8016343
Testing coupling relations in SUSY QCD at a linear collider
Supersymmetry predicts that gauge couplings are equal to the corresponding gaugino-sfermion-fermion Yukawa couplings. This prediction can be tested for the QCD sector of the MSSM by studying the processes eplus+eminus -> squark+antisquark+gluon and eplus+eminus -> squark+antiquark+gluino at a future linear collider. We present results for these processes at next-to-leading order in alpha_s in the framework of the MSSM. We find sizable SUSY-QCD corrections. The renormalization scale dependence is significantly reduced at next-to-leading order.
117974501
Radiative corrections to W gamma gamma production at the LHC
Radiative W production at hadron colliders is an important testing ground for the Standard Model. We consider W gamma gamma production which is sensitive to the quartic WW gamma gamma coupling. Furthermore the Standard Model amplitude for this process contains a radiation zero. We present a calculation of the NLO QCD corrections for W gamma gamma production at the LHC.
15696182
Precision calculations for H -> WW/ZZ -> 4fermions with PROPHECY4f
PROPHECY4f is a Monte Carlo event generator for precise simulations of the Higgs-boson decay H -> WW/ZZ -> 4fermions, supporting leptonic, semileptonic, and four-quark final states. Both electroweak and QCD corrections are included. Treating the intermediate gauge bosons as resonances, the calculation covers the full Higgs-boson mass range above, near, and below the gauge-boson pair thresholds. In this article we pay particular attention to the recently implemented option of PROPHECY4f to generate unweighted events.
119932741
Electroweak radiative corrections to e+ e- -> t anti-t H
We have calculated the complete electroweak O(alpha) radiative corrections to the Higgs-boson production process e+ e- -> t anti-t H in the electroweak Standard Model. Initial-state radiation beyond O(alpha) is included in the structure-function approach. The calculation of the corrections is briefly described, and numerical results are presented for the total cross section. Both the photonic and the genuine weak corrections reach the order of about 10% or even more and show a non-trivial dependence on the Higgs-boson mass and on the scattering energy. We compare our results with two previous calculations that obtained differing results at high energies.
118320839
Gluon-Induced Weak Boson Fusion
The gluon-gluon induced terms for Higgs production through weak boson fusion (WBF) are computed. Formally, these are of next-to-next-to-leading order in the strong coupling constant. This is the lowest order at which nonzero color exchange occurs between the scattering quarks, leading to a color field and thus additional hadronic activity between the outgoing jets. Using a minimal set of cuts, the numerical impact of these terms is at the percent level with respect to the next-to-leading order rate for weak boson fusion. Applying the so-called WBF cuts leads to an even stronger suppression, so that we do not expect a significant deterioration of the WBF signal by these color exchange effects.
10525627
Electroweak radiative corrections to single Higgs-boson production in e+e− annihilation
Abstract We have calculated the complete electroweak O (α) radiative corrections to the single Higgs-boson production processes e + e − →ν l ν l H ( l =e, μ , τ ) in the electroweak Standard Model. Initial-state radiation beyond O (α) is included in the structure-function approach. The calculation of the corrections is briefly described, and numerical results are presented for the total cross-section. In the G μ scheme, the bulk of the corrections is due to initial-state radiation, which affects the cross-section at the level of −7% at high energies and even more in the ZH threshold region. The remaining bosonic and fermionic corrections are at the level of a few percent. The confusing situation in the literature regarding differing results for the fermionic corrections to this process is clarified.
14039647
JET SHAPES AND DETERMINATIONS OF s FROM HADRONIC FINAL STATES IN DEEP INELASTIC SCATTERING AT HERA
Recent results from the study of hadronic nal states in deep inelastic scattering at HERA are reviewed. Jet shapes from neutral and charged current interactions at HERA are compared to those from e + e ? annihilation and p p collisions. The (2+1) jet event rate distributions R2+1(Q 2) and y2 are measured using the modiied JADE jet algorithm. The value of the strong coupling constant s is determined from a comparison with QCD predictions in next{ to{leading order. An analysis of event shape distributions in terms of next{to{leading order QCD calculations and power corrections is presented.
19455268
CDF run IIb silicon vertex detector DAQ upgrade
The Collider Detector at Fermilab (CDF) operates in the beamline of the Tevatron proton-antiproton collider at Batavia, IL. The Tevatron is expected to undergo luminosity upgrades (Run IIb) in the future, resulting in a higher number of interactions per beam crossing. To operate in this dense radiation environment, an upgrade of the CDF's silicon vertex detector subsystem and a corresponding upgrade of its VME-based DAQ system has been explored. Prototypes of all the Run IIb SVX DAQ components have been constructed, assembled into a test stand, and operated successfully using an adapted version of the CDF's network-capable DAQ software. In addition, a PCI-based DAQ system has been developed as a fast and inexpensive tool for silicon detector and DAQ component testing in the production phase. We present an overview of the Run IIb silicon DAQ upgrade, emphasizing the new features and improvements incorporated into the constituent VME boards and discuss a PCI-based DAQ system developed to facilitate production tests.
118621343
Validation of Kalman Filter alignment algorithm with cosmic-ray data using a CMS silicon strip tracker endcap
A Kalman Filter alignment algorithm has been applied to cosmic-ray data. We discuss the alignment algorithm and an experiment-independent implementation including outlier rejection and treatment of weakly determined parameters. Using this implementation, the algorithm has been applied to data recorded with one CMS silicon tracker endcap. Results are compared to both photogrammetry measurements and data obtained from a dedicated hardware alignment system, and good agreement is observed.
109891378
The DØ silicon micro-strip tracker
The D0 silicon micro-strip tracker (SMT) is part of the D0 upgrade for the Tevatron RunII at Fermilab. The detector has been running successfully since the start of the RunII physics data taking. The tracking and vertexing performance match the expectation from Monte-Carlo studies. An additional inner layer (Layer0) of silicon sensors at R = 1.6cm will be installed in 2005.
121444397
New results from NA52 on particle production in Pb+Pb collisions at 158 GeV per nucleon
Abstract We present new results on the centrality and rapidity dependence and on azimuthal anisotropies of particle production in Pb+Pb collisions at 158 GeV per nucleon.