Related papers: Effects of mixing with quark singlets
Our main aim in this paper is to present detailed studies to probe the top quark flavor changing neutral current (FCNC) interactions at $tqg$, $tq\gamma$, $tqH$ and $tqZ (\sigma^{\mu \nu}, \gamma_{\mu})$ vertices in the triple-top signal $p…
The phenomenon of $B^0_q-\bar B^0_q$ mixing ($q=d,s$) provides a sensitive probe for physics beyond the Standard Model. We explore the corresponding space for New Physics left through the current data, having a careful look at analyses of…
The rates and corresponding jet distributions for the decay $Z\to b\bar bg$ and the process $e^+e^-\to t\bar tg$ may be sensitive to anomalous dipole-like couplings of heavy quarks to the photon and $Z$. In the $b$-quark case, after…
The effective renormalizable theory describing electromagnetic and strong interactions of quarks of five light flavors ($n_f = 5$ QCD$\times$QED) is considered as a low-energy limit of the full Standard Model. Two-loop relation between the…
A tree-level flavor changing neutral current in the up-like quark sector appears in one of the variations of the Littlest Higgs model. We investigate the effects of this coupling in the D+ -> pi+ l+ l- and D0 -> rho0 l+ l- decays, which are…
Large top quark flavor changing through neutral currents is expected by many extensions of the standard model. Direct and indirect searches for flavor changing neutral currents (FCNC) in the top quark decays to an up type quark (up,charm)…
In this paper, we study the phenomenology of right-handed neutrino isosinglets. We consider the general situation where the neutrino masses are not necessarily given by $m_D^2/M$, where $m_D$ and $M$ are the Dirac and Majorana mass terms…
We present a search for flavor changing neutral currents (FCNC) in decays of top quarks. The analysis is based on a search for $t\bar{t}\rightarrow\ell'\nu\ell\bar{\ell}$+jets ($\ell, \ell' = e,\mu$) final states using 4.1 {\rm fb}$^{-1}$…
We present a simple method for analyzing the impact of precision electroweak data above and below the Z-peak on flavour-conserving heavy new physics. We find that experiments have probed about ten combinations of new physics effects, which…
Two twisted doublets, one containing the up and down quarks and the other containing the strange quark with an SU(2)-flavor partner, are used for studies in the meson sector. The relevant chiral perturbation theory is presented, and…
In the contest of a Two Higgs Doublet Model without flavor conservation, the presence of Flavor Changing Neutral Scalar Currents may affect in particular the couplings of the top quark. Some ideas on how to look for new signals from Flavor…
Considering the experimental constraints given by CMS collaboration at $\sqrt{s} = 8$ TeV on the strength of top quark flavour-changing neutral-current (FCNC) couplings $tq\gamma$ and $tqg$, we investigate the production of top quark in…
The mixings of $d_R$ quarks, hidden from view in Standard Model (SM), are naturally the largest if one has an Abelian flavor symmetry. With supersymmetry (SUSY) their effects can surface via $\tilde d_R$ squark loops. Squark and gluino…
The influence of the top quark mass on mixing processes and precise electroweak measurements is described. Experimental observation of the top quark in proton-antiproton collisions is discussed, and some brief remarks are made about…
In top quark production, the polarization of top quarks, decided by the chiral structure of couplings, is likely to be modified in the presence of any new physics contribution to the production. Hence the same is a good discriminator for…
Within the standard model (SM), the time dependent CP asymmetries in B -> psi K_S, B -> eta' K_S and B -> phi K_S are expected to give the same result i.e. sin (2 beta). However recent measurements of the mixing induced CP asymmetries in B…
The loop corrections to the couplings of Higgs bosons to quarks and charged leptons are calculated within supersymmetric versions of the Standard Model, extended by a gauge singlet. The effective couplings of the $SU(2)_L$ doublet and…
In many extensions of the standard model an additional up-like heavy quark appears. Its appearance induces flavour changing neutral current transition in the up-quark region at the tree level. We investigate possible effects of these models…
In a recent paper, we pointed out that mixing of the light neutrinos with heavy gauge singlet states could reconcile the Z-pole data from e+e- colliders and the nu_mu (anti-nu_mu) scattering data from the NuTeV experiment at Fermilab. We…
We review the theory and phenomenology of isosinglet vector-like quarks (VLQs). In recent years, interest in VLQs has been increasing, due to their contributions to new physics effects that can be tested in experiments at LHC and…