S. Menke

Over the past decade, a large number of jet substructure observables have been proposed in the literature, and explored at the LHC experiments. Such observables attempt to utilize the internal structure of jets in order to distinguish those initiated by quarks, gluons, or by boosted heavy objects, such as top quarks and W bosons. This report, originating from and motivated by the BOOST2013 workshop, presents original particle-level studies that aim to improve our understanding of the relationships between jet substructure observables, their complementarity, and their dependence on the underlying jet properties, particularly the jet radius and jet transverse momentum. This is explored in the context of quark/gluon discrimination, boosted W boson tagging and boosted top quark tagging.

This note describes the performance of the ATLAS calorimeter clustering algorithms, which provide inputs for particle identification. ATLAS uses two principal alg orithms. The first is the “sliding-window” algorithm, which clusters calorimeter cells within fixe d-size rectangles; results from this are used for electron, photon, and tau lepto n identification. The second is the “topological” algorithm, which clusters together neighboring ce lls, as long as the signal in the cells is significant compared to noise. The results of this seco nd algorithm are further used for jet and missing transverse energy reconstruction . This note first summarizes the steps of the calorimeter reconstruction softwar e. A detailed description of the two clustering algorithms is then given. A last section su mmarizes their performance. The results presented in this note are obtained with the ATLAS ATHENA software releases 12 and 13. ATL-LARG-PUB-2008-002

The hadronic decays of the $\ensuremath{\tau}$ lepton can be used to determine the effective charge ${\ensuremath{\alpha}}_{\ensuremath{\tau}}{(m}_{{\ensuremath{\tau}}^{\ensuremath{'}}}^{2})$ for a hypothetical $\ensuremath{\tau}$ lepton with a mass in the range $0<{m}_{{\ensuremath{\tau}}^{\ensuremath{'}}}<{m}_{\ensuremath{\tau}}.$ This definition provides a fundamental definition of the QCD coupling at low mass scales. We study the behavior of ${\ensuremath{\alpha}}_{\ensuremath{\tau}}$ at low mass scales directly from first principles and without any renormalization-scheme dependence by looking at the experimental data from the OPAL Collaboration. The results are consistent with the freezing of the physical coupling at mass scales ${s=m}_{{\ensuremath{\tau}}^{\ensuremath{'}}}^{2}$ of order $1{\mathrm{GeV}}^{2}$ with a magnitude ${\ensuremath{\alpha}}_{\ensuremath{\tau}}\ensuremath{\sim}0.9\ifmmode\pm\else\textpm\fi{}0.1.$

These are the proceedings of the "Workshop on Precision Measurements of alphas" held at the Max-Planck-Institute for Physics, Munich, February 9-11, 2011. The workshop explored in depth the determination of alphas(mZ) in the MS-bar scheme from the key categories where high precision measurements are currently being made, including DIS and global PDF fits, tau-decays, electroweak precision observables and Z-decays, event-shapes, and lattice QCD. These proceedings contain a short summary contribution from the speakers, as well as the lists of authors, conveners, participants, and talks.

A full azimuthal phi-wedge of the ATLAS liquid argon end-cap calorimeter has been exposed to beams of electrons, muons and pions in the energy range 6 GeV <= E <= 200 GeV at the CERN SPS. The angular region studied corresponds to the ATLAS impact position around the pseudorapidity interval 1.6 < |eta| < 1.8. The beam test set-up is described. A detailed study of the performance is given as well as the related intercalibration constants obtained. Following the ATLAS hadronic calibration proposal, a first study of the hadron calibration using a weighting ansatz is presented. The results are compared to predictions from Monte Carlo simulations, based on GEANT 3 and GEANT 4 models.

The pseudorapidity region 2.5<|η|<4.0 in ATLAS is a particularly complex transition zone between the endcap and forward calorimeters. A set-up consisting of 14 resp. 18 of the full azimuthal acceptance of the ATLAS liquid argon endcap and forward calorimeters has been exposed to beams of electrons, pions and muons in the energy range E⩽200GeV at the CERN SPS. Data have been taken in the endcap and forward calorimeter regions as well as in the transition region. This beam test set-up corresponds very closely to the geometry and support structures in ATLAS. A detailed study of the performance in the endcap and forward calorimeter regions is described. The data are compared with MC simulations based on GEANT 4 models.

