123 research outputs found
Mass Determination in SUSY-like Events with Missing Energy
We describe a kinematic method which is capable of determining the overall
mass scale in SUSY-like events at a hadron collider with two missing (dark
matter) particles. We focus on the kinematic topology in which a pair of
identical particles is produced with each decaying to two leptons and an
invisible particle (schematically, followed by each
decaying via where is invisible). This topology
arises in many SUSY processes such as squark and gluino production and decay,
not to mention t\anti t di-lepton decays. In the example where the final
state leptons are all muons, our errors on the masses of the particles ,
and in the decay chain range from 4 GeV for 2000 events after cuts to 13
GeV for 400 events after cuts. Errors for mass differences are much smaller.
Our ability to determine masses comes from considering all the kinematic
information in the event, including the missing momentum, in conjunction with
the quadratic constraints that arise from the , and mass-shell
conditions. Realistic missing momentum and lepton momenta uncertainties are
included in the analysis.Comment: 41 pages, 14 figures, various clarifications and expanded discussion
included in revised version that conforms to the version to be publishe
Next-to-leading order QCD corrections to W+W- production via vector-boson fusion
Vector-boson fusion processes constitute an important class of reactions at
hadron colliders, both for signals and backgrounds of new physics in the
electroweak interactions.
We consider what is commonly referred to as W+W- production via vector-boson
fusion (with subsequent leptonic decay of the Ws), or, more precisely, e+ nu_e
mu- nubar_mu + 2 jets production in proton-proton scattering, with all resonant
and non-resonant Feynman diagrams and spin correlations of the final-state
leptons included, in the phase-space regions which are dominated by t-channel
electroweak-boson exchange.
We compute the next-to-leading order QCD corrections to this process, at
order alpha^6 alpha_s.
The QCD corrections are modest, changing total cross sections by less than
10%. Remaining scale uncertainties are below 2%. A fully-flexible
next-to-leading order partonic Monte Carlo program allows to demonstrate these
features for cross sections within typical vector-boson-fusion acceptance cuts.
Modest corrections are also found for distributions.Comment: 29 pages, 14 figure
Catching-up and falling behind knowledge spillover from American to German machine tool makers
In our days, German machine tool makers accuse their Chinese competitors of violating patent rights and illegally imitating German technology. A century ago, however, German machine tool makers used exactly the same methods to imitate American technology. To understand the dynamics of this catching-up process we use patent statistics to analyze firms? activities between 1877 and 1932. We show that German machine tool makers successfully deployed imitating and counterfeiting activities in the late 19th century and the 1920s to catchup to their American competitors. The German administration supported this strategy by stipulating a patent law that discriminated against foreign patent holders and probably also by delaying the granting of patents to foreign applicants. Parallel to the growing international competitiveness of German firms, however, the willingness to guarantee intellectual property rights of foreigners was also increasing because German firms had now to fear retaliatory measures in their own export markets when violating foreign property rights within Germany
Measuring the Higgs Sector
If we find a light Higgs boson at the LHC, there should be many observable
channels which we can exploit to measure the relevant parameters in the Higgs
sector. We use the SFitter framework to map these measurements on the parameter
space of a general weak-scale effective theory with a light Higgs state of mass
120 GeV. Our analysis benefits from the parameter determination tools and the
error treatment used in new--physics searches, to study individual parameters
and their error bars as well as parameter correlations.Comment: 45 pages, Journal version with comments from refere
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Observing atmospheric formaldehyde (HCHO) from space: validation and intercomparison of six retrievals from four satellites (OMI, GOME2A, GOME2B, OMPS) with SEAC(4)RS aircraft observations over the southeast US
