Search results for "QK"
showing 10 items of 311 documents
Search for Heavy, Long-Lived Neutralinos that Decay to Photons at CDF II Using Photon Timing
2008
We present the results of the first hadron collider search for heavy, long-lived neutralinos that decay via lightest neutralino to gamma gravitino in gauge-mediated supersymmetry breaking models. Using an integrated luminosity of $570\pm34 pb^{-1}$ of $p\bar{p}$ collisions at $\sqrt{s}=1.96$ TeV, we select $\gamma$+jet+missing transverse energy candidate events based on the arrival time of a high-energy photon at the electromagnetic calorimeter as measured with a timing system that was recently installed on the CDF II detector. We find 2 events, consistent with the background estimate of 1.3$\pm$0.7 events. While our search strategy does not rely on model-specific dynamics, we set cross sec…
Observation of Exclusive Dijet Production at the Fermilab Tevatron p-pbar Collider
2007
We present the first observation and cross section measurement of exclusive dijet production in pbar-p interactions, pbar + p --> pbar + dijet + p. Using a data sample of 310 pb-1 collected by the Run II Collider Detector at Fermilab at sqrt{s}=1.96 TeV, exclusive cross sections for events with two jets of transverse energy ET >= 10 GeV have been measured as a function of minimum ET(jet). The exclusive signal is extracted from fits to data distributions based on Monte Carlo simulations of expected dijet signal and background shapes. The simulated background distribution shapes are checked in a study of a largely independent data sample of 200 pb-1 of b-tagged jet events, where exclusi…
Search for right-handed W bosons in top quark decay
2005
We present a measurement of the fraction f+ of right-handed W bosons produced in top quark decays, based on a candidate sample of $t\bar{t}$ events in the lepton+jets decay mode. These data correspond to an integrated luminosity of 230pb^-1, collected by the DO detector at the Fermilab Tevatron $p\bar{p}$ Collider at sqrt(s)=1.96 TeV. We use a constrained fit to reconstruct the kinematics of the $t\bar{t}$ and decay products, which allows for the measurement of the leptonic decay angle $\theta^*$ for each event. By comparing the $\cos\theta^*$ distribution from the data with those for the expected background and signal for various values of f+, we find f+=0.00+-0.13(stat)+-0.07(syst). This …
Characterization of a Cucumber mosaic virus isolate infecting Mandevilla sanderi (Hemsl.) Woodson
2005
In 2004, virus-like symptoms consisting of yellow rings in older leaves were observed in the foliage of Mandevilla sanderi grown from shoots in the province of Catania (Sicily, Italy). The plants were tested for virus presence using DAS-ELISA, mechanical inoculations to the host, RT-PCR and SSCP. Serological tests detected Cucumber mosaic virus (CMV) in all symptomatic leaf samples. The virus was mechanically transmitted to 11 of the 15 host species tested, including some of the Chenopodiaceae and Solanaceae families; indicator plants showed symptoms typical of CMV subgroup I. RT-PCR, SSCP and cloning were employed to characterize this CMV isolate, and to make clear its genetic relationship…
A syntaxonomical survey of the Sicilian dwarf shrub vegetation belonging to the class Rumici-Astragaletea siculi
2005
Basing on literature data and unpublished relevés from Sicily, a survey of the syntaxa belonging to the class Rumici-Astragaletea siculi Pignatti & Nimis 1980 em. Mucina 1997 (= Cerastio-Carlinetea nebrodensis Brullo 1984) is presented. The class groups orophilous plant communities dominated by dwarf- shrubs, often with a pulvinate and thorny growth form. The class is represented in Sicily by two orders: Rumici-Astragaletalia siculi Pignatti & Nimis 1980, including the sole alliance Rumici-Astragalion siculi Poli 1965, restricted to Mount Aetna, and Erysimo-Jurinetalia bocconei Brullo 1984, including two alliances: the acidophilous Armerion nebrodensis Brullo 1984 and the basiphilous Cerast…
Search for Supersymmetry with Gauge-Mediated Breaking in Diphoton Events with Missing Transverse Energy at CDF II
2010
8 páginas, 3 figuras.-- PACS numbers: 12.60.Jv, 13.85.Rm, 13.85.Qk, 14.80.Ly.-- CDF Collaboration: et al.
Direct measurement of the W boson width
2009
We present a direct measurement of the width of the W boson using the shape of the transverse mass distribution of W->enu candidates selected in 1 fb-1 of data collected with the D0 detector at the Fermilab Tevatron collider in ppbar collisions at sqrt{s}=1.96 TeV. We use the same methods and data sample that were used for our recently published W boson mass measurement, except for the modeling of the recoil, which is done with a new method based on a recoil library. Our result, 2.028 +- 0.072 GeV, is in agreement with the predictions of the standard model.
Search for large extra spatial dimensions in dimuon production with the D0 detector
2005
We present the results of a search for the effects of large extra spatial dimensions in $p{\bar p}$ collisions at $\sqrt{s} =$ 1.96 TeV in events containing a pair of energetic muons. The data correspond to 246 \ipb of integrated luminosity collected by the \D0 experiment at the Fermilab Tevatron Collider. Good agreement with the expected background was found, yielding no evidence for large extra dimensions. We set 95% C.L. lower limits on the fundamental Planck scale between 0.85 TeV and 1.27 TeV within several formalisms. These are the most stringent limits achieved in the dimuon channel to date.
Components from the Essential oil of Centaurea aeolica Guss. and C-diluta Aiton from Sicily, Italy
2015
Volatile components from florets, leaves and stems and branches of Centaurea aeolica Guss. harvested in Lipari, Sicily, Italy, were analysed by gas phase chomatography (GC) and gas chomatography mass spectrometry (GC-MS). The main constituents were β-eudesmol, caryophyllene oxide, ( E )-12-norcaryophyll-5-en-2-one and hexahydrofarnesylacetone in flowers, hexahydrofarnesylacetone, 2-methyloctadecane and tricosane in the leaves and hexadecanoic acid , caryophyllene oxide and β-eudesmol in the stems and branches . The analysis of the essential oil of the aerial parts of Centaurea diluta Aiton gave mainly fatty acids and derivatives, the main ones being hexadecanoic acid and (Z,Z)-9,12-octadeca…
Cytotoxicity of Secondary Metabolites from Dracaena viridiflora Engl & Krause and their Semisynthetic Analogues
2017
The MeOH extract of Dracaena viridiflora was found to display significant cytotoxicity against some cancer cell lines. Systematic phytochemical investigation of this extract led to the isolation and structure elucidation of ten secondary metabolites including five spirostane (1-5) and one furostane (6) steroidal saponins. Furthermore, some acetylated spirostane analogues and three previously unreported derivatives with the 22,26-epoxycholesta-5,22-diene skeleton (15-17) were prepared from trillin (1), prosapogenin A of dioscin (2) and dioscin (4) by reaction with ZnCl 2/Ac 2O. Among the isolated and semisynthetic compounds, dioscin showed the most potent cytotoxicity against A549, Jurkat an…