385 research outputs found

    Design of the TEPX luminometer for the CMS experiment at the HL-LHC

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    Se describe el dise√Īo y el rendimiento esperado para la medici√≥n precisa de la luminosidad del detector Tracker Endcap Pixel (TEPX) para el experimento CMS en el pr√≥ximo High-Luminosity LHC (HL-LHC). El detector TEPX est√° compuesto por 4 discos dobles de doble cara en cada extremo de CMS que cubren el rango de | z | de 175 a 265 cm, cada disco est√° formado por 5 anillos compuestos por sensores de silicio, con un total de 800 millones de p√≠xeles distribuidos en los 8 discos. El disco 4, anillo 1 (TEPXD4R1) se dedicar√° a la luminosidad y las mediciones de fondo inducidas por el haz, utilizando el mismo m√©todo que el resto de TEPX, es decir, el conteo de grupos de p√≠xeles. Para el HL-LHC, el objetivo es lograr una incertidumbre final del 1 % para las mediciones de luminosidad offline. Se presenta el rendimiento esperado de los lumin√≥metros TEPX y TEPXD4R1 en t√©rminos de precisi√≥n estad√≠stica para la calibraci√≥n de barrido de van der Meer y para las condiciones f√≠sicas, as√≠ como el rendimiento de linealidad de cada disco

    The Pixel Luminosity Telescope: a detector for luminosity measurement at CMS using silicon pixel sensors

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    International audienceThe Pixel Luminosity Telescope is a silicon pixel detector dedicated to luminosity measurement at the CMS experiment at the LHC. It is located approximately 1.75 m from the interaction point and arranged into 16 ‚Äútelescopes‚ÄĚ, with eight telescopes installed around the beam pipe at either end of the detector and each telescope composed of three individual silicon sensor planes. The per-bunch instantaneous luminosity is measured by counting events where all three planes in the telescope register a hit, using a special readout at the full LHC bunch-crossing rate of 40 MHz. The full pixel information is read out at a lower rate and can be used to determine calibrations, corrections, and systematic uncertainties for the online and offline measurements. This paper details the commissioning, operational history, and performance of the detector during Run¬†2 (2015‚Äď18) of the LHC, as well as preparations for Run 3, which will begin in 2022

    Search for stealth supersymmetry in final states with two photons, jets, and low missing transverse momentum in proton-proton collisions at s\sqrt{s} = 13 TeV

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    International audienceThe results of a search for stealth supersymmetry in final states with two photons and jets, targeting a phase space region with low missing transverse momentum (pTmissp_\text{T}^\text{miss}), are reported. The study is based on a sample of proton-proton collisions at s\sqrt{s} =13 TeV collected by the CMS experiment, corresponding to an integrated luminosity of 138 fb‚ąí1^{-1}. As LHC results continue to constrain the parameter space of the minimal supersymmetric standard model, the low pTmissp_\text{T}^\text{miss} regime is increasingly valuable to explore. To estimate the backgrounds due to standard model processes in such events, we apply corrections derived from simulation to an estimate based on a control selection in data. The results are interpreted in the context of simplified stealth supersymmetry models with gluino and squark pair production. The observed data are consistent with the standard model predictions, and gluino (squark) masses of up to 2150 (1850) GeV are excluded at the 95% confidence level

    Search for narrow trijet resonances in proton-proton collisions at s\sqrt{s} = 13 TeV