Related papers: B meson decay anomaly with a non-universal U(1)' e…
We consider variations of the standard leptogenesis picture arising from the presence of an additional scale related to the breaking of a $U(1)_X$ abelian flavor symmetry. We show that quite generically the presence of an additional energy…
As the Higgs boson properties settle, the constraints on the Standard Model extensions tighten. We consider all possible new fermions that can couple to the Higgs, inspecting sets of up to four chiral multiplets. We confront them with…
There are four models of tree-level new physics (NP) that can potentially explain the $b\to s \mu^+ \mu^-$ and $b \to c\ell \bar \nu$ anomalies simultaneously. They are the S3, U3, and U1 leptoquarks and a standard-model-like triplet vector…
Leptoquarks with masses between 2 TeV and 50 TeV are commonly invoked to explain deviations between data and Standard-Model (SM) predictions of several observables in the decays $b\to c\tau \bar\nu$ and $b\to s \ell^+\ell^-$ with…
The simplest extension of the standard model consists in adding one singlet scalar field which mixes with the Higgs boson. O(GeV) masses of the new scalar carry strong motivation from relaxion, dark matter and inflation models. The decay of…
There are indications of a possible breakdown of the standard model, suggesting that $\tau$ lepton interactions violate flavor universality. BABAR, Belle and LHCb report high ratios of $B\to D^{(*)}\tau\nu$. There are long-standing excesses…
We consider a conformal complex singlet extension of the Standard Model with a Higgs portal interaction. Two different scenarios depending on whether the global U(1) symmetry is broken or not have been studied. In the unbroken phase, the…
LHCb found hints for physics beyond the standard model in $B\to K^*\mu^+\mu^-$, $B\to K^*\mu^+\mu^-/B\to K^*e^+e^-$ and $B_s\to\phi\mu^+\mu^-$. In addition, the BABAR results for $B\to D^{(*)}\tau\nu$ and the CMS excess in…
We consider $U(1)_H$ extensions of Type-I 2HDM plus a singlet scalar $\phi_H$, introducing a new Higgs doublet $H_2$ and a singlet $\phi_H$ charged under $U(1)_H$. The SM Higgs doublet $H_1$ as well as all the SM fermions and three…
There are presently several discrepancies in $b \to s \ell^+ \ell^-$ decays of $B$ mesons suggesting new physics coupling to $b$ quarks and leptons. We show that a $Z'$, with couplings to quarks and muons that can explain the $B$-decay…
In order to simultaneously account for both $R_{D^{(\ast)}}$ and $R_{K^{(\ast)}}$ anomalies in $B$-decays, we consider an extension of the Standard Model by a single vector leptoquark field, and study how one can achieve the required lepton…
The apparent excess of $Z \rightarrow b \bar b$ events at LEP may be an indication of new physics beyond the standard model. However, in either the two-Higgs-doublet model or the minimal supersymmetric standard model, any explanation would…
Rare decays mediated by $b \to s \nu \bar \nu$ transitions have been reported by the Belle II experiment. The branching ratio of the decay $B^+ \to K^+ \nu \bar \nu$ is found to be enhanced with respect to the standard model value. If taken…
We consider the Standard Model (SM) with the addition of a $\mathrm{U(1)^\prime}$ gauge symmetry and a complete fourth family of quarks and leptons which are vector-like with respect to the full $\mathrm{SU(3)_C}\times \mathrm{SU(2)_L}…
We study lepton flavor violating (LFV) $B$ decays in a general two Higgs doublet model with sub-TeV exotic scalars. Two different parameter spaces are explored: one dominated by extra top Yukawa coupling $\rho_{tt}$, the other by LFV…
In recent years, exciting (indirect) hints for physics beyond the Standard Model (SM) have been accumulated. In particular, semi-leptonic $B$ decays show deviations from the SM predictions, which, due to the ratios $R(K^{(*)})$ and…
We propose a generation dependent lepton/baryon gauge symmetry, $U(1)_{B_3 - x_\mu L_\mu - x_\tau L_\tau} \equiv U(1)_X$ (with $x_\mu + x_\tau =1$ for anomaly cancellation), as a possible solution for the $b \rightarrow s \mu^+ \mu^-$…
The most statistically significant hints for new physics in the flavor sector are discrepancies between theory and experiment in $B$ decays to lepton pairs ($b\to s\ell^+\ell^-$) and a deficit in $1^{\rm st}$ row CKM unitarity (the Cabibbo…
I present a model addressing coherently the naturalness problem of the electroweak scale and the observed pattern of deviations from the Standard Model in semi-leptonic decays of $B$ mesons. The Higgs and the two scalar leptoquarks…
We present a new model based on the SU(3)xSU(2)xU(1) symmetry, in which there is a new consistent set of chiral fermion fields that renders the model free from anomalies. The new fermions do not share the usual family structure of the…