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Prestations financières lors de l'entrée en fonctions et de l'extinction du contrat - Arbre de décision - option 1
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Visit by Mr Mike Headley, Executive Director, South Dakota Science and Technology Authority and Director, Sanford Underground Research Facility (SURF), USA
No full textVisit by Mr Mike Headley, Executive Director, South Dakota Science and Technology Authority and Director, Sanford Underground Research Facility (SURF), United States of Americ
Investigating initial state of heavy-ion collisions using fluctuations and correlations in ATLAS
No full textThis paper presents recent studies of event-wise mean transverse momentum, that can help differentiate the interplay between the effect of radial collectivity, random thermal motion and deformation in nuclear geometry. In addition, the Pearson Correlation Coefficient (PCC) between flow, and , ), will be shown. The results bear on aspects of the initial state, such as nuclear deformation and initial momentum anisotropy. This talk presents new precise ATLAS measurements of cumulants up to 3rd order and correlations in Xe+Xe, Pb+Pb and pp collisions. This measurement provides the first experimental handle to isolate initial state and medium evolution contributing to final state momentum fluctuations. The PCC coefficients show a non-monotonic dependence on centrality, and , reflecting the fact that different aspects of the initial conditions affect different regions of the phase space. The ratio of between the two systems in the ultra-central region suggests that has large quadrupole deformation but with a significant triaxiality. The measurement of correlation provides the first measurement of triaxiality in \mbox{}^{129}Xe using heavy ion collisions and provides new constraints to current models which fail to describe many of the observed trends in data
Measurement of the W boson properties in the forward region in pp collisions at TeV
No full textThis thesis primarily presents a detailed study of the fiducial cross--sections for and boson production at TeV, using data from the LHCb experiment at the Large Hadron Collider at CERN. The dataset corresponds to an integrated luminosity of , recorded during 2017. The research focusses on muonic decays of W bosons. The cross--sections are measured differentially in intervals of the muon transverse momentum between 25 and 55 GeV, with the pseudorapidity ranging from 2.2 to 2.4. Integrated over this 2D fiducial sub--volume, the cross--sections are measured to be: \begin{align*} \sigma_{W^+ \to \mu^+ \nu} &= 301.62 \pm 3.00 \pm 3.74 \pm 6.03 \ \text{pb}, \\ \sigma_{W^- \to \mu^- \bar{\nu}_\mu} &= 237.80 \pm 2.72 \pm 2.67 \pm 4.76 \ \text{pb}, \end{align*} where the first uncertainty is statistical, the second systematic, and the third is attributed to the luminosity determination. A fit to the differential cross--sections yields the following determination of the \W boson mass: \begin{align*} m_W = 80355 \pm 128 \pm 21 \ \text{MeV}, \end{align*} where the first error is experimental (statistical and systematic errors combined) and the second error is theory systematic errors for measuring . It is important to note that the result is currently blinded, and the analysis is in internal review within the international LHCb collaboration. This analysis serves as a proof--of--principle for determining the W boson mass with intermediate measurements of the differential cross--sections in intervals of the muon transverse momentum. The method of investigation involves novel techniques to extract the W boson mass using differential cross--sections in bins of transverse momentum. By eventually applying this approach to the full Run 2 dataset at = 13 TeV, we expect a precision of around 15 MeV, which would be a competitive measurement that enriches the findings of ATLAS and CMS. Furthermore, the thesis covers the author’s role in the Real--Time Analysis (RTA) project at the LHCb experiment. This involves developing data processing software and optimising workflows for the Run 3 data collection phase