In this section we prove Theorem 1.8. There are earlier results on the existence of non constant stable steady states for bistable reaction-diffusion equations with Neumann boundary con- ditions when there is a narrow passage in a number of cases. Matano [29] first showed the existence of non-constant stable solutions in the case of a bounded domain having the shape of an hourglass. The first author of the present paper together with Hamel and Matano [7] established an analogous result for an exterior domain having a narrow passage to a confined region. The paper [7] exhibits a non constant stable steady state in an exterior do- main with narrow passage where the area in which the solution is close to 0 is bounded whereas the area where the solution is close to 1 is unbounded.
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