Search results for "Lhc"
showing 10 items of 342 documents
Freeze-out radii extracted from three-pion cumulants in pp, p–Pb and Pb–Pb collisions at the LHC
2014
In high-energy collisions, the spatio-temporal size of the particle production region can be measured using the Bose-Einstein correlations of identical bosons at low relative momentum. The source radii are typically extracted using two-pion correlations, and characterize the system at the last stage of interaction, called kinetic freeze-out. In low-multiplicity collisions, unlike in high-multiplicity collisions, two-pion correlations are substantially altered by background correlations, e.g. mini-jets. Such correlations can be suppressed using three-pion cumulant correlations. We present the first measurements of the size of the system at freeze-out extracted from three-pion cumulant correl…
Jet fragmentation transverse momentum from h-h correlations in pp and p-Pb collisions
2017
Design and development of safety and control systems in ATLAS
2021
El gran colisionador de hadrones, o LHC, es el acelerador de partículas más grande y potente del mundo. Ha sido construido por el CERN, la Organización Europea para la Investigación Nuclear, entre 1998 y 2008 en Ginebra, Suiza. Sucesivas mejoras en el LHC supondrán a partir de mediados del 2027 un incremento de la luminosidad, cuando pasará a llamarse High Luminosity LHC (HL-LHC). Esta tesis se divide en dos partes, por una parte la seguridad y operación de la infraestructura y por otra los sistemas de control y toma de datos. La primera parte de la tesis se dedica a la seguridad y operación de la infraestructura. Después de más de 10 años de funcionamiento, el riesgo de posibles fallos en …
Search for pair production of first or second generation leptoquarks in proton-proton collisions at sqrt(s)=7 TeV using the ATLAS detector at the LHC
2011
This paper describes searches for the pair production of first or second generation scalar leptoquarks using 35 pb−1 of proton-proton collision data recorded by the ATLAS detector at √s=7 TeV. Leptoquarks are searched in events with two oppositely-charged muons or electrons and at least two jets, and in events with one muon or electron, missing transverse momentum and at least two jets. After event selection, the observed yields are consistent with the predicted backgrounds. Leptoquark production is excluded at the 95% CL for masses MLQ<376 (319) GeV and MLQ<422 (362) GeV for first and second generation scalar leptoquarks, respectively, when assuming the branching fraction of a leptoquark…
lhc phenomenology and neutrino physics in gut inspired susy models
2014
En la primera parte de la tesis investigamos un modelo supersimetrico con un mecanismo seesaw para explicar las masas de los neutrinos. Implementamos el modelo en SPheno que nos permitió calcular observables de LHC (Large Hardron Collider) como por ejemplo los ``Edge observables''. Con la ayuda de estos observables pudimos reconstruir el espectro de masa de una teoría como SUSY y compararlo con los resultados de los experimentos. Como no hemos observado SUSY en ningún experimento calculamos para diferentes parámetros de SUSY el espectro usando errores esperados para nuestra análisis. Para poder decidir si un modelo resulta verdadero necesitamos un valor independiente que nos permita cuantif…
Study of Bs->PhiGamma decays at LHCb
2021
This thesis describes two different analyses performed at LHCb using the B0s→φγ and B0→K∗0γ decay channels. First, the measurement of the ratio of branching fractions B(B0→K∗0γ)/B(B0s→φγ) is presented, giving the most precise value for B(B0s→φγ) to date. Secondly, the CP-violating observables S and C, as well as the mixing-induced A∆ parameter are measured through a time-dependent analysis of the B0s→φγ decay channel, this being the first time the S and C observables are probed in the Bs system. These studies are performed using data collected in 2011 and 2012 by the LHCb experiment at CERN, corresponding to an integrated luminosity of 3.0 fb−1 of pp collisions at a center-of-mass energy of…
New models in particle and astroparticle physics: consequences for dark matter and LHC
2013
226 páginas. Tesis Doctoral del Departamento de Física Teórica, de la Universidad de Valencia.
Neutrino masses and their implications for low energy experiments and the LHC
2020
Neutrino oscillations constitute the first experimental evidence of new physics. Con- trary to the prediction of the Standard Model, neutrinos are now well-established as particles with mass. In this thesis we study four topics related to neutrino masses. We examine a class of patterns of Majorana neutrino mass matrices, called two-zero textures, that could lead to the building of the underlying flavour theory. Using a purely numerical technique, we compare the constraints given by the textures with the most updated data of oscillation parameters. We find that the most promising textures are those of class A with normal ordering. Further, we revisit the case of excluded textures and study t…
"Table 2" of "Search for Higgs boson decays into a $Z$ boson and a light hadronically decaying resonance using 13 TeV $pp$ collision data from the AT…
2020
Efficiencies of the MLP selection, complete selection and total expected signal yields for each signal sample, assuming B$(H\to Z(Q/a))=100\%$ and $\sigma(pp\to H) = \sigma_\text{SM}(pp\to H)$. Pythia 8 branching fractions of $a$ are assumed using a $\tan\beta$ value of 1. The MLP efficiencies, total efficiencies, and expected yields are determined using MC samples, with uncertainties due to MC sample statistics, except for the expected background yield. The expected background yield and its uncertainty is calculated as described in the main text of the paper.
"Table 1" of "Search for Higgs boson decays into a $Z$ boson and a light hadronically decaying resonance using 13 TeV $pp$ collision data from the AT…
2020
Observed number of data events and expected number of background events in the signal region.