Related papers: Road map through the desert with scalars
Gauge unification is widely considered to be a desirable feature for extensions of the standard model. Unfortunately the standard model itself does not exhibit a unification of its running gauge couplings but it is required by grand unified…
We construct extensions of the Standard Model in which the gauge symmetries and supersymmetry prevent the dangerously large effects that may potentially be induced in a supersymmetric standard model by Planck scale physics. These include…
We discuss the unification of gauge couplings within the framework of a wide class of realistic free-fermionic string models which have appeared in the literature, including the flipped SU(5), SO(6)xSO(4), and various SU(3)xSU(2)xU(1)…
The observed Standard Model is consistent with the existence of vector-like species with electric charge a multiple of $e/6$. The discovery of a fractionally charged particle would provide nonperturbative information about Standard Model…
We consider the viability of new heavy gauge singlet scalar particles at colliders such as the LHC. Our original motivation for this study came from the possibility of a new heavy particle of mass ~ TeV decaying significantly into two…
We construct models of warped unification with a bulk SO(10) gauge symmetry and boundary conditions that preserve the SU(4)_C x SU(2)_L x SU(2)_R Pati-Salam gauge group (422). In the dual 4D description, these models are 422 gauge theories…
Tests of gauge coupling unification require knowledge of thresholds between the weak scale and the high scale of unification. If these scales are far separated, as is the case in most unification scenarios considered in the literature, the…
We study a non-supersymmetric SO(10) Grand Unification Theory with a very high energy intermediate symmetry breaking scale in which not only gauge but also Yukawa coupling unification are enforced via suitable threshold corrections and…
We study the impact of multiple vector-like fermions in SU(5) grand unified theory (GUT). Threshold effects from extra fermions allow the observed gauge couplings to be consistently matched to a single unified gauge coupling, and typically…
We construct three flipped SU(5) X U(1)_X models from F-theory, and consider two such models from free fermionic string model building. To achieve the decoupling scenario in F-theory models and the string-scale gauge coupling unification in…
Scalars and pseudoscalars with masses in the MeV to GeV range are of interest in different extensions of the Standard Model. Such particles are often associated with dark matter, the strong CP problem and the $\left(g-2\right)_{\mu}$…
We discuss a possibility to explain the LHC diphoton excesses at $750$GeV by the new scalar $X$ that couples to the gauge bosons through the loop of new massive particles with Standard Model charges. We assume that the new particles decay…
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…
Supersymmetric particles at the multi-TeV scale will escape direct detection at planned future colliders. However, such particles induce non-decoupling corrections in processes involving the accessible superparticles through violations of…
We provide a list of particle physics models at the TeV-scale that are compatible with neutrino masses and dark matter. In these models, the Standard Model particle content is extended with a small number (\leq 4) of scalar and fermion…
We study grand unified models in the five-dimensional space-time where the extra dimension is compactified on $S^1/Z_2$. The spontaneous breaking of unified gauge symmetries is achieved via vacuum expectation values of the extra-dimensional…
We explore possibilities of gauge coupling unification in left--right symmetric models with non--minimal particle content. In addition to unification we require the absence of anomalies and sufficient proton lifetime. Numerous previously…
Gauge coupling unification in the Supersymmetric Standard Models strongly implies the Grand Unified Theories (GUTs). With the grand desert hypothesis, we show that the supersymmetric GUTs can be probed at the future proton-proton (pp)…
We study gauge coupling unification in supersymmetric $E_6$ models where an additional $\mathrm{U}(1)'$ gauge symmetry is broken near the TeV scale and a number of exotic matter fields from the $\bm{27}$ representations have…
Efforts to unify group-theoretically the standard-model gauge interactions with the generation structure of fermions and their mirror partners should be accompanied with the unification of the corresponding gauge couplings. In this paper…