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).
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.
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 80b and 107±9(stat)±4(syst)±3.0(lumi) fb at s=7 and 8 TeV, respectively. by subtracting the nonresonant 4ℓ production contributions and normalizing with Z→μ+μ− events, the branching fraction for the Z boson decay to 4ℓ is determined to be (3.20±0.25(stat)±0.13(syst))×10−6, consistent with the standard model prediction.
This Letter presents a search for quantum black-hole production using 20.3 fb−1 of data collected with the ATLAS detector in pp collisions at the LHC at s=8 TeV. The quantum black holes are assumed to decay into a f...
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This Letter presents a search for quantum black-hole production using 20.3 fb−1 of data collected with the ATLAS detector in pp collisions at the LHC at s=8 TeV. The quantum black holes are assumed to decay into a final state characterized by a lepton (electron or muon) and a jet. In either channel, no event with a lepton-jet invariant mass of 3.5 TeV or more is observed, consistent with the expected background. Limits are set on the product of cross sections and branching fractions for the lepton+jet final states of quantum black holes produced in a search region for invariant masses above 1 TeV. The combined 95% confidence level upper limit on this product for quantum black holes with threshold mass above 3.5 TeV is 0.18 fb. This limit constrains the threshold quantum black-hole mass to be above 5.3 TeV in the model considered.
Recent advances in technology and wireless sensor networks made new trends to emerge in agriculture sector. One such new trend is Precision Agriculture(PA). This paper presents an automatic Irrigation Controller for p...
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Recent advances in technology and wireless sensor networks made new trends to emerge in agriculture sector. One such new trend is Precision Agriculture(PA). This paper presents an automatic Irrigation Controller for precision agriculture. The irrigation controller regulates the desired moisture level in agricultural soil by making the irrigation pump on or off based on the sensor readings. This controller efficiently monitors moisture level in soil and proves efficient in both dry and heavy rainfall conditions.
This article presents measurements of the t-channel single top-quark (t) and top-antiquark (t¯) total production cross sections σ(tq) and σ(t¯q), their ratio Rt=σ(tq)/σ(t¯q), and a measurement of th...
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This article presents measurements of the t-channel single top-quark (t) and top-antiquark (t¯) total production cross sections σ(tq) and σ(t¯q), their ratio Rt=σ(tq)/σ(t¯q), and a measurement of the inclusive production cross section σ(tq+t¯q) in proton-proton collisions at s=7 TeV at the LHC. Differential cross sections for the tq and t¯q processes are measured as a function of the transverse momentum and the absolute value of the rapidity of t and t¯, respectively. The analyzed data set was recorded with the ATLAS detector and corresponds to an integrated luminosity of 4.59 fb−1. Selected events contain one charged lepton, large missing transverse momentum, and two or three jets. The cross sections are measured by performing a binned maximum-likelihood fit to the output distributions of neural networks. The resulting measurements are σ(tq)=46±1(stat)±6(syst) pb, σ(t¯q)=23±1(stat)±3(syst) pb, Rt=2.04±0.13(stat)±0.12(syst), and σ(tq+t¯q)=68±2(stat)±8(syst) pb, consistent with the Standard Model expectation. The uncertainty on the measured cross sections is dominated by systematic uncertainties, while the uncertainty on Rt is mainly statistical. Using the ratio of σ(tq+t¯q) to its theoretical prediction, and assuming that the top-quark-related CKM matrix elements obey the relation |Vtb|≫|Vts|,|Vtd|, we determine |Vtb|=1.02±0.07.
Results of a search for supersymmetry via direct production of third-generation squarks are reported, using 20.3 fb−1 of proton-proton collision data at s=8 TeV recorded by the ATLAS experiment at the LHC in 2012. T...
