The resonant substructure of Bs0→D¯0K−π+ decays is studied using a data sample corresponding to an integrated luminosity of 3.0 fb−1 of pp collision data recorded by the LHCb detector. An excess at m(D¯0...
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The resonant substructure of Bs0→D¯0K−π+ decays is studied using a data sample corresponding to an integrated luminosity of 3.0 fb−1 of pp collision data recorded by the LHCb detector. An excess at m(D¯0K−)≈2.86 GeV/c2 is found to be an admixture of spin-1 and spin-3 resonances. Therefore, the DsJ*(2860)− state previously observed in inclusive e+e−→D¯0K−X and pp→D¯0K−X processes consists of at least two particles. This is the first observation of a heavy flavored spin-3 resonance, and the first time that any spin-3 particle has been seen to be produced in B decays. The masses and widths of the new states and of the Ds2*(2573)− meson are measured, giving the most precise determinations to date.
We present a measurement of the ratio of the B¯s0 meson lifetime, in the flavor-specific decay to Ds+π−, to that of the B¯0 meson. The pp collision data used correspond to an integrated luminosity of 1 fb−...
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We present a measurement of the ratio of the B¯s0 meson lifetime, in the flavor-specific decay to Ds+π−, to that of the B¯0 meson. The pp collision data used correspond to an integrated luminosity of 1 fb−1, collected with the LHCb detector, at a center-of-mass energy of 7 TeV. Combining our measured value of 1.010±0.010±0.008 for this ratio with the known B¯0 lifetime, we determine the flavor-specific B¯s0 lifetime to be τ(B¯s0)=1.535±0.015±0.014 ps, where the uncertainties are statistical and systematic, respectively. This is the most precise measurement to date, and is consistent with previous measurements and theoretical predictions.
We report on measurements of the mass and lifetime of the Ξb− baryon using about 1800 Ξb− decays reconstructed in a proton-proton collision data set corresponding to an integrated luminosity of 3.0 fb−1 collected b...
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We report on measurements of the mass and lifetime of the Ξb− baryon using about 1800 Ξb− decays reconstructed in a proton-proton collision data set corresponding to an integrated luminosity of 3.0 fb−1 collected by the LHCb experiment. The decays are reconstructed in the Ξb−→Ξc0π−, Ξc0→pK−K−π+ channel and the mass and lifetime are measured using the Λb0→Λc+π− mode as a reference. We measure M(Ξb−)−M(Λb0)=178.36±0.46±0.16 MeV/c2, (τΞb−/τΛb0)=1.089±0.026±0.011, where the uncertainties are statistical and systematic, respectively. These results lead to a factor of 2 better precision on the Ξb− mass and lifetime compared to previous best measurements, and are consistent with theoretical expectations.
A search is presented for dark matter pair production in association with a W or Z boson in pp collisions representing 20.3 fb−1 of integrated luminosity at s=8 TeV using data recorded with the ATLAS detector at the...
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A search is presented for dark matter pair production in association with a W or Z boson in pp collisions representing 20.3 fb−1 of integrated luminosity at s=8 TeV using data recorded with the ATLAS detector at the Large Hadron Collider. Events with a hadronic jet with the jet mass consistent with a W or Z boson, and with large missing transverse momentum are analyzed. The data are consistent with the standard model expectations. Limits are set on the mass scale in effective field theories that describe the interaction of dark matter and standard model particles, and on the cross section of Higgs production and decay to invisible particles. In addition, cross section limits on the anomalous production of W or Z bosons with large missing transverse momentum are set in two fiducial regions.
The pT-differential production cross sections of the prompt charmed mesons D0, D+, D*+, and Ds+ and their charge conjugate in the rapidity interval −0.96<ycms<0.04 were measured in p−Pb collisions at a center-of...
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The pT-differential production cross sections of the prompt charmed mesons D0, D+, D*+, and Ds+ and their charge conjugate in the rapidity interval −0.96nuclear modification factor RpPb, quantifying the D-meson yield in p−Pb collisions relative to the yield in pp collisions scaled by the number of binary nucleon-nucleon collisions, is compatible within the 15%–20% uncertainties with unity in the transverse momentum interval 1
A search for scalar particles decaying via narrow resonances into two photons in the mass range 65–600 GeV is performed using 20.3 fb−1 of s=8 TeV pp collision data collected with the ATLAS detector at the Large Ha...
