We investigate the possibility of observable proton decay within the improved missing doublet model (IMDM75), which utilizes a Higgs in 75 representation for $SU(5)$ gauge symmetry breaking. The realization of observable proton decay in IMDM75 is made feasible primarily due to chirality nonflipping color-triplet mediation, while chirality flipping mediation is adequately suppressed. Our predictions suggest a range of proton lifetimes between $10^{34}-10^{36}$ yr, which can be observed in upcoming experiments such as Hyper-K and DUNE, for a corresponding range of color-triplet mass parameter $M_T$ in the order of $10^{11}-10^{14}$GeV. IMDM75 is shown to offer unique predictions for branching ratios when compared to other grand unified theory models. Finally, a realization of successful gauge coupling unification is achieved, even with the presence of particles at intermediate scales.
We discuss the Yukawa coupling unification, a very interesting prediction of the grand unified theory, in the context of scenarios with more than one pair of Higgs doublet since the current LHC constraint has become a problem for the Yukawa unification scenarios with just one pair of Higgs doublet. More than one pair of Higgs doublets can easily arise in missing partner mechanism which solves the doublet-triplet splitting problem. In such a scenario, the Yukawa unification occurs at a medium $\tanβ$ value, e.g., $\sim$ 30, which corresponds to much smaller threshold corrections compared to usu…
We study the Two-Higgs-Doublet Model predicted in the minimal theory for quark-lepton unification that can describe physics at the low scale. We discuss the relations among the different decay widths of the new Higgs bosons and study their phenomenology at the Large Hadron Collider. As a result of matter unification, this theory predicts a correlation between the decay widths of the heavy Higgs bosons into tau leptons and bottom quarks. We point out how to probe this theory using these relations and discuss the relevant flavor constraints.
We consider a version of Left-Right Symmetric Model in which the scalar sector consists of a Higgs bidoublet ($Φ$) with $B-L=0$, Higgs doublets ($H_{L,R}$) with $B-L=1$ and a charged scalar ($δ^+$) with $B-L=2$ leading to radiatively generated Majorana masses for neutrinos and thereby, leads to new physics contributions to neutrinoless double beta decay ($0νββ$). We show that such a novel framework can be embedded in a non-SUSY $SO(10)$ GUT leading to successful gauge coupling unification at around $10^{16}$ GeV with the scale of left-right symmetry breaking around $10^{10}$ GeV. The model can…
Gauge coupling unification and doublet-triplet splitting via GUT dynamical breaking
Ferrara University（费拉拉大学）；Istituto Nazionale di Fisica Nucleare (INFN), Sez. di Ferrara（意大利国家核物理研究所（INFN）费拉拉分部）；Institut de Física d’Altes Energies (IFAE)（高能物理研究所 (IFAE)）；The Barcelona Institute of Science and Technology (BIST)（巴塞罗那科学技术研究所 (BIST)）
We discuss the possibility of unifying in a simple and economical manner the Yukawa couplings of third generation fermions in a non-supersymmetric SO(10) model with an intermediate symmetry breaking, focusing on two possible patterns with intermediate Pati-Salam and minimal left-right groups. assume a minimal Yukawa sector at high energy, starting with two Higgs bi-doublets at the intermediate scale which then simply reduce to a two Higgs doublet model at the electroweak scale. We first enforce gauge coupling unification at the two-loop level by including the threshold corrections in the renor…
A new vector dark matter (DM) scenario in the context of the gauge-Higgs unification (GHU) is proposed. The DM particle is identified with an electric-charge neutral component in an $SU(2)_L$ doublet vector field with the same quantum number as the Standard Model Higgs doublet. Since such an $SU(2)_L$ doublet vector field is incorporated in any models of the GHU scenario, it is always a primary and model-independent candidate for the DM in the scenario. The observed relic density is reproduced through a DM pair annihilations into the weak gauge bosons with a TeV-scale DM mass, which is nothing…
We analyze the structure of the Higgs potential in gauge-Higgs unification with a flat extra dimension. As a concrete model, we first consider the cases where the Standard Model Higgs doublet is embedded into a higher-dimensional $SU(3)_{w}^{}$ gauge multiplet with five-dimensional Lorentz symmetry relaxed. In this $SU(3)_{w}^{}$ model with Lorentz violation, the deviation of the resulting triple Higgs boson coupling from its SM prediction is shown to be less than $10\%$ when the compactification scale is larger than the experimental lower bound, which is around 5 TeV. Next, we examine the Hig…
在没有超对称性的情况下，具有5个希格斯双重态的标准模型中的规范耦合统一在10^14 GeV附近。在这种情况下，具有对称性破缺所需的最小希格斯扇区的三化模型SU（3）_C x SU（3）_L x SU（3）_R x Z_3是理想的大统一候选者。小质量的中微子是通过辐射跷跷板机制产生的，不需要中间尺度，额外的希格斯场或高维算子。质子寿命高于实验极限，衰变模式p -> \bar νK^+和p -> mu^+ K^0是可能观测到的。这个模型的分裂超对称性版本，有一个轻的希格斯双重态，同样有吸引力。
Using properties of Goldstino, we show that in generic grand unified theories with gravity-mediated supersymmetry breaking the $μ$-problem is non-existent. What happens is that supersymmetry breaking universally induces the shifts of the heavy fields that generate $μ$ and $B_μ$ terms. In the leading order, these are given by the mass of gravitino and are insensitive to the scale of grand unification. The mechanism works regardless whether doublet-triplet splitting is achieved via fine-tuning or not. Moreover, we illustrate this general phenomenon on explicit examples of theories that achieve d…
We present the complete set of continuous maximal symmetries that the potential of an $n$-Higgs Doublet Model ($n$HDM) should satisfy for natural Standard Model (SM) alignment. As a result, no large mass scales or fine-tuning is required for such alignment, which still persists even if these symmetries were broken softly by bilinear mass terms. In particular, the Maximal Symmetric $n$HDM (MS-$n$HDM) can provide both natural SM alignment and quartic coupling unification up to the Planck scale. Most remarkably, we show that the MS-2HDM is a very predictive extension of the SM governed by two onl…
Two models that extend the particle content of the SM and provide dark matter candidates, namely the Inert Doublet Model and the Two-Higgs Doublet model with additional pseudoscalar, are confronted with current experimental and theoretical constraints and predictions for production cross sections for various standard pair-production modes within these models at future lepton colliders are presented.
