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A search for direct pair production of scalar partners of the top quark (top squarks or scalar third-generation up-type leptoquarks) in the all-hadronic $$t{\bar{t}}$$tt¯ plus missing transverse momentum final state is presented. The analysis of 139 $$\hbox {fb}^{-1}$$fb-1 of $${\sqrt{s}=13}$$s=13 TeV proton–proton collision data collected using the ATLAS detector at the LHC yields no significant excess over the Standard Model background expectation. To interpret the results, a supersymmetric model is used where the top squark decays via $${\tilde{t}} \rightarrow t^{(*)} {\tilde{\chi }}^0_1$$t~→t(∗)χ~10, with $$t^{(*)}$$t(∗) denoting an on-shell (off-shell) top quark and $${\tilde{\chi }}^0_1$$χ~10 the lightest neutralino. Three specific event selections are optimised for the following scenarios. In the scenario where $$m_{{\tilde{t}}}> m_t+m_{{\tilde{\chi }}^0_1}$$mt~>mt+mχ~10, top squark masses are excluded in the range 400–1250 GeV for $${\tilde{\chi }}^0_1$$χ~10 masses below 200 GeV at 95% confidence level. In the situation where $$m_{{\tilde{t}}}\sim m_t+m_{{\tilde{\chi }}^0_1}$$mt~∼mt+mχ~10, top squark masses in the range 300–630 GeV are excluded, while in the case where $$m_{{\tilde{t}}}< m_W+m_b+m_{{\tilde{\chi }}^0_1}$$mt~<mW+mb+mχ~10 (with $$m_{{\tilde{t}}}-m_{{\tilde{\chi }}^0_1}\ge 5$$mt~-mχ~10≥5 GeV), considered for the first time in an ATLAS all-hadronic search, top squark masses in the range 300–660 GeV are excluded. Limits are also set for scalar third-generation up-type leptoquarks, excluding leptoquarks with masses below 1240 GeV when considering only leptoquark decays into a top quark and a neutrino.

A search for pair production of scalar leptoquarks, each decaying into either an electron or a muon and a top quark, is presented. This is the first leptoquark search using ATLAS data to investigate top-philic cross-generational couplings that could provide explanations for recently observed anomalies in B meson decays. This analysis targets high leptoquark masses which cause the decay products of each resultant top quark to be contained within a single high-$$p_{\mathrm {T}}$$ p T large-radius jet. The full Run 2 dataset is exploited, consisting of $$139~\hbox {fb}^{-1}$$ 139 fb - 1 of data collected from proton–proton collisions at $$\sqrt{s}=13~\mathrm {TeV}$$ s = 13 TeV from 2015 to 2018 with the ATLAS detector at the CERN Large Hadron Collider. In the absence of any significant deviation from the background expectation, lower limits on the leptoquark masses are set at $$1480~\mathrm {GeV}$$ 1480 GeV and $$1470~\mathrm {GeV}$$ 1470 GeV for the electron and muon channel, respectively.

