CERN Accelerating science

Thesis
Report number CERN-THESIS-2023-186
Title Direct production of J/ψϕ vector mesons at the LHCb experiment without additional activity
Author(s) Meyer Garcia, Lucas (Federal University of Rio de Janeiro (BR))
Publication 250.
Thesis note PhD : Universidade Federal Do Rio De Janeiro, Instituto De Fisica : 2023-08-07
Thesis supervisor(s) Santana Rangel, Murilo
Note Presented 30 Aug 2023
Subject category Particle Physics - Experiment ; Detectors and Experimental Techniques
Accelerator/Facility, Experiment CERN LHC ; LHCb
Abstract The first study of the production of J/ψϕ vector meson pairs with no additional activity in the LHCb detector is presented. This analysis is based on data from proton-proton collisions at a center-of-mass energy of s=13\,TeV collected during Run 2 of LHC (2016-2018), which corresponds to a single-interaction integrated luminosity of 1.73 fb1. The J/ψϕ candidates are reconstructed from the decays of J/ψ and ϕ into pairs of muons and kaons, respectively, detected within the pseudorapidity region 2<η<5 and with pT>200\,MeV. 989 candidate events are selected. The J/ψ(μ+μ)ϕ(K+K) production fiducial cross-section for m(J/ψϕ)<6000 MeV/c2 is measured to be σJ/ψϕ=(2.66±0.08±0.13±0.08)\,pb where the first uncertainty is statistical, the second is systematic and the third is due to the luminosity determination. Furthermore, information from the \textsc{HeRSCheL} subdetector is used to estimate the fraction of exclusively produced events, which is found to be about 32%. A five-resonance model is fitted to the data with a combined significance of 8.6σ compared to a resonance-free model. The mass and width parameters are fixed for three resonances, X(4140), X(4685) and X(4700), while the parameters of the other two resonances, X(4274) and X(4500), are determined in this analysis. Additionally, this thesis presents two separate contributions to the LHCb Upgrade I, which was performed during LHC's Long Shutdown 2 (2019-2022). The first one concerns contributions made in 2019 to the validation of the new VELO modules that are currently installed in the LHCb for the Run 3 data-taking period (2022-2025). The second one concerns contributions made in 2022 to the RTA project, which is responsible for the developing and maintaining LHCb's new fully-software trigger.
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Corresponding record in: Inspire
Email contact: lhcb.secretariat@cern.ch

 Record creato 2023-10-06, modificato l'ultima volta il 2023-10-11


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