452 research outputs found

    Atlas de las flotas de pesca españolas de aguas europeas atlånticas

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    The European Commission has acknowledged the value of fleet-based management approaches since the 2001 Green Paper on the Common Fisheries Policy (CFP). In the 2009 Green Paper, this was again recognized as a key area of interest for future development of the CFP, in particular setting the technical basis for the recent Data Collection Framework (DCF), which specifies the standard for national fishery sampling programs within a pan-European context. These policy changes require deeper and up to date knowledge about European fleets and fisheries, thus encouraging Member States to undertake scientific projects in order to obtain appropriate fleet segmentations classifying their fishing activities within a hierarchical structure. The work presented in this book is the first comprehensive analysis of the Spanish fleets operating in Atlantic European waters, taking into account both European and national management requirements. This has been possible due to the availability of official logbooks, which provide the broadest perspective on the activity of Spanish fleets in the study area. The only exception to this is small scale fisheries, pursued mainly by vessels of less than 10 m of length and, therefore, not subject to the requirement of keeping logbooks. In order to match better European and Spanish fleet classifications, a new level (“Management Unit”) is proposed here, which is placed between “modalidad”, used in the Spanish regulations, and “mĂ©tier”, as is defined by the recent DCF. Spanish national waters comprise four fishing grounds, two of which are in the European Atlantic. Nine Management Units have been identified in the Northern Spanish fishing ground: bottom otter trawl (OTB10), bottom pair trawl (PTB10), purse seine (PSN10), set long line (LLS10), set gillnet targeting hake (GNS11), set gillnet targeting anglerfish (GNS12), trolling (LTL11) and bait-boats (LHP11) targeting albacore, and hand line targeting mackerel (LHP12). Two Management Units have been identified in Southern Spanish waters: bottom otter trawl (OTB20) and purse seine (PSN20). In European waters outside Spain, six Management Units have been identified in non-Iberian waters: bottom otter trawl (OTB50), bottom pair trawl (PTB50), set long line (LLS50) and set gillnet (GNS50) by vessels of more than 100 GRT, and set long line (LLS60) and set gillnet (GNS60) by vessels of less than 100 GRT. Finally, one Management Unit using bottom otter trawl has been found to operate in Portuguese waters (OTB70). Unluckily, the analyses made on the logbooks of the Spanish fleet using drifting long line could not be used to categorize this fleet due to the geographical limitations of the logbooks available. After detailed analyses and categorization of the Management Units, the results obtained were used in an exercise to test the usefulness and feasibility of using logbook information to answer some DCF requirements. This revealed that logbooks are an essential tool to deal with bioeconomic challenges posed by the new CFP.VersiĂłn del edito

    Observation of the doubly charmed baryon decay Ξcc++→Ξcâ€Č+π+

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    The Ξcc++→Ξcâ€Č+π+ decay is observed using proton-proton collisions collected by the LHCb experiment at a centre-of-mass energy of 13 TeV, corresponding to an integrated luminosity of 5.4 fb−1. The Ξcc++→Ξcâ€Č+π+ decay is reconstructed partially, where the photon from the Ξcâ€Č+→Ξc+Îł decay is not reconstructed and the pK−π+ final state of the Ξc+ baryon is employed. The Ξcc++→Ξcâ€Č+π+branching fraction relative to that of the Ξcc++→Ξc+π+ decay is measured to be 1.41 ± 0.17 ± 0.10, where the first uncertainty is statistical and the second systematic. [Figure not available: see fulltext.

    Angular analysis of D0→π+π−Ό+Ό−D^0 \to \pi^+\pi^-\mu^+\mu^- and D0→K+K−Ό+Ό−D^0 \to K^+K^-\mu^+\mu^- decays and search for CPCP violation

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    The first full angular analysis and an updated measurement of the decay-rate CPCP asymmetry of the D0→π+π−Ό+Ό−D^0 \to \pi^+\pi^-\mu^+\mu^- and D0→K+K−Ό+Ό−D^0 \to K^+K^-\mu^+\mu^- decays are reported. The analysis uses proton-proton collision data collected with the LHCb detector at centre-of-mass energies of 7, 8 and 13 TeV. The data set corresponds to an integrated luminosity of 9 fb−1^{-1}. The full set of CPCP-averaged angular observables and their CPCP asymmetries are measured as a function of the dimuon invariant mass. The results are consistent with expectations from the standard model and with CPCP symmetry.Comment: All figures and tables, along with any supplementary material and additional information, are available at https://cern.ch/lhcbproject/Publications/p/LHCb-PAPER-2021-035.html (LHCb public pages

    Measurement of antiproton production from antihyperon decays in pHe collisions at √sNN=110GeV

