Related papers: Large effects on $\BsBs$ mixing by vector-like qua…
The radiative decay $\BSgamma$ and the mixing $\BsBs$ are discussed in the vector-like quark model which contains extra SU(2)-singlet quarks with the same electric charges as the up-type and down-type quarks. Constraints on the extended…
We study a simple extension of the Standard Model with a vector-like down-type quark $D$ and a neutral singlet scalar ${\cal S}=S_R,\Phi$. The scalar is considered in two forms, a real field $S_R=S_R^\dagger$ and a complex field…
$B_s - \bar B_s$ mixing has been measured recently by D0 and CDF. The range predicted in the standard model is consistent with data. However, the standard model central values for $\Delta M_{B_s}$ and also $\Delta M_ {B_d}$ are away from…
We carry out a general analysis of tree level flavor changing neutral currents in the context of 331 models, considering arbitrary quark and gauge boson mixing matrices. The results are applied to definite textures of quark mass matrices,…
The vector-like quark model is one of the extensions of the standard model (SM) of particle physics. The simplest version of this model introduces a vector-like singlet quark which can mix with SM quarks and give rise to new contributions…
We study B_s-\bar{B}_s mixing in grand unified SO(10), SU(5) models where the mixings among the second and third generation squarks arise due to the existence of flavor violating sources in the Dirac and Majorana couplings which are…
We study the $B$ meson radiative decay $B \to X_s \gamma$ in the vector quark model. Deviation from the Standard Model arises from the non-unitarity of the charged current KM matrix and related new FCNC interactions. We establish the…
We study the decay B\to X_s\gamma in a minimal extension of the standard model with extra up- and down-type quarks whose left- and right-handed components are both SU(2) singlets. Constraints on the extended Cabibbo-Kobayashi-Maskawa matrix…
The extra contributions due to an extra generation of vector-like quarks to the isospin symmetry breaking observable associated with the radiative B->K^* \gamma decay is obtained. It is shown that this additional contribution is sensitive…
We consider in the 3-3-1 model with heavy leptons the box contributions to the mass difference in $K$ and $B$ neutral mesons induced by neutral (pseudo)scalars, exotic charged quarks, singly and doubly charged scalar and gauge bosons. In…
Meson and anti-meson mixing processes constitute an important source of constraints on models that give tree level contributions to flavor violating neutral processes. In electroweak $ \text{SU}(3)_\text{L} \times \text{U}(1)_N $ models,…
The recent observation of the mass difference in $B_s$ system seems to be not in complete agreement with the corresponding standard model value. We consider the model with an extra vector like down quark to explain this discrepancy and…
We show that in the supersymmetric standard model (SSM) box diagrams mediated by charginos and up-type squarks may give large contributions to $\BB$ and $\KK$ mixings. This is due to the fact that a heavy top quark mass allows large mass…
The rare decay $b\to ss\bar{d}$ is studied in a vector quark model by adding the contributions from exotic vector-like quarks. We find that the contribution from box diagrams amounts to $10^{-9}$ in the branching ratio, while the…
We show that the observed pattern of quark flavor mixing, such as |V_{us}| \simeq |V_{cd}|, |V_{cb}| \simeq |V_{ts}|, |V_{cd}/V_{td}| \simeq |V_{cs}/V_{ts}| \simeq |V_{tb}/V_{cb}| and |V_{ub}/V_{cb}| < |V_{td}/V_{ts}|, can essentially be…
We explore the impact of topflavour model to $B-\bar{B}$ mixings and rare decays of $B$ mesons. By the flavour-changing neutral current interactions of this model, the $B-\bar{B}$ mixing amplitudes are substantially affected while it is…
The branching ratio of the rare decay B->X_s gamma provides potentially strong constraints on models beyond the Standard Model. Considering a general scenario with new heavy neutral gauge bosons, present in particular in Z' and gauge…
We have witnessed some flavor anomalies appeared in the past years, and explanations based on extended gauge sectors are among the most popular solutions. These beyond the Standard Model (SM) theories often assume flavor changing…
In models with an extra U(1)' gauge boson family non-universal couplings to the weak eigenstates of the standard model fermions generally induce flavor-changing neutral currents. This phenomenon leads to interesting results in various B…
Using the example of the rare decay $B \to X_s \gamma$, we analyse the importance of interference effects for the bounds on the parameters in the squark mass matrices within the unconstrained MSSM. In former model-independent analyses no…