Big Bang Day: The Making of CERN (Episode 2)

A two-part history of the CERN project. Quentin Cooper explores the fifty-year history of CERN, the European particle physics laboratory in Switzerland

Measurements of the Higgs boson inclusive and differential fiducial cross-sections in the diphoton decay channel with collisions at 13TeV with the ATLAS detector

A measurement of inclusive and differential fiducial cross-sections for the production of the Higgs boson decaying into two photons is performed using 139 fb-1 of proton–proton collision data recorded at 13 TeV by the ATLAS experiment at the Large Hadron Collider. The inclusive cross-section times branching ratio, in a fiducial region closely matching the experimental selection, is measured to be 67   6 fb, which is in agreement with the state-of-the-art Standard Model prediction of 64 +_4 fb. Extrapolating this result to the full phase space and correcting for the branching ratio, the total cross-section for Higgs boson production is estimated to be 58 +- 6 pb. In addition, the cross-sections in four fiducial regions sensitive to various Higgs boson production modes and differential cross-sections as a function of either one or two of several observables are measured. All the measurements are found to be in agreement with the Standard Model predictions. The measured transverse momentum distribution of the Higgs boson is used as an indirect probe of the Yukawa coupling of the Higgs boson to the bottom and charm quarks. In addition, five differential cross-section measurements are used to constrain anomalous Higgs boson couplings to vector bosons in the Standard Model effective field theory framework.Fil: The ATLAS Collaboration. The ATLAS Collaboration; ArgentinaFil: Dova, Maria Teresa. Atlas Experiment, Cern; Suiza. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - La Plata. Instituto de Física La Plata. Universidad Nacional de La Plata. Facultad de Ciencias Exactas. Instituto de Física La Plata; ArgentinaFil: Aad, Georges. Centre National de la Recherche Scientifique; FranciaFil: Abbott, Braden. Oklahoma State University; Estados UnidosFil: Abed Abud, Adam. Cern - European Organization For Nuclear Research. The Cern Council; SuizaFil: Abeling, Kira. Universität Göttingen; AlemaniaFil: Abidi, Syed Haider. Brookhaven National Laboratory; Estados UnidosFil: Aboulhorma, Asmaa. Universite Mohammed V. Rabat; Otros paises de ÁfricaFil: Abramowicz, Halina. Universitat Tel Aviv; IsraelFil: Abreu, Henso. Technion - Israel Institute of Technology; IsraelFil: Abulaiti, Yiming. University of New York; Estados UnidosFil: Achkar, Baida. Universität Göttingen; AlemaniaFil: Adam, Lennart. Johannes Gutenberg Universitat Mainz; AlemaniaFil: Adamczyk, Leszek. AGH University of Science and Technology; PoloniaFil: Adamek, Lukas. University of Toronto; CanadáFil: Adelman, Jahred. Northeastern Illinois University (northeastern Illinois);Fil: Adye, Tim. Rutherford Appleton Laboratory; Reino UnidoFil: Afik, Yoav. Cern - European Organization For Nuclear Research. The Cern Council; SuizaFil: Agapopoulou, Christina. Universite Paris-saclay (universite Paris-saclay);Fil: Agaras, Merve Nazlim. Institut de Fisica D Altes Energies (ifae);Fil: Agarwala, Jinky. Istituto Nazionale di Fisica Nucleare; ItaliaFil: Aggarwal, Anamika. Radboud Universiteit Nijmegen; Países BajosFil: Aguilar Saavedra, Juan Antonio. Universidad de Granada; EspañaFil: Ahmed, Waleed Syed. McGill University. Montreal Neurological Institute and Hospital; CanadáFil: Aizenberg, Iakov. Weizmann Institute of Science; IsraelFil: Akatsuka, Shunichi. Kyoto University; JapónFil: Akbiyik, Melike. Johannes Gutenberg Universitat Mainz; AlemaniaFil: Akesson, Torsten. Lund University; SueciaFil: Akimov, Andrey. Russian Academy of Sciences; RusiaFil: Al Khoury, Konie. Columbia University; Estados UnidosFil: Alberghi, Gian Luigi. Istituto Nazionale di Fisica Nucleare; Itali

Charged-particle multiplicities in pp interactions at root s=900 GeV measured with the ATLAS detector at the LHC ATLAS Collaboration [Elektronisk resurs]

The first measurements from proton-proton collisions recorded with the ATLAS detector at the LHC are presented. Data were collected in December 2009 using a minimum-bias trigger during collisions at a centre-of-mass energy of 900 GeV. The charged-particle multiplicity, its dependence on transverse momentum and pseudorapidity, and the relationship between mean transverse momentum and charged-particle multiplicity are measured for events with at least one charged particle in the kinematic range vertical bar eta vertical bar 500 MeV. The measurements are compared to Monte Carlo models of proton-proton collisions and to results from other experiments at the same centre-of-mass energy. The charged-particle multiplicity per event and unit of pseudorapidity eta = 0 is measured to be 1.333 +/- 0.003(stat.) +/- 0.040(syst.), which is 5-15% higher than the Monte Carlo models predict. 2010 Published by Elsevier B.V.AuthorOverflow(3220

Search for the Higgs boson decay to a ZZ boson and a photon in pppp collisions at s=13\sqrt{s}=13 TeV and 13.613.6 TeV with the ATLAS detector

International audienceA search for the Higgs boson decay to a $Z$ boson and a photon in the $\ell\ellγ$ ($\ell = e, μ$) final state is performed using $pp$ collisions at $\sqrt{s}=13.6$ TeV recorded with the ATLAS detector at the Large Hadron Collider during 2022-2024, corresponding to an integrated luminosity of 165 fb$^{-1}$. The signal yield, normalised to the Standard Model prediction, is measured to be $μ=0.9^{+0.7}_{-0.6}$, compared to an expected value of $μ=1.0\pm0.7$. This corresponds to an observed (expected) signal significance of 1.4 (1.5) standard deviations for the background-only hypothesis. This result is combined with that of a similar search performed with 140 fb$^{-1}$ of $\sqrt{s}=13$ TeV $pp$ collisions to provide the most stringent expected sensitivity to date to this rare decay, namely an observed (expected) signal strength of $μ= 1.3^{+0.6}_{-0.5}$ ($μ= 1.0^{+0.6}_{-0.5}$), corresponding to an observed (expected) significance of 2.5 (1.9) standard deviations. The measurement is consistent with the Standard Model expectation