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Measurements of the top quark polarization and top quark pair (t¯t) spin correlations are presented using events containing two oppositely charged leptons (e+e−, e±μ∓, or μ+μ−) produced in proton-proton collisions at a center-of-mass energy of 13 TeV. The data were recorded by the CMS experiment at the LHC in 2016 and correspond to an integrated luminosity of 35.9  fb−1. [...]

The running of the top quark mass is experimentally investigated for the first time. The mass of the top quark in the modified minimal subtraction ($\mathrm{\overline{MS}}$) renormalization scheme is extracted from a comparison of the differential top quark-antiquark ($\mathrm{t\overline{t}}$) cross section as a function of the invariant mass of the $\mathrm{t\overline{t}}$ system to next-to-leading-order theoretical predictions. [...]

This work presents several measurements of the inclusive top pair production cross sectionat a center of mass energy of√s = 13 TeV with the CMS detector. The cross section ismeasured using several data sets collected by the CMS detector in 2015 and 2016. [...]

The next generation of observatories will facilitate the discovery of new types of astrophysical transients. The detection of such phenomena, whose characteristics are presently poorly constrained, will hinge on the ability to perform blind searches. [...]

The European XFEL GmbH (EuXFEL) is a FEL userfacility based on a superconducting accelerator with highduty cycle. Three movable gap SASE Undulator Systems using hybrid NdFeB permanent magnet segments are in operation. [...]

The European XFEL uses a unique beam distribution scheme to direct electron bunches to its three undulator lines.The accelerator delivers up to 600 microsecond long bunchtrains, out of which parts or individual bunches can be selectedfor photon production in any of the FELs. This contribution gives a brief overview of the kicker-septum scheme facilitating this and highlights how even complex bunch patterns can easily be configured via the timing system..

The influence of β′ and γ' precipitates on prismatic and basal planes and long-period stacking ordered (LPSO) fibers on the compressive behavior of high strength Mg-Gd-Y-Zn alloy was investigated using the combination of in-situ synchrotron radiation diffraction and acoustic emission, as well as transmission electron microscopy. After extrusion, the microstructure is characterized by highly oriented LPSO fibers elongated along the extrusion direction within the magnesium matrix. [...]

Standard transverse beam profile measurements at the European XFEL are based on scintillating screen monitors using LYSO:Ce as scintillator material. While it is possible to resolve beam sizes down to a few micrometers with this material, the experience during the XFEL commissioning showed that the measured emittance values were significantly larger than the expected ones. [...]

Since 2016 DESY has been pursuing R towards upgrading its PETRA synchrotron light source to a fourth-generation machine, PETRA IV, which is expected to start operation in 2027. The conceptual design of a 6 GeV seven-bend-achromat-based lattice with an approx. [...]

Bunch compressors are essential for the generation of short bunches with applications in e.g. colliders, free electron lasers, and advanced accelerator concepts. [...]