In gauge-Higgs unification (GHU), the 4D Higgs boson appears as a part of the fifth dimensional component of 5D gauge field. Recently, an $SO(11)$ GUT inspired $SO(5)\times U(1)\times SU(3)$ GHU model has been proposed. In the GHU, Kaluza-Klein (KK) excited states of neutral vector bosons, photon, $Z$ boson and $Z_R$ boson, appear as neutral massive vector bosons $Z'$s. The $Z'$ bosons in the GHU couple to quarks and leptons with large parity violation, which leads to distinctive polarization dependence in, e.g., cross sections and forward-backward asymmetries in $e^-e^+\toμ^-μ^+,q\bar{q}$ processes. In the talk, we discuss fermion pair production in $e^-e^+$ linear collider experiments with polarized $e^-$ and $e^+$ beams in the GUT inspired GHU. Deviations from the SM are shown in the early stage of planned international linear collider (ILC) with 250 GeV experiments. The deviations can be tested for the KK mass scale up to about 15 TeV. This talk is mainly based on Phys.Rev.D102(2020)015029.
Dimension-5 corrections to the gauge kinetic term of Grand Unified Theories (GUTs) may capture effects of quantum gravity or string compactification. Such operators modify the usual gauge coupling unification prediction in a calculable manner. Here we examine SU(5), SO(10), and E(6) GUTs in the light of all such permitted operators and calculate the impact on the intermediate scales and the unification programme. We show that in many cases at least one intermediate scale can be lowered to even 1-10 TeV, where a neutral Z' and possibly other states are expected.
Fermion Multiplicities at the GUT Scale: A Statistical Study of Unification and Proton Decay
ICRR, The University of Tokyo（东京大学宇宙射线研究所）；Kavli Institute for the Physics and Mathematics of the Universe (WPI), The University of Tokyo Institutes for Advanced Study, The University of Tokyo（东京大学前沿研究机构 Kavli宇宙物理数学研究所）
Bottom-Tau Unification in SUSY SU(5) GUT and Constraints from b to s gamma and Muon g-2
在最小超引力框架下，分析了超对称SU（5）大统一理论中的底τ汤川统一，其中参数空间受到Br（b to s gamma）和μ介子g-2等实验约束的限制.如果超粒子质量相对较重且希格西诺质量参数μ为负，则底τ统一可以适应于所测得的分支比Br（b对s γ）。另一方面，如果我们采用最新的μ子g-2数据，要求正的超对称贡献，那么在超对称尺度上的错误符号阈值校正会以超过20%的差异打乱汤川统一。它必须通过围绕大统一理论尺度的超重阈值校正来补偿，这限制了超对称大统一理论中的风味模型。一种模式的超粒子质量的三个要求的首选也进行了评论。
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 estimate the CKM matrix elements in the recently proposed minimal model, anti-SU(7) GUT for the family unification, $[\,3\,]+2\,[\,2\,]+8\,[\,\bar{1}\,]$+\,(singlets). It is shown that the real angles of the right-handed unitary matrix diagonalizing the mass matrix can be determined to fit the Particle Data Group data. However, the phase in the right-handed unitary matrix is not constrained very much. We also includes an argument about allocating the Jarlskog phase in the CKM matrix. Phenomenologically, there are three classes of possible parametrizations, $\delq=α,β,$ or $γ$ of the unitari…
An analytical formalism, including RG running at two loop order, is used to link the supersymmetric and GUT spectra in any GUT model in which the three gauge couplings unify. In each specific GUT model, one can then fully explore the interplay between the pattern of supersymmetry breaking and the prediction for the proton lifetime. With this formalism at hand, we study three concrete GUT models: (i) Minimal SU(5) SUSY GUT, (ii) Missing Partner SU(5) SUSY GUT, and (iii) an orbifold SU(5) SUSY GUT. In each case we derive interesting conclusions about the possible patterns of the supersymmetric s…
Fermion pair production at $e^-e^+$ linear collider experiments with polarized $e^-$ and $e^+$ beams is examined in the GUT inspired $SO(5)\times U(1)\times SU(3)$ gauge-Higgs unification. There arises large parity violation in the couplings of leptons and quarks to Kaluza-Klein (KK) excited neutral vector bosons $Z'$s, which leads to distinctive polarization dependence in cross sections, forward-backward asymmetries, left-right asymmetries, and left-right forward-backward asymmetries in various processes. Those effects are detectable even for the KK mass scale up to about 15 TeV at future $e^…
In this paper we analyze Yukawa unification in a three family SO(10) SUSY GUT. We perform a global $χ^2$ analysis and show that SUSY effects do not decouple even though the universal scalar mass parameter at the GUT scale, $m_{16}$, is found to lie between 15 and 30 TeV with the best fit given for $m_{16} \approx 25$ TeV. Note, SUSY effects don't decouple since stops and bottoms have mass of order 5 TeV, due to RG running from $M_{GUT}$. The model has many testable predictions. Gauginos are the lightest sparticles and the light Higgs boson is very much Standard Model-like. The model is consist…
With the recent experimental hint of new physics from flavor physics anomalies, combined with the evidence from neutrino mass and dark matter, we consider a minimal extension of SM with a scalar leptoquark and a fermion triplet. The scalar leptoquark with couplings to leptons and quarks can explain lepton flavor non-universality observables $R_K$, $R_{K^{(*)}}$, $R_{D^{(*)}}$ and $R_{J/ψ}$. Neutral component of fermion triplet provides current abundance of dark matter in the Universe. The interesting feature of the proposal is that the minimal addition of these phenomenologically rich particle…
The Weinberg angle is an important parameter in Grand Unified Theories (GUT) as its size is crucially influenced by the assumption of unification. In scenarios with different steps of symmetry breaking, in particular in models that involve gauge-Higgs unification, the connection of the ultraviolet theory and the TeV scale-relevant, effective Standard Model description is an important test of the models' validity. In this work, we consider a 6D gauge-Higgs unification GUT scenario and explore the TeV scale-GUT relation using a detailed RGE analysis in the 4D and 5D regimes of the theory, includ…
