CP violation in top physics is reviewed. The Standard Model has negligible effects, consequently CP violation searches involving the top quark may constitute the best way to look for physics beyond the Standard Model. Non-standard sources of CP violation due to an extended Higgs sector with and without natural flavor conservation and supersymmetric theories are discussed. Experimental feasibility of detecting CP violation effects in top quark production and decays in high energy e + e − , γγ, µ + µ − , pp and pp colliders are surveyed. Searches for the electric, electro-weak and the chromo-electric dipole moments of the top quark in e + e − → tt and in pp → ttX are descibed. In addition, other mechanisms that appear promising for experiments, e.g., tree-level CP violation in e + e − → tth, ttZ, ttν eνe and in the top decay t → bτ ν τ and CP violation driven by s-channel Higgs exchanges in pp, γγ, µ + µ − → tt etc., are also discussed. * A 2-up version of this postscript file may be obtained at the url

We construct a class of two Higgs doublets models with a 4th sequential generation of fermions that may effectively accommodate the low energy characteristics and phenomenology of a dynamical electroweak symmetry breaking scenario which is triggered by the condensates of the 4th family fermions. In particular, we single out the heavy quarks by coupling the "heavier" Higgs doublet (Φ h ) which possesses a much larger VEV only to them while the "lighter" doublet (Φ ℓ ) couples only to the light fermions. We study the constraints on these models from precision electroweak data as well as from flavor data. We also discuss some distinct new features that have direct consequences on the production and decays of the 4th family quarks and leptons in high energy colliders; in particular the conventional search strategies for t ′ and b ′ may need to be significantly revised.

We consider the effects of heavy Majorana neutrinos N with sub-TeV masses. We argue that the mere presence of these particles would be a signal of physics beyond the minimal seesaw mechanism and their interactions are, therefore, best described using an effective Lagrangian. We then consider the complete set of leading effective operators (up to dimension 6) involving the N and Standard Model fields and show that these interactions can be relatively easy to track at high-energy colliders. For example, we find that an exchange of a TeV-scale heavy vector field can yield thousands of characteristic same-sign lepton number violating ℓ + ℓ + jj events (j = light jet) at the LHC if m N < ∼ 600 GeV, which can also have a distinctive forward-backward asymmetry signal; even the Tevatron has good prospects for this signature if m N < ∼ 300 GeV.The spectacular discovery in the past decade of neutrino oscillation and its interpretation in terms of a non-vanishing neutrino mass matrix is one of the most important recent discoveries in particle physics. The m ν > ∼ O(10 −2 ) eV neutrino masses that appear in this scenario are difficult to generate naturally in the Standard Model (SM) using the Yukawa interactions; the sub-eV mass *

The reaction p p ! t bX is found to be rather rich in exhibiting several di erent types of CP asymmetries. The spin of the top quark plays an important role. Asymmetries are related to form factors arising from radiative corrections of the tbW production vertex due to non-standard physics. As illustrations, e ects are studied in two Higgs Doublet Models and in Supersymmetric Models; asymmetries up to a few % may be possible.The origin of CP violation remains a pressing issue in Particle Physics. The Standard Model (SM), with three generations of quarks, can accommodate a CP violating phase, the Cabibbo-Kobayashi-Maskawa (CKM) phase 1]. However it is widely believed that this phase cannot account for baryogenesis 2]. Additional CP violating phases due to new physics are therefore a necessity. Besides, in extensions of the SM, new phase(s) appear rather readily. It is therefore quite unlikely that the CKM phase is the only CP violating 1