Recent stellar mass assembly of low-mass star-forming galaxies at redshifts 0.3 < z < 0.9

The epoch when low-mass star forming galaxies (LMSFGs) form the bulk of their stellar mass is uncertain. While some models predict an early formation, others favor a delayed scenario until later ages of the universe. We present constraints on the star formation histories (SFHs) of a sample of LMSFGs obtained through the analysis of their spectral energy distributions using a novel approach that (1) consistently combines photometric (broadband) and spectroscopic (equivalent widths of emission lines) data, and (2) uses physically motivated SFHs with non-uniform variations of the star formation rate (SFR) as a function of time. The sample includes 31 spectroscopically confirmed LMSFGs (7.3 < log M*/Msun < 8.0) at 0.3 < z_spec < 0.9 in the Extended-Chandra Deep Field-South field (E-CDF-S). Among them, 24 were selected with photometric stellar mass log M*/Msun < 8.0, 0.3 < z_phot < 1.0, and NB816 < 26 AB mag; the remaining 7 were selected as blue compact dwarfs (BCDs) within the same photometric redshift and magnitude ranges. We also study a secondary sample of 43 more massive spectroscopically confirmed galaxies (8.0 < log M*/Msun < 9.1), selected with the same criteria. The SFRs and stellar masses derived for both samples place our targets on the standard main sequence of star forming galaxies. The median SFH of LMSFGs at intermediate redshifts appears to form 90% of the median stellar mass inferred for the sample in the 0.5-1.8 Gyr immediately preceding the observation. These results suggest a recent stellar mass assembly for LMSFGs, consistent with the cosmological downsizing trends. We find similar median SFH timescales for the more massive secondary sample.Comment: 7 pages, 3 figures, 2 tables; ApJ, in pres

Estrategias para el avance de la RSE en las universidades y la cooperación interuniversitaria

El desarrollo de las crisis mundiales de las últimas décadas, y su impacto sobre las condiciones de vida de estas generaciones, pusieron en evidencia la necesidad de repensar los valores asociados al paradigma del desarrollo. Existe hoy, consenso generalizado respecto a que el logro del desarrollo de las sociedades de manera sostenible y equitativa, solo es posible desde el ejercicio de la solidaridad de sus actores. Desde este paradigma, tanto la implementación de políticas públicas como la evaluación de su impacto, son responsabilidad del Estado, como así también de todas las organizaciones; y que las universidades están en condiciones de posibilitar, no solo la formación orientada hacia el compromiso social, sino también su práctica. El proyecto presentado pretende descubrir las condiciones para la creación de una Cátedra optativa orientada a la “Formación ética y el compromiso social de los estudiantes de Ciencias Económicas, de la Universidad Nacional de la Matanza.”Fil: Cruz, Adriana Olga. Universidad Nacional de La Matanza; Argentina.Fil: De Mendonςa, Ángel Héctor. Universidad Nacional de La Matanza; Argentina.Fil: Tutau, Armando Rufino. Universidad Nacional de La Matanza; Argentina.Fil: Crocco, Carla. Universidad Nacional de La Matanza; Argentina.Fil: Franco, Jorge Amadeo. Universidad Nacional de La Matanza; Argentina.Fil: Devesa, Jorge Eduardo. Universidad Nacional de La Matanza; Argentina.Fil: Castelli, Marcela I. Universidad Nacional de La Matanza; Argentina.Fil: Galardo, Verónica Elisa. Universidad Nacional de La Matanza; Argentina.Fil: Gil, Víctor Armando. Universidad Nacional de La Matanza; Argentina

Mejoramiento de la rotación de tracto camiones en la compañía DIC S.A.S.

La compañía distribuidora internacional colombiana S.A.S. (DIC S.A.S), es una compañía creada por el grupo empresarial Corona, quienes dedicaron, ésta unidad de negocio al apoyo del transporte de las cargas de producto terminado que se movilizan desde el centro de producción en la población de Sopó hasta sus principales centros de distribución ubicados en las ciudades de Cartagena y Medellín. Usando una metodología de investigación descriptiva, cuantitativa, se ha querido realizar un diagnostico al funcionamiento actual de la operación de transporte, donde se usan tracto camiones y sus respectivos tráilers, con el fin de buscar problemáticas presentadas y formular soluciones hacia la compañía. Para realizar el ejercicio se tiene como premisa la solución de la incógnita de que si ¿La implementación de la metodología Lean aporta soluciones a la problemática del uso de los tracto camiones pertenecientes a la empresa DIC S.A.S.?, basado en el objetivo de proponer una metodología que aporte al mejoramiento en la utilización de los tracto camiones a fin de disminuir los tiempos de estadía en planta, buscando maximizar los beneficios económicos y aumentar la productividad y eficiencia en la distribución. Para lo cual se busca sortear los pasos consecuentes para su alcance, los cuales plantean que se debe diagnosticar la empresa y los tiempos muertos en la operación con sus costos asociados, describiendo la metodología Lean aplicable a la cadena logística, usando herramientas como el benchmarking, para formar una imagen frente a empresas lideres en el mercado y ejecutar el beneficio que se adquiere midiendo el beneficio adquirido.PregradoIngeniero en IndustrialIngeniería Industria

Measurement of t(t)over-bar normalised multi-differential cross sections in pp collisions at root s=13 TeV, and simultaneous determination of the strong coupling strength, top quark pole mass, and parton distribution functions

Peer reviewe

Measurement of the top quark forward-backward production asymmetry and the anomalous chromoelectric and chromomagnetic moments in pp collisions at √s = 13 TeV

Abstract The parton-level top quark (t) forward-backward asymmetry and the anomalous chromoelectric (d̂ t) and chromomagnetic (μ̂ t) moments have been measured using LHC pp collisions at a center-of-mass energy of 13 TeV, collected in the CMS detector in a data sample corresponding to an integrated luminosity of 35.9 fb−1. The linearized variable AFB(1) is used to approximate the asymmetry. Candidate t t ¯ events decaying to a muon or electron and jets in final states with low and high Lorentz boosts are selected and reconstructed using a fit of the kinematic distributions of the decay products to those expected for t t ¯ final states. The values found for the parameters are AFB(1)=0.048−0.087+0.095(stat)−0.029+0.020(syst),μ̂t=−0.024−0.009+0.013(stat)−0.011+0.016(syst), and a limit is placed on the magnitude of | d̂ t| &lt; 0.03 at 95% confidence level. [Figure not available: see fulltext.

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

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

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

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

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

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

An embedding technique to determine ττ backgrounds in proton-proton collision data

An embedding technique is presented to estimate standard model tau tau backgrounds from data with minimal simulation input. In the data, the muons are removed from reconstructed mu mu events and replaced with simulated tau leptons with the same kinematic properties. In this way, a set of hybrid events is obtained that does not rely on simulation except for the decay of the tau leptons. The challenges in describing the underlying event or the production of associated jets in the simulation are avoided. The technique described in this paper was developed for CMS. Its validation and the inherent uncertainties are also discussed. The demonstration of the performance of the technique is based on a sample of proton-proton collisions collected by CMS in 2017 at root s = 13 TeV corresponding to an integrated luminosity of 41.5 fb(-1).Peer reviewe

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

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