A new method of solving the hierarchy problem in the SM has been proposed. This method leads to the so-called " Little Higgs " models. The ATLAS experiment at LHC has undertaken studies of the new particles predicted by these model: a heavy top quark, heavy gauge bosons and additional Higgs bosons. Simulations of their decays have been carried out. The sensitivity of the ATLAS experiment to dis...

Higgs decays to Z boson pairs may be exploited to determine spin and parity of the Higgs boson, a method complementary to spin–parity measurements in Higgs-strahlung. For a Higgs mass above the on-shell ZZ decay threshold, a model-independent analysis can be performed, but only by making use of additional angular correlation effects in gluon-gluon fusion at the LHC and γγ fusion at linear colli...

In this article the potential of the ATLAS experiment to discover MSSM Higgs bosons is discussed. Various Monte-Carlo studies for SM Higgs boson production and dedicated MSSM Higgs boson analyses are taken into account to investigate the discovery potential in four different CPconserving MSSM benchmark scenarios, the Mh–max scenario, the no mixing scenario, the gluophobic scenario and the small...

The measurement of Higgs pair production will be one of the cornerstones of the LHC physics program in the coming years, with the upcoming high-energy and high-luminosity phase. The Vector Boson Fusion (VBF) production channel probes directly the coupling of new physics and of Higgs to gauge bosons, in addition to reducing background contribution. The production via VBF of an heavy object on-sh...

We discuss the possibility of detecting a Higgs boson in electron-positron collider experiments if large extra dimensions are realized in nature. In such a case, the Higgs boson can decay invisibly by oscillating into a graviscalar Kaluza-Klein (KK) tower. We show that the search for such a Higgs at an ee linear collider entails more complications than are usually thought of in relation to an i...

A non-standard symmetry breaking sector may lead to derivative couplings of the Higgs boson and thereby to anomalous interactions with the electroweak gauge bosons. In the framework of gauge-invariant effective Lagrangians the resulting changes in Higgs boson production and decay mechanisms are related to anomalous triple vector boson couplings. Using low energy constraints on the dimension-six...

In the minimal supersymmetric Standard Model, the heaviest CP-even Higgs boson H and the CP-odd Higgs scalar A are predicted to be almost degenerate in mass at the tree level, for the wide kinematic range MA > 2MZ and tanβ ≥ 2. However, if large soft-CPviolating Yukawa interactions involving scalar quarks of the third generation are present in the theory, then the CP invariance of the Higgs pot...

Most recent models assuming the Higgs Boson is a pseudo-Nambu-Goldstone Boson (pNGb) are motivated by the indication from Standard Model fits that its mass is ≤ 200GeV .Starting from a modified SM. of Forshaw et. al. with a triplet boson added and a heavier Higgs Boson, we consider a pNGb model.This differs in several ways from most little Higgs models: apart from using only one loop, the cutof...

The existence of neutrino masses strongly suggests that right-handed neutrinos exist, but the data do not favor any particular scale for the Majorana mass parameters. Here I explore the possibility that these particles exist at the electroweak scale along with additional new physics at the TeV scale . Higher dimension operators involving right-handed neutrinos and the Higgs boson can introduce ...

Preliminary results from the four LEP experiments using data collected at 189 GeV have shown no evidence for the Standard Model Higgs boson. The preliminary 95% confidence level lower limits on the SM Higgs boson mass from ALEPH, DELPHI, OPAL, and L3 are 90.4 GeV/c, 94.1 GeV/c, 95.5 GeV/c, and 95.2 GeV/c, respectively. When LEP finishes in the year 2000, each experiment expects to collect 200 p...