Performance of the ATLAS trigger system in 2015 Aliev, M.; Alison, J.; Alpigiani, C. ...
The European physical journal. C, Particles and fields,
05/2017, Volume:
77, Issue:
5
Journal Article
Evidence for the decay mode X(3872)→ψ(2S)γ in B+→X(3872)K+ decays is found with a significance of 4.4 standard deviations. The analysis is based on a data sample of proton–proton collisions, ...corresponding to an integrated luminosity of 3 fb−1, collected with the LHCb detector, at centre-of-mass energies of 7 and 8 TeV. The ratio of the branching fraction of the X(3872)→ψ(2S)γ decay to that of the X(3872)→J/ψγ decay is measured to beB(X(3872)→ψ(2S)γ)B(X(3872)→J/ψγ)=2.46±0.64±0.29, where the first uncertainty is statistical and the second is systematic. The measured value does not support a pure DD¯⁎ molecular interpretation of the X(3872) state.
Two searches for new phenomena in final states containing a same-flavour opposite-sign lepton (electron or muon) pair, jets, and large missing transverse momentum are presented. These searches make ...use of proton–proton collision data, collected during 2015 and 2016 at a centre-of-mass energy √s = 13 TeV by the ATLAS detector at the large hadron collider, which correspond to an integrated luminosity of 14.7 fb–1. Both searches target the pair production of supersymmetric particles, squarks or gluinos, which decay to final states containing a same-flavour opposite-sign lepton pair via one of two mechanisms: a leptonically decaying Z boson in the final state, leading to a peak in the dilepton invariant-mass distribution around the Z boson mass; and decays of neutralinos (e.g. χ~02 → ℓ+ℓ–χ~01), yielding a kinematic endpoint in the dilepton invariant-mass spectrum. The data are found to be consistent with the Standard Model expectation. Results are interpreted in simplified models of gluino-pair (squark-pair) production, and provide sensitivity to gluinos (squarks) with masses as large as 1.70 TeV (980 GeV).
Here, a search for heavy resonances decaying into a pair of Z bosons leading to ℓ+ℓ-ℓ+ℓ- and ℓ+ℓ-$v\bar{v}$ final states, where ℓ stands for either an electron or a muon, is presented. The search ...uses proton–proton collision data at a centre-of-mass energy of 13 TeV corresponding to an integrated luminosity of 36.1 fb-1 collected with the ATLAS detector during 2015 and 2016 at the Large Hadron Collider. Different mass ranges for the hypothetical resonances are considered, depending on the final state and model. The different ranges span between 200 and 2000 GeV . The results are interpreted as upper limits on the production cross section of a spin-0 or spin-2 resonance. The upper limits for the spin-0 resonance are translated to exclusion contours in the context of Type-I and Type-II two-Higgs-doublet models, while those for the spin-2 resonance are used to constrain the Randall–Sundrum model with an extra dimension giving rise to spin-2 graviton excitations.
A search for heavy resonances decaying into a pair of Z bosons leading to ℓ+ℓ-ℓ+ℓ- and ℓ+ℓ-$v\bar{v}$ final states, where ℓ stands for either an electron or a muon, is presented. The search uses ...proton–proton collision data at a centre-of-mass energy of 13 TeV corresponding to an integrated luminosity of 36.1 fb-1 collected with the ATLAS detector during 2015 and 2016 at the Large Hadron Collider. Different mass ranges for the hypothetical resonances are considered, depending on the final state and model. The different ranges span between 200 and 2000 GeV . The results are interpreted as upper limits on the production cross section of a spin-0 or spin-2 resonance. The upper limits for the spin-0 resonance are translated to exclusion contours in the context of Type-I and Type-II two-Higgs-doublet models, while those for the spin-2 resonance are used to constrain the Randall–Sundrum model with an extra dimension giving rise to spin-2 graviton excitations.
A search for new phenomena in final states containing an e+e- or μ+μ- pair, jets, and large missing transverse momentum is presented. This analysis makes use of proton–proton collision data with an ...integrated luminosity of 36.1 fb-1 , collected during 2015 and 2016 at a centre-of-mass energy s√=13 TeV with the ATLAS detector at the Large Hadron Collider. The search targets the pair production of supersymmetric coloured particles (squarks or gluinos) and their decays into final states containing an e+e- or μ+μ- pair and the lightest neutralino ( χ~01 ) via one of two next-to-lightest neutralino ( χ~02 ) decay mechanisms: χ~02→Zχ~01 , where the Z boson decays leptonically leading to a peak in the dilepton invariant mass distribution around the Z boson mass, and χ~02→ℓ+ℓ-χ~01 with no intermediate ℓ+ℓ- resonance, yielding a kinematic endpoint in the dilepton invariant mass spectrum. The data are found to be consistent with the Standard Model expectation. Results are interpreted using simplified models, and exclude gluinos and squarks with masses as large as 1.85 and 1.3 TeV at 95% confidence level, respectively.
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