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    The interpretation of cosmic antiproton flux measurements from space-borne experiments is currently limited by the knowledge of the antiproton production cross-section in collisions between primary cosmic rays and the interstellar medium. Using collisions of protons with an energy of 6.5 TeV incident on helium nuclei at rest in the proximity of the interaction region of the LHCb experiment, the ratio of antiprotons originating from antihyperon decays to prompt production is measured for antiproton momenta between 12 and 110GeV\!/c . The dominant antihyperon contribution, namely Λ¯ → pÂŻ π+ decays from promptly produced Λ¯ particles, is also exclusively measured. The results complement the measurement of prompt antiproton production obtained from the same data sample. At the energy scale of this measurement, the antihyperon contributions to antiproton production are observed to be significantly larger than predictions of commonly used hadronic production models

    Study of charmonium and charmonium-like contributions in B+ → J/ψηK+ decays

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    A study of B+→ J/ψηK+ decays, followed by J/ψ → ÎŒ+Ό− and η → γγ, is performed using a dataset collected with the LHCb detector in proton-proton collisions at centre-of-mass energies of 7, 8 and 13 TeV, corresponding to an integrated luminosity of 9 fb−1. The J/ψη mass spectrum is investigated for contributions from charmonia and charmonium-like states. Evidence is found for the B+→ (ψ2(3823) → J/ψη)K+ and B+→ (ψ(4040) → J/ψη)K+ decays with significance of 3.4 and 4.7 standard deviations, respectively. This constitutes the first evidence for the ψ2(3823) → J/ψη decay

    Measurement of the photon polarization in Λb→Λγ\Lambda_b \to \Lambda \gamma decays

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    The photon polarization in b→sÎłb \to s \gamma transitions is measured for the first time in radiative b-baryon decays exploiting the unique spin structure of Λb→Λγ\Lambda_b \to \Lambda \gamma decays. A data sample corresponding to an integrated luminosity of 6  fb−16\;fb^{-1} collected by the LHCb experiment in pppp collisions at a center-of-mass energy of 13  TeV13\;TeV is used. The photon polarization is measured to be αγ=0.82 − 0.26 − 0.13 + 0.17 + 0.04\alpha_{\gamma}= 0.82^{\,+\,0.17\,+\,0.04}_{\,-\,0.26\,-\,0.13}, where the first uncertainty is statistical and the second systematic. This result is in agreement with the Standard Model prediction and previous measurements in b-meson decays. Charge-parity breaking effects are studied for the first time in this observable and found to be consistent with CPCP symmetry.Comment: All figures and tables, along with machine-readable versions and any supplementary material and additional information, are available at https://cern.ch/lhcbproject/Publications/p/LHCb-PAPER-2021-030.html (LHCb public pages

    Studies of η\eta and ηâ€Č\eta' production in pppp and ppPb collisions

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    The production of η\eta and ηâ€Č\eta' mesons is studied in proton-proton and proton-lead collisions collected with the LHCb detector. Proton-proton collisions are studied at center-of-mass energies of 5.025.02 and 13 TeV13~{\rm TeV}, and proton-lead collisions are studied at a center-of-mass energy per nucleon of 8.16 TeV8.16~{\rm TeV}. The studies are performed in center-of-mass rapidity regions 2.5<yc.m.<3.52.5<y_{\rm c.m.}<3.5 (forward rapidity) and −4.0<yc.m.<−3.0-4.0<y_{\rm c.m.}<-3.0 (backward rapidity) defined relative to the proton beam direction. The η\eta and ηâ€Č\eta' production cross sections are measured differentially as a function of transverse momentum for 1.5<pT<10 GeV1.5<p_{\rm T}<10~{\rm GeV} and 3<pT<10 GeV3<p_{\rm T}<10~{\rm GeV}, respectively. The differential cross sections are used to calculate nuclear modification factors. The nuclear modification factors for η\eta and ηâ€Č\eta' mesons agree at both forward and backward rapidity, showing no significant evidence of mass dependence. The differential cross sections of η\eta mesons are also used to calculate η/π0\eta/\pi^0 cross section ratios, which show evidence of a deviation from the world average. These studies offer new constraints on mass-dependent nuclear effects in heavy-ion collisions, as well as η\eta and ηâ€Č\eta' meson fragmentation.Comment: All figures and tables, along with machine-readable versions and any supplementary material and additional information, are available at https://lhcbproject.web.cern.ch/Publications/p/LHCb-PAPER-2023-030.html (LHCb public pages

    Searches for rare Bs0 and B 0 decays into four muons

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    Searches for rare Bs0 and B0 decays into four muons are performed using proton-proton collision data recorded by the LHCb experiment, corresponding to an integrated luminosity of 9 fb−1. Direct decays and decays via light scalar and J/ψ resonances are considered. No evidence for the six decays searched for is found and upper limits at the 95% confidence level on their branching fractions ranging between 1.8 × 10−10 and 2.6 × 10−9 are set. [Figure not available: see fulltext.
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