相关论文: $t\rightarrow \gamma$ decay in the ACD model

As an alternative to the standard model, we couple two scalar doublets such that, in the third family, one (${\cal H}$) couples only to the top quark, the other ($H$), that is identified as the 126 GeV state already observed, to the bottom…

We analyze the contributions to rare kaon decays mediated by flavor-changing Z-penguin diagrams in a generic low-energy supersymmetric extension of the Standard Model. In order to perform a model-independent analysis we expand the squark…

We give a more complete calculation of $b \to s\gamma $ decay in 2-Higgs doublet model, including leading log QCD corrections from $m_{top}$ to $M_W$ in addition to corrections from $M_{W}$ to $m_b$. The inclusive decay rate in the first…

Our recently completed analysis of the decay constants of both pseudoscalar and vector beauty mesons reveals that in the bottom-quark sector two specific features of the sum-rule predictions show up: (i) For the input value of the…

We investigate the impact of new physics beyond the Standard Model to the $s \rightarrow d \gamma$ process, which is responsible for the short-distance contribution to the radiative decay $\Otogamma$. We study three representative…

We discuss exclusive radiative decays in QCD factorization within the Standard Model. In particular, we consider the decays B -> V gamma, with a vector meson K* or rho in the final state, and the double radiative modes B_s -> gamma gamma…

We explore corrections to electroweak parameters in the context of Extended Technicolor (ETC) models in which the ETC gauge-boson which generates the top-quark mass carries weak $SU(2)$ charge. For $m_t \sim 150$ GeV there exist potentially…

We analyze the semileptonic $B \to a_1 \ell^+\ell^-$, $\ell=\tau, \mu, e$ transitions in the frame work of the three-point QCD sum rules in the standard model. These rare decays governed by flavor-changing neutral current transition of $b…

We study the effects of a vector-like SU(2) quark doublet as a fourth generation. In this model we examine the chiral structure and the FCNC in the quark sector by using radiative B meson decays in the allowed region for parameters from…

Recently, the Belle II Collaboration reported the branching fraction $\mathcal{B}(B^+ \to K^+ \nu \bar{\nu})=(2.3\pm0.7)\times10^{-5}$ with a significance of $3.5\sigma$, which is $2.7\sigma$ above the SM expectation. Motivated by this…

Motivated by the recent measurement of $D^0\to\rho^0\gamma$ improved standard model (SM) predictions for branching ratios and CP asymmetries of radiative charm decay are given. Weak annihilation induced decays are probes of non-perturbative…

In this paper, I study the branching ratio of the rare radiative decay $B_s \to \nu \bar{\nu} \gamma$ in the framework of the Fourth-Generation Standard Model and the Two-Higgs-Doublet Model. It is shown that this quantity is a very…

The rare t-quark decays $t \to c l_j^{+} l_k^{-}$, $t \to c \tilde{\nu_j} \nu_k$ via the scalar leptoquark doublets are investigated in the minimal four color symmetry model with the Higgs mechanism of the quark-lepton mass splitting. The…

We present an update of the branching ratios for Higgs-boson decays in the Standard Model. We list results for all relevant branching ratios together with corresponding uncertainties resulting from input parameters and missing higher-order…

We argue that it is possible to make a consistent picture of FNAL data including the production and decay of gluinos and squarks. The additional cross section is several pb, about the size of that for Standard Model (SM) top quark pair…

Many standard model extensions that address the hierarchy problem contain Dirac-fermion partners of the top quark, which are typically expected around the TeV scale. Searches for these vector-like quarks mostly focus on their decay into…

The dependence of the $K^+ \to \pi^0 l^+ \nu_l \gamma$ decay width on the $T$-odd kinematical variable, $ \xi = {\vec q \cdot [\vec p_l \times \vec p_\pi]} / {M^3}$, is studied at the tree and one-loop levels of Standard Model. It is shown…

A few $B_{d,s}$ and $\Lambda_b$ decays induced by $b \to s$ transition are studied in the Standard Model and in the framework of the Appelquist, Cheng and Dobrescu (ACD) model, which is a New Physics scenario where a single universal extra…

We study the color-allowed $\Lambda_b\rightarrow \Lambda_c \pi, \Lambda_cK$ decays in the perturbative QCD approach (PQCD) to lowest order in strong coupling constant $\alpha_s$. Both the factorizable and nonfactorizable contributions are…

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…