The CDF and D0 experiments at the Fermilab Tevatron have measured the asymmetry between yields of forward- and backward-produced top and antitop quarks based on their rapidity difference and the ...asymmetry between their decay leptons. These measurements use the full data sets collected in proton-antiproton collisions at a center-of-mass energy of root s = 1.96 TeV. We report the results of combinations of the inclusive asymmetries and their differential dependencies on relevant kinematic quantities. The combined inclusive asymmetry is A(FB)(t (t) over bar) = 0.128 +/- 0.025. The combined inclusive and differential asymmetries are consistent with recent standard model predictions.
This Letter describes the current most precise measurement of the \(WZ\) production cross section as well as limits on anomalous \(WWZ\) couplings at a center-of-mass energy of 1.96 TeV in ...proton-antiproton collisions for the Collider Detector at Fermilab (CDF). \(WZ\) candidates are reconstructed from decays containing three charged leptons and missing energy from a neutrino, where the charged leptons are either electrons or muons. Using data collected by the CDF II detector (7.1 fb\(^{-1}\) of integrated luminosity), 63 candidate events are observed with the expected background contributing \(8 \pm 1\) events. The measured total cross section \(\sigma (p \bar p \to WZ) = 3.93_{-0.53}^{+0.60}(\text{stat})_{-0.46}^{+0.59}(\text{syst}) \) pb is in good agreement with the standard model prediction of \(3.50\pm 0.21\). The same sample is used to set limits on anomalous \(WWZ\) couplings.
We present a search for the standard model Higgs boson produced in association with a \(Z\) boson, using up to 7.9 fb\(^{-1}\) of integrated luminosity from \(p\bar{p}\) collisions collected with the ...CDF II detector. We utilize several novel techniques, including multivariate lepton selection, multivariate trigger parametrization, and a multi-stage signal discriminant consisting of specialized functions trained to distinguish individual backgrounds. By increasing acceptance and enhancing signal discrimination, these techniques have significantly improved the sensitivity of the analysis above what was expected from a larger dataset alone. We observe no significant evidence for a signal, and we set limits on the \(ZH\) production cross section. For a Higgs boson with mass 115 GeV/\(c^2\), we expect (observe) a limit of 3.9 (4.8) times the standard model predicted value, at the 95% credibility level.
We report on a search for the standard model Higgs boson decaying into pairs of tau leptons in \(p\bar{p}\) collisions produced by the Tevatron at \(\sqrt{s}\) = 1.96 TeV. The analyzed data sample ...was recorded by the CDFII detector and corresponds to an integrated luminosity of 6.0 fb\(^{-1}\). The search is performed in the final state with one tau decaying leptonically and the second one identified through its semi-hadronic decay.Since no significant excess is observed, a 95% credibility level upper limit on the production cross section times branching ratio to the tau-tau final state is set for hypothetical Higgs boson masses between 100 and 150 GeV/\(c^2\). For a Higgs boson of 120 GeV/\(c^2\) the observed (expected) limit is 14.6 (15.3) the predicted value.
Nucl.Instrum.Meth. A564 (2006) 597-607 The front-end electronics of the ATLAS hadronic calorimeter (Tile Cal) is
housed in a unit, called {\it PMT-Block}. The PMT-Block is a compact instrument
...comprising a light mixer, a PMT together with its divider and a {\it 3-in-1}
card, which provides shaping, amplification and integration for the signals.
This instrument needs to be qualified before being assembled on the detector. A
PMT-Block test bench has been developed for this purpose. This test bench is a
system which allows fast, albeit accurate enough, measurements of the main
properties of a complete PMT-Block. The system, both hardware and software, and
the protocol used for the PMT-Blocks characterisation are described in detail
in this report. The results obtained in the test of about 10000 PMT-Blocks
needed for the instrumentation of the ATLAS (LHC-CERN) hadronic Tile
Calorimeter are also reported.
We present a search for new phenomena in events with two reconstructed \(Z\) bosons and large missing transverse momentum, sensitive to processes \(p\bar{p}\rightarrow X_2X_2 \rightarrow Z Z X_1 ...X_1\), where \(X_2\) is an unstable particle decaying as \(X_2\rightarrow ZX_1\) and \(X_1\) is undetected. The particles \(X_1\) and \(X_2\) may be, among other possibilities, fourth generation neutrinos or supersymmetric particles. We study the final state in which one \(Z\) boson decays to two charged leptons and the second decays hadronically. In data corresponding to an integrated luminosity of 4.2 fb\(^{-1}\) from proton-antiproton collisions recorded by the CDF II detector at the Tevatron, with center-of-mass energy of 1.96 TeV, we find agreement between data and standard-model backgrounds. We calculate 95% confidence level upper limits on the cross section of the process \(p\bar{p}\rightarrow X_2X_2 \rightarrow Z Z X_1 X_1\) ranging from 50 fb to 1 pb, depending on the masses of \(X_1\) and \(X_2\).
We search for high-mass resonances decaying into Z boson pairs using data corresponding to 6 fb^-1 collected by the CDF experiment in p\bar{p} collisions at sqrt{s}=1.96 TeV. The search is performed ...in three distinct final states: ZZ --> l^+l^-l^+l^-, ZZ --> l^+l^-\nu\nu, and ZZ --> l^+l^-jj. For a Randall-Sundrum graviton G*, the 95% CL upper limits on the production cross section times branching ratio to ZZ, sigma(p\bar{p} --> G^* --> ZZ), vary between 0.26 pb and 0.045 pb in the mass range 300 < M_{G*} < 1000 GeV/c^2.
A PMT-Block test bench Adragna, P; Antonaki, A; Boudagov, I ...
arXiv.org,
05/2006
Paper
Odprti dostop
The front-end electronics of the ATLAS hadronic calorimeter (Tile Cal) is housed in a unit, called {\it PMT-Block}. The PMT-Block is a compact instrument comprising a light mixer, a PMT together with ...its divider and a {\it 3-in-1} card, which provides shaping, amplification and integration for the signals. This instrument needs to be qualified before being assembled on the detector. A PMT-Block test bench has been developed for this purpose. This test bench is a system which allows fast, albeit accurate enough, measurements of the main properties of a complete PMT-Block. The system, both hardware and software, and the protocol used for the PMT-Blocks characterisation are described in detail in this report. The results obtained in the test of about 10000 PMT-Blocks needed for the instrumentation of the ATLAS (LHC-CERN) hadronic Tile Calorimeter are also reported.
