Related papers: $B \to X_s \mu^+ \mu^-$ in Technicolor with Scalar…
We analyse scalar flavour-changing neutral currents of down-type quarks in models with two Higgs doublets, coupled separately to up- and down-type quarks, in the limit where the ratio of the two expectation values ($\tan \beta = v_u/v_d$)…
Based on a data sample of $(10087 \pm 44) \times 10^6$ $J/\psi$ events taken with the BESIII detector, we search for the flavor-changing neutral current charmonium decay $J/\psi \to D^{0} \mu^{+} \mu^{-} + \text{c.c.}$. No significant…
$B_s - \bar B_s$ 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…
Measurements of Flavor Changing Neutral Current (FCNC) processes (rare decays, flavor mixing) play a key role to pursue new physics beyond the Standard Model. We present recent analysis results about some FCNC transitions performed by CDF…
We study the implications of flavour-changing neutral currents (FCNC's) in a model with the $SU(2)_l\times SU(2)_h\times U(1)_Y$ electroweak gauge symmetry for several anomalies appearing in $b\to s \ell\bar \ell$ induced $B$ decays in LHCb…
Flavor changing neutral currents coming from a new non-universal neutral Gauge-Boson and from the non-unitary quark mixing matrix for the $SU(3)_c\otimes SU(3)_L\otimes U(1)_X$ model with right handed neutrinos are studied. By imposing as…
We examine the decays $t\rightarrow c\gamma$ and $c Z^0$ in the Standard Model with an extra scalar doublet and no discrete symmetry preventing tree-level flavour changing neutral currents. The Yukawa couplings of the new scalars are…
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 preliminary results from a search for the rare, flavor-changing neutral current decays B to K l+ l- and B to K* l+ l-, where l+ l- is either an e+ e- or mu+ mu- pair. The data sample comprises (84.4 +- 0.9) X 10e6 upsilon(4S) to…
We present measurements of the flavor-changing neutral current decays B --> Kl+l- and B --> K*l+l-, where l+l- is either an e+e- or mu+mu- pair. The data sample comprises 229 x 10^6 Y(4s) -->to BBbar decays collected with the BaBar detector…
The ability of present and future experiments to test the Standard Model in the $B$ meson sector is described. We examine the loop effects of new interactions in flavor changing neutral current $B$ decays and in $Z\to b\bar b$,…
Pure leptonic and semileptonic rare B decays, $B_s \to \mu^+ \mu^-$ and $B \to X_s \mu^+ \mu^-$ in the minimal supersymmetric Standard Model (MSSM), in particular, gluino and neutralino contributions to the decays, are discussed under Br($B…
In the $SU(3)_C \times SU(2)_L \times SU(2)_R \times U(1)_{(B-L)/2}$ extension of the standard model, a minimal (but asymmetric) scalar sector consists of one $SU(2)_R \times U(1)_{(B-L)/2}$ doublet and one $SU(2)_L \times SU(2)_R$…
We present a search for the rare flavor-changing neutral-current decay $B^+ \to K^+ \nu \bar{\nu}$ based on data sample of 82 fb$^{-1}$ collected with the BABAR detector at the PEP-II B-factory. Signal events are selected by examining the…
We consider the exclusive B_s -> phi mu+ mu- process in the standard model using a constituent quark loop model approach together with a simple parameterization of the quark dynamics. The model allows to compute the decay form factors and…
A search for the flavor-changing neutral-current decay $B^{+}\to K^{+}\nu\bar{\nu}$ is performed at the Belle II experiment at the SuperKEKB asymmetric energy electron-positron collider. The results are based on a data sample corresponding…
We propose a novel method to study flavor-changing neutral currents in the $e^+e^-\to D^{*0}$ and $e^+e^-\to B_{s}^* $ transitions, tuning the energy of $e^+e^-$- collisions to the mass of the narrow vector resonance $D^{*0}$ or $ B_{s}^*$.…
The ratio of the measured $\bar B\to D^{(*)}\ell\bar{\nu}$ decay rates for $\ell = \tau$ vs. $e,\mu$ deviate from the Standard Model (SM) by about $4\sigma$. We show that the data are in tension with the SM, independent of form factor…
The flavor changing neutral top quark decay t -> c X is computed, where X is a neutral standard model particle, in a extended model with a single extra dimension. The cases for the photon, X= \gamma$, and a Standard Model Higgs boson, X =…
We study the effect of -mediated flavor-changing neutral current on the decays. The branching ratios of these decays can be enhanced remarkably in the non-universal model. Our estimated branching ratios are enhanced significantly from their…