Measurement of associated Z+charm production and search for W' bosons in the CMS experimented at the LHC

¿Sabemos cómo interaccionan las partículas elementales entre ellas?, ¿somos capaces de predecir cual ser¿¿a el resultado de colisiones entre dichas partículas elementales en el LHC? Después del descubrimiento del bosón de Higgs en 2012, todas las partículas elementales en la versión original del Modelo Estándar de F¿¿sica de Partículas (ME), han sido descubiertas de forma experimental. A día de hoy, el ME es una teoría con una alta capacidad predictiva, ya que es capaz de hacer predicciones teóricas con gran precisión que han sido verificadas de forma experimental en los últimos 50 años. El objetivo científico de esta tesis doctoral es investigar usando datos del detector CMS, si el ME es capaz de predecir la frecuencia a la cual los procesos Z+c y W prima (Wp) son producidos en las colisiones entre protones en el LHC. La primera mitad de la tesis doctoral se dedica a estudiar la posible existencia de un nuevo proceso, Wp desintegrándose en un muon y un neutrino, mediado por la existencia de un bosón Wp que sería responsable de un nuevo tipo de interacción entre partículas. Este tipo de interacciones no existen el ME, sin embargo aparecen en predicciones teóricas en muchas de sus extensiones. En el caso de que dichas interacciones hubiesen ocurrido en la naturaleza, la existencia del bosón Wp podr¿¿a ser demostrada gracias a las energías alcanzas en las colisiones del LHC. La estrategía del análisis se basa en encontrar un exceso de producción en los primeros 2.3 fb¿1 a 13 TeV en sucesos en los cuales se ha formado un muon de alto momento y mucha energía perdida, ambos medidos en el plano transverso del detector. Una vez analizada la muestra, la frecuencia a la cual estos procesos se han medido en CMS se encuentra en acuerdo con las predicciones del ME, desfavoreciendo la producción de nuevas interacciones Wp. Este resultado en el marco teórico del Modelo Estándar Secuencial (SSM), modelo de referencia usado por colaboraciones experimentales para interpretar sus búsquedas, excluye la existencia de bosones W SSM en las cuales el bosón tiene masa menor de 3.9 TeV. Le segunda parte del manuscrito presenta la primera medida en CMS de la producción de un bosón Z asociada con quarks de tipo charm, Z+c. El objetivo del análisis es medir la sección eficaz de producción del proceso Z+c, así como medir su producción relativa respecto al quark bottom, Z+b. Esta nueva medida servirá para poder cuantificar el nivel de precisión las prediciones teóricas del sector fuerte (QCD) del ME y las funciones de distribución de partones (PDF). Para este estudio se ha empleado una muestra de colisiones a 8 TeV de 19.7 fb ¿1 de tamaño. La estrateg¿¿a del análisis experimental se basa en la identificación del bosón Z a través de su desintegración en parejas de electrones o muones con carga opuesta, y la identificación de quarks de tipo charm en tres estados finales independientes: desintegraciones semileptónicas de hadrones de tipo B y D y la reconstrucción de hadrones D± o D¿± (2010). Como resultado de este estudio, la sección eficaz del proceso Z + c ha sido medida en la región fiducial sigma(Z+c) = 8.6+-0.5 (stat)+-0.7 (syst) pb y su producción relativa respecto al quark bottom sigma(Z+c)/sigma(Z+b) = 2.0+-0.2 (stat)+-0.2 (syst)..

Gestión del conocimiento. Perspectiva multidisciplinaria. Volumen 9

El libro “Gestión del Conocimiento. Perspectiva Multidisciplinaria”, volumen 9, de la Colección Unión Global, es resultado de investigaciones. Los capítulos del libro, son resultados de investigaciones desarrolladas por sus autores. El libro es una publicación internacional, seriada, continua, arbitrada de acceso abierto a todas las áreas del conocimiento, que cuenta con el esfuerzo de investigadores de varios países del mundo, orientada a contribuir con procesos de gestión del conocimiento científico, tecnológico y humanístico que consoliden la transformación del conocimiento en diferentes escenarios, tanto organizacionales como universitarios, para el desarrollo de habilidades cognitivas del quehacer diario. La gestión del conocimiento es un camino para consolidar una plataforma en las empresas públicas o privadas, entidades educativas, organizaciones no gubernamentales, ya sea generando políticas para todas las jerarquías o un modelo de gestión para la administración, donde es fundamental articular el conocimiento, los trabajadores, directivos, el espacio de trabajo, hacia la creación de ambientes propicios para el desarrollo integral de las instituciones

Identification of heavy-flavour jets with the CMS detector in pp collisions at 13 TeV

Many measurements and searches for physics beyond the standard model at the LHC rely on the efficient identification of heavy-flavour jets, i.e. jets originating from bottom or charm quarks. In this paper, the discriminating variables and the algorithms used for heavy-flavour jet identification during the first years of operation of the CMS experiment in proton-proton collisions at a centre-of-mass energy of 13 TeV, are presented. Heavy-flavour jet identification algorithms have been improved compared to those used previously at centre-of-mass energies of 7 and 8 TeV. For jets with transverse momenta in the range expected in simulated $\mathrm{t}\overline{\mathrm{t}}$ events, these new developments result in an efficiency of 68% for the correct identification of a b jet for a probability of 1% of misidentifying a light-flavour jet. The improvement in relative efficiency at this misidentification probability is about 15%, compared to previous CMS algorithms. In addition, for the first time algorithms have been developed to identify jets containing two b hadrons in Lorentz-boosted event topologies, as well as to tag c jets. The large data sample recorded in 2016 at a centre-of-mass energy of 13 TeV has also allowed the development of new methods to measure the efficiency and misidentification probability of heavy-flavour jet identification algorithms. The heavy-flavour jet identification efficiency is measured with a precision of a few per cent at moderate jet transverse momenta (between 30 and 300 GeV) and about 5% at the highest jet transverse momenta (between 500 and 1000 GeV)

