OpenAccess

Photon-science facilities such as X-ray free-electron lasers (XFELs) and intense-laser facilities are emerging world-wide with some of them producing sub-fs X-ray pulses. These facilities are in need of a high-precision timing distribution system, which can synchronize various microwave and optical sub-sources across multi-km distances with attosecond precision. [...]

XFEL läuft schon seit einiger Zeit im Routinebetrieb. Jedoch sind noch Bemühungen im Gange, den Betrieb weiter zu optimieren, und insbesondere auch höhere Energien zu erreichen.Hierzu werden die Cavitiy-Spannungen sukzessiv erhöht, bis das sogenannte Quench-Limit erreicht wird. [...]

Abstract (Springer)Hard processes in diffractive deep-inelastic scattering can be described by a factorisation into parton-level subprocesses and diffractive parton distributions. In this framework, cross sections for inclusive dijet production in diffractive deep-inelastic electron–proton scattering (DIS) are computed to next-to-next-to-leading order (NNLO) QCD accuracy and compared to a comprehensive selection of data. [...]

Using the entire Belle data sample of 980 ${\rm fb}^{-1}$ of $e^+e^-$ collisions, we present the results of a study of excited $\Omega_c$ charmed baryons in the decay mode $\Xi_c^+K^-$. We show confirmation of four of the five narrow states reported by the LHCb Collaboration: the $\Omega_c(3000)$ , $\Omega_c(3050)$, $\Omega_c(3066)$, and $\Omega_c(3090)$..

We present a measurement of the Michel parameters of the $\tau$ lepton, $\bar{\eta}$ and $\xi\kappa$, in the radiative leptonic decay $\tau^- \rightarrow \ell^- \nu_{\tau} \bar{\nu}_{\ell} \gamma$ using 711~f$\mathrm{b}^{-1}$ of collision data collected with the Belle detector at the KEKB $e^+e^-$ collider. The Michel parameters are measured in an unbinned maximum likelihood fit to the kinematic distribution of $e^+e^-\rightarrow\tau^+\tau^-\rightarrow (\pi^+\pi^0 \bar{\nu}_\tau)(\ell^-\nu_{\tau}\bar{\nu}_{\ell}\gamma)$ $(\ell=e$ or $\mu)$. [...]

A search for the electroweak production of supersymmetric particles in proton-proton collisions at a center-of-mass energy of 13 TeV is presented in final states with a $\tau$ lepton pair. Both hadronic and leptonic decay modes are considered for the $\tau$ leptons. [...]

Thermoluminoscense dosimeters (TLD) are installed at several positions along the XFEL main linac tunnel inside the concrete shielding of the electronics racks. They have been readout regularly in every longer shutdown. [...]

Little Higgs models - which can most easily be thought of as a variant ofcomposite Higgs models - explain a light Higgs boson at 125 GeV as anpseudo-Nambu-Goldstone boson of a spontaneously broken global symmetry.The mechanism of collective symmetry breaking shifts the UV scale ofthese models to the 10 TeV scale and higher. T-parity is introduced asa discrete symmetry to remove tree-level constraints on the electroweakprecision data. [...]