17284154
Precise predictions for Higgs production at e+ e- colliders and numerical calculation of one-loop integrals
Some of the most interesting Higgs-production processes at future ee colliders are of the type ee → f fH . 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 ee colliders.
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.
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.
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.
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.
122217457
The low energy effective Higgs potential of the minimal nonlinear supersymmetric SU(5)-model and its phenomenology
Abstract. The low energy effective Higgs potential of the minimal nonlinear supersymmetric SU(5)-Model is derived. The physical Higgs particle spectra are the same as those of the linear supersymmetric model MSSM: two scalar bosons, a pseudo-scalar and a charged scalar. Mass relations are derived and compared to those of the MSSM. Production cross sections are calculated for LEP1, LEP2, LC-500, LC-1000 and LC-2000 and discussed how far this model might be tested at these colliders.

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.
16665734
Top Quark Production and Decay Properties at the Tevatron
The latest results from the CDF and D0 collaborations on the top-quark pair-production cross section and limits on electroweak production are presented. Included are measurements of properties of the top quark such as charge, lifetime, and the decay branching ratio t->Wb. In addition to measurements about the top quark, the selected event samples are used to study the helicity of the W boson and to search for additional exotic quarks (t') and resonances in the ttbar invariant mass spectrum.
11389899
Centrality dependence of K+ produced in Pb+Pb collisions at 158 GeV per nucleon
The NA52 collaboration searches for a discontinuous behaviour of charged kaons produced in Pb+Pb collisions at 158 A GeV as a function of the impact parameter, which could reveal a hadron to quark-gluon plasma (QGP) phase transition. The K+ yield is found to grow proportional to the number of participating ('wounded') nucleons N, above N=100. Previous NA52 data agree with the above finding and show a discontinuous behaviour in the kaon centrality dependence near N=100, marking the onset of strangeness enhancement -over e.g. p+A data at the same \sqrt{s}- in a chemically equilibrated phase.