4,894 research outputs found
Exotic vertolike quark phenomenology in the minimal linear σ model
Extensions of the Standard Model that include vectorlike quarks commonly also include additional particles that may mediate new production or decay modes. Using the minimal linear σ model as an example, which reduces to the minimal SO (5)/SO (4) composite Higgs model in a specific limit, we consider the phenomenology of vectorlike quarks when a scalar singlet σ is present. This new particle may be produced in the decays T → tσ, B → bσ, where T and B are vectorlike quarks of charges 2/3 and −1/3, respectively, with the subsequent decay σ → W+W−, ZZ, hh. By scanning over the allowed parameter space we find that these decays may be dominant. In addition, we find that the presence of several new particles allows for single T production cross sections larger than those expected in minimal models. We discuss the observability of these new signatures in existing searchesThe authors acknowledge partial financial support by the Spanish MINECO through the Centro de excelencia Severo Ochoa Program under Grant No. SEV2016-0597. J. A. G., L. M. and J. A. A. S. acknowledge partial financial support by the Spanish “Agencia Estatal de Investigación” (AEI) and the EU “Fondo Europeo de Desarrollo Regional” (FEDER) through the Projects
No. FPA2016-78645-P and No. FPA2016-78220-C3-1-P. L. M. acknowledges partial financial support by the Spanish MINECO through the “Ramón y Cajal” programme (RYC-2015-17173). J. M. N. acknowledges support from the Ramón y Cajal Fellowship Contract No. RYC-2017-22986 and from the Spanish Proyectos de I + D de Generación de Conocimiento via Grant No. PGC2018-096646-A-I00. L. M. and J. M. N. also acknowledge support from the European Union’s Horizon 2020 research and innovation programme under the Marie Sklodowska-Curie Grant agreements No. 690575 (RISE InvisiblesPlus) and No. 674896 (ITN ELUSIVES
Search for the Higgs boson decays H → ee and H → eμ in pp collisions at √s = 13 TeV with the ATLAS detector
Artículo escrito por un elevado número de autores, sólo se referencian el que aparece en primer lugar, el nombre del grupo de colaboración, si le hubiera, y los autores pertenecientes a la UAMSearches for the Higgs boson decays H→eeand H→eμare performed using data corresponding to an integrated luminosity of 139 fb−1collected with the ATLAS detector in ppcollisions at √s=13 TeV at the LHC. No significant signals are observed, in agreement with the Standard Model expectation. For a Higgs boson mass of 125 GeV, the observed (expected) upper limit at the 95% confidence level on the branching fraction β(H→ee)is 3.6 ×10−4(3.5 ×10−4) and on β(H→eμ)is 6.2 ×10−5(5.9 ×10−5). These results represent improvements by factors of about five and six on the previous best limits on β(H→ee)and β(H→eμ)respectivelyWe acknowledge the support of ANPCyT, Argentina; YerPhI, Armenia; ARC, Australia; BMWFW and FWF, Austria; ANAS, Azerbaijan; SSTC, Belarus; CNPq and FAPESP, Brazil; NSERC, NRC and CFI, Canada; CERN; CONICYT, Chile; CAS, MOST and NSFC, China; COLCIENCIAS, Colombia; MSMT CR, MPO CR and VSC CR, Czech Republic; DNRF and DNSRC, Denmark; IN2P3-CNRS, CEA-DRF/IRFU, France; SRNSFG, Georgia; BMBF, HGF, and MPG, Germany; GSRT, Greece; RGC, Hong Kong SAR, China; ISF and Benoziyo Center, Israel; INFN, Italy; MEXT and JSPS, Japan; CNRST, Morocco; NWO, Netherlands; RCN, Norway; MNiSW and NCN, Poland; FCT, Portugal; MNE/IFA, Romania; MES of Russia and NRC KI, Russian