Technical University of Dortmund

About: Technical University of Dortmund is a education organization based out in Dortmund, Nordrhein-Westfalen, Germany. It is known for research contribution in the topics: Context (language use) & Large Hadron Collider. The organization has 13028 authors who have published 27666 publications receiving 615557 citations. The organization is also known as: Dortmund University & University of Dortmund.

Measurement of Higgs boson production in the diphoton decay channel in pp collisions at center-of-mass energies of 7 and 8 TeV with the ATLAS detector

Abstract: A measurement of the production processes of the recently discovered Higgs boson is performed in the two-photon final state using 4.5 fb(-1) of proton-proton collisions data at root s = 7 TeV and 20.3 fb(-1) at root s = 8 TeV collected by the ATLAS detector at the Large Hadron Collider. The number of observed Higgs boson decays to diphotons divided by the corresponding Standard Model prediction, called the signal strength, is found to be mu = 1.17 +/- 0.27 at the value of the Higgs boson mass measured by ATLAS, m(H) = 125.4 GeV. The analysis is optimized to measure the signal strengths for individual Higgs boson production processes at this value of m(H). They are found to be mu(ggF) = 1.32 +/- 0.38, mu(VBF) = 0.8 +/- 0.7, mu(WH) = 1.0 +/- 1.6, mu(ZH) = 0.1(-0.1)(+3.7), and mu t (t) over barH = 1.6(-1.8)(+2.7), for Higgs boson production through gluon fusion, vector-boson fusion, and in association with a W or Z boson or a top-quark pair, respectively. Compared with the previously published ATLAS analysis, the results reported here also benefit from a new energy calibration procedure for photons and the subsequent reduction of the systematic uncertainty on the diphoton mass resolution. No significant deviations from the predictions of the Standard Model are found.

$R_K$ and $R_{K^{\ast}}$ beyond the Standard Model

Abstract: Measurements of the ratio of $B\ensuremath{\rightarrow}{K}^{*}\ensuremath{\mu}\ensuremath{\mu}$ to $B\ensuremath{\rightarrow}{K}^{*}ee$ branching fractions, ${R}_{{K}^{*}}$, by the LHCb Collaboration strengthen the hints from previous studies with pseudoscalar kaons, ${R}_{K}$, for the breakdown of lepton universality, and therefore the Standard Model (SM), to $\ensuremath{\sim}3.5\ensuremath{\sigma}$. Complementarity between ${R}_{K}$ and ${R}_{{K}^{*}}$ allows us to pin down the Dirac structure of the new contributions to be predominantly SM-like chiral, with possible admixture of chirality-flipped contributions of up to $\mathcal{O}(\mathrm{few}10%)$. Scalar and vector leptoquark representations $({S}_{3},{V}_{1},{V}_{3})$ plus possible (${\stackrel{\texttildelow{}}{S}}_{2},{V}_{2}$) admixture can explain ${R}_{K,{K}^{*}}$ via tree-level exchange. Flavor models naturally predict leptoquark masses not exceeding a few TeV, with couplings to third-generation quarks at $O(0.1)$, implying that this scenario can be directly tested at the LHC.

Searches for Extended and Point-like Neutrino Sources with Four Years of IceCube Data

Abstract: We present results on searches for point-like sources of neutrinos using four years of IceCube data, including the first year of data from the completed 86 string detector The total livetime of the combined data set is 1373 days For an E-2 spectrum, the observed 90% C L flux upper limits are similar to 10(-12) TeV-1 cm(-2) s(-1) for energies between 1 TeV and 1 PeV in the northern sky and similar to 10(-11) TeV-1 cm(-2) s(-1) for energies between 100 TeV and 100 PeV in the southern sky This represents a 40% improvement compared to previous publications, resulting from both the additional year of data and the introduction of improved reconstructions In addition, we present the first results from an all-sky search for extended sources of neutrinos We update the results of searches for neutrino emission from stacked catalogs of sources and test five new catalogs; two of Galactic supernova remnants and three of active galactic nuclei In all cases, the data are compatible with the background-only hypothesis, and upper limits on the flux of muon neutrinos are reported for the sources considered

Thermodynamics and correlation functions of the Falicov-Kimball model in large dimensions

Abstract: In this contribution we present the exact solution of the Falicow-Kimball-model for large dimensions and finite temperatures. We find the phase-transition, give an expression for the critical temperature and calculate several correlation functions of this system. Our result is obtained by mapping the lattice problem on a soluble atomic problem in a generalized time-dependent external field, which allows the extraction of the exact functional dependence of the self-energy on the Green's function.