We project the performance of the ATLAS liquid argon endcap and forward calorimeters at the planned high luminosity LHC option HL-LHC by exposing small calorimeter modules of the electromagnetic, hadronic, and forward calorimeters to high intensity beams at IHEP/Protvino. The beam intensity extends well beyond the maximum expected for these calorimeters at HL-LHC. The signal reconstruction and calorimeter performance have been studied in full detail.

One of the largest theoretical uncertainties assigned to the strong coupling constant alpha_s as determined from hadronic tau decays stems from the differences in the results for Fixed Order Perturbation Theory (FOPT), Contour Improved Perturbation Theory (CIPT) and Renormalon Chain Perturbation Theory (RCPT). It is often argued that the three methods differ in the treatment of higher orders only and therefore the full difference should be treated as theoretical error. Recently other arguments either in favor of FOPT, CIPT or RCPT have been given, but none of those is able to combine all three to a single value in the strong coupling constant. In this note I will show that FOPT alone has a much larger uncertainty than previously assumed and therefore agrees within error with CIPT. Furthermore a more appropriate matching of the different schemes used in RCPT reduces the difference to the CIPT result by a factor of 6. Together with recently published results for the 4th order term K_4 this reduces the theoretical error on alpha_s by a factor of 2.5 compared to the previously assumed spread of the three perturbative approaches.

In this paper it is shown that a measurement of the relative luminosity changes at the LHC may be obtained by analysing the currents drawn from the high voltage power supplies of the electromagnetic section of the forward calorimeter of the ATLAS detector. The method was verified with a reproduction of a small section of the ATLAS forward calorimeter using proton beams of known beam energies and variable intensities at the U-70 accelerator at IHEP in Protvino, Russia. The experimental setup and the data taking during a test beam run in April 2008 are described in detail. A comparison of the measured high voltage currents with reference measurements from beam intensity monitors shows a linear dependence on the beam intensity. The non-linearities are measured to be less than 0.5 % combining statistical and systematic uncertainties.

The local hadronic calibration scheme developed for the reconstruction and calibration of jets and missing transverse energy in ATLAS has been evaluated using data obtained during combined beam tests of modules of the ATLAS liquid argon endcap and forward calorimeters. These tests covered the pseudorapidity range of 2.5<|η|<4.0. The analysis has been performed using special sets of calibration weights and corrections obtained with the Geant4 simulation of a detailed beam-test setup. The evaluation itself has been performed through the careful study of specific calorimeter performance parameters such as e.g. energy response and resolution, shower shapes, as well as different physics lists of the Geant4 simulation.

Over the past decade, a large number of jet substructure observables have been proposed in the literature, and explored at the LHC experiments. Such observables attempt to utilize the internal structure of jets in order to distinguish those initiated by quarks, gluons, or by boosted heavy objects, such as top quarks and W bosons. This report, originating from and motivated by the BOOST2013 workshop, presents original particle-level studies that aim to improve our understanding of the relationships between jet substructure observables, their complementarity, and their dependence on the underlying jet properties, particularly the jet radius and jet transverse momentum. This is explored in the context of quark/gluon discrimination, boosted W boson tagging and boosted top quark tagging.

The determination of |Vub| from inclusive semileptonic B decays is limited by uncertainties in modeling the decay distributions in b→uℓν transitions. The largest uncertainties arise from the limited knowledge of the appropriate b quark mass and Fermi momentum to use in the parameterization of the shape function. This Letter presents a new method in which these shape function parameters are constrained by the same data used to measure |Vub|. The method requires measurements of the momenta of both the charged lepton and the neutrino in semileptonic B decays. From these quantities two complementary observables can be constructed, one for discriminating between b→uℓν transitions and background and the other for constraining the shape function. Using this technique the uncertainties in |Vub| from the shape function may be significantly reduced.

