Englische Version: A search for a long-lived, heavy neutral lepton ($\mathcal{N}$) in 139~fb$ {-1}$ of $\sqrt{s}=13$~TeV $pp$ collision data collected between 2015 and 2018 by the ATLAS detector at the Large Hadron Collider is presented. The $\mathcal{N}$ is assumed to be produced via $W \rightarrow \mathcal{N} \mu$ or $W \rightarrow \mathcal{N} e$ and decays into two charged leptons and a neutrino, forming a unique displaced vertex signature. A novel technique is used to reconstruct the $\mathcal{N}$ mass that discriminates between signal and background. No signal is observed, and limits are set on the squared mixing parameters of the $\mathcal{N}$ with the left-handed neutrino states for the $\mathcal{N}$ mass range $3$~GeV~$

This second open access volume of the handbook series deals with detectors, large experimental facilities and data handling, both for accelerator and non-accelerator based experiments. It also covers applications in medicine and life sciences. A joint CERN-Springer initiative, the "Particle Physics Reference Library" provides revised and updated contributions based on previously published material in the well-known Landolt-Boernstein series on particle physics, accelerators and detectors (volumes 21A, B1,B2,C), which took stock of the field approximately one decade ago. Central to this new initiative is publication under full open access

Since the 1980s the cross-disciplinary, multidimensional field of links between cosmology and particle physics has been widely recognised by theorists, studying cosmology, particle and nuclear physics, gravity, as well as by astrophysicists, astronomers, space physicists, experimental particle and nuclear physicists, mathematicians and engineers.The relationship between cosmology and particle physics is now one of the important topics of discussion at any scientific meeting both on astrophysics and high energy physics.Cosmoparticle physics is the result of the mutual relationship between cosmology and particle physics in their search for physical mechanisms of inflation, baryosynthesis, nonbaryonic dark matter, and for fundamental unity of the natural forces underlying them. The set of nontrivial links between cosmological consequences of particle models and the astrophysical data on matter and radiation in the modern universe maintains cosmoarcheology, testing self-consistently particular predictions of particle models on the base of cosmological scenarios, following from them. Complex analysis of all the indirect cosmological, astrophysical and microphysical phenomena makes cosmoparticle physics the science of the world and renders quantitatively definite the correspondence between its micro- and macroscopic structure.This book outlines the principal ideas of the modern particle theory and cosmology, their mutual relationship and the nontrivial correspondence of their physical and astrophysical effects.

Describes the technology and engineering of the Large Hadron collider (LHC), one of the greatest scientific marvels of this young 21st century. This book traces the feat of its construction, written by the head scientists involved, placed into the context of the scientific goals and principles.

This book reviews the present state of knowledge of the anomalous magnetic moment a=(g-2)/2 of the muon. The muon anomalous magnetic moment is one of the most precisely measured quantities in elementary particle physics and provides one of the most stringent tests of relativistic quantum field theory as a fundamental theoretical framework. It allows for an extremely precise check of the standard model of elementary particles and of its limitations.