72 Works

European XFEL Annual Report 2013

Massimo Altarelli

Diffraction Orders of the SASE3 Monochromator

Natalia Gerasimova
The data presented in this work comprises a detailed analysis on the interplay between diffraction orders of the SASE3 monochromator, which includes transmission by optics (both due to efficiency and geometrical transmission), constraints on operational range, and details on spatial separation of the orders. The possible harmful orders to be dumped and their geometry are identified and described; the dispersed beam at exit slit plane is discussed. In addition to simultaneous usage of different diffraction...

The ZFITTER homepage (June 25, 2014)

Tord Riemann

Proceedings of the 6th International Workshop on Top-Quark Physics (TOP 2013).

Ulrich Husemann, Hannes Mildner & Frank Roscher
Proc. of TOP 2013; DESY-PROC-2014-02; ISSN 1435-8077

Measurement of the top polarization in the lepton+jets decay channel with the D0 detector.

Kamil Augsten
Contribution to Proceedings

Measurement of the leptonic $\mathbf{t\bar t}$ charge asymmetry in the dilepton channel with the D0 detector.

Antoine Chapelain
Contribution to Proceedings

Tau (or no) leptons in top quark decays at hadron colliders.

Michele Gallinaro
Measurements in the final states with taus or with no-leptons are among the most challenging as they are those with the smallest signal-to-background ratio. However, these final states are of particular interest as they can be important probes of new physics. Tau identification techniques and cross section measurements in top quark decays in these final states are discussed. The results, limited by systematical uncertainties, are consistent with standard model predictions, and are used to set...

Inclusive single top cross section at the LHC.

Rebeca Gonzalez Suarez
The three single-top-quark production modes are presented. The t-channel, established at the Tevatron, has the highest production rate and its cross-section has been measured at the LHC at 7 and 8~TeV. Evidence of the tW associated production was presented with 7~TeV data by ATLAS and CMS and observation was achieved at 8~TeV by the CMS experiment. An upper limit on the s-channel cross-section was set with 7~TeV data by ATLAS.

Heavy resonances and top production Overview of top tagging techniques.

Jose Juknevich
Contribution to Proceedings

Measurements of $\mathbf{t\bar t} \pmb{\gamma}$ , $\mathbf{t\bar t + Z}$, and $\mathbf{t\bar t + W}$ production.

James Keaveney
Measurements of the production of top quark pairs in association with electroweak vector bosons from the CMS, ATLAS and CDF collaborations are presented. The CDF collaboration measures the cross section of top pair plus photon production and the ratio of this cross section the to inclusive top pair cross section using 6 fb$^{-1}$ of data at $\sqrt{s} = 1.96$ TeV with the results $\sigma_{t\bar{t}\gamma} = 0.18 \pm 0.07 (stat.) \pm 0.04 (sys.) \pm 0.01 (lumi.)$...

Observation of associated production of a single top quark and W boson at 8 TeV.

Duncan Leggat
Contribution to Proceedings

Leptons: $\mathbf{e}$, $\boldsymbol{\mu}$, $\boldsymbol{\tau}$ + systematic uncertainties.

Timothee Theveneaux-Pelzer & Javier Fernandez Menendez
An overview of the charged lepton performance in the ATLAS and CMS experiments at the LHC and in the CDF and D0 experiments at the Tevatron is given, in the specific context of physics analyses requiring the selection of leptons from top-quark decays. The trigger and reconstruction algorithms are presented, as well as the identification and isolation criteria, pointing out the specificities of top-quark analysis selections. The impact of the lepton-related experimental systematic uncertainties are...

Measurement of jet multiplicity distributions insemi-leptonic top quark pair events.

Shawn Williamson
The normalized differential cross section of $t\bar{t}$ events in the semileptonic decay channel in jet multiplicity bins is presented, measured in proton-proton collisions using $5.0\,\text{fb}^{-1}$ of data collected at $\sqrt{s} = 7\,\text{TeV}$. Additionally, the normalized differential cross section of top quark pair production in bins of the number of radiated additional hard partons is measured. These measurements are sensitive to additional radiation at the top quark scale. Comparisons of data with predictions from different Monte...

Recent CMS Results on Heavy Quarks and Hadrons.

Alice Bean
Using dedicated dimuon triggers with the CMS detector, several results are presented from data collected during 2010, 2011, and 2012. Polarization measurements are shown for the $J/\Psi$ and $\Upsilon$ states. A search for states decaying to $\Upsilon(1S)\pi^+\pi^-$ is presented. The $\Lambda_b^0$ lifetime has been measured. An observation of the decay $B_S\rightarrow \mu^+\mu^-$ decay is presented.