Federation; JINR; MESTD, Serbia; MSSR, Slovakia; ARRS and MIZŠ, Slovenia; DST/NRF, South Africa; MINECO, Spain; SRC and Wallenberg Foundation, Sweden; SERI, SNSF and Cantons of Bern and Geneva, Switzerland; MOST, Taiwan; TAEK, Turkey; STFC, United Kingdom; DOE and NSF, United States of America. In addition, individual groups and members have received support from BCKDF, CANARIE, CRC and Compute Canada, Canada; COST, ERC, ERDF, Horizon 2020, and Marie Skłodowska-Curie Actions, European Union; Investissements d' Avenir Labex and Idex, ANR, France; DFG and AvH Foundation, Germany; Herakleitos, Thales and Aristeia programmes co-financed by EU-ESF and the Greek NSRF, Greece; BSF-NSF and GIF, Israel; CERCA Programme Generalitat de Catalunya, Spain; The Royal Society and Leverhulme Trust, United Kingdo
Mineralogical characterization of silica sinters from the El Tatio geothermal field, Chile
11 páginas.Silica sinters, deposited from alkali chloride waters in the El Tatio geothermal field in northern Chile (22°20'S, 68°01'W), have been characterized by XRD, SEM, TG-DTA, and FTIR. The dominant silica phase is opal-A. Minor contents of opal-A/-CT and opal-CT are also present together with halite (NaCl), sylvite (KCl), and realgar (AsS). Accessory phases include teruggite [Ca4MgAs2B12O22(OH)12·12(H2O)], sassolite (H3BO3), and detrital quartz (SiO2). FWHM values reflect the immature nature of the studied opal-A. DTA heating experiments of opal-A show cristobalite crystallization at ~1000 °C, whereas DTA cooling experiments show the β -alfacristobalite transformation at ~200 °C. The total weight loss is related to changes in the sinter microtextures, mineral phases, and organic matter contents. FTIR spectra show the effects of silica maturation as consequence of the loss of trapped and absorbed water attached to silanols.Peer reviewe
Influencia de las condiciones experimentales en la determinación de S, Cl, Br y I en agua por espectrometría de masas de alta resolución (HR-ICP-MS)
A systematic study was undertaken to optimize a method to determine S, Cl, Br and I in water by high resolution inductively coupled plasma mass spectrometry (HR-ICP-MS). The sample composition and preparation conditions (the total dissolved solids -TDS-, the total organic compounds -TOC- and the addition of nitric acid) were evaluated to assess the sample matrix influence. Furthermore, the effect of instrumental parameters (carrier gas flow rate, sample flow rate, radiofrequency -RF- power and analyzer resolution) was also studied to minimize the
contribution of polyatomic species, and to establish the required resolution. Low, medium or high resolutions were compared in terms of background level and sensitivity. After optimization, a multivariate robustness test was carried out by means of a Placket-Burman design. This method was applied to samples of the Llobregat and Ter rivers which are used for the drinking water system of the Metropolitan Area of Barcelona (~4.5 million inhabitants), Catalonia, northeast Spain.Este estudio fue financiado a través del Proyecto QUECA del Ministerio de Economía y Competitividad de España (CGL2011-23307) y el Proyecto PICT-2013-1259 (FONCyT, Argentina). Los análisis se realizaron en el Laboratorio de Geoquímica labGEOTOP en el ICTJA CSIC, infraestructura cofinanciada por FEDER-UE(Ref. CSIC08-4E-001).Peer Reviewe
Granate con alto contenido de tierras raras pesadas (HREE) y elevada relación Sm/Nd, en pegmatitas de la Sierra de Valle Fértil (Sierras Pampeanas, Argentina).
