874 research outputs found

    Actualización taxonómica de las algas rojas (Rhodophyta) marinas bentónicas del Atlántico mexicano

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    Background and Aims: Since the contributions of Dreckmann in 1998, and Ortega et al. in 2001, there are no other integrative studies for the Mexican Atlantic seaweeds in which modifications and taxonomic actualizations were considered for this regional phycological flora. Hence, our main objective was to present an update for the marine benthic red algae from the Mexican coast of the Gulf of Mexico, and the Mexican Caribbean Sea, in which all the new records are included for the region since the contributions mentioned above. Materials and Methods: The information about the species was obtained through the analysis of all the specialized literature published for the region since 2001, as well as some previous records not considered before, and a revision of the databases of the UAMIZ Metropolitan Herbarium. Synonymy and nomenclatural status, as well as the classification system used, were revised in AlgaeBase. Key results: A checklist composed of 451 species and 13 infraespecific categories of red algae was obtained; these where distributed in 4 classes, 23 orders, 52 families, and 171 genera. The currently accepted name, synonymy, and distribution are mentioned for each species. An asterisk indicates previous records (prior to 2002), as well as its distribution in different habitats. Conclusions: The present contribution revealed two main changes to the previously known flora of the red algae from the study area. The first one falls in the domain of nomenclature, and implies a modification in their classification (families, genera, and species). The second one has an effect on the number of species present. As a consequence, it is evident that constant floristic monitoring is required along the coasts of the Mexican Atlantic.Antecedentes y Objetivos: Desde las contribuciones de Dreckmann en 1998 y Ortega et al. en 2001, no se han realizado otros trabajos compilatorios para el Atlántico mexicano en los que se consideren modificaciones y actualizaciones taxonómicas para la flora ficológica de la zona. El objetivo de este trabajo fue presentar un listado actualizado de las algas rojas de la costa mexicana del Golfo de México y el Caribe mexicano, en el que se consideran los nuevos registros para la región a partir de los trabajos mencionados hasta la fecha. Métodos: La información de las especies se obtuvo revisando la mayor cantidad de literatura publicada para el área de estudio, desde 2001 a la fecha y algunos registros previos no considerados antes, así como las bases de datos del Herbario Metropolitano UAMIZ. La sinonimia y el estatus nomenclatural de cada nombre, así como el sistema de clasificación utilizado, fueron revisados en AlgaeBase. Resultados clave: Se obtuvo un listado florístico con 451 especies y 13 categorias infraespecificas de algas rojas distribuidas en 4 clases, 23 órdenes, 52 familias y 171 géneros. Para cada especie se menciona su estado nomenclatural actualmente aceptado, su sinonimia y su distribución. Además, se resaltan con un asterisco aquellos registros antiguos (previos al 2002), así como su distribución por ambiente. Conclusiones: El presente listado reveló dos grandes cambios a la previamente conocida flora de las algas rojas de la zona de estudio. El primero de ellos se encuentra en el terreno de la nomenclatura, e implica una modificación a la clasificación de los taxones (familias, géneros, especies). El segundo repercute en el número de especies presentes. Dado lo anterior, es evidente la necesidad de un monitoreo florístico constante a lo largo del litoral del Atlántico mexicano

    MUSiC : a model-unspecific search for new physics in proton-proton collisions at root s=13TeV

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    Results of the Model Unspecific Search in CMS (MUSiC), using proton-proton collision data recorded at the LHC at a centre-of-mass energy of 13 TeV, corresponding to an integrated luminosity of 35.9 fb(-1), are presented. The MUSiC analysis searches for anomalies that could be signatures of physics beyond the standard model. The analysis is based on the comparison of observed data with the standard model prediction, as determined from simulation, in several hundred final states and multiple kinematic distributions. Events containing at least one electron or muon are classified based on their final state topology, and an automated search algorithm surveys the observed data for deviations from the prediction. The sensitivity of the search is validated using multiple methods. No significant deviations from the predictions have been observed. For a wide range of final state topologies, agreement is found between the data and the standard model simulation. This analysis complements dedicated search analyses by significantly expanding the range of final states covered using a model independent approach with the largest data set to date to probe phase space regions beyond the reach of previous general searches.Peer reviewe

    Search for new particles in events with energetic jets and large missing transverse momentum in proton-proton collisions at root s=13 TeV

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    A search is presented for new particles produced at the LHC in proton-proton collisions at root s = 13 TeV, using events with energetic jets and large missing transverse momentum. The analysis is based on a data sample corresponding to an integrated luminosity of 101 fb(-1), collected in 2017-2018 with the CMS detector. Machine learning techniques are used to define separate categories for events with narrow jets from initial-state radiation and events with large-radius jets consistent with a hadronic decay of a W or Z boson. A statistical combination is made with an earlier search based on a data sample of 36 fb(-1), collected in 2016. No significant excess of events is observed with respect to the standard model background expectation determined from control samples in data. The results are interpreted in terms of limits on the branching fraction of an invisible decay of the Higgs boson, as well as constraints on simplified models of dark matter, on first-generation scalar leptoquarks decaying to quarks and neutrinos, and on models with large extra dimensions. Several of the new limits, specifically for spin-1 dark matter mediators, pseudoscalar mediators, colored mediators, and leptoquarks, are the most restrictive to date.Peer reviewe

