Discovering Technicolor Andersen, J. R.; Antipin, O.; Azuelos, G. ...
European physical journal plus,
09/2011, Letnik:
126, Številka:
9
Journal Article
Recenzirano
Odprti dostop
We provide a pedagogical introduction to extensions of the Standard Model in which the Higgs is composite. These extensions are known as models of dynamical electroweak symmetry breaking or, in ...brief, Technicolor. Material covered includes: motivations for Technicolor, the construction of underlying gauge theories leading to minimal models of Technicolor, the comparison with electroweak precision data, the low-energy effective theory, the spectrum of the states common to most of the Technicolor models, the decays of the composite particles and the experimental signals at the Large Hadron Collider. The level of the presentation is aimed at readers familiar with the Standard Model but who have little or no prior exposure to Technicolor. Several extensions of the Standard Model featuring a composite Higgs can be reduced to the effective Lagrangian introduced in the text. We establish the relevant experimental benchmarks for Vanilla, Running, Walking, and Custodial Technicolor, and a natural fourth family of leptons, by laying out the framework to discover these models at the Large Hadron Collider.
The CLEO RICH detector Artuso, M.; Ayad, R.; Bukin, K. ...
Nuclear instruments & methods in physics research. Section A, Accelerators, spectrometers, detectors and associated equipment,
12/2005, Letnik:
554, Številka:
1
Journal Article
Recenzirano
Odprti dostop
We describe the design, construction and performance of a Ring Imaging Cherenkov Detector (RICH) constructed to identify charged particles in the CLEO experiment. Cherenkov radiation occurs in LiF ...crystals, both planar and ones with a novel “sawtooth”-shaped exit surface. Photons in the wavelength interval 135–165
nm are detected using multi-wire chambers filled with a mixture of methane gas and triethylamine vapor. Excellent
π
/
K
separation is demonstrated.
Using data collected with the D0 detector at the Fermilab Tevatron Collider, corresponding to 5.3 fb(-1) of integrated luminosity, we search for violation of Lorentz invariance by examining the ...ttover ¯ production cross section in lepton+jets final states. We quantify this violation using the standard-model extension framework, which predicts a dependence of the ttover ¯ production cross section on sidereal time as the orientation of the detector changes with the rotation of the Earth. Within this framework, we measure components of the matrices (c(Q))(μν33) and (c(U))(μν33) containing coefficients used to parametrize violation of Lorentz invariance in the top quark sector. Within uncertainties, these coefficients are found to be consistent with zero.
Using 7.3 fb⁻¹ of pp collisions collected by the D0 detector at the Fermilab Tevatron, we measure the distribution of the variable φ(η)*, which probes the same physical effects as the Z/γ* boson ...transverse momentum, but is less susceptible to the effects of experimental resolution and efficiency. A QCD prediction is found to describe the general features of the φ(η)* distribution, but is unable to describe its detailed shape or dependence on boson rapidity. A prediction that includes a broadening of transverse momentum for small values of the parton momentum fraction is strongly disfavored.
The DO central track trigger Olsen, J.; Anderson, J.; Angstadt, R. ...
IEEE transactions on nuclear science,
2004-June, 2004-06-00, 20040601, Letnik:
51, Številka:
3
Journal Article
Recenzirano
Odprti dostop
An overview of the system architecture and algorithms used for the DO Central Track Trigger (CTT) in the Run 2 of the Fermilab Tevatron Proton-Antiproton Collider is presented. This system uses ...information from the newly commissioned Central Fiber Tracker and Preshower Detectors to generate Level 1 trigger decisions. It also generates lists of seed tracks and preshower clusters that are sent to the Level 1 Muon Trigger, L2 Silicon Track Trigger, and Central and Forward Preshower Level 2 preprocessors. The system consists of modular boards which utilize field-programmable gate arrays (FPGAs) to implement trigger algorithms. The system delivers trigger decisions every 132 ns, based on input data flowing at a maximum sustained rate of 475 gigabits per second. The first results of trigger efficiency studies are presented.
We determine the fraction of tt events with spin correlation, assuming that the spin of the top quark is either correlated with the spin of the top antiquark as predicted by the standard model or is ...uncorrelated. For the first time we use a matrix-element-based approach to study tt spin correlation. We use tt → W+ b W- b → ℓ+ νbℓ- ν b final states produced in pp collisions at a center-of-mass energy sqrt(s)=1.96 TeV, where ℓ denotes an electron or a muon. The data correspond to an integrated luminosity of 5.4 fb(-1) and were collected with the D0 detector at the Fermilab Tevatron collider. The result agrees with the standard model prediction. We exclude the hypothesis that the spins of the tt are uncorrelated at the 97.7% C.L.
We have measured the branching fraction and photon energy spectrum for the radiative penguin process b-->s gamma. We find Beta(b-->s gamma) = (3.21+/-0.43+/-0.27(+0.18)(-0.10))x10(-4), where the ...errors are statistical, systematic, and from theory corrections. We obtain first and second moments of the photon energy spectrum above 2.0 GeV, <E( gamma)> = 2.346+/-0.032+/-0.011 GeV, and <E(2)(gamma)>-<E(gamma)>(2) = 0.0226+/-0.0066+/-0.0020 GeV(2), where the errors are statistical and systematic. From the first moment, we obtain (in the modified minimal subtraction renormalization scheme, to order 1/M(3)(B) and beta(0)alpha(2)(s)) the heavy quark effective theory parameter Lambda = 0.35+/-0.08+/-0.10 GeV.
We present the results of the combination of searches for the standard model Higgs boson produced in association with a W or Z boson and decaying into bb using the data sample collected with the D0 ...detector in pp collisions at √s = 1.96 TeV at the Fermilab Tevatron Collider. We derive 95% C.L. upper limits on the Higgs boson cross section relative to the standard model prediction in the mass range 100 GeV ≤ M(H) ≤ 150 GeV, and we exclude Higgs bosons with masses smaller than 102 GeV at the 95% C.L. In the mass range 120 GeV ≤ M(H) ≤145 GeV, the data exhibit an excess above the background prediction with a global significance of 1.5 standard deviations, consistent with the expectation in the presence of a standard model Higgs boson.
We study WW and WZ production with ℓνqq (ℓ=e,μ) final states using data collected by the D0 detector at the Fermilab Tevatron Collider corresponding to 4.3 fb(-1) of integrated luminosity from pp ...collisions at sqrts=1.96 TeV. Assuming the ratio between the production cross sections σ(WW) and σ(WZ) as predicted by the standard model, we measure the total WV (V=W,Z) cross section to be σ(WV)=19.6(-3.0)(+3.2) pb and reject the background-only hypothesis at a level of 7.9 standard deviations. We also use b-jet discrimination to separate the WZ component from the dominant WW component. Simultaneously fitting WW and WZ contributions, we measure σ(WW)=15.9(-3.2)(+3.7) pb and σ(WZ)=3.3(-3.3)(+4.1) pb, which is consistent with the standard model predictions.
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