Related papers: FCNC in Concurrent Dark Photon and Dark $Z$ Models
In a recent work [Phys. Rev. D 98, 043521 (2018)], we have investigated a dark matter (DM)-photon coupling model in which the DM decays into photons in the presence of dark energy (DE) with the constant equation of state (EoS) parameter.…
The study of flavour-changing neutral currents (FCNC) gives access to important tests of the Standard Model (SM) and allows to search for hints of beyond the SM phenomena. We present here the study of the very rare decays $B^0\rightarrow…
Non-unitarity of the neutrino mixing matrix is expected in many scenarios with physics beyond the Standard Model. Motivated by the search for deviations from unitary, we study two neutrino counting observables: the neutrino-antineutrino…
We investigate an extension of the $\Lambda$CDM model where the dark matter (DM) is coupled to photons, inducing a nonconservation of the numbers of particles for both species, where the DM particles are allowed to dilute throughout the…
The gauged $U(1)_{L_\mu-L_\tau}$ extension of the Standard Model is a very simple framework that can alleviate the tension in muon anomalous magnetic dipole moment, reinforced by the recent Fermilab measurement. We explore experimental…
Mesogenesis provides a path for generating the baryon asymmetry of the Universe, using only the CP violation furnished by the Standard Model in the decay of $B$ mesons. While this is an intriguing possibility, it is largely constrained by…
As an alternative to direct measurements, we extract exclusive branching fractions of semileptonic B-meson decays to charmed mesons, $BF_i(B\to X_c^il\nu)$ with $X_c^i = D, D^*, D_0, D'_1, D_1, D_2, D', D'^*$ and non-resonant final states…
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 consider experimental constraints in the MeV region in order to determine the parameter space for the $U(1)_X$ extension of the Standard Model, presented in the first part of our work. In particular, we focus on the model UV-completed by…
Collider searches for energetic particles recoiling against missing transverse energy allow to place strong bounds on the interactions between dark matter (DM) and standard model particles. In this article we update and extend LHC…
The interaction between the dark $U(1)_d$ sector with the visible Standard Model (SM) sector takes place through the kinetic mixing between the dark photon $U(1)_d$ field $Z_d^\mu$ and the SM $U(1)_Y$ gauge field $B_\mu$. After the…
We investigate the dark matter phenomenology of a Dirac fermion together with kinetic mixing in the context of an $L_\mu - L_\tau$ model. We analyze which part of the parameter space can provide a viable dark matter candidate and explain…
After an introduction to the Standard-Model description of CP violation and a brief look at the present status of this phenomenon in the kaon system, a classification of non-leptonic B-decays is given and the formalism of…
b to s transitions are flavour-changing neutral current (FCNC) processes that play an important role in the search for physics beyond the Standard Model (SM). Contributions from virtual particles in the loop are predicted to deviate…
We investigate a so-called 331 extension of the Standard Model gauge sector which accommodates neutrino masses and where the lightest of the new neutral fermions in the theory is a viable particle dark matter candidate. In this model,…
We investigate the landscape of constraints on MeV-GeV scale, hidden U(1) forces with nonzero axial-vector couplings to Standard Model fermions. While the purely vector-coupled dark photon, which may arise from kinetic mixing, is a…
Small neutrino masses can arise in some grand unified models or superstring theories. We consider a model with an enhanced fermion sector containing Dirac neutral heavy leptons. The dependence on the mass and mixing parameters of these new…
We discuss the constraints from rare B and K decays on the Electroweak Symmetry Breaking (EWSB) sector, as well as on theories of fermion masses. We focus on models involving new strong dynamics and show that transitions involving Flavor…
In the wake of the recent measurements of the decays $B_c\to J/\psi\,\pi(K)$ and $B_c\to J/\psi\,\ell\nu_\ell$ reported by the LHCb Collaboration we calculate the form factors for the $B_c\to J/\psi$ and $B_c\to \eta_{c}$ transitions in…
We investigate the effect of scalar leptoquarks and family non-universal $Z^\prime$ boson on the rare leptonic decays of $B_{s, d}^*$ mesons, mediated by the FCNC transitions $b \to (d, s) l^+ l^-$. They are sensitive to a variety of new…