Deviations from the standard Higgs sector generated by some new physics at an energy scale $Lambda$ could be described by an effective $SU(3)_c times SU(2)_L times U(1)$ invariant non-renormalizable Lagrangian terms of dimension six. A systematic stu
dy of various Higgs boson production channels ($gamma gamma$, $ZZ$, $WW$, $b bar b$, $tau bar tau$) at the International Linear Collider (ILC) in the SM extension by effective operators is carried out. Statistical methods are used to establish a degree of consistency for the standard Higgs sector with the forthcoming data, using the expected ILC accuracies of the Higgs boson production channels. Global fits in the two-parametric anomalous coupling space indicating to possible deviations from the standard Higgs-fermion and Higgs-gauge boson couplings are performed.
The single top quark production has an electroweak nature and provides an additional to the top pair production source of the top quarks. The processes involving single top have unique properties, they are very interesting from both theoretical and e
xperimental view points. Short review of the single top quark production processes is given in the paper.
We propose to combine and slightly extend two existing Les Houches Accords to provide a simple generic interface between beyond-the-standard-model parton-level and event-level generators. All relevant information - particle content, quantum numbers o
f new states, masses, cross sections, parton-level events, etc - is collected in one single file, which adheres to the Les Houches Event File (LHEF) standard.
Prospects to search for a new massless neutral gauge boson, the paraphoton, in e+ e- collisions at center-of-mass energies of 0.5 and 1 TeV are studied. The paraphoton naturally appears in models with abelian kinetic mixing. A possible realistic mode
l independent lowest order effective Lagrangian contains magnetic interactions of the paraphoton with the Standard Model fermion fields. These interactions are proportional to the fermion mass and grow with energy, with however very weak paraphoton couplings to ordinary matter. At the ILC, a potentially interesting process to search for the paraphoton is its radiation off top quarks, so that the event topology to be searched for is a pair of acoplanar top quark jets with missing energy. By combining many discriminating features of signal and background events efficient paraphoton event selection was achieved allowing to set limits for the top-paraphoton coupling. Arguments in favor of the missing energy as the paraphoton with spin 1 are discussed.