    Measurement of prompt open-charm production cross sections in proton-proton collisions at root s=13 TeV

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    The production cross sections for prompt open-charm mesons in proton-proton collisions at a center-of-mass energy of 13TeV are reported. The measurement is performed using a data sample collected by the CMS experiment corresponding to an integrated luminosity of 29 nb(-1). The differential production cross sections of the D*(+/-), D-+/-, and D-0 ((D) over bar (0)) mesons are presented in ranges of transverse momentum and pseudorapidity 4 < p(T) < 100 GeV and vertical bar eta vertical bar < 2.1, respectively. The results are compared to several theoretical calculations and to previous measurements.Peer reviewe

    Combined searches for the production of supersymmetric top quark partners in proton-proton collisions at root s=13 TeV

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    A combination of searches for top squark pair production using proton-proton collision data at a center-of-mass energy of 13 TeV at the CERN LHC, corresponding to an integrated luminosity of 137 fb(-1) collected by the CMS experiment, is presented. Signatures with at least 2 jets and large missing transverse momentum are categorized into events with 0, 1, or 2 leptons. New results for regions of parameter space where the kinematical properties of top squark pair production and top quark pair production are very similar are presented. Depending on themodel, the combined result excludes a top squarkmass up to 1325 GeV for amassless neutralino, and a neutralinomass up to 700 GeV for a top squarkmass of 1150 GeV. Top squarks with masses from 145 to 295 GeV, for neutralino masses from 0 to 100 GeV, with a mass difference between the top squark and the neutralino in a window of 30 GeV around the mass of the top quark, are excluded for the first time with CMS data. The results of theses searches are also interpreted in an alternative signal model of dark matter production via a spin-0 mediator in association with a top quark pair. Upper limits are set on the cross section for mediator particle masses of up to 420 GeV

    Probing effective field theory operators in the associated production of top quarks with a Z boson in multilepton final states at root s=13 TeV

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    Measurement of B-c(2S)(+) and B-c*(2S)(+) cross section ratios in proton-proton collisions at root s=13 TeV

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    Reconstruction of signal amplitudes in the CMS electromagnetic calorimeter in the presence of overlapping proton-proton interactions

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    A template fitting technique for reconstructing the amplitude of signals produced by the lead tungstate crystals of the CMS electromagnetic calorimeter is described. This novel approach is designed to suppress the contribution to the signal of the increased number of out-of-time interactions per beam crossing following the reduction of the accelerator bunch spacing from 50 to 25 ns at the start of Run 2 of the LHC. Execution of the algorithm is sufficiently fast for it to be employed in the CMS high-level trigger. It is also used in the offline event reconstruction. Results obtained from simulations and from Run 2 collision data (2015-2018) demonstrate a substantial improvement in the energy resolution of the calorimeter over a range of energies extending from a few GeV to several tens of GeV.Peer reviewe

    Observation of the Production of Three Massive Gauge Bosons at root s=13 TeV

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    The first observation is reported of the combined production of three massive gauge bosons (VVV with V = W, Z) in proton-proton collisions at a center-of-mass energy of 13 TeV. The analysis is based on a data sample recorded by the CMS experiment at the CERN LHC corresponding to an integrated luminosity of 137 fb(-1). The searches for individualWWW, WWZ, WZZ, and ZZZ production are performed in final states with three, four, five, and six leptons (electrons or muons), or with two same-sign leptons plus one or two jets. The observed (expected) significance of the combinedVVV production signal is 5.7 (5.9) standard deviations and the corresponding measured cross section relative to the standard model prediction is 1.02(-0.23)(+0.26). The significances of the individual WWW and WWZ production are 3.3 and 3.4 standard deviations, respectively. Measured production cross sections for the individual triboson processes are also reported

    Measurement of the W gamma Production Cross Section in Proton-Proton Collisions at root s=13 TeV and Constraints on Effective Field Theory Coefficients

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    A fiducial cross section for W gamma production in proton-proton collisions is measured at a center-of-mass energy of 13 TeV in 137 fb(-1) of data collected using the CMS detector at the LHC. The W -> e nu and mu nu decay modes are used in a maximum-likelihood fit to the lepton-photon invariant mass distribution to extract the combined cross section. The measured cross section is compared with theoretical expectations at next-to-leading order in quantum chromodynamics. In addition, 95% confidence level intervals are reported for anomalous triple-gauge couplings within the framework of effective field theory.Peer reviewe
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