2 p.El trabajo se realizó en el marco de lso proyectos PB97-1246 (MEC) y BTE2001-1486 (MCYT) y PICT98-4189 (Argentina
Los depósitos de ceniza volcánica del Pleistoceno Superior-Holoceno de la región de Tafí del Valle-Cafayate, noroeste de Argentina
[EN]We identified volcanic ash deposits, whose thickness can exceed sometimes the 4 m, in the southeastern margin of La Puna and neighbouring areas (Provinces of Tucuman and Salta, Argentina). These Late Pleistocene and Holocene deposits show the existence of a highly explosive volcanism only some few thousand years ago, without comparison with any historical volcanic episode in northwestern Argentina. We have characterized the size distribution of ash (laser diffraction), morphology of particles (SEM), mineralogy (XRD) and the geochemistry of major and trace elements in bulk sample using mass spectrometry (HR-ICP-MS). The information provided by these deposits is of great interest to size adequately the geochemical impact models of ashfall in future volcanic eruptions in the Central Volcanic Zone of the Andes, quantifying the contribution of volcanic ash to the regional geochemical balances, both with respect to nutrients (e.g., Ca and Fe) and potentially toxic elements (e.g., As and F), among other elements of interest.[ES] Se han localizado diversos depósitos de ceniza volcánica, cuyos espesores llegan a superar en ocasiones los 4 m al suroeste de La Puna y áreas limítrofes (Provincias de Tucumán y Salta, Argentina). Estos depósitos son de edad Pleistoceno Superior y Holoceno y muestran la existencia hace pocos miles de años de volcanismo altamente explosivo, sin comparación con ningún episodio volcánico histórico en el noroeste de Argentina. Se han caracterizado la distribución granulométrica de la ceniza (difracción laser), la morfología de las partículas (microscopía electrónica de barrido), mineralogía (difracción de rayos X) y la geoquímica de elementos mayores y trazas en muestra total mediante espectrometría de masas (HR-ICP-MS). La información suministrada por estos depósitos tiene gran interés a la hora de dimensionar los modelos de impacto geoquímico de la caída de ceniza de futuras erupciones volcánicas en la Zona Volcánica Central de los Andes, cuantificando la contribución de la ceniza volcánica a los balances geoquímicos regionales, tanto por lo que respecta a nutrientes (p. ej., Ca y Fe), como de elementos potencialmente tóxicos (p. ej., As y F), entre otros elementos de interés.Agradecemos el apoyo técnico del labGEOTOP (infraestructura cofinanciada por FEDER, CSIC08-4E-001) del ICTJA-CSIC; de los Grupos PEGEFA (2009-SGR-972) y GEOVOL y fue financiado por el Proyecto QUECA (CGL2011-23307).Peer reviewe
Hot spring arsenic distribution in the Andes Cordillera (18-52oS)
1 página.-- Resumen presentado en el 23rd International Applied Geochemistry Symposium (IAGS), Oviedo, 14-19 Jun. 2007.-- Edited by Jorge Loredo Pérez.One of the most extensive areas around the world where the low quality of
groundwater due to the presence of high concentrations of arsenic of
natural origin is a major concern is Argentina-Chile. The exhaustive
knowledge of the geological, hydrogeological, and geochemical setting
can be very effective to define an alternative strategy to mitigate the
arsenic problem in water. The magnitude and extension of the arsenic
affected areas is not well known. In order to understand the source of the
arsenic, the development of a database of thermal waters in the Andean
region is in progress. We present in this work the assessment of more
than 360 hot springs and wells located in the Andes between 14 and 52oS
of latitude. This information comes from projects carried out by our team in
the area and from references. The hot waters with higher concentrations
of arsenic (50-30,000 μg/l) are mainly located in volcanic areas with
hydrothermal activity of the Andes Cordillera between 14 and 28oS.Peer reviewe
Ranibizumab for the treatment of retinopathy of prematurity: systematic review and meta-analysis
Anti-VEGF drugs like ranibizumab can be used to treat retinopathy of prematurity (ROP) by halting the formation of abnormal blood vessels, or lasers can be used to burn the edges of the retina where these vessels are present. The objective is to compare the efficacy for ROP between ranibizumab and laser therapy. Material and methods: Electronic searches will be carried out in medical databases with key words and controlled vocabulary terms. Randomized controlled trials (RCT) will be assessed. The primary outcome will be the full ROP regression. Two reviewers will extract the data using predefined forms and, to assess the quality of the study, we will use RoB 2.0, the tool for randomized controlled trials developed by the Cochrane Collaboration. We used a combination of the inverse-variance approach and random-effects models for the meta-analysis. Results: The eyes of 182 preterm infants who had ranibizumab treatment were assessed in a total of 364 eyes, and 135 infants received laser therapy. The follow-up period was between 6 and 24 months. Ranibizumab was not associated with greater regression of ROP compared to laser therapy in preterm infants (RR: 1.09, CI 95%: 0.95–1.24; p: 0.22). Also, ranibizumab was not associated with recurrence of ROP compared to laser therapy in preterm infants (RR: 3.77, CI 95%: 0.55–25.81; p: 0.22). Conclusions: The efficacy of ranibizumab compared to laser is very uncertain in terms of ROP regression and decreased ROP recurrence in preterm infants. Systematic Review Registration: identifier PROSPERO (CRD42022324150)Revisión por pare
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