The readout electronics of the ATLAS Hadronic Endcap Calorimeter will have to withstand the about ten times larger radiation environment of the future high-luminosity LHC (HL-LHC) compared to their design values. The GaAs ASIC which comprises the heart of the readout electronics has been exposed to neutron and proton radiation with fluences up to ten times the total expected fluences for ten years of running of the HL-LHC. Neutron tests were performed at the NPI in Rez, Czech Republic, where a 36 MeV proton beam is directed on a thick heavy water target to produce neutrons. The proton irradiation was done with 200 Me V protons at the PROSCAN area of the Proton Irradiation Facility at the PSI in Villigen, Switzerland. In-situ measurements of S-parameters in both tests allow the evaluation of frequency dependent performance parameters - like gain and input impedance - as a function of the fluence. The linearity of the ASIC response has been measured directly in the neutron tests with a triangular input pulse of varying amplitude. The performance measurements and expected performance degradations under HL-LHC conditions are presented.

The uncertainty in jet energy scale is one of the dominating systematic errors for many measurements at hadron colliders – most notably for the measurement of the top-quark-mass, inclusive jet cross section measurements and last but not least for events with large missing transverse energy as expected in searches beyond the standard model. This talk will review the approaches taken at Tevatron towards controlling the jet energy scale and discuss prospects for the LHC experiments.

A beam telescope consisting of four double sided, DC coupled microstrip detectors with VLSI readout electronics has been built and tested in a 70 GeV μ− beam at CERN. A signal-to-noise ratio of 53:1 and a spatial resolution of 2.7 μm (junction side) and 4.8 μm (ohmic side) have been observed on the best detectors. A telescope performance for a particle track of σxy = 2–3 μm and σslope = 2–3 μrad on the front face of a test object was achieved.

Abstract The spectral functions of the vector current and the axial-vector current have been measured in hadronic τ decays using the OPAL detector at LEP. Within the framework of the Operator Product Expansion a simultaneous determination of the strong coupling constant α s , the non-perturbative operators of dimension 6 and 8 and of the gluon condensate has been performed. Different perturbative descriptions have been compared to the data. The Contour Improved Fixed Order Perturbation Theory gives α s ( m τ 2 ) = 0.348 ± 0.009 exp ± 0.019 theo at the τ-mass scale and α s ( m Z 2 ) = 0.1219 ± 0.0010 exp ± 0.0017 theo at the Z 0 -mass scale. The values obtained for α s ( m Z 2 ) using Fixed Order Perturbation Theory or Renormalon Chain Resummation are 2.3% and 4.1% smaller, respectively. The ‘running’ of the strong coupling between s 0 ≅ 1.3 GeV 2 and s 0 = m τ 2 has been tested from direct fits to the integrated differential hadronic decay rate R τ ( s 0 ). A test of saturation of QCD sum rules at the τ-mass scale has been performed.

The latest measurements of the top quark mass obtained by the ATLAS and CMS experiments at the LHC for centre-of-mass energies of 7 and 8 TeV are presented.The mass of the top quark is measured using several methods and channels, including the reconstructed invariant mass distribution of the top quark and shapes of top quark decay distributions.Measurements based on the inclusive t t cross section and novel observables based on the differential cross section in the t t + 1jet channel are also discussed.The results of the various channels are combined and compared to the world average.

The latest measurements of the top quark mass obtained by the ATLAS and CMS experiments at the LHC for centre-of-mass energies of 7 and 8 TeV are presented. The mass of the top quark is measured using several methods and channels, including the reconstructed invariant mass distribution of the top quark and shapes of top quark decay distributions. Measurements based on the inclusive tt-bar cross section and novel observables based on the differential cross section in the tt-bar + 1 jet channel are also discussed. The results of the various channels are combined and compared to the world average.

We review one of the most accurate low-energy determinations of αs. Comparing at short distances the QCD static energy at three loops and resummation of the next-to-next-to leading logarithms with its determination in 2+1-flavor lattice QCD, we obtain αs (1.5 GeV) = 0.336+0.012-0.008, which corresponds to αs (MZ) = 0.1166+0.012-0.008. We discuss future perspectives.

The latest measurements of the top quark mass obtained by the ATLAS and CMS experiments at the LHC for centre-of-mass energies of 7 and 8 TeV are presented. The mass of the top quark is measured using several methods and channels, including the reconstructed invariant mass distribution of the top quark and shapes of top quark decay distributions. Measurements based on the inclusive tt-bar cross section and novel observables based on the differential cross section in the tt-bar + 1 jet channel are also discussed. The results of the various channels are combined and compared to the world average.

