Search NASA⌕ Search

Engineering topics

Aoun, S.

Publications and source records attributed to Aoun, S..

At least 19 records
All sourcesNASA NTRSDOE OSTI
DOE OSTI2014

The differential production cross section of the $\phi $ (1020) meson in $\sqrt{s}$ TeV $pp$ collisions measured with the ATLAS detector

Ameasurement is presented of the $\phi $×BR($\phi $ →K < sup > + < /sup > K < sup > - < /sup > ) production cross section at √s = 7 TeV using pp collision data corresponding to an integrated luminosity of 383 μb -1 , collected with the ATLAS experiment at the HC. Selection of $\phi $(1020) mesons is based on the identification of charged kaons by their energy loss in the pixel detector. The differential cross section ismeasured as a function of the transverse momentum, pT,$\phi $ , and rapidity, y$\phi $, of the $\phi $(1020) meson in the fiducial region 500 < pT,$\phi $ < 1200MeV, |y$\phi $ | < 0.8, kaon p T,K > 230 MeV and kaon momentum p K < 800 MeV. The integrated $\phi $(1020)-meson production cross section in this fiducial range is measured to be sφ×BR($\phi $ →K < sup > + < /sup > K < sup > - < /sup > ) = 570 ± 8 (stat) ± 66 (syst) ± 20 (lumi) μb.

72 PHYSICS OF ELEMENTARY PARTICLES AND FIELDS↗
DOE OSTI2013

Improved luminosity determination in pp collisions at $\sqrt {s} = 7\ \mathrm{TeV}$ using the ATLAS detector at the LHC

The luminosity calibration for the ATLAS detector at the LHC during pp collisions at √s = 7 TeV in 2010 and 2011 is presented. Evaluation of the luminosity scale is performed using several luminosity-sensitive detectors, and comparisons are made of the long-term stability and accuracy of this calibration applied to the pp collisions at √s = 7 TeV. A luminosity uncertainty of δL/L= ± 3.5 % is obtained for the 47 pb -1 of data delivered to ATLAS in 2010, and an uncertainty of δL/L= ± 1.8 % is obtained for the 5.5 fb -1 delivered in 2011.

72 PHYSICS OF ELEMENTARY PARTICLES AND FIELDS↗
DOE OSTI2013

Measurement of the inclusive jet cross-section in pp collisions at $\sqrt{s}=2.76\ \mbox{TeV}$ and comparison to the inclusive jet cross-section at $\sqrt{s} =7\ \mbox{TeV}$ using the ATLAS detector

The inclusive jet cross-section has been measured in proton–proton collisions at $\sqrt{s}=2.76\ \mbox{TeV}$ in a dataset corresponding to an integrated luminosity of 0.20 pb -1 collected with the ATLAS detector at the Large Hadron Collider in 2011. Jets are identified using the anti-k t algorithm with two radius parameters of 0.4 and 0.6. The inclusive jet double-differential cross-section is presented as a function of the jet transverse momentum p T and jet rapidity y, covering a range of 20 ≤ p T < 430 GeV and |y| < 4.4. The ratio of the cross-section to the inclusive jet cross-section measurement at $\sqrt{s} =7\ \mbox{TeV}$, published by the ATLAS Collaboration, is calculated as a function of both transverse momentum and the dimensionless quantity x T = 2p T / √s, in bins of jet rapidity. The systematic uncertainties on the ratios are significantly reduced due to the cancellation of correlated uncertainties in the two measurements. Results are compared to the prediction from next-to-leading order perturbative QCD calculations corrected for non-perturbative effects, and next-to-leading order Monte Carlo simulation. Furthermore, the ATLAS jet cross-section measurements at $\sqrt{s}=2.76\ \mbox{TeV}$ and $\sqrt{s} =7\ \mbox{TeV}$ are analysed within a framework of next-to-leading order perturbative QCD calculations to determine parton distribution functions of the proton, taking into account the correlations between the measurements.

72 PHYSICS OF ELEMENTARY PARTICLES AND FIELDS↗
DOE OSTI2013

Search for a light charged Higgs boson in the decay channel $H^{+} \rightarrow c\bar{s}$ in $t\bar{t}$ events using pp collisions at $\sqrt{s} = 7\ \mathrm{TeV}$ with the ATLAS detector

A search for a charged Higgs boson (H + ) in $t\bar{t}$decays is presented, where one of the top quarks decays via t →H + b, followed by H + → two jets ($c\bar{s}$). The other top quark decays to Wb, where the W boson then decays into a lepton (e/μ) and a neutrino. The data were recorded in pp collisions at √ s = 7 TeV by the ATLAS detector at the LHC in 2011, and correspond to an integrated luminosity of 4.7 fb -1 . Finally, with no observation of a signal, 95 % confidence level (CL) upper limits are set on the decay branching ratio of top quarks to charged Higgs bosons varying between 5 % and 1 % for H + masses between 90 GeV and 150 GeV, assuming B(H + →cs) = 100%.

72 PHYSICS OF ELEMENTARY PARTICLES AND FIELDS↗
DOE OSTI2013

Multi-channel search for squarks and gluinos in $\sqrt{s}=7\mbox{ TeV}$ pp collisions with the ATLAS detector at the LHC

A search for supersymmetric particles in final states with zero, one, and two leptons, with and without jets identified as originating from b-quarks, in 4.7 fb -1 of √s=7 TeV pp collisions produced by the Large Hadron Collider and recorded by the ATLAS detector is presented. The search uses a set of variables carrying information on the event kinematics transverse and parallel to the beam line that are sensitive to several topologies expected in supersymmetry. Mutually exclusive final states are defined, allowing a combination of all channels to increase the search sensitivity. No deviation from the Standard Model expectation is observed. Upper limits at 95 % confidence level on visible cross-sections for the production of new particles are extracted. Results are interpreted in the context of the constrained minimal supersymmetric extension to the Standard Model and in supersymmetry-inspired models with diverse, high-multiplicity final states.

72 PHYSICS OF ELEMENTARY PARTICLES AND FIELDS↗
DOE OSTI2013

Measurement of hard double-parton interactions in W (→ℓ ν ) + 2-jet events at $\sqrt{s}\,=7$ TeV with the ATLAS detector

The production of W bosons in association with two jets in proton–proton collisions at a centre-of-mass energy of $\sqrt {s} = 7\,{\mathrm {TeV}}$ has been analysed for the presence of double-parton interactions using data corresponding to an integrated luminosity of 36 pb -1 , collected with the ATLAS detector at the Large Hadron Collider. The fraction of events arising from double-parton interactions, f (D) DP, has been measured through the pT balance between the two jets and amounts to f(D)DP = 0.08 ± 0.01 (stat.) ± 0.02 (sys.) for jets with transverse momentum pT > 20 GeV and rapidity |y| < 2.8. This corresponds to a measurement of the effective area parameter for hard double-parton interactions of σ eff = 15 ± 3 (stat.) +5 -3 (sys.) mb.

72 PHYSICS OF ELEMENTARY PARTICLES AND FIELDS↗