Formaldehyde (HCHO) column data from satellites are widely used as a proxy for emissions of volatile organic compounds (VOCs), but validation of the data has been extremely limited. Here we use highly accurate HCHO aircraft observations from the NASA SEAC4RS (Studies of Emissions, Atmospheric Composition, Clouds and Climate Coupling by Regional Surveys) campaign over the southeast US in August–September 2013 to validate and intercompare six retrievals of HCHO columns from four different satellite instruments (OMI, GOME2A, GOME2B and OMPS; for clarification of these and other abbreviations used in the paper, please refer to Appendix A) and three different research groups. The GEOS-Chem chemical transport model is used as a common intercomparison platform. All retrievals feature a HCHO maximum over Arkansas and Louisiana, consistent with the aircraft observations and reflecting high emissions of biogenic isoprene. The retrievals are also interconsistent in their spatial variability over the southeast US (râŻ = âŻ0.4–0.8 on a 0.5°âŻ × âŻ0.5°âŻ grid) and in their day-to-day variability (râŻ = âŻ0.5–0.8). However, all retrievals are biased low in the mean by 20–51âŻ%, which would lead to corresponding bias in estimates of isoprene emissions from the satellite data. The smallest bias is for OMI-BIRA, which has high corrected slant columns relative to the other retrievals and low scattering weights in its air mass factor (AMF) calculation. OMI-BIRA has systematic error in its assumed vertical HCHO shape profiles for the AMF calculation, and correcting this would eliminate its bias relative to the SEAC4RS data. Our results support the use of satellite HCHO data as a quantitative proxy for isoprene emission after correction of the low mean bias. There is no evident pattern in the bias, suggesting that a uniform correction factor may be applied to the data until better understanding is achieved.</p
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Impacts of the Denver Cyclone on regional air quality and aerosol formation in the Colorado Front Range during FRAPPE 2014
We present airborne measurements made during the 2014 Front Range Air Pollution and Photochemistry Experiment (FRAPPÉ) project to investigate the impacts of the Denver Cyclone on regional air quality in the greater Denver area. Data on trace gases, non-refractory submicron aerosol chemical constituents, and aerosol optical extinction (βext) at λâŻ = âŻ632âŻnm were evaluated in the presence and absence of the surface mesoscale circulation in three distinct study regions of the Front Range: In-Flow, Northern Front Range, and the Denver metropolitan area. Pronounced increases in mass concentrations of organics, nitrate, and sulfate in the Northern Front Range and the Denver metropolitan area were observed during the cyclone episodes (27–28 July) compared to the non-cyclonic days (26 July, 2–3 August). Organic aerosols dominated the mass concentrations on all evaluated days, with a 45âŻ% increase in organics on cyclone days across all three regions, while the increase during the cyclone episode was up to  ∼ âŻ80âŻ% over the Denver metropolitan area. In the most aged air masses (NOxâŻ/âŻNOyâŻ < âŻ0.5), background organic aerosols over the Denver metropolitan area increased by a factor of ∼ âŻ2.5 due to transport from Northern Front Range. Furthermore, enhanced partitioning of nitric acid to the aerosol phase was observed during the cyclone episodes, mainly due to increased abundance of gas phase ammonia. During the non-cyclone events, βext displayed strong correlations (râŻ = âŻ0.71) with organic and nitrate in the Northern Front Range and only with organics (râŻ = âŻ0.70) in the Denver metropolitan area, while correlation of βext during the cyclone was strongest (râŻ = âŻ0.86) with nitrate over Denver. Mass extinction efficiency (MEE) values in the Denver metropolitan area were similar on cyclone and non-cyclone days despite the dominant influence of different aerosol species on βext. Our analysis showed that the meteorological patterns associated with the Denver Cyclone increased aerosol mass loadings in the Denver metropolitan area mainly by transporting aerosols and/or aerosol precursors from the northern regions, leading to impaired visibility and air quality deterioration.</p
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Aerosol optical extinction during the Front Range Air Pollution and Photochemistry Experiment (FRAPP) 2014 summertime field campaign, Colorado, USA
Summertime aerosol optical extinction (βext) was measured in the Colorado Front Range and Denver metropolitan area as part of the Front Range Air Pollution and Photochemistry Éxperiment (FRAPPÉ) campaign during July–August 2014. An Aerodyne cavity attenuated phase shift particle light extinction monitor (CAPS-PMex) was deployed to measure βext (at average relative humidity of 20⯱âŻ7âŻ%) of submicron aerosols at λ = 632âŻnm at 1âŻHz. Data from a suite of gas-phase instrumentation were used to interpret βext behavior in various categories of air masses and sources. Extinction enhancement ratios relative to CO (ΔβextâŻââŻΔCO) were higher in aged urban air masses compared to fresh air masses by  ∼ âŻ50âŻ%. The resulting increase in ΔβextâŻââŻΔCO for highly aged air masses was accompanied by formation of secondary organic aerosols (SOAs). In addition, the impacts of aerosol composition on βext in air masses under the influence of urban, natural oil and gas operations (O&G;), and agriculture and livestock operations were evaluated. Estimated non-refractory mass extinction efficiency (MEE) values for different air mass types ranged from 1.51 to 2.27âŻm2âŻg-1, with the minimum and maximum values observed in urban and agriculture-influenced air masses, respectively. The mass distribution for organic, nitrate, and sulfate aerosols presented distinct profiles in different air mass types. During 11–12 August, regional influence of a biomass burning event was observed, increasing the background βext and estimated MEE values in the Front Range.</p