. 2002. Temporal trends in soil properties at a soil quality benchmark site in the Lower Fraser Valley, British Columbia. Can. J. Soil Sci. 82: 499-509. A national soil quality monitoring program was established in 1990 to address concerns that the quality of Canada's agricultural soils was in decline. The British Columbia benchmark site (01-BC) was established in 1991 and is located on the Pelly soil series (Orthic Humic Gleysol) supporting a corn-forage-pasture rotation in the Lower Mainland ecoregion. The objectives of this study were to report on the differences in: (1) the measured soil properties for the 5-yr period between baseline data collection in 1991 and resampling in 1996 and (2) the properties measured annually as indicators of soil compaction. A 25-m × 25-m grid was used at the site to locate sampling points for bulk density and collecting soil samples of the Ap, BCg, and Cg horizons, as well as the measurement locations for saturated hydraulic conductivity and penetration resistance. A 5-yr interval sampling regime was used to sample the Ap, BCg, and Cg horizons and bulk density. Saturated hydraulic conductivity and penetration resistance were sampled annually from 1992 to 1998. Between 1991 and 1996 in the A horizons, pH, available P, C:N ratio and bulk density increased by 4.6, 7.8, 2.5, and 8%, respectively, and available K, total C and total N decreased by 21, 16.5, and 18.3%, respectively. In the BCg horizon, pH, available P and C:N ratio increased by 5, 126, and 8%, respectively, and the available K and total N both decreased by 21%. Bulk density remained unchanged. The assumption that the soil chemical properties in the Cg horizon would remain stable during the study period did not hold. The trends detected for the Cg horizon were similar to those measured for the upper two horizons. However, only the reductions in available K and total N and increases in C:N were significant. The changes in the soil physical properties measured at this site indicate that some soil compaction has occurred. Both bulk density at 20 cm and penetration resistance increased at all depths between 1994 and 1998, which coincided with the time period that grazing was included in the crop rotation. Field saturated hydraulic conductivity at 25 cm (Ap2 horizon), although highly variable from year to year also tended to be lower during the pasture rotation. The penetration resistance measurements, which detected changes at all depths, appeared to be a more sensitive indicator of soil compaction than either bulk density or field saturated hydraulic conductivity.Key words: Soil quality, soil monitoring, soil properties, soil compaction, temporal change Kenney, E. A., Hall, J. W. et Wang, C. 2002. Évolution des propriétés pédologiques dans le temps à un site de contrôle de la qualité du sol dans la basse vallée du Fraser, en Colombie-Britannique. Can. J. Soil Sci. 82: 499-509. Face à la crainte d'une détérioration des sols agricoles au Canada, un programme national de contrôle de la qualité voyait le jour en 1990. L'année...

A study of $$ {B}_c^{+}\to J/\psi {D}_s^{+} $$ B c + → J / ψ D s + and $$ {B}_c^{+}\to J/\psi {D}_s^{\ast +} $$ B c + → J / ψ D s ∗ + decays using 139 fb−1 of integrated luminosity collected with the ATLAS detector from $$ \sqrt{s} $$ s = 13 TeV pp collisions at the LHC is presented. The ratios of the branching fractions of the two decays to the branching fraction of the $$ {B}_c^{+} $$ B c + → J/ψπ+ decay are measured: $$ \mathcal{B}\left({B}_c^{+}\to J/\psi {D}_s^{+}\right)/\mathcal{B}\left({B}_c^{+}\to J/{\psi \pi}^{+}\right) $$ B B c + → J / ψ D s + / B B c + → J / ψπ + = 2.76 ± 0.47 and $$ \mathcal{B}\left({B}_c^{+}\to J/\psi {D}_s^{\ast +}\right)/\mathcal{B}\left({B}_c^{+}\to J/{\psi \pi}^{+}\right) $$ B B c + → J / ψ D s ∗ + / B B c + → J / ψπ + = 5.33 ± 0.96. The ratio of the branching fractions of the two decays is found to be $$ \mathcal{B}\left({B}_c^{+}\to J/\psi {D}_s^{\ast +}\right)/\mathcal{B}\left({B}_c^{+}\to J/\psi {D}_s^{\ast +}\right) $$ B B c + → J / ψ D s ∗ + / B B c + → J / ψ D s ∗ + = 1.93 ± 0.26. For the $$ {B}_c^{+}\to J/\psi {D}_s^{\ast +} $$ B c + → J / ψ D s ∗ + decay, the transverse polarization fraction, Γ±±/Γ, is measured to be 0.70 ± 0.11. The reported uncertainties include both the statistical and systematic components added in quadrature. The precision of the measurements exceeds that in all previous studies of these decays. These results supersede those obtained in the earlier ATLAS study of the same decays with $$ \sqrt{s} $$ s = 7 and 8 TeV pp collision data. A comparison with available theoretical predictions for the measured quantities is presented.