213 research outputs found

    Management models applied to the human-wolf conflict in agro-forestry-pastoral territories of two italian protected areas and one spanish game area

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    Our work shows that, despite the persistence of persecutory actions, conservation activity has proved successful for the return of numerous wild mammals to different habitats, including the wolf. The human-wolf conflict is still described in all countries where the wolf is present. This is evidenced by the high number of damages on livestock, and the corpses of wolves found both in protected areas and in those where hunting is permitted. The diagnosis of road accidents, together with poisoning and poaching, are major causes of mortality. Although hunting records the highest percentage of kills in Spain, the demographic stability reported by the censuses suggests that this activity does not have a consistent influence on the Iberian wolf population’s survival. In Italy, where wolf hunting is prohibited, wolf populations are to be increasing. In some Italian situations, wolf attacks on horses seem to cause unwanted damage to foals, but they represent a very precious source of information about the habits of carnivores. A simple management plan would be sufficient to help the coexistence between the productive parts and the ecosystem services ensured by the presence of the wolf. The presence of hybrids is a negative factor

    Management Models Applied to the Human-Wolf Conflict in Agro-Forestry-Pastoral Territories of Two Italian Protected Areas and One Spanish Game Area

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    Our work shows that, despite the persistence of persecutory actions, conservation activity has proved successful for the return of numerous wild mammals to different habitats, including the wolf. The human-wolf conflict is still described in all countries where the wolf is present. This is evidenced by the high number of damages on livestock, and the corpses of wolves found both in protected areas and in those where hunting is permitted. The diagnosis of road accidents, together with poisoning and poaching, are major causes of mortality. Although hunting records the highest percentage of kills in Spain, the demographic stability reported by the censuses suggests that this activity does not have a consistent influence on the Iberian wolf population’s survival. In Italy, where wolf hunting is prohibited, wolf populations are to be increasing. In some Italian situations, wolf attacks on horses seem to cause unwanted damage to foals, but they represent a very precious source of information about the habits of carnivores. A simple management plan would be sufficient to help the coexistence between the productive parts and the ecosystem services ensured by the presence of the wolf. The presence of hybrids is a negative factor

    Search for long-lived particles decaying in the CMS muon detectors in proton-proton collisions at s\sqrt{s} = 13 TeV

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    International audienceA search for long-lived particles (LLPs) decaying in the CMS muon detectors is presented. A data sample of proton-proton collisions at s\sqrt{s} = 13 TeV corresponding to an integrated luminosity of 138 fb1^{-1} recorded at the LHC in 2016-2018, is used. The decays of LLPs are reconstructed as high multiplicity clusters of hits in the muon detectors. In the context of twin Higgs models, the search is sensitive to LLP masses from 0.4 to 55 GeV and a broad range of LLP decay modes, including decays to hadrons, τ\tau leptons, electrons, or photons. No excess of events above the standard model background is observed. The most stringent limits to date from LHC data are set on the branching fraction of the Higgs boson decay to a pair of LLPs with masses below 10 GeV. This search also provides the best limits for various intervals of LLP proper decay length and mass. Finally, this search sets the first limits at the LHC on a dark quantum chromodynamic sector whose particles couple to the Higgs boson through gluon, Higgs boson, photon, vector, and dark-photon portals, and is sensitive to branching fractions of the Higgs boson to dark quarks as low as 2×\times103^{-3}

    Search for the lepton flavor violating τ\tau \to 3μ\mu decay in proton-proton collisions at s\sqrt{s} = 13 TeV

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    International audienceA search for the lepton flavor violating τ\tau \to 3μ\mu decay is performed using proton-proton collision events at a center-of-mass energy of 13 TeV collected by the CMS experiment at the LHC in 2017-2018, corresponding to an integrated luminosity of 97.7 fb1^{-1}. Tau leptons produced in both heavy-flavor hadron and W boson decays are exploited in the analysis. No evidence for the decay is observed. The results of this search are combined with an earlier null result based on data collected in 2016 to obtain a total integrated luminosity of 131 fb1^{-1}. The observed (expected) upper limits on the branching fraction B\mathcal{B}(τ\tau \to 3μ\mu) at confidence levels of 90 and 95% are 2.9×\times108^{-8} (2.4×\times108^{-8}) and 3.6×\times108^{-8} (3.0×\times108^{-8}), respectively

