Search results for " Collider"
showing 10 items of 1415 documents
Technical design report for the $\overline{{\rm{P}}}\mathrm{ANDA}$ Barrel DIRC detector
2019
The $\overline{{\rm{P}}}\mathrm{ANDA}$ (anti-Proton ANnihiliation at DArmstadt) experiment will be one of the four flagship experiments at the new international accelerator complex FAIR (Facility for Antiproton and Ion Research) in Darmstadt, Germany. $\overline{{\rm{P}}}\mathrm{ANDA}$ will address fundamental questions of hadron physics and quantum chromodynamics using high-intensity cooled antiproton beams with momenta between 1.5 and 15 GeV/c and a design luminosity of up to 2 × 1032 cm−2 s−1. Excellent particle identification (PID) is crucial to the success of the $\overline{{\rm{P}}}\mathrm{ANDA}$ physics program. Hadronic PID in the barrel region of the target spectrometer will be per…
Azimuthal anisotropy ofπ0andηmesons in Au + Au collisions atsNN=200GeV
2013
The azimuthal anisotropy coefficients v2 and v4 of p 0 and. mesons are measured in Au + Au collisions at root s(NN) = 200 GeV as a function of transverse momentum p(T) (1-14 GeV/c) and centrality. The extracted v(2) coefficients are found to be consistent between the two meson species over the measured p(T) range. The ratio of v(4)/v(2)(2) for pi(0) mesons is found to be independent of p(T) for 1- 9 GeV/c, implying a lack of sensitivity of the ratio to the change of underlying physics with p(T). Furthermore, the ratio of v(4)/v(2)(2) is systematically larger in central collisions, which may reflect the combined effects of fluctuations in the initial collision geometry and finite viscosity i…
Performance of the ATLAS Hadronic End-Cap Calorimeter in Beam Tests
2001
Abstract Modules of the ATLAS liquid argon Hadronic End-cap Calorimeter (HEC) were exposed to beams of electrons, muons and pions in the energy range 6⩽ E ⩽200 GeV at the CERN SPS. A description of the HEC and of the beam test setup are given. Results on the energy response and resolution are presented and compared with simulations. The ATLAS energy resolution for jets in the end-cap region is inferred and meets the ATLAS requirements.
Search for a neutral Higgs particle in the decay sequence $K^{0}_{L} \to \pi^{0}H^{0}$ and $H^{0} \to e^{+}e^{-}$
1990
Abstract We have searched for the sequence of decays K L 0 → π 0 H 0 and H 0 →e + e − at the CERN Super Proton Synchrotron (SPS), and have allowed for a non-zero H 0 lifetime. Three candidates have been seen, consistent with an expected background of 3.3. Limits on the branching ratio product in the range 10 −8 –10 −7 are presented as a function of the mass and lifetime of the H 0 . These can be used to restrict the neutral Higgs of the minimal standard model.
Neutrino Physics at the Turn of the Millenium
1999
Recent solar & atmospheric nu-data strongly indicate need for physics beyond the Standard Model. I review the ways of reconciling them in terms of 3-nu oscillations. Though not implied by data, bi-maximal nu-mixing models emerge as a possibility. SUSY with broken R-parity provides an attractive way to incorporate it, opening the possibility of testing nu-anomalies at high- energy colliders such as the LHC or at the upcoming long-baseline or nu- factory experiments. Reconciling, in addition, the LSND hint requires a fourth, light sterile neutrino, nus. The simplest are the most symmetric scenarios, in which 2 of the 4 neutrinos are maximally-mixed and lie at the LSND scale, while the oth…
Status and Prospects of Top-Quark Physics
2009
The top quark is the heaviest elementary particle observed to date. Its large mass of about 173 GeV/c^2 makes the top quark act differently than other elementary fermions, as it decays before it hadronises, passing its spin information on to its decay products. In addition, the top quark plays an important role in higher-order loop corrections to standard model processes, which makes the top quark mass a crucial parameter for precision tests of the electroweak theory. The top quark is also a powerful probe for new phenomena beyond the standard model. During the time of discovery at the Tevatron in 1995 only a few properties of the top quark could be measured. In recent years, since the star…
Electroweak Precision Tests of the Standard Model after the Discovery of the Higgs Boson
2019
The global fit of the Standard Model predictions to electroweak precision data, which has been routinely performed in the past decades by several groups, led to the prediction of the top quark and the Higgs boson masses before their respective discoveries. With the measurement of the Higgs boson mass at the Large Hadron Collider (LHC) in 2012 by the ATLAS and CMS collaborations, the last free parameter of the Standard Model of particle physics has been fixed, and the global electroweak fit can be used to test the full internal consistency of the electroweak sector of the Standard Model and constrain models beyond. In this article, we review the current state-of-the-art theoretical calculati…
Measurement of the t-channel single top-quark production cross section in pp collisions at s=7 TeV with the ATLAS detector
2012
We report a measurement of the cross section of single top-quark production in the t-channel using 1.04 fb -1 of pp collision data at s=7 TeV recorded with the ATLAS detector at the LHC. Selected e ...
Experimental results on the electroweak interaction
1999
Recent results from the four experiments ALEPH, DELPHI, L3 and OPAL at the Large Electron-Positron collider, LEP at CERN, and by the SLD collaboration at the Stanford Linear Collider, SLC, are reviewed. Analyses from an integrated luminosity of about 150 pb− recorded by each experiment at LEP, taken at different centre-of-mass energies within ±3 GeV around the peak of the Z resonance during the years 1989 to 1995 are available now. Repeated accurate calibrations of the beam energy lead to precise measurements of the mass and of the total width of the Z boson. These results are complemented by measurements at the Z resonance with polarised beams at Stanford. First results from an integrated …
The Matrix Element Method and its Application to Measurements of the Top Quark Mass
2010
The most precise measurements of the top quark mass are based on the Matrix Element method. We present a detailed description of this analysis method, taking the measurements of the top quark mass in final states with one and two charged leptons as concrete examples. In addition, we show how the Matrix Element method is suitable to reduce the dominant systematic uncertainties related to detector effects, by treating the absolute energy scales for b-quark and light-quark jets independently as free parameters in a simultaneous fit together with the top quark mass. While the determination of the light-quark jet energy scale has already been applied in several recent measurements, the separate …