Too Big to Fail â U.S. Banksâ Regulatory Alchemy: Converting an Obscure Agency Footnote into an âAt Willâ Nullification of Dodd-Frankâs Regulation of the Multi-Trillion Dollar Financial Swaps Market
The multi-trillion-dollar market for, what was at that time wholly unregulated, over-the-counter derivatives (âswapsâ) is widely viewed as a principal cause of the 2008 worldwide financial meltdown. The Dodd-Frank Act, signed into law on July 21, 2010, was expressly considered by Congress to be a remedy for this troublesome deregulatory problem. The legislation required the swaps market to comply with a host of business conduct and anti-competitive protections, including that the swaps market be fully transparent to U.S. financial regulators, collateralized, and capitalized. The statute also expressly provides that it would cover foreign subsidiaries of big U.S. financial institutions if their swaps trading could adversely impact the U.S. economy or represent the use of extraterritorial trades as an attempt to âevadeâ Dodd-Frank. In July 2013, the CFTC promulgated an 80-page, triple-columned, and single-spaced âguidanceâ implementing Dodd-Frankâs extraterritorial reach, i.e., that manner in which Dodd-Frank would apply to swaps transactions executed outside the United States. The key point of that guidance was that swaps trading within the âguaranteedâ foreign subsidiaries of U.S. bank holding company swaps dealers were subject to all of Dodd-Frankâs swaps regulations wherever in the world those subsidiariesâ swaps were executed. At that time, the standardized industry swaps agreement contemplated that, inter alia, U.S. bank holding company swaps dealersâ foreign subsidiaries would be âguaranteedâ by their corporate parent, as was true since 1992. In August 2013, without notifying the CFTC, the principal U.S. bank holding company swaps dealer trade association privately circulated to its members standard contractual language that would, for the first time, âdeguaranteeâ their foreign subsidiaries. By relying only on the obscure footnote 563 of the CFTC guidanceâs 662 footnotes, the trade association assured its swaps dealer members that the newly deguaranteed foreign subsidiaries could (if they so chose) no longer be subject to Dodd-Frank. As a result, it has been reported (and it also has been understood by many experts within the swaps industry) that a substantial portion of the U.S. swaps market has shifted from the large U.S. bank holding companies swaps dealers and their U.S. affiliates to their newly deguaranteed âforeignâ subsidiaries, with the attendant claim by these huge big U.S. bank swaps dealers that Dodd-Frank swaps regulation would not apply to these transactions. The CFTC also soon discovered that these huge U.S. bank holding company swaps dealers were âarranging, negotiating, and executingâ (âANEâ) these swaps in the United States with U.S. bank personnel and, only after execution in the U.S., were these swaps formally âassignedâ to the U.S. banksâ newly âdeguaranteedâ foreign subsidiaries with the accompanying claim that these swaps, even though executed in the U.S., were not covered by Dodd-Frank. In October 2016, the CFTC proposed a rule that would have closed the âdeguaranteeâ and âANEâ loopholes completely. However, because it usually takes at least a year to finalize a âproposedâ rule, this proposed rule closing the loopholes in question was not finalized prior to the inauguration of President Trump. All indications are that it will never be finalized during a Trump Administration. Thus, in the shadow of the recent tenth anniversary of the Lehman failure, there is an understanding among many market regulators and swaps trading experts that large portions of the swaps market have moved from U.S. bank holding company swaps dealers and their U.S. affiliates to their newly deguaranteed foreign affiliates where Dodd- Frank swaps regulation is not being followed. However, what has not moved abroad is the very real obligation of the lender of last resort to rescue these U.S. swaps dealer bank holding companies if they fail because of poorly regulated swaps in their deguaranteed foreign subsidiaries, i.e., the U.S. taxpayer. While relief is unlikely to be forthcoming from the Trump Administration or the Republican-controlled Senate, some other means will have to be found to avert another multi-trillion-dollar bank bailout and/or a financial calamity caused by poorly regulated swaps on the books of big U.S. banks. This paper notes that the relevant statutory framework affords state attorneys general and state financial regulators the right to bring so-called âparens patriaeâ actions in federal district court to enforce, inter alia, Dodd- Frank on behalf of a stateâs citizens. That kind of litigation to enforce the statuteâs extraterritorial provisions is now badly needed
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