43 research outputs found

    Динаміка алелопатичної активності продуктів деструкції рослинних решток Syringa josikaea Jacq. f., S. microphylla Diels. та S. persica L.

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    To explain ecological significance of plant residues of Syringa josikaea Jacq. f., S. microphylla Diels. and S. persica L. the effect of theirs decay products on allelopathic properties of soil during 18 months was studied. Under greenhouse conditions crushed roots, fallen flowers and leaves, and mixture thereof (1:1:1) of the Syringa species were mixed (at 2 % to soil weight) with grey forest soil collected from the corresponding areas of the arboretum of M.M. Gryshko National Botanical Garden of the NAS of Ukraine. The grey forest soil (fallow) without plant residues was used as control. Analysis of allelopathic activity by direct bioassay method indicated that phytotoxicity increased in soil with decaying residues. Volatile and watersoluble decay products of the Syringa species residues inhibited growth of plant-acceptors (Lepidium sativum L., Amaranthus paniculatus L., Triticum aestivum L., Cucumis sativus L.). Theirs allelopathic activity depended on decay time, type of plant material and sensibility of used plantacceptors. C. sativus was the most sensitive test-object. Cytostatic effect (bioassay – number of C. sativus lateral roots) of soil volatile and water-soluble substances under decay of plant residues was found. Decay of the Syringa species residues promoted accumulation of phenolic compounds in soil. Thus, the Syringa species residues are source of allelochemicals which are released into environment by means of theirs decay. This should be considered under long-term cultivation.Для з’ясування екологічного значення рослинних решток Syringa josikaea Jacq. f., S. microphylla Diels. і S. persica L. вивчали вплив продуктів їх деструкції на алелопатичні властивості ґрунту протягом 18 міс. В умовах вегетаційного досліду вносили (2 % маси ґрунту) подрібнені корені, опалі листки і квітки згаданих видів Syringa, а також їх суміш (1:1:1) у сірий лісовий ґрунт з відповідних ділянок дендрарію Національного ботанічного саду ім. М.М. Гришка НАН України. Контролем був сірий лісовий ґрунт (пар) без внесення рослинних решток. Аналіз алелопатичної активності методом прямого біотестування виявив, що в процесі деструкції органічних решток ґрунт набував фітотоксичності. Леткі та водорозчинні продукти деструкції решток видів Syringa пригнічували ростові процеси рослин-акцепторів (Lepidium sativum L., Amaranthus paniculatus L., Triticum aestivum L., Cucumis sativus L.). Їх алелопатична активність залежала від тривалості розкладання, типу рослинного матеріалу та чутливості використаних рослин-акцепторів. C. sativus виявився найчутливішим тест-об’єктом. Спостерігали цитостатичну дію (біотест – кількість бічних коренів C. sativus) летких та водорозчинних речовин ґрунту при деструкції рослинних решток. Деструкція решток видів Syringa сприяла акумуляції в ґрунті фенольних сполук. Отже, рештки видів Syringa є джерелом органічних сполук з високою алелопатичною активністю, які вивільняються в навколишнє середовище в процесі їх трансформації, що слід ураховувати за умов тривалої культури

    Measurement of prompt D0^{0} and D\overline{D}0^{0} meson azimuthal anisotropy and search for strong electric fields in PbPb collisions at root SNN\sqrt{S_{NN}} = 5.02 TeV

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    The strong Coulomb field created in ultrarelativistic heavy ion collisions is expected to produce a rapiditydependent difference (Av2) in the second Fourier coefficient of the azimuthal distribution (elliptic flow, v2) between D0 (uc) and D0 (uc) mesons. Motivated by the search for evidence of this field, the CMS detector at the LHC is used to perform the first measurement of Av2. The rapidity-averaged value is found to be (Av2) = 0.001 ? 0.001 (stat)? 0.003 (syst) in PbPb collisions at ?sNN = 5.02 TeV. In addition, the influence of the collision geometry is explored by measuring the D0 and D0mesons v2 and triangular flow coefficient (v3) as functions of rapidity, transverse momentum (pT), and event centrality (a measure of the overlap of the two Pb nuclei). A clear centrality dependence of prompt D0 meson v2 values is observed, while the v3 is largely independent of centrality. These trends are consistent with expectations of flow driven by the initial-state geometry. ? 2021 The Author. Published by Elsevier B.V. This is an open access article under the CC BY licens

