We report on the W and Z/γ* differential and total cross sections as well as the W+/W− and (W++W−)/(Z/γ*) cross section ratios measured by the STAR experiment at RHIC in p+p collisions at s=500 GeV and 510 GeV. The...
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We report on the W and Z/γ* differential and total cross sections as well as the W+/W− and (W++W−)/(Z/γ*) cross section ratios measured by the STAR experiment at RHIC in p+p collisions at s=500 GeV and 510 GeV. The cross sections and their ratios are sensitive to quark and antiquark parton distribution functions. In particular, at leading order, the W cross section ratio is sensitive to the d¯/u¯ ratio. These measurements were taken at high Q2∼MW2,MZ2 and can serve as input into global analyses to provide constraints on the sea quark distributions. The results presented here combine three STAR datasets from 2011, 2012, and 2013, accumulating an integrated luminosity of 350 pb−1 . We also assess the expected impact that our W+/W− cross section ratios will have on various quark distributions, and find sensitivity to the u¯−d¯ and d¯/u¯ distributions.
A search for the electroweak production of charginos and sleptons decaying into final states with two electrons or muons is presented. The analysis is based on 139 fb \(^{-1}\) of proton–proton collisions recorded by...
A search for the electroweak production of charginos and sleptons decaying into final states with two electrons or muons is presented. The analysis is based on 139 fb \(^{-1}\) of proton–proton collisions recorded by the ATLAS detector at the Large Hadron Collider at \(\sqrt{s}=13\) \(\text {TeV}\) . Three R -parity-conserving scenarios where the lightest neutralino is the lightest supersymmetric particle are considered: the production of chargino pairs with decays via either W bosons or sleptons, and the direct production of slepton pairs. The analysis is optimised for the first of these scenarios, but the results are also interpreted in the others. No significant deviations from the Standard Model expectations are observed and limits at 95% confidence level are set on the masses of relevant supersymmetric particles in each of the scenarios. For a massless lightest neutralino, masses up to 420 \(\text {Ge}\text {V}\) are excluded for the production of the lightest-chargino pairs assuming W -boson-mediated decays and up to 1 \(\text {TeV}\) for slepton-mediated decays, whereas for slepton-pair production masses up to 700 \(\text {Ge}\text {V}\) are excluded assuming three generations of mass-degenerate sleptons. A preprint version of the article is available at ArXiv.
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