Related papers: Rare baryonic decays $\Lambda_b \to \Lambda l^+ l^…
In this work we study the flavor changing neutral current(FCNC) decays of the top quark, $t\to c\gamma$ and $t\to c g$. The Standard Model, predictions for the branching ratios of these decays are about $\sim 5\times 10^{-14}$, and $\sim…
Rare and very rare decays of third-generation particles, including $b$-hadrons and $\tau$ leptons, provide sensitive probes of physics beyond the Standard Model (SM). Unlike direct searches limited by collider energies, they probe new…
A lattice QCD determination of the $\Lambda_c \to N$ vector, axial vector, and tensor form factors is reported. The calculation was performed with $2+1$ flavors of domain wall fermions at lattice spacings of $a\approx 0.11\:{\rm…
The current experimental status of the searches for the very rare decays $B^0_s \rightarrow \mu^+ \mu^-$ and $B^0 \rightarrow \mu^+ \mu^-$ is discussed. These channels are highly sensitive to various extensions of the Standard Model,…
We investigate the rare decay $\Lambda_b \to \Lambda \gamma$ which receives both short and long distance contributions. We estimate the long distance contributions and find them very small. The form factors are obtained from $\Lambda_c \to…
The persistent tensions between inclusive and exclusive determinations of $|V_{cb}|$ and $|V_{ub}|$ weaken the power of theoretically clean rare $K$ and $B$ decays in the search for new physics (NP). We demonstrate how this uncertainty can…
We provide improved Standard Model theory predictions for the exclusive rare semimuonic processes $B\to K^{(*)}\mu^+\mu^-$ and $B_s\to\phi\mu^+\mu^-$. Our results are based on a novel parametrization of the non-local form factors, which…
The exclusive rare radiative $B$-decays are studied in the framework of the relativistic quark model based on the quasipotential approach in quantum field theory. The large recoil momentum of the final vector meson allows for the expansion…
We search for b to s\mu^+\mu^- transitions in B meson (B^+, B^0, or B^0_s) decays with 924pb^{-1} of p pbar collisions at sqrt(s)=1.96 TeV collected with the CDF II detector at the Fermilab Tevatron. We find excesses with significances of…
In this article, we study the rare decays corresponding to $b \to d$ transition in the framework of the covariant confined quark model. The transition form factors for the channels $B^{+(0)} \to (\pi^{+(0)}, \rho^{+(0)},\omega)$ and $B_s^0…
Our study focuses on the weak decay of $ D_s^+ \to p \overline{n} $, which is the only possible two-body baryonic decay in the $ D $ meson system. An analysis using perturbative quantum chromodynamics (pQCD) is challenging in this decay due…
We present the first lattice QCD determination of the $\Lambda_b \to \Lambda^*(1520)$ vector, axial vector, and tensor form factors that are relevant for the rare decays $\Lambda_b \to \Lambda^*(1520)\ell^+\ell^-$. The lattice calculation…
A search for the nonresonant $\Lambda_c^+ \to p \mu^+ \mu^-$ decay is performed using proton-proton collision data recorded at a centre-of-mass energy of 13 TeV by the LHCb experiment, corresponding to an integrated luminosity of 5.4…
Using the light-front quark model, we calculate the transition form factors, decay rates, and longitudinal lepton polarization asymmetries for the exclusive rare $B\to K\ell^+\ell^-(\ell=e,\mu,\tau$) decays within the standard model.…
The rare decays mediated by flavor-changing neutral current processes, such as $b \to s \ell^{+}\ell^{-}$, provide powerful probes of the Standard Model and potential windows into new physics. Particularly, the angular observables in these…
We calculate the branching ratio of $\Lambda_b \to \Lambda \gamma$ in the standard model using the PQCD method. The predicted branching ratio $B(\Lambda_b \to \Lambda \gamma)$ is about $(4.3\sim 8.6)\times 10^{-8}$, with reasonable…
Measurements at B factories have provided important constraints on new physics in several rare processes involving the B meson. New Physics, if present in the b quark sector may also affect the top sector. In an effective Lagrangian…
We obtain a lower limit on the compactification scale of extra dimension via comparison of the branching ratio in the baryonic $\Lambda_b\rightarrow \Lambda \mu^+ \mu^-$ decay channel recently measured by CDF collaboration and our previous…
Rare $B$-meson decays, suppressed in the Standard Model (SM) by the GIM mechanism, are sensitive probes of new physics. In particular, loop-level $b \to s$ transitions can reveal effects of heavy virtual particles such as vector-like quarks…
We consider the rare top quark decays in the framework of topcolor-assisted technicolor (TC2) model. We find that the contributions of top-pions and top-Higgs predicted by the TC2 model can enhance the SM branching ratios by as much as 6-9…