Related papers: Limits on scalar leptoquark interactions and conse…
Recently we proposed a natural scenario of grand unified theories with anomalous U(1)_A gauge symmetry, in which doublet-triplet splitting is realized in SO(10) unification using Dimopoulos-Wilczek mechanism and realistic quark and lepton…
Results are presented from a search for the pair production of third-generation scalar and vector leptoquarks, as well as for top squarks in R-parity-violating supersymmetric models. In either scenario, the new, heavy particle decays into a…
We explore predictive flavor models based on subgroups of the standard-model $SU(3)^5$ flavor symmetry. Restricting to products of $SU(3)$, we find that a global $SU(3)^3$ flavor symmetry, broken only by two Yukawa spurions, leads to a…
The alternative $SU(4) \otimes SU(2)_L \otimes SU(2)_R$ gauge model, which allows unification of the quarks and leptons at the TeV scale, is studied in detail. We discuss the implications for nucleon decay, B and K rare meson decays and…
Lepton number as a fourth color is the intriguing theoretical idea of the famous Pati-Salam (PS) model. While in conventional PS models, the symmetry breaking scale and the mass of the resulting vector leptoquark are stringently constrained…
An extended Higgs sector may allow for new scalar particles well below the weak scale. In this work, we present a detailed study of a light scalar $S$ with enhanced coupling to leptons, which could be responsible for the existing…
A search for scalar or pseudoscalar states decaying to a top quark-antiquark pair ($\mathrm{t \bar{t}}$), using $138\,\mathrm{fb}^{-1}$ of pp collision data taken at $\sqrt{s} = 13\,\mathrm{TeV}$ using the CMS detector, is presented. Events…
We consider a minimal renormalizable non-supersymmetric $E_6$ Grand Unified Theory using fundamental representation $27$ for fermions and scalars. The scalar with adjoint representation ${78}$ is also taken for direct breaking of $E_{6}$ to…
New light singlet scalars with flavor-specific couplings represent a phenomenologically distinctive and flavor-safe alternative to the well-studied possibility of Higgs-portal scalars. However, in contrast to the Higgs portal,…
We show that in a self-consistent preon model, where Standard Model quarks and leptons are three-body composites confined at a metacolor scale Lambda_cr ~ 10^14 GeV, both leptoquarks and the Standard Model gauge group SU(3)_c x SU(2)_L x…
We introduce a physical scalar sector in a SU(2)xU(1) electroweak theory in which the gauge group is realized non linearly. By invoking theoretical as well as experimental constraints, we build a phenomenologically viable model in which a…
The presence of colored particles can affect both the single and the pair Higgs productions substantially. For scalar particles, this happens if their portal couplings to the Standard Model Higgs are large and their masses are not too high.…
Most general tbW couplings were investigated in the process \gamma \gamma -> ttbar -> l^{+-} X for unpolarized photon beams. The double angular and energy distribution of the lepton was calculated and an optimal-observable analysis on it…
We investigate the $R_{D}$ and $R_{D^*}$ anomalies in the context of non-minimal $SU(5)$, where Higgs sector is extended by adjoint 45-dimensional multiplet. One of the light spectrum of this model could be the scalar triplet leptoquark…
The discrepancies between $b\to s\ell^+\ell^-$ data and the corresponding Standard Model predictions point to the existence of new physics with a significance at the $5\sigma$ level. While previously a lepton flavour universality violating…
We study low energy implications of F-theory GUT models based on $SU(5)$ extended by a $U(1)'$ symmetry which couples non-universally to the three families of quarks and leptons. This gauge group arises naturally from the maximal…
Data from HERA, LEP and the Tevatron, as well as from low energy experiments are used to constrain the Yukawa couplings for scalar and vector leptoquarks in the Buchmuller-Ruckl-Wyler effective model. In the limit of very high leptoquark…
We study extensions of the standard model with additional colored scalar fields which can couple directly to quarks. Natural suppression of flavor changing neutral currents implies minimal flavor violation, and fixes the scalars to…
We analyze the relation between the present (and foreseen) bounds on matter stability and the presence of TeV-scale color octet scalar states in nonsupersymmetric SO(10) grand unification with one adjoint Higgs representation triggering the…
Leptoquark (LQ) models can be the solution to the $(g-2)_{\mu}$ anomaly because of the chiral enhancements. In this work, we consider the models extended by the LQ and vector-like quark (VLQ) simultaneously, which can be used to explain the…