Related papers: Penguin-like Diagrams from the Standard Model
Penguin, or loop, decays of B mesons induce effective flavor-changing neutral currents, which are forbidden at tree level in the Standard Model. These decays give special insight into the CKM matrix and are sensitive to non-standard model…
The flavour-changing quark-Higgs coupling does not arise at the tree level in the Standard Model. It is, however, induced by one-loop effects. In this paper, we present an exact calculation of the Higgs-penguin vertex in the tHooft-Feynman…
We evaluate one-loop diagrams in the unitary gauge that contribute to flavor-changing neutral current (FCNC) transitions involving two and four fermions. Specifically, we deal with penguin and box diagrams arising within the standard model…
We systematically analyse the gluonic penguin-induced charmless decays $B \ra K_X\phi$($K_X$ denotes the meson state $s\bar q \;(q=u\ {\rm or}\ d)$ ), in the standard model and the two-Higgs-doublet model. These processes, being induced at…
We study renormalizable extensions of the standard model that contain vector-like fermions in a (single) complex representation of the standard model gauge group. There are 11 models where the vector-like fermions Yukawa couple to the…
We show that, unlike mass matrices, the fermionic gauge currents of the Standard Model exhibit, at the quantum level, remarkable SU(2)_f flavor properties at the observed values of the mixing angles. They accommodate all measured mixing for…
Flavour changing neutral currents are only allowed via loop diagrams in the Standard Model (SM). Electroweak penguin processes are therefore sensitive probes for new physics, as physics beyond the Standard Model can enter via virtual…
Using the $SU(3)$ flavour symmetry of strong interactions, we propose strategies for extracting both the CKM-angle $\gamma$ and the $\bar b\to\bar uu\bar s$ tree-level amplitude $T'$. We present also an approximate approach using the…
The Standard model of particle physics provides a successful theory to understand the experimental results of the electroweak and strong interactions. However, it does not have a satisfactory explanation for the hierarchy problem. Many…
In a previous study, the flavor-changing fermion-graviton interactions have been analyzed in the framework of the standard model, where analytical results for the relevant form factors were obtained at the leading order in the external…
We analyze the lepton flavor violating process $\mu-e$ conversion in the framework of the minimal R-symmetric supersymmetric standard model. The theoretical predictions are determined by considering the experimental constraint on parameter…
The Standard Model of electroweak interactions is shown to include a gauge theory for the observed scalar and pseudoscalar mesons. This is done by exploiting the consequences of embedding the SU(2)left X U(1) group into the chiral group of…
In this paper, the lepton flavor violating $\tau^- \to \mu^- V^0(V^0=\rho^0,\phi,\omega)$ decays are studied in the framework of the two Higgs doublet model(2HDM) III. We present a computation of the the $\gamma-$, $Z$ penguin and box…
Leptoquarks are hypothetical new particles, which couple quarks directly to leptons. They experienced a renaissance in recent years as they are prime candidates to explain the so-called \textit{flavor anomalies}, i.e. the deviations between…
The complex phases $\phi_d$ and $\phi_s$, associated with the mixing between neutral $B_q^0$ and $\bar B_q^0$ mesons ($q\in\{d,s\}$), are key observables to test the Standard Model and search for contributions from new physics. They are…
We present results for the \Delta S=2 matrix elements which are required to study neutral kaon mixing in the standard model (SM) and beyond (BSM). We also provide leading chiral order results for the matrix elements of the electroweak…
Precision flavour observables play an important role in the interpretation of results at the LHC in terms of models of new physics. We present the result for the one-loop Z penguin in generic extensions of the standard model which exhibit…
We have revisited the computations of the flavor violating leptonic decays of the $\tau$ and $\mu$ leptons into three lighter charged leptons in the Standard Model with non-vanishing neutrino masses. We were driven by a claimed unnaturally…
We examine the effects of standard model-like interactions on the near-conformal dynamics of a theory featuring a dilatonic state identified with the standard model-like Higgs. As template for near-conformal dynamics we use a gauge theory…
Beyond Standard Model physics frequently connects flavor symmetry with a discrete group. If the discrete symmetry arises spontaneously from a gauge theory, one can maintain compatibility with quantum gravity and avoid anomalies. We provide…