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.
115688949
Tests of supersymmetric couplings at high-energy colliders
119389130
Electroweak corrections to e+ e- -> nu anti-nu H and e+ e- -> t anti-t H
The most interesting Higgs-production processes at future e+ e- colliders belong to the process class e+ e- ->f anti-f H. We study the full O(alpha) corrections to this reaction in the Standard Model for neutrinos and top quarks in the final state. Leading higher-order corrections from initial-state radiation and QCD corrections are also taken into account. Although cancellations between the different kinds of corrections occur, the full corrections are of the order of +/-10% and thus important ingredients in the theoretical predictions for future e+ e- colliders.
16334731
Higgs Production by Gluon initiated Weak Boson Fusion
The gluon-gluon induced terms for Higgs production through weak-boson fusion are calculated. They form a finite and gauge-invariant subset of the NNLO corrections in the strong coupling constant. This is also the lowest order with sizeable t-channel colour exchange contributions, leading to additional hadronic activity between the outgoing jets.
15674174
Electroweak corrections to e+ e- ---> f anti-f H
Some of the most interesting Higgs-production processes at future e + e − colliders are of the type e + e − → f f ¯ H . We present a calculation of the complete O ( α ) corrections to these processes in the Standard Model for final-state neutrinos and top quarks. Initial-state radiation beyond O ( α ) at the leading-logarithmic level as well as QCD corrections are also included. The electroweak corrections turn out to be sizable and reach the order of ±10% and will thus be an important part of precise theoretical predictions for future e + e − colliders.
123036925
The low energy limit of the minimal nonlinear supersymmetric SU(5)-model; production and decay of Higgs particles
Abstract. We consider the Higgssector in the low energy limit of the minimal nonlinear supersymmetric SU(5) model. We estimate radiative corrections to the Higgs masses using the effective potential. Furthermore Higgs boson decays are investigated and differences to the MSSM are discussed.
54868784
Series tests of fine mesh photomultiplier tubes in magnetic fields of up to 1.2 Tesla
Abstract The new lead/scintillating-fibre calorimeter (“SpaCal”) for the backward region of the H1 experiment at HERA (DESY) is equipped with fine mesh phototubes which operate in a magnetic field close to 1 T. A large sample of these tubes of the types Hamamatsu R5505 and R5506, and Hamamatsu R2490-05, have been tested in fields of up to 1.2T. We have investigated the cathode homogeneity with and without magnetic field, the gain loss under the influence of the magnetic field, and stability with time. For a subsample of tubes, we have performed additional studies on stability with respect to temperature changes, variation of gain as a function of the magnetic field, high voltage discharges, single photo-electron response, and linearity. We finally summarize the experience with these tubes after one year of operation in the experiment.
55139157
SLHC tracker upgrade: challenges and strategies in ATLAS
The Large Hadron Collider (LHC) will be upgraded to the Super-LHC in ≈2016 to provide a ten-fold increased luminosity and data rate. The inner silicon tracking detectors of the ATLAS and CMS experiments will be replaced by even more powerful devices. The new detectors will face unprecedented particle densities and radiation levels. Limiting the power consumption of the front-end electronics, distributing power efficiently and minimizing detector mass, while keeping the costs of the detector affordable, are key challenges. Possible design solutions and the status of R&D for ATLAS are described.
122225376
An investigation of the antinuclei and nuclei production mechanism in Pb + Pb collisions at 158 A GeV
We investigate the production mechanisms of p, d, t, 3He, 4He, 6Li, , and in Pb+Pb collisions at 158 A GeV measured near zero transverse momentum with the NA52 experiment at the CERN SPS. We find evidence that nuclei and antinuclei in Pb+Pb collisions are mainly produced via the coalescence mechanism out of a thermalized source of hadrons, at a time close to the thermal freeze-out of hadrons corresponding to a temperature of ~120 MeV.
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.