    Measurement of the CP-violating phase ϕs_{s} in the B0^{0}s_{s}→J/ψ φ(1020) →μ⁺μ⁻K⁺K⁻ channel in proton-proton collisions at √s = 13 TeV

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    Observation of electroweak production of Wγ with two jets in proton-proton collisions at √s = 13 TeV

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    A first observation is presented for the electroweak production of a W boson, a photon, and two jets in proton-proton collisions. The W boson decays are selected by requiring one identified electron or muon and an imbalance in transverse momentum. The two jets are required to have a high dijet mass and a large separation in pseudorapidity. The measurement is based on data collected with the CMS detector at a center-of-mass energy of 13 TeV, corresponding to an integrated luminosity of 35.9 fb1^{-1}. The observed (expected) significance for this process is 4.9 (4.6) standard deviations. After combining with previously reported CMS results at 8 TeV, the observed (expected) significance is 5.3 (4.8) standard deviations. The cross section for the electroweak Wγjj_{γjj} production in a restricted fiducial region is measured as 20.4 +/- 4.5 fb and the total cross section for Wγ_{γ} production in association with 2 jets in the same fiducial region is 108 +/- 16 fb. All results are in good agreement with recent theoretical predictions. Constraints are placed on anomalous quartic gauge couplings in terms of dimension-8 effective field theory operators

    Measurements of production cross sections of polarized same-sign W boson pairs in association with two jets in proton-proton collisions at s=13 TeV

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    The first measurements of production cross sections of polarized same-sign W±W±boson pairs in proton-proton collisions are reported. The measurements are based on a data sample collected with the CMS detector at the LHC at a center-of-mass energy of 13TeV, corresponding to an integrated luminosity of 137fb−1. Events are selected by requiring exactly two same-sign leptons, electrons or muons, moderate missing transverse momentum, and two jets with a large rapidity separation and a large dijet mass to enhance the contribution of same-sign W±W±scattering events. An observed (expected) 95% confidence level upper limit of 1.17 (0.88)fbis set on the production cross section for longitudinally polarized same-sign W±W±boson pairs. The electroweak production of same-sign W±W±boson pairs with at least one of the Wbosons longitudinally polarized is measured with an observed (expected) significance of 2.3 (3.1) standard deviations.SCOAP

    Dynamics of allelopathic activity of decay products of plant residues of Syringa josikaea Jacq. f., S. microphylla Diels. and S. persica L.

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    To explain ecological significance of plant residues of Syringa josikaea Jacq. f., S. microphylla Diels. and S. persica L. the effect of theirs decay products on allelopathic properties of soil during 18 months was studied. Under greenhouse conditions crushed roots, fallen flowers and leaves, and mixture thereof (1:1:1) of the Syringa species were mixed (at 2 % to soil weight) with grey forest soil collected from the corresponding areas of the arboretum of M.M. Gryshko National Botanical Garden of the NAS of Ukraine. The grey forest soil (fallow) without plant residues was used as control. Analysis of allelopathic activity by direct bioassay method indicated that phytotoxicity increased in soil with decaying residues. Volatile and watersoluble decay products of the Syringa species residues inhibited growth of plant-acceptors (Lepidium sativum L., Amaranthus paniculatus L., Triticum aestivum L., Cucumis sativus L.). Theirs allelopathic activity depended on decay time, type of plant material and sensibility of used plantacceptors. C. sativus was the most sensitive test-object. Cytostatic effect (bioassay – number of C. sativus lateral roots) of soil volatile and water-soluble substances under decay of plant residues was found. Decay of the Syringa species residues promoted accumulation of phenolic compounds in soil. Thus, the Syringa species residues are source of allelochemicals which are released into environment by means of theirs decay. This should be considered under long-term cultivation

    Search for supersymmetry in proton-proton collisions at <mml:msqrt>s</mml:msqrt>=13 TeV in events with high-momentum Z bosons and missing transverse momentum

