Austrian Institute of High Energy Physics

Vienna, Austria

Austrian Institute of High Energy Physics

Vienna, Austria
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Kratschmer I.,Austrian Institute of High Energy Physics
Few-Body Systems | Year: 2017

A multitude of precise measurements of J/ ψ, ψ(2 S) and Υ (nS) (n = 1 , 2 , 3) production cross sections and polarizations have been conducted in recent years. These make the investigation of feed-down decays from heavier states crucial to fully comprehend their production mechanisms. Also the study of new, so far unmeasured quarkonium states is essential to complete our picture of quarkonium production. This paper discusses the experimental results of prompt ηc, χc and χb production cross sections, ratios and feed-down fractions in proton–proton (pp) and proton–antiproton (pp¯) collisions. Comparing these measurements to calculations in the NRQCD framework shows a dominance of the color-singlet contribution in case of the χc and χb production, while the ηc cross section is already well described by only the color-singlet contribution. © 2017, The Author(s).

Grossmann J.,Austrian Institute of High Energy Physics
Journal of Instrumentation | Year: 2017

During the HL-LHC era an instantaneous luminosity of 5×1034 cm-2s-1 will be reached and possibly 3000 fb-1 integrated luminosity will be delivered. This results in the requirement for a major upgrade of the CMS Outer Tracker detector. This contribution briefly reviews the module types and the front end readout electronics foreseen in the preparation program known as phase 2 upgrade. R&D towards the construction of full module prototypes for the Pixel-Strip (PS) module is ongoing. The module combines a macro-pixel sensor and a strip sensor and has pT -discrimination capability at module level. The current experience from module construction with a demonstrator assembly and initial laboratory testing with an alternative module concept for the PS-module is shown. A possible calibration method is introduced. © 2017 IOP Publishing Ltd and Sissa Medialab srl.

Gambino P.,University of Turin | Schwanda C.,Austrian Institute of High Energy Physics
Physical Review D - Particles, Fields, Gravitation and Cosmology | Year: 2014

We perform global fits to the moments of semileptonic B-decay distributions and extract |Vcb|, the heavy quark masses, and the nonperturbative parameters of the heavy quark expansion. We include next-to-next-to-leading-order perturbative corrections and recent determinations of the charm mass and discuss how they improve the precision of the global fit. In particular, using the mc determination of Chetyrkin et al. [Phys. Rev. D80, 074010 (2009)], we get mbkin=4.541(23) GeV and |Vcb|=(42.42±0.86)×10-3. We also discuss the implications of the new fits for the normalization of rare B decays, the zero-recoil sum rule in B→D*ℓν, and the inclusive determination of |Vub|. © 2014 American Physical Society.

Deppisch F.F.,University College London | Graf L.,University College London | Kulkarni S.,Austrian Institute of High Energy Physics | Patra S.,Max Planck Institute for Nuclear Physics | And 4 more authors.
Physical Review D - Particles, Fields, Gravitation and Cosmology | Year: 2016

We interpret the 2 TeV excesses at the LHC in a left-right symmetric model with Higgs doublets and spontaneous D-parity violation. The light neutrino masses are understood via a linear seesaw, suppressed by a high D-parity breaking scale, and the heavy neutrinos have a pseudo-Dirac character. In addition, with a suppressed right-handed gauge coupling gR/gL≈0.6 in an SO(10) embedding, we can thereby interpret the observed eejj excess at CMS. We show that it can be reconciled with the diboson and dijet excesses within a simplified scenario based on our model. Moreover, we find that the mixing between the light and heavy neutrinos can be potentially large, which would induce dominant nonstandard contributions to neutrinoless double beta decay via long-range λ and η neutrino exchange. © 2016 American Physical Society.

Neudecker D.,Vienna University of Technology | Fruhwirth R.,Austrian Institute of High Energy Physics | Leeb H.,Vienna University of Technology
Nuclear Science and Engineering | Year: 2012

The occurrence of unexpected mean values in statistical analyses of experimental data, known as Peelle's pertinent puzzle in nuclear data evaluation, is revisited. It is shown in terms of Bayesian statistics, it is not caused exclusively by nonlinearities but is due to improper estimates of covariance matrices of experiments. Applying the correct covariance matrix leads to the exact posterior expectation value and variance for an arbitrary number of uncorrelated measurement points that are normalized with the same quantity.