    The CMS Statistical Analysis and Combination Tool: COMBINE

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    International audienceThis paper describes the COMBINE software package used for statistical analyses by the CMS Collaboration. The package, originally designed to perform searches for a Higgs boson and the combined analysis of those searches, has evolved to become the statistical analysis tool presently used in the majority of measurements and searches performed by the CMS Collaboration. It is not specific to the CMS experiment, and this paper is intended to serve as a reference for users outside of the CMS Collaboration, providing an outline of the most salient features and capabilities. Readers are provided with the possibility to run COMBINE and reproduce examples provided in this paper using a publicly available container image. Since the package is constantly evolving to meet the demands of ever-increasing data sets and analysis sophistication, this paper cannot cover all details of COMBINE. However, the online documentation referenced within this paper provides an up-to-date and complete user guide

    Search for production of a single vector-like quark decaying to tH or tZ in the all-hadronic final state in pp collisions at s\sqrt{s} = 13 TeV

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    International audienceA search for electroweak production of a single vector-like T quark in association with a bottom (b) quark in the all-hadronic decay channel is presented. This search uses proton-proton collision data at s\sqrt{s} = 13 TeV collected by the CMS experiment at the CERN LHC during 2016-2018, corresponding to an integrated luminosity of 138 fb1^{-1} The T quark is assumed to have charge 2/3 and decay to a top (t) quark and a Higgs (H) or Z boson. Event kinematics and the presence of jets containing b hadrons are used to reconstruct the hadronic decays of the t quark and H or Z boson. No significant deviation from the standard model prediction is observed in the data. The 95% confidence level upper limits on the product of the production cross section and branching fraction of a T quark produced in association with a b quark and decaying via tH or tZ range from 1260 to 68 fb for T quark masses of 600-1200 GeV

    Search for flavor-changing neutral current interactions of the top quark mediated by a Higgs boson in proton-proton collisions at 13 TeV

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    International audienceA search for flavor-changing neutral current interactions of the top quark (t) and the Higgs boson (H) is presented. The search is based on proton-proton collision data collected in 2016-2018 at a center-of-mass energy of 13 TeV with the CMS detector at the LHC, and corresponding to an integrated luminosity of 138 fb1^{-1}. Events containing a pair of leptons with the same-sign electric charge and at least one jet are considered. The results are used to constrain the branching fraction (B\mathcal{B}) of the top quark decaying to a Higgs boson and an up (u) or charm (c) quark. No significant excess above the estimated background was found. The observed (expected) upper limits at 95% confidence level are found to be 0.072% (0.059%) for B\mathcal{B}(t \to Hu) and 0.043% (0.062%) for B\mathcal{B}(t \to Hc). These results are combined with two other searches performed by the CMS Collaboration for flavor-changing neutral current interactions of top quarks and Higgs bosons in final states with a pair of photons or of bottom quarks. The resulting observed (expected) upper limits at 95% confidence level are 0.019% (0.027%) for B\mathcal{B}(t \to Hu) and 0.037% (0.035%) for B\mathcal{B}(t \to Hc). These results constitute the most stringent limits on these branching fractions to date

    Observation of double J/ψ\psi meson production in pPb collisions at sNN\sqrt{s_\mathrm{NN}} = 8.16 TeV