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A search for scalar particles decaying via narrow resonances into two photons in the mass range 65–600 GeV is performed using 20.3 fb−1 of s=8 TeV pp collision data collected with the ATLAS detector at the Large Hadron Collider. The recently discovered Higgs boson is treated as a background. No significant evidence for an additional signal is observed. The results are presented as limits at the 95% confidence level on the production cross section of a scalar boson times branching ratio into two photons, in a fiducial volume where the reconstruction efficiency is approximately independent of the event topology. The upper limits set extend over a considerably wider mass range than previous searches.
A search for evidence of invisible-particle decay modes of a Higgs boson produced in association with a Z boson at the Large Hadron Collider is presented. No deviation from the standard model expectation is observed i...
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A search for evidence of invisible-particle decay modes of a Higgs boson produced in association with a Z boson at the Large Hadron Collider is presented. No deviation from the standard model expectation is observed in 4.5 fb−1 (20.3 fb−1) of 7 (8) TeV pp collision data collected by the ATLAS experiment. Assuming the standard model rate for ZH production, an upper limit of 75%, at the 95% confidence level is set on the branching ratio to invisible-particle decay modes of the Higgs boson at a mass of 125.5 GeV. The limit on the branching ratio is also interpreted in terms of an upper limit on the allowed dark matter-nucleon scattering cross section within a Higgs-portal dark matter scenario. Within the constraints of such a scenario, the results presented in this Letter provide the strongest available limits for low-mass dark matter candidates. Limits are also set on an additional neutral Higgs boson, in the mass range 110
A search for excited states of the Bc± meson is performed using 4.9 fb−1 of 7 TeV and 19.2 fb−1 of 8 TeV pp collision data collected by the ATLAS experiment at the LHC. A new state is observed through its hadro...
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A search for excited states of the Bc± meson is performed using 4.9 fb−1 of 7 TeV and 19.2 fb−1 of 8 TeV pp collision data collected by the ATLAS experiment at the LHC. A new state is observed through its hadronic transition to the ground state, with the latter detected in the decay Bc±→J/ψπ±. The state appears in the m(Bc±π+π−)−m(Bc±)−2m(π±) mass difference distribution with a significance of 5.2 standard deviations. The mass of the observed state is 6842±4±5 MeV, where the first error is statistical and the second is systematic. The mass and decay of this state are consistent with expectations for the second S-wave state of the Bc± meson, Bc±(2S).
This Letter presents the first study of W±W±jj, same-electric-charge diboson production in association with two jets, using 20.3 fb−1 of proton-proton collision data at s=8 TeV recorded by the ATLAS detect...
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This Letter presents the first study of W±W±jj, same-electric-charge diboson production in association with two jets, using 20.3 fb−1 of proton-proton collision data at s=8 TeV recorded by the ATLAS detector at the Large Hadron Collider. Events with two reconstructed same-charge leptons (e±e±, e±μ±, and μ±μ±) and two or more jets are analyzed. Production cross sections are measured in two fiducial regions, with different sensitivities to the electroweak and strong production mechanisms. First evidence for W±W±jj production and electroweak-only W±W±jj production is observed with a significance of 4.5 and 3.6 standard deviations, respectively. The measured production cross sections are in agreement with standard model predictions. Limits at 95% confidence level are set on anomalous quartic gauge couplings.
Measurements of four-lepton (4ℓ, ℓ=e,μ) production cross sections at the Z resonance in pp collisions at the LHC with the ATLAS detector are presented. For dilepton and four-lepton invariant mass regions mℓ+ℓ−>5 ...
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Measurements of four-lepton (4ℓ, ℓ=e,μ) production cross sections at the Z resonance in pp collisions at the LHC with the ATLAS detector are presented. For dilepton and four-lepton invariant mass regions mℓ+ℓ−>5 GeV and 80
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