Eberl H.,Austrian Institute of High Energy Physics
Fortschritte der Physik | Year: 2010

Loop calculations in the MSSM have become a vast field. Some related works done in the theory SUSY group at the HEPHY Vienna are presented. The basics of regularisation and renormalization in the MSSM are discussed. We further study CP violating rate asymmetries induced by loops. A recent study on H±t production at the LHC combined with subsequent H± decays is presented. © 2010 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

Kratschmer I.,Austrian Institute of High Energy Physics
Journal of Physics: Conference Series | Year: 2014

The CMS experiment at the LHC studies conventional and exotic quarkonia. CMS measured the quarkonium polarization of prompt Ψ (nS) and Υ (nS) states, using 2011 data taken in pp collisions at √s = 7 TeV. No strong polarization was observed in any of the states. Using the Ψ (nS) polarization results and other polarization hypotheses, the prompt Ψ(nS) differential production cross section was determined up to and even beyond 100 GeV. The production of X(3872) in its decay to J/ψπ+π- was also measured, using data taken in pp collisions at √s = 7 TeV. The cross section times the branching fraction of the X(3872) relative to the one of ψ(2S) and the fraction of X(3872) originating from B decays were determined. With the help of these results, the prompt X(3872) differential cross section times branching fraction as a function of pT was extracted. Furthermore, a search for the exotic quarkonium, Xb, decaying to Ψ(1S) π+π- in the mass range of 10 to 11 GeV was conducted, using data collected in pp collisions at √s = 8 TeV. No evidence of a Xb signal was observed. An upper limit on the relative inclusive production cross section times branching ratio of the Xb and Ψ(2S) states at 95% CL was set. © Published under licence by IOP Publishing Ltd.

Friedl M.,Austrian Institute of High Energy Physics
Nuclear Instruments and Methods in Physics Research, Section A: Accelerators, Spectrometers, Detectors and Associated Equipment | Year: 2010

The Belle experiment at KEK (Tsukuba, Japan) was inaugurated in 1999 and has delivered excellent physics results since then, which were, for example, recognized in the Nobel Prize award 2008 to Kobayashi and Masukawa. An overall luminosity of 895 fb-1 has been recorded as of December 2008, and the present system will be running until 1 ab-1 is achieved. After that, a major upgrade is foreseen for both the KEK-B machine and the Belle detector. Already in 2004, the Letter of Intent for KEK Super B Factory was published. Intermediate steps of upgrade were considered for the Silicon Vertex Detector (SVD), which performs very well but already got close to its limit regarding the occupancy in the innermost layer and dead time. Eventually it was decided to keep the existing SVD2 system until 1 ab-1 and completely replace the silicon detector as well as its readout system for Super-Belle. The future SVD will be composed of double-sided silicon sensors as the present detector, but equipped with faster readout electronics, namely the APV25 chips originally made for CMS at CERN. Moreover, it will be enlarged by two additional layers and equipped with a double layer of DEPFET pixel detectors surrounding the beam pipe. The silicon sensors will be fabricated from 6 in. wafers (compared to the current 4 in. types) and the readout chain will be completely replaced, including front-end, repeaters and the back-end electronics in the counting house. © 2010 Elsevier B.V. All rights reserved.

Brandstetter J.,Austrian Institute of High Energy Physics
Nuclear and Particle Physics Proceedings | Year: 2016

The measurements of Higgs boson properties, mass, spin/CP, couplings, off-shell cross sections and constraints on invisible width are summarized and compared with standard model expectations. The analysis is based on pp collision data collected at centre-of-mass energies of 7 and 8 TeV by the CMS experiment at the LHC, corresponding to integrated luminosities of 5 fb-1 and 20 fb-1, respectively. © 2016 Elsevier B.V.

Kratschmer I.,Austrian Institute of High Energy Physics
Nuclear and Particle Physics Proceedings | Year: 2016

The performance of the muon reconstruction and identification in the CMS experiment at the LHC has been studied on data collected in pp collisions at √s=7 and 8 TeV. Results from the measurements of the muon identification efficiencies, hadron misidentification probabilities as well as the muon momentum scale and resolution are presented. © 2015 Elsevier B.V.

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