Hard QCD results in proton-proton collisions at sqrt(s) = 7 TeV with jets from data recorded up to the end of 2010 by the CMS and ATLAS experiments at the LHC are reported. Inclusive jet and di-jet cross section measurements as well as observables sensitive to multi-jet activity are shown and compared to simulations based on leading log parton showers as well as NLO QCD predictions. Novel approaches to identify highly boosted massive final states by exploiting the jet substructure are tested on the dominant QCD background.

The spectral functions of the vector current and the axial-vector current have been measured in hadronic τ decays using the OPAL detector at LEP. Within the framework of the Operator Product Expansion a simultaneous determination of the strong coupling constant αs, the non-perturbative operators of dimension 6 and 8 and of the gluon condensate has been performed. Different perturbative descriptions have been compared to the data. The Contour Improved Fixed Order Perturbation Theory gives αs(mτ2) = 0.348 ± 0.009exp ± 0.019theo at the τ-mass scale and αs(mZ2) = 0.1219 ± 0.0010exp ± 0.0017theo at the Z0-mass scale. The values obtained for αs(mZ2) using Fixed Order Perturbation Theory of Renormalon Chain Resummation are 2.3% and 4.1% smaller, respectively. The ‘running’ of the strong coupling between s0 ⋍ 1.3 GeV2 and s0 = mτ2 has been tested from direct fits to the integrated differential hadronic decay rate Rτ(s0). A test of the saturation of chiral sum rules at the τ-mass scale has been performed.

In 2002 the first combined beam test of the hadronic and electromagnetic liquid-argon endcap calorimeters of the ATLAS experiment took place at the SPS test beam at CERN. A total of 15 million events from electrons, muons and pions in the energy range from 6 to 200 GeV were recorded. The entire calibration chain, from digital filter weights, over calibration constants, to clustering and energy weights, as is relevant for the energy calibration of hadronic and electromagnetic showers in ATLAS was tested and applied to the beam test data. The calibration methods and first results for the combined performance of the two calorimeters are presented.

Der BGH verweigert dem Hinterzieher von Umsatzsteuer die spatere Berufung auf den nicht ausgeubten Vorsteuerabzug. Dieses vom Schrifttum grostenteils kritisierte Ergebnis ist nach Ansicht des Verfassers logische Folge umsatzsteuerlicher Systematik, da eine Herabsetzung der Umsatzsteuer nach den §§ 15, 16 UStG die tatsachliche Nutzung des Anspruchs auf Vorsteuerabzug durch den Steuerpflichtigen voraussetzt, welche hier jedoch gerade unterblieben ist. Holt der Tater die Absetzung im Verwaltungsverfahren schlieslich nach, konne dieses fur die Frage der Tatbestandsmasigkeit keine Rolle mehr spielen, da der einmal eingetretene Hinterziehungserfolg nicht mehr ruckgangig zu machen sei. Dass abziehbare Vorsteuerbetrage nach der Rechtsprechung im Hinblick auf die subjektive Tatseite sowie unter Strafzumessungsgesichtspunkten zugunsten des Taters Berucksichtigung finden konnen, stelle keinen Widerspruch dar, sondern entspreche letztlich nur allgemeinen strafrechtlichen Grundsatzen.

The determination of |Vub| from inclusive semileptonic B decays is limited by uncertainties in modeling the decay distributions in b → ulν transitions. The largest uncertainties arise from the limited knowledge of the appropriate b quark mass and Fermi momentum to use in the parameterization of the shape function. In this talk a new method is presented in which these parameters are constrained by the same data used to measure |Vub|. Two complementary observables can be constructed, one for discriminating between b → ulν transitions and background and the other for constraining the b quark mass and the shape function, thereby reducing the theoretical uncertaintites in |Vub|.