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Results of a search for supersymmetry via direct production of third-generation squarks are reported, using 20.3 fb−1 of proton-proton collision data at s=8 TeV recorded by the ATLAS experiment at the LHC in 2012. Two different analysis strategies based on monojetlike and c-tagged event selections are carried out to optimize the sensitivity for direct top squark-pair production in the decay channel to a charm quark and the lightest neutralino (t˜1→c+χ˜10) across the top squark–neutralino mass parameter space. No excess above the Standard Model background expectation is observed. The results are interpreted in the context of direct pair production of top squarks and presented in terms of exclusion limits in the (mt˜1, mχ˜10) parameter space. A top squark of mass up to about 240 GeV is excluded at 95% confidence level for arbitrary neutralino masses, within the kinematic boundaries. Top squark masses up to 270 GeV are excluded for a neutralino mass of 200 GeV. In a scenario where the top squark and the lightest neutralino are nearly degenerate in mass, top squark masses up to 260 GeV are excluded. The results from the monojetlike analysis are also interpreted in terms of compressed scenarios for top squark-pair production in the decay channel t˜1→b+ff′+χ˜10 and sbottom pair production with b˜1→b+χ˜10, leading to a similar exclusion for nearly mass-degenerate third-generation squarks and the lightest neutralino. The results in this paper significantly extend previous results at colliders.
The ATLAS detector at the Large Hadron Collider is used to search for the lepton flavor violating process Z→eμ in pp collisions using 20.3 fb−1 of data collected at s=8 TeV. An enhancement in the eμ invariant mas...
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The ATLAS detector at the Large Hadron Collider is used to search for the lepton flavor violating process Z→eμ in pp collisions using 20.3 fb−1 of data collected at s=8 TeV. An enhancement in the eμ invariant mass spectrum is searched for at the Z-boson mass. The number of Z bosons produced in the data sample is estimated using events of similar topology, Z→ee and μμ, significantly reducing the systematic uncertainty in the measurement. There is no evidence of an enhancement at the Z-boson mass, resulting in an upper limit on the branching fraction, b(Z→eμ)<7.5×10−7 at the 95% confidence level.
A measurement of the parity-violating decay asymmetry parameter, αb, and the helicity amplitudes for the decay Λb0→J/ψ(μ+μ−)Λ0(pπ−) is reported. The analysis is based on 1400 Λb0 and Λ¯b0 baryons select...
A measurement of the parity-violating decay asymmetry parameter, αb, and the helicity amplitudes for the decay Λb0→J/ψ(μ+μ−)Λ0(pπ−) is reported. The analysis is based on 1400 Λb0 and Λ¯b0 baryons selected in 4.6 fb−1 of proton–proton collision data with a center-of-mass energy of 7 TeV recorded by the ATLAS experiment at the LHC. by combining the Λb0 and Λ¯b0 samples under the assumption of CP conservation, the value of αb is measured to be 0.30±0.16(stat)±0.06(syst). This measurement provides a test of theoretical models based on perturbative QCD or heavy-quark effective theory.
The ATLAS detector at the Large Hadron Collider is used to search for high-mass resonances decaying to dielectron or dimuon final states. Results are presented from an analysis of proton-proton (pp) collisions at a ce...
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The ATLAS detector at the Large Hadron Collider is used to search for high-mass resonances decaying to dielectron or dimuon final states. Results are presented from an analysis of proton-proton (pp) collisions at a center-of-mass energy of 8 TeV corresponding to an integrated luminosity of 20.3 fb−1 in the dimuon channel. A narrow resonance with Standard Model Z couplings to fermions is excluded at 95% confidence level for masses less than 2.79 TeV in the dielectron channel, 2.53 TeV in the dimuon channel, and 2.90 TeV in the two channels combined. Limits on other model interpretations are also presented, including a grand-unification model based on the E6 gauge group, Z* bosons, minimal Z′ models, a spin-2 graviton excitation from Randall-Sundrum models, quantum black holes, and a minimal walking technicolor model with a composite Higgs boson.
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