343 Search Results

One correction is noted for the paper. The branching fraction ($$\mathcal{B}$$($$W →{ℓv}$$) = 0.3246 was not included in the conversion of the observed cross-section limit, σ x $$\mathcal{B}$$( $t →Wb$) x ($$\mathcal{B}$$($$W →{ℓv}$$) < 2.9to the coupling constants $$κ_{ugt}$$ and $$κ_{cgt}$$ and the branching fractions $$\mathcal{B}$$( $t →ug$) and $$\mathcal{B}$$( $t →cg$). The inclusion leads to weaker observed exclusion limits on the coupling constants divided by the scale of new physics of $$k_{ugt}$$/ Λ <10 x 10^-3 TeV^-1 and $$k_{cgt}$$/Λ <23 x 10^-3 TeV^-1 and on the branching fractions $$\mathcal{B}$$( $t →ug$) < 1.2 x10^-4 and $$\mathcal{B}$$( $t →cg$) <more » 6.4 x 10^-4. The predicted exclusion limits on the coupling constants divided by the scale of new physics are $$k_{ugt}$$/ Λ < 9.5 x 10^-3 TeV^-1and $$\mathcal{B}$$( $t →cg$)/ Λ < 22 x 10^-3 TeV^-1 and on the branching fractions $$\mathcal{B}$$( $t →ug$) < 1.1 x 10^-4 and $$\mathcal{B}$$( $t →cg$) < 5.7 x 10^-4. Updated distributions of the observed upper limits on the coupling constants for combinations of cgt and ugt channels are shown in Figure 10a and on the branching fractions in Figure 10b.« less

We report demonstrations of both quadrature-squeezed vacuum and photon number difference squeezing generated in an integrated nanophotonic device. Squeezed light is generated via strongly driven spontaneous four-wave mixing below threshold in silicon nitride microring resonators. The generated light is characterized with both homodyne detection and direct measurements of photon statistics using photon number–resolving transition-edge sensors. We measure 1.0(1) decibels of broadband quadrature squeezing (~4 decibels inferred on-chip) and 1.5(3) decibels of photon number difference squeezing (~7 decibels inferred on-chip). Nearly single temporal mode operation is achieved, with measured raw unheralded second-order correlations g⁽²⁾ as high as 1.95(1). Multiphoton events ofmore » over 10 photons are directly detected with rates exceeding any previous quantum optical demonstration using integrated nanophotonics. These results will have an enabling impact on scaling continuous variable quantum technology.« less

We uncover the exact mechanisms that lead to a quenching of the photoluminescence in a Zn-based metal organic framework (MOF) material upon nitroaromatic molecule adsorption. We present evidence based on ab initio simulations, coupled with in situ IR spectroscopy and photoluminescence measurements, showing that quenching occurs as the result of a shift of the lowest unoccupied orbital from the MOF host to the guest molecule. Our results provide a mechanistic understanding of quenching of photoluminescence in MOFs and are of importance for chemical sensing applications, where they aid the design of novel MOFs with increased sensing selectivity.

The inclusive cross-section for the associated production of a W boson and top quark is measured using data from proton-proton collisions at s√=13 TeV. The dataset corresponds to an integrated luminosity of 3.2 fb^-1, and was collected in 2015 by the ATLAS detector at the Large Hadron Collider at CERN. Events are selected requiring two opposite sign isolated leptons and at least one jet; they are separated into signal and control regions based on their jet multiplicity and the number of jets that are identified as containing b hadrons. The W t signal is then separated from the $$t\bar{t}$$ backgroundmore » using boosted decision tree discriminants in two regions. The cross-section is extracted by fitting templates to the data distributions, and is measured to be σ _{W t} =94 ± 10(stat.) _-22 ⁺²⁸ (syst.)±2(lumi.) pb. Lastly, the measured value is in good agreement with the SM prediction of σ_theory = 71.7±1.8 (scale)± 3.4 (PDF) pb.« less

The top-quark mass is measured in the all-hadronic top-antitop quark decay channel using proton-proton collisions at a centre-of-mass energy of √s=8 TeV with the ATLAS detector at the CERN Large Hadron Collider. The data set used in the analysis corresponds to an integrated luminosity of 20.2 fb^–1 . The large multi-jet background is modelled using a data-driven method. We obtained the top-quark mass from template fits to the ratio of the three-jet to the dijet mass. The three-jet mass is obtained from the three jets assigned to the top quark decay. And from these three jets the dijet mass ismore » obtained using the two jets assigned to the W boson decay. The top-quark mass is measured to be 173.72 ± 0.55 (stat.) ± 1.01 (syst.) GeV.« less

The reconstruction of the signal from hadrons and jets emerging from the proton–proton collisions at the Large Hadron Collider (LHC) and entering the ATLAS calorimeters is based on a three-dimensional topological clustering of individual calorimeter cell signals. The cluster formation follows cell signal-significance patterns generated by electromagnetic and hadronic showers. In this, the clustering algorithm implicitly performs a topological noise suppression by removing cells with insignificant signals which are not in close proximity to cells with significant signals. The resulting topological cell clusters have shape and location information, which is exploited to apply a local energy calibration and corrections dependingmore » on the nature of the cluster. Lastly, topological cell clustering is established as a well-performing calorimeter signal definition for jet and missing transverse momentum reconstruction in ATLAS.« less

In the original paper, Fig. 4 contains the wrong label preliminary. The label has been fixed, while none of the results have changed.