Simulating radiation environments is crucial in the design phase of new hadron collider experiments or upgrades, especially when extrapolating to new centre of mass collision energies where previous experience cannot be relied on. The generation of radiation fields in the LHC experiments is dominated by proton–proton collisions, with contributions from beam-gas interactions and other machine losses. It is therefore essential to first reproduce the proton–proton collisions, using Monte Carlo event generators such as PYTHIA8 and DPMJET-III. This part of the simulation chain is discussed in Section 4.1. The particles originating from the proton–proton collisions interact with the detector and machine material, causing electromagnetic and hadronic showers which give rise to the complex radiation fields seen in the LHC experiments. This second part of the simulation is dealt with using advanced Monte Carlo particle transport codes such as FLUKA, MARS, or GEANT4. An overview of these codes is given in Section 4.2. Key radiation quantities of interest are extracted from the simulations, such as 1 MeV neutron equivalent fluence and total ionizing dose, and these are discussed in Section 4.3. It is these quantities that are needed by the detector systems for evaluating radiation damage and predicting sensor and electronic performance over the lifetime of the experiment. In Section 4.4, the simulated predictions of radiation backgrounds for each of the experiments is presented. Finally, in Section 4.5, we offer general conclusions and recommendations for the future.

Measurements of inclusive and differential production cross-sections of top-quarks in pairs and in single top-quark modes as well as properties of their subsequent decays at the LHC are presented.Recent analyses of proton-proton collisions recorded by the ATLAS, CMS and LHCb detectors at centre-of-mass energies of 5, 7, 8 and 13 TeV and combinations of the results are discussed.Among the properties analysed are tests of lepton universality, the W-boson helicity, tests of CP violation, studies of b-quark-fragmentation, top-quark polarisation measurements and the mass of the top-quark.

ATLAS-TPX detectors were used to measure ionising dose and charged particle fluences in the ATLAS experiment. We present a study of the detector responses to the different particle species and compare measurements with Geant4 simulations.

A sample of 23 million B B-bar events collected with the BABAR detector at the PEP-II collider is used in a search for direct CP violation in charmless two-body B decays, quasi two-body B decays, and the radiative penguin decays B to K* gamma. No evidence for direct CP violation is found in the considered modes and 90% confidence level limits are reported. We also present a limit on the branching fraction of the decay B0 to gamma gamma.

It has been shown in recent analyses by ALEPH [1] and OPAL [2] that precision QCD tests are possible with hadronic tau decays by comparing spectral moments of the hadronic decay ratio of the tau with QCD calculations. In principle e+e- data can be used in a similar manner by evaluating spectral moments of R. The current e+e- data is compared with the OPAL tau data and a prediction is made on the achievable accuracy of QCD tests with the projected precision of PEP-N [3].

It has been shown in recent analyses by ALEPH [1] and OPAL [2] that precision QCD tests are possible with hadronic {tau} decays by comparing spectral moments of the hadronic decay ratio of the {tau} with QCD calculations. In principle e{sup +}e{sup -} data can be used in a similar manner by evaluating spectral moments of R. The current e{sup +}e{sup -} data is compared with the OPAL {tau} data and a prediction is made on the achievable accuracy of QCD tests with the projected precision of PEP-N [3].

A sample of 23 million BB events collected with the BABAR detector at the PEP-II collider is used in a search for direct CP violation in charmless two-body B decays, quasi two-body B decays, and the radiative penguin decays B → K * γ.No evidence for direct CP violation is found in the considered modes and 90 % confidence level limits are reported.We also present a limit on the branching fraction of the decay B 0 → γγ.

A sample of 23 million B{bar B} events collected with the BABAR detector at the PEP-II collider is used in a search for direct CP violation in charmless two-body B decays, quasi two-body B decays, and the radiative penguin decays B {yields} K*{gamma}. No evidence for direct CP violation is found in the considered modes and 90% confidence level limits are reported. We also present a limit on the branching fraction of the decay B{sup 0} {yields} {gamma}{gamma}.

The determination of |V{sub ub}| from inclusive semileptonic B decays is limited by uncertainties in modeling the decay distributions in b {yields} u{ell}{nu} transitions. The largest uncertainties arise from the limited knowledge of the appropriate b quark mass and Fermi momentum to use in the parameterization of the shape function. This paper presents a new method in which these shape function parameters are constrained by the same data used to measure |V{sub ub}|. The method requires measurements of the momenta of both the charged lepton and the neutrino in semileptonic B decays. From these quantities two complementary observables can be constructed, one for discriminating between b {yields} u{ell}{nu} transitions and background and the other for constraining the shape function. Using this technique the uncertainties in |V{sub ub}| from the shape function may be significantly reduced.