We study $3$rd family Yukawa unification in the context of supersymmetric (SUSY) $\mathrm{SO}(10)$ GUTs and $\mathrm{SO}(10)$-motivated boundary conditions for the SUSY-breaking soft terms. We consider $μ<0$ such that the SUSY loop-threshold effects enable a good fit to all third family masses of the charged Standard Model (SM) fermions. We find that fitting the third family masses together with the mass of the SM-like Higgs particle, the scenario predicts the masses of the superpartner particles and of the extra Higgs states of the MSSM: while the sparticles are predicted to be comparatively …
$SO(5) \times U(1) \times SU(3)$ gauge-Higgs unification model inspired by $SO(11)$ gauge-Higgs grand unification is constructed in the Randall-Sundrum warped space. The 4D Higgs boson is identified with the Aharonov-Bohm phase in the fifth dimension. Fermion multiplets are introduced in the bulk in the spinor, vector and singlet representations of $SO(5)$ such that they are implemented in the spinor and vector representations of $SO(11)$. The mass spectrum of quarks and leptons in three generations is reproduced except for the down quark mass. The small neutrino masses are explained by the ga…
The effective potential for the Aharonov-Bohm phase $θ_H$ in the fifth dimension in GUT inspired $SO(5)\times U(1) \times SU(3)$ gauge-Higgs unification is evaluated to show that dynamical electroweak symmetry breaking takes place with $θ_H \not= 0$, the 4D Higgs boson mass 125$\,$GeV being generated at the quantum level. The cubic and quartic self-couplings $(λ_3, λ_4)$ of the Higgs boson are found to satisfy universal relations, i.e. they are determined, to high accuracy, solely by $θ_H$, irrespective of values of other parameters in the model. For $θ_H=0.1$ ($0.15$), $λ_3$ and $λ_4$ are sma…
A constraint on masses of superheavy gauge and Higgs multiplets at the grand unification (GUT) scale is obtained from the gauge coupling unification in the case of high-scale supersymmetry. We found that all of the particles may lie around a scale of 10^16 GeV so that the threshold corrections to the gauge coupling constants at the GUT scale are smaller than those in the case of the low-energy supersymmetry. In addition, the GUT scale tends to be slightly lower when the gauginos are heavier and, thus, the proton decay rate via the X-boson exchange process is expected to be enhanced.
Nucleon lifetimes for various decay modes via dimension 6 operators are calculated in the anomalous $U(1)_A$ GUT scenario, in which the unification scale $Λ_u$ becomes smaller than the usual supersymmetric (SUSY) unification scale $Λ_G=2\times 10^{16}$ GeV in general. Since the predicted lifetime $τ(p\rightarrow π^0+e^c)$ becomes around the experimental lower bound though it is strongly dependent on the explicit models, the discovery of the nucleon decay in near future can be expected. We explain why the two ratios $R_1\equiv\frac{Γ_{n \rightarrow π^0 + ν^c}}{Γ_{p \rightarrow π^0 + e^c}}$ and …
In this paper we examine gauge coupling unification of the the non-SUSY SO(10) grand unified theory proposed by Babu and Mohapatra at the two loop level. This theory breaks down to the standard model in a single step and has the distinguishing feature of TeV non-standard model scalars. This leads to a plethora of interesting new physics at the TeV scale and the discovery of new particles at the LHC. This model gives rise to testable proton decay, neutron-antineutron oscillations, provides a mechanism for baryogenesis, and contains potential dark matter candidates. In this paper, we compute the…
In this article, we review gauge-Higgs unification models based on gauge theories defined on six-dimensional spacetime with $S^2/Z_2$ topology in the extra spatial dimensions. On the extra $S^2/Z_2$ space, non-trivial boundary conditions are imposed. This review considers two scenarios for constructing a four-dimensional theory from the six-dimensional model. One scheme utilizes the SO(12) gauge symmetry with a special symmetry condition imposed on the gauge field, whereas the other employs the E$_6$ gauge symmetry without requiring the additional symmetry condition. Both models lead to a Stan…
Supersymmetric Grand Unification usually provides unification of the bottom quark and the tau lepton Yukawa couplings at the GUT scale. In the CMSSM this can be realised only for a very particular choice of parameters. In this letter we study the GUT scale ratio y_tau/y_b for less peculiar parameters in the large tan beta regime and identify one parameter region preferred by current experimental data. In this region, which is well within the reach of the LHC, the ratio is very close to the recently proposed value of 3/2.
We explore the gauge coupling relations and the unification scale in F-theory SU(5) GUT broken down to the Standard Model by an internal U(1)Y gauge flux. We consider variants with exotic matter representations which may appear in these constructions and investigate their role in the effective field theory model. We make a detailed investigation on the conditions imposed on the extraneous matter to raise the unification scale and make the color triplets heavy in order to avoid fast proton decay. We also discuss in brief the implications on the gaugino masses.
Even if the concerns related to the naturalness of the electroweak scale are repressed, the Higgs mass and stability of the electroweak vacuum do not allow arbitrarily large supersymmetry breaking scale, $M_S$, in the minimal models with split or high-scale supersymmetry. We show that $M_S$ can be raised to the GUT scale if the theory below $M_S$ contains a Higgs doublet, a pair of TeV scale Higgsino and widely separated gauginos in addition to the Standard Model particles. The presence of wino and gluino below ${\cal O}(100)$ TeV leads to precision unification of the gauge couplings consisten…