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    A search for new physics in events with two highly Lorentz-boosted Z bosons and large missing transverse momentum is presented. The analyzed proton-proton collision data, corresponding to an integrated luminosity of 137 fb(-1), were recorded at s = 13 TeV by the CMS experiment at the CERN LHC. The search utilizes the substructure of jets with large radius to identify quark pairs from Z boson decays. Backgrounds from standard model processes are suppressed by requirements on the jet mass and the missing transverse momentum. No significant excess in the event yield is observed beyond the number of background events expected from the standard model. For a simplified supersymmetric model in which the Z bosons arise from the decay of gluinos, an exclusion limit of 1920 GeV on the gluino mass is set at 95% confidence level. This is the first search for beyond-standard-model production of pairs of boosted Z bosons plus large missing transverse momentum

    Search for new heavy resonances decaying to WW, WZ, ZZ, WH, or ZH boson pairs in the all-jets final state in proton-proton collisions at s=13TeV

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    A search for new heavy resonances decaying to WW, WZ, ZZ, WH, or ZH boson pairs in the all-jets final state is presented. The analysis is based on proton-proton collision data recorded by the CMS detector in 2016–2018 at a centre-of-mass energy of 13 TeV at the CERN LHC, corresponding to an integrated luminosity of 138fb−1. The search is sensitive to resonances with masses between 1.3 and 6TeV, decaying to bosons that are highly Lorentz-boosted such that each of the bosons forms a single large-radius jet. Machine learning techniques are employed to identify such jets. No significant excess over the estimated standard model background is observed. A maximum local significance of 3.6 standard deviations, corresponding to a global significance of 2.3 standard deviations, is observed at masses of 2.1 and 2.9 TeV. In a heavy vector triplet model, spin-1 Z′ and W′ resonances with masses below 4.8TeV are excluded at the 95% confidence level (CL). These limits are the most stringent to date. In a bulk graviton model, spin-2 gravitons and spin-0 radions with masses below 1.4 and 2.7TeV, respectively, are excluded at 95% CL. Production of heavy resonances through vector boson fusion is constrained with upper cross section limits at 95% CL as low as 0.1fb

    Measurement of the tt¯ charge asymmetry in events with highly Lorentz-boosted top quarks in pp collisions at s=13 TeV

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    The measurement of the charge asymmetry in top quark pair events with highly Lorentz-boosted top quarks decaying to a single lepton and jets is presented. The analysis is performed using proton-proton collisions at s=13TeV with the CMS detector at the LHC and corresponding to an integrated luminosity of 138 fb−1. The selection is optimized for top quarks produced with large Lorentz boosts, resulting in nonisolated leptons and overlapping jets. The top quark charge asymmetry is measured for events with a tt¯ invariant mass larger than 750 GeV and corrected for detector and acceptance effects using a binned maximum likelihood fit. The measured top quark charge asymmetry of (0.42−0.69+0.64)% is in good agreement with the standard model prediction at next-to-next-to-leading order in quantum chromodynamic perturbation theory with next-to-leading-order electroweak corrections. The result is also presented for two invariant mass ranges, 750–900 and >900GeV

    Measurement of the CP-violating phase phi(s) in the B-s(0) -> J/psi phi(1020) -> mu(+)mu-K+K- channel in proton-proton collisions at root s=13 TeV

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    The CP-violating weak phase ?s and the decay width difference ??s between the light and heavy B0s mass eigenstates are measured with the CMS detector at the LHC in a sample of 48 500 reconstructed B0s? J/I) d (1020) ?11+11? K+K? events. The measurement is based on a data sample corresponding to an integrated luminosity of 96.4 fb?1, collected in proton-proton collisions at ?s = 13 TeV in 2017?2018. To extract the values of ?s and ??s, a time-dependent and flavor-tagged angular analysis of the 11+11?K+K? final state is performed. The analysis employs a dedicated tagging trigger and a novel opposite-side muon flavor tagger based on machine learning techniques. The measurement yields ?s = ?11 ?50 (stat) ? 10 (syst) mrad and ??s = 0.114 ? 0.014 (stat)? 0.007 (syst) ps?1, in agreement with the standard model predictions. When combined with the previous CMS measurement at ?s = 8 TeV, the following values are obtained: ?s = ?21 ? 44 (stat) ? 10 (syst) mrad, ??s = 0.1032 ? 0.0095 (stat) ? 0.0048 (syst) ps?1, a significant improvement over the 8 TeV result. ? 2021 The Author(s). Published by Elsevier B.V. This is an open access article under the CC BY licens
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