Lectures on new physics searches in $B\to D^{(*)}\tau\nu_\tau$.

Svjetlana Fajfer & Ivan Nisandzic
The Standard model's predictions for the rates for $B\to D^{*} \tau \nu_\tau$ and $B\to D\tau\nu_\tau$ differ from the experimental results. The difference might be accounted by the presence of new physics. The understanding of the non-perturbative QCD dynamics in the meson transitions is crucial in order to refine the searches for new physics effects. We give short introduction to heavy quark effective theory (HQET) and then investigate the most general set of lowest dimensional effective...

Spectroscopy and Regge Trajectories of Heavy Quarkonia.

D. Ebert, R. N. Faustov & V. O. Galkin
The mass spectra of charmonia and bottomonia are calculated in the framework of the relativistic quark model. The Regge trajectories of heavy quarkonia are constructed. All daughter trajectories are almost linear and parallel, while parent trajectories exhibit some nonlinearity. Such nonlinearity occurs only in the vicinity of ground states and few lowest excitations and is more pronounced for bottomonia, while it is only marginal for charmonia. The obtained results are compared with available experimental data,...

Small-$x$ behavior of deep-inelastic structure functions F$_2$ and F$^{cc}_2$.

Anatoly Kotikov
It is shown that in the leading twist approximation of the Wilson operator product expansion with ``frozen'' and analytic strong coupling constants, Bessel-inspired behavior of the structure functions $F_2$ and $F_2^{cc}$ at small $x$ values, obtained for a flat initial condition in the DGLAP evolution equations, leads to good agreement with the deep inelastic scattering experimental data from HERA.

Rare Semileptonic $B^+ \to \pi^+ \ell^+ \ell^-$ Decay.

Ahmed Ali, Alexander Parkhomenko & Aleksey Rusov
We present a precise calculation of the dilepton invariant-mass spectrum and branching fraction for $B^+ \to \pi^+ \ell^+ \ell^-$ ($\ell^\pm = e^\pm, \mu^\pm $) in the Standard Model (SM) based on the effective Hamiltonian approach for the $b \to d \ell^+ \ell^-$ transitions. Theoretical estimates strongly depend on the form factors~$f_+ (q^2)$, $f_0 (q^2)$ and~$f_T (q^2)$. Of these, $f_+ (q^2)$ is well measured in the semileptonic decays $B \to \pi \ell \nu_\ell$ and we use...

The rise and fall of the fourth quark-lepton generation.

M. I. Vysotsky
The existence of the fourth quark-lepton generation is not excluded by the electroweak precision data. However, the recent results on the 126 GeV higgs boson production and decay do not allow an extra generation at least as far as the perturbation theory can be used.

Proceedings of the Helmholtz International Summer School Physics of Heavy Quarks and Hadrons, Dubna, July, 15-28 2013.

Ahmed Ali, Yury Bystritskiy & Mikhail Ivanov
Proc. of HQ2013; DESY-PROC-2013-03; ISSN 1435-8077

Particle physics 2013 - Highlights and Annual Report

Thomas Schoerner-Sadenius, Manfred Fleischer, Michael Medinnis & Ilka Flegel

The ZFITTER homepage (June 25, 2014)

Tord Riemann

Stop and other searches.

Caroline Collard
The latest results from LHC on direct pair production of third-generation squarks are reviewed. We present searches performed for different decay modes of stop and sbottom using the full set of 8 TeV LHC data recorded in 2012 (corresponding to 20/fb).

New physics in single-top production.

Oliver Maria Kind
In this paper an overview of recent results on the search for physics beyond the Standard Model in the electro-weak top-quark production from the ATLAS, D0, CDF and CMS collaborations is given. This includes searches for $\Wprime$ and $\bstar$ resonances as well as measurements of $\CP$ violation, the $\Wboson$ helicity fractions and the top-quark polarisation in single-top production. A brief review on the search for flavour-changing neutral currents and cross-section measurements with respect to the...

Theoretical summary.

Eric Laenen
This is a summary of theoretical progress presented at TOP2013. I review new results and methods in producing top quarks singly, in pairs or in association with other particles and/or jets, in addition to special aspects of its production like the forward-backward asymmetry. The role of top in certain New Physics models was discussed, as well as the careful definition of its mass. The emergent picture is one of impressive progress on the theoretical front...

Registration Year

  • 2014

Resource Types

  • Text