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Energy-energy correlation in Z boson tagged PbPb and pp collisions at sqrt(sNN) = 5.02 TeV
No full textThe first measurement of a Z boson tagged energy-energy correlator (EEC) using charged particle tracks in PbPb collisions at TeV is presented. This study utilizes PbPb collision data recorded in 2018 with an integrated luminosity of nb, as well as pp collision data acquired in 2017 with an integrated luminosity of pb. The energy-energy correlator of charged hadrons associated with the Z boson, which is predicted to be sensitive to modifications of in-medium parton showers and medium recoils, is measured in bins of event centrality for the first time in PbPb collisions. Significant modification of the EEC is observed in central PbPb collisions compared to pp reference data. The effect disappears in the more peripheral events. The results provide new insight into the jet quenching mechanism and the inner workings of the quark-gluon plasma
CERN celabrates the 90th birthday of medical physics pioneer Ugo Amaldi
No full textCERN celebrates the achievements and long career of Ugo Amaldi as he turns 90
RPC Link Board Multi-Gigabit Transceiver Test
No full textThis study presents the results from the RPC Link Board Multi-Gigabit Transceiver test
Inclusive semileptonic decays from lattice QCD: analysis of systematic effects
No full textLattice QCD calculations of inclusive semileptonic decay rates involve new types of systematic effects, such as truncation errors in the estimation of energy integrals, or finite-volume effects for multi-body final states. We investigate them for the lattice data of decays, obtained using Möbius domain-wall fermions. Separating the ground-state and excited-state contributions results in better control over these systematic effects. With the Chebyshev polynomial approximation, the truncation error is under control, while the finite-volume effects are estimated using a model to describe two-body final states
Analysis of very forward neutral particle spectra with the LHCf experiment at the LHC
No full textCosmic rays, especially ultra-high energy cosmic rays (UHECRs), have been the subject of extensive study due to their relevance to astrophysics and particle physics. Although substantial progress has been made through ground-based experiments, like the Pierre Auger and Telescope Array Observatories, several uncertainties remain due to the dependence on hadronic interaction models for data interpretation. These models are critical for understanding cosmic ray composition and the mechanisms behind their production and acceleration. The LHC-forward (LHCf) experiment at the Large Hadron Collider (LHC) plays a key role in addressing these uncertainties by providing valuable measurements of forward particle production in proton-proton and proton-ion collisions. This thesis presents a detailed overview of the LHCf experiment, its role in forward physics, and its recent contributions to the so-called "Muon Puzzle" in hadronic interaction models. Chapter 1 presents an overview of cosmic ray physics and the challenges in detecting UHECRs, including the simulation and experimental techniques used in extended air shower models. Special attention is given to the hadronic interaction models and their limitations, which are crucial for interpreting UHECR data. Chapter 2 discusses the Large Hadron Collider (LHC) and its experiments, with a focus on their results concerning the Muon Puzzle and the LHCf experiment, detailing its experimental apparatus, data acquisition systems, and published results. A major part of this work is the analysis of the production of the meson in proton-proton collisions at TeV with the LHCf-Arm2 detector, detailed in Chapter 3. The production rate as a function of the Feynman-x variable is measured, and the results are compared with predictions from widely used hadronic interaction models. The future prospects of this analysis, leveraging data collected by LHCf during the LHC RUN III at TeV, are discussed, highlighting the necessity for the calibration of the LHCf-Arm2 detector, described in Chapter 4, with a focus on the SPS H2 beam test, which assesses energy resolution, linearity, and systematic uncertainties affecting the detector absolute energy scale. Finally, Chapter 5 presents the conclusions of this thesis and outlines future perspectives, including two ongoing works, the measurement of the production ratio and the application of machine learning techniques to enhance the reconstruction of multiple calorimetric clusters in the LHCf experiment
Differential measurements of using TeV Pb+Pb collisions with the ATLAS detector
No full textThis study presents differential fiducial cross-section measurements of photon-induced -lepton pair production. The results are obtained using ultraperipheral lead-lead collisions recorded in 2015 and 2018 at TeV by the ATLAS experiment at the LHC. The dataset corresponds to an integrated luminosity of 1.93 nb. Events are selected using topologies with one of the -leptons decaying to a muon and two neutrinos and by the presence of an electron or charged-particle track(s) from the second -lepton decay. Events with low activity in the zero-degree calorimeters are used, corresponding to a topology without forward neutron emissions. The data are corrected for detector-related effects through an iterative Bayesian unfolding procedure, obtaining differential fiducial cross-sections at particle level for seven kinematic variables of the -lepton decay products for each of the three considered final state categories