Evidence for the Higgs boson decay to a bottom quark–antiquark pair

info:eu-repo/semantics/publishe

Impacts of the Tropical Pacific/Indian Oceans on the Seasonal Cycle of the West African Monsoon

The current consensus is that drought has developed in the Sahel during the second half of the twentieth century as a result of remote effects of oceanic anomalies amplified by local land–atmosphere interactions. This paper focuses on the impacts of oceanic anomalies upon West African climate and specifically aims to identify those from SST anomalies in the Pacific/Indian Oceans during spring and summer seasons, when they were significant. Idealized sensitivity experiments are performed with four atmospheric general circulation models (AGCMs). The prescribed SST patterns used in the AGCMs are based on the leading mode of covariability between SST anomalies over the Pacific/Indian Oceans and summer rainfall over West Africa. The results show that such oceanic anomalies in the Pacific/Indian Ocean lead to a northward shift of an anomalous dry belt from the Gulf of Guinea to the Sahel as the season advances. In the Sahel, the magnitude of rainfall anomalies is comparable to that obtained by other authors using SST anomalies confined to the proximity of the Atlantic Ocean. The mechanism connecting the Pacific/Indian SST anomalies with West African rainfall has a strong seasonal cycle. In spring (May and June), anomalous subsidence develops over both the Maritime Continent and the equatorial Atlantic in response to the enhanced equatorial heating. Precipitation increases over continental West Africa in association with stronger zonal convergence of moisture. In addition, precipitation decreases over the Gulf of Guinea. During the monsoon peak (July and August), the SST anomalies move westward over the equatorial Pacific and the two regions where subsidence occurred earlier in the seasons merge over West Africa. The monsoon weakens and rainfall decreases over the Sahel, especially in August.Peer reviewe

Differential cross section measurements for the production of a W boson in association with jets in proton–proton collisions at √s = 7 TeV

Measurements are reported of differential cross sections for the production of a W boson, which decays into a muon and a neutrino, in association with jets, as a function of several variables, including the transverse momenta (pT) and pseudorapidities of the four leading jets, the scalar sum of jet transverse momenta (HT), and the difference in azimuthal angle between the directions of each jet and the muon. The data sample of pp collisions at a centre-of-mass energy of 7 TeV was collected with the CMS detector at the LHC and corresponds to an integrated luminosity of 5.0 fb[superscript −1]. The measured cross sections are compared to predictions from Monte Carlo generators, MadGraph + pythia and sherpa, and to next-to-leading-order calculations from BlackHat + sherpa. The differential cross sections are found to be in agreement with the predictions, apart from the pT distributions of the leading jets at high pT values, the distributions of the HT at high-HT and low jet multiplicity, and the distribution of the difference in azimuthal angle between the leading jet and the muon at low values.United States. Dept. of EnergyNational Science Foundation (U.S.)Alfred P. Sloan Foundatio

Optimasi Portofolio Resiko Menggunakan Model Markowitz MVO Dikaitkan dengan Keterbatasan Manusia dalam Memprediksi Masa Depan dalam Perspektif Al-Qur`an

Risk portfolio on modern finance has become increasingly technical, requiring the use of sophisticated mathematical tools in both research and practice. Since companies cannot insure themselves completely against risk, as human incompetence in predicting the future precisely that written in Al-Quran surah Luqman verse 34, they have to manage it to yield an optimal portfolio. The objective here is to minimize the variance among all portfolios, or alternatively, to maximize expected return among all portfolios that has at least a certain expected return. Furthermore, this study focuses on optimizing risk portfolio so called Markowitz MVO (Mean-Variance Optimization). Some theoretical frameworks for analysis are arithmetic mean, geometric mean, variance, covariance, linear programming, and quadratic programming. Moreover, finding a minimum variance portfolio produces a convex quadratic programming, that is minimizing the objective function ðð¥with constraintsð ð 𥠥 ðandð´ð¥ = ð. The outcome of this research is the solution of optimal risk portofolio in some investments that could be finished smoothly using MATLAB R2007b software together with its graphic analysis

Search for heavy resonances decaying to two Higgs bosons in final states containing four b quarks

A search is presented for narrow heavy resonances X decaying into pairs of Higgs bosons (H) in proton-proton collisions collected by the CMS experiment at the LHC at root s = 8 TeV. The data correspond to an integrated luminosity of 19.7 fb(-1). The search considers HH resonances with masses between 1 and 3 TeV, having final states of two b quark pairs. Each Higgs boson is produced with large momentum, and the hadronization products of the pair of b quarks can usually be reconstructed as single large jets. The background from multijet and t (t) over bar events is significantly reduced by applying requirements related to the flavor of the jet, its mass, and its substructure. The signal would be identified as a peak on top of the dijet invariant mass spectrum of the remaining background events. No evidence is observed for such a signal. Upper limits obtained at 95 confidence level for the product of the production cross section and branching fraction sigma(gg -> X) B(X -> HH -> b (b) over barb (b) over bar) range from 10 to 1.5 fb for the mass of X from 1.15 to 2.0 TeV, significantly extending previous searches. For a warped extra dimension theory with amass scale Lambda(R) = 1 TeV, the data exclude radion scalar masses between 1.15 and 1.55 TeV

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