Related papers: Proton Decay in Teravolt Unification
Grand unified theories (GUTs) and extra dimensions are potential ingredients of the new physics that may resolve various outstanding problems of the Standard Model. If the inverse size of (one of) the extra dimension(s) is smaller than the…
We analyze gauge coupling unification in the context of heterotic strings on anisotropic orbifolds. This construction is very much analogous to effective 5 dimensional orbifold GUT field theories. Our analysis assumes three fundamental…
Dark matter candidates and proton decay in a class of models based on the AdS/CFT correspondence are discussed. We show that the present bound on the proton decay lifetime is inconsistent with ${\cal N} = 1$ SUSY, and strongly constrains…
Proton decay, although unobserved so far, is a natural expectation when attempting to explain the baryon asymmetry of the universe. $p\to K^+\bar{\nu}$ or $p\to K^+\tilde{\chi}_1^0$, with $\tilde{\chi}_1^0$ a light exotic neutral particle,…
It is pointed out that a class of flipped SU(5) models based on F-theory naturally explains the gauge coupling unification. It is because the group SU(5) x U(1)_X is embedded in SO(10) and E_8. To prohibit the dimension 4 and 5 proton decay…
Grand unified theories based on large groups (with rank greater or equal to 6 are a natural context for dark matter models. They contain Standard-Model-singlet fermions that could be dark matter candidates, and can contain new non-abelian…
It is shown that in realistic SUSY GUT models of quark and lepton masses both the proton decay rate and branching ratios differ in general from those predicted in the minimal $SU(5)$ supersymmetric model. The observation of proton decay,…
We study two phases of a heterotic standard model, obtained from a Calabi-Yau compactification of the E8xE8 heterotic string, in the context of the associated four-dimensional effective theories. In the first phase we have a standard model…
We present a new mechanism for generating the baryon asymmetry of the universe directly in the decay of a singlet scalar field $S_r$ with a weak scale mass and a high dimensional baryon number violating coupling. Unlike most currently…
We propose an interpretation of the gauge coupling unification scale which is not related to any new particle threshold. We revisit Grand Unified Theories and show that it is possible to completely eliminate the scalar as well as vector…
Unparticle physics from a hidden conformal sector can alter the evolution of the Standard Model (SM) gauge couplings via TeV scale threshold corrections. We discuss how this may lead to gauge coupling unification at M_{GUT}\approx 2 \times…
We investigate the prospects to achieve unification of the gauge couplings in models without supersymmetry. We restrict our discussion to $SU(5), SO(10)$ and $E_6$ models that mimic the structure of the Standard Model as much as possible…
The significant heavy threshold effect is found in the supersymmetric SU(5) model with two adjoint scalars, one of which is interpreted as a massive string mode decoupled from the lower-energy particle spectra. This threshold related with…
We investigate quartification models in five dimensions, with the fifth dimension forming an $S^1/Z_2\times Z_2'$ orbifold. The orbifold construction is combined with a boundary Higgs sector to break the quartified gauge group directly to a…
We consider the three lepton decay modes of the proton within the proton decay interpretation of the atmospheric neutrino anomaly. We construct higher dimensional operators in the framework of the standard model. The operators which allow…
In supersymmetry, there are gauge invariant dimension 5 proton decay operators which must be suppressed by a mass scale much larger than the Planck mass. It is natural to expect that this suppression should be explained by a mechanism that…
In the context of $\mathrm{E}_{6}$ Grand Unified Theories (GUTs), an intriguing possibility for symmetry breaking to the Standard Model (SM) group involves an intermediate stage characterized by either…
In models with a low quantum gravity scale, one might expect sizable effects from nonrenormalizable interactions that violate the global symmetries of the standard model. While some mechanism must be invoked in such theories to suppress…
Within low scale theories traditional see-saw and scalar triplet mechanisms, for neutrino mass suppression, do not work out anymore and for realistic model building some new ideas are needed. In this paper we suggest mechanism, different…
We consider gauge coupling unification in models with TeV scale strings and large compact dimensions realized as type IIB string orientifolds. Following an observation by Ibanez we show that the gauge couplings at low energies can behave as…