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    International audienceThe first observation of the concurrent production of two J/ψ\psi mesons in proton-nucleus collisions is presented. The analysis is based on a proton-lead (pPb) data sample recorded at a nucleon-nucleon center-of-mass energy of 8.16 TeV by the CMS experiment at the CERN LHC and corresponding to an integrated luminosity of 174.6 nb1^{-1}. The two J/ψ\psi mesons are reconstructed in their μ+μ\mu^+\mu^- decay channels with transverse momenta pTp_\mathrm{T}>\gt 6.5 GeV and rapidity y\lvert y \rvert<\lt 2.4. Events where one of the J/ψ\psi mesons is reconstructed in the dielectron channel are also considered in the search. The pPb \to J/ψ\psiJ/ψ\psi+X process is observed with a significance of 5.3 standard deviations. The measured inclusive fiducial cross section, using the four-muon channel alone, is σ\sigma(pPb\to J/ψ\psiJ/ψ\psi+X)= 22.0 ±\pm 8.9 (stat) ±\pm 1.5 (syst) nb. A fit of the data to the expected rapidity separation for pairs of J/ψ\psi mesons produced in single (SPS) and double (DPS) parton scatterings yields σSPSpPbJ/ψJ/ψ+X\sigma^{\mathrm{pPb}\to\mathrm{J}/\psi\mathrm{J}/\psi+\mathrm{X}}_\text{SPS} = 16.5 ±\pm 10.8 (stat) ±\pm 0.1 (syst) nb and σDPSpPbJ/ψJ/ψ+X\sigma^{\mathrm{pPb}\to \mathrm{J}/\psi\mathrm{J}/\psi+\mathrm{X}}_\text{DPS} = 5.4 ±\pm 6.2 (stat) ±\pm 0.4 (syst) nb, respectively. This latter result can be transformed into a lower bound on the effective DPS cross section, closely related to the squared average interparton transverse separation in the collision, of σeff\sigma_\text{eff}>\gt 1.0 mb at 95% confidence level

    Search for new resonances decaying to pairs of merged diphotons in proton-proton collisions at s\sqrt{s} = 13 TeV

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    International audienceA search is presented for an extended Higgs sector with two new particles, X and ϕ\phi, in the process X \toϕϕ\phi\phi\to(γγ)(γγ)(\gamma\gamma)(\gamma\gamma). Novel neural networks classify events with diphotons that are merged and determine the diphoton masses. The search uses LHC proton-proton collision data at s\sqrt{s} = 13 TeV collected with the CMS detector, corresponding to an integrated luminosity of 138 fb1^{-1}. No evidence of such resonances is seen. Upper limits are set on the production cross section versus the resonance masses, representing the most sensitive search in this channel

    Searches for violation of Lorentz invariance in tt \mathrm{t} \overline{\mathrm{t}} production using dilepton events in proton-proton collisions at s= \sqrt{s}= 13 TeV

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    A search for violation of Lorentz invariance in the production of top quark pairs (tt \mathrm{t} \overline{\mathrm{t}} ) is presented. The measured normalized differential tt \mathrm{t} \overline{\mathrm{t}} production cross section, as function of the sidereal time, is examined for potential modulations induced by Lorentz-invariance breaking operators in an effective field theory extension of the standard model (SM). The cross section is measured from collision events collected by the CMS detector at a center-of-mass-energy of 13 TeV, corresponding to an integrated luminosity of 77.8 fb1 ^{-1} , and containing one electron and one muon. The results are found to be compatible with zero, in agreement with the SM, and are used to bound the Lorentz-violating couplings to be in ranges of 1-8 × \times 103^{-3} at 68% confidence level. This is the first precision test of the isotropy in special relativity with top quarks at the LHC, restricting further the bounds on such couplings by up two orders of magnitude with respect to previous searches conducted at the Tevatron.A search for violation of Lorentz invariance in the production of top quark pairs (ttˉ\mathrm{t\bar{t}}) is presented. The measured normalized differential ttˉ\mathrm{t\bar{t}} production cross section, as function of the sidereal time, is examined for potential modulations induced by Lorentz-invariance breaking operators in an effective field theory extension of the standard model (SM). The cross section is measured from collision events collected by the CMS detector at a center-of-mass-energy of 13 TeV, corresponding to an integrated luminosity of 77.8 fb1^{-1}, and containing one electron and one muon. The results are found to be compatible with zero, in agreement with the SM, and are used to bound the Lorentz-violating couplings to be in ranges of 1 - 8 ×\times 103^{-3} at 68% confidence level. This is the first precision test of the isotropy in special relativity with top quarks at the LHC, restricting further the bounds on such couplings by up two orders of magnitude with respect to previous searches conducted at the Tevatron
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