We study the predictions for sfermion masses and Lepton Flavour Violation (LFV) for the WMAP preferred parameter space in $b-τ$ Yukawa-unified models with massive neutrinos. A soft term structure as predicted by an Abelian flavour symmetry combined with SU(5) RGEs for scales above $M_{GUT}$, results to an efficient suppression of the off-diagonal terms in the scalar soft matrices, particularly for $m_0< 100$ GeV. Using the WMAP bounds, this implies $35\le\tanβ\le 45$, $350\,\mathrm{GeV}\le m_{1/2}\le 1\,\mathrm{TeV}$, with the higher $\tanβ$ values being favored. Within this framework, SU(5) unification becomes compatible with the current experimental bounds, in contrast to the conventional case where the soft terms are postulated at the GUT scale.
We discuss how flavour GUT models in the context of supergravity can be completed with a simple SUSY breaking sector, such that the flavour-dependent (non-universal) soft breaking terms can be calculated. As an example, we discuss a model based on an SU(5) GUT symmetry and $A_4$ family symmetry, plus additional discrete "shaping symmetries" and a $\mathbb{Z}_4^\mathrm{R}$ symmetry. We calculate the soft terms and identify the relevant high scale input parameters, and investigate the resulting predictions for the low scale observables, such as flavour violating processes, the sparticle spectrum…
We study CP-conserving non-minimal flavour violation in $A_4 \times SU(5)$ inspired Supersymmetric Grand Unified Theories (GUTs), focussing on the regions of parameter space where dark matter is successfully accommodated due to a light right-handed smuon a few GeV heavier than the lightest neutralino. In this region of parameter space we find that some of the flavour-violating parameters are constrained by the requirement of the dark matter relic density, due to the delicate interplay between the smuon and neutralino masses. By scanning over GUT scale flavour violating parameters, constrained …
We study CP-conserving non-minimal flavour violation in $A_4 \times SU(5)$ inspired Supersymmetric Grand Unified Theories (GUTs), focussing on the regions of parameter space where dark matter is successfully accommodated due to a light right-handed smuon a few GeV heavier than the lightest neutralino. We find that it is necessary to scan over all NMFV parameters simultaneously in order to properly constrain the space of the model.
We study the so-called new minimal supersymmetric SO(10) GUT(NMSGUT) where explicit spontaneous symmetry breaking allows determination of superheavy spectrum and thus threshold corrections to the effective MSSM couplings. This provides a generic mechanism to resolve the long standing super fast proton decay in Susy GUTs. We estimate lepton flavor violation associated with realistic charged fermion and (Type I seesaw) neutrino fit and show compatibility with baryon number and lepton flavour violation limits. We improve NMSGUT fits by including important loop corrections to sparticle spectra. Ou…
We discuss how the double missing partner mechanism solution to the doublet-triplet splitting problem in four-dimensional supersymmetric SU(5) Grand Unified Theories (GUTs) can be combined with predictive models for the quark-lepton Yukawa coupling ratios at the GUT scale. It is argued that towards this goal a second SU(5) breaking Higgs field in the adjoint representation is very useful and we discuss all possible renormalizable superpotentials with two adjoint Higgs fields and calculate the constraints on the GUT scale and effective triplet mass from a two-loop gauge coupling unification ana…
Atmospheric Neutrino Oscillation and Large Lepton-Flavour Violation in the SUSY SU(5) GUT
由超级神冈合作报告的大气中微子异常表明在轻子扇区中存在违反汤川耦合的大味。本文在含有右手中微子的超对称SU（5）_{GUT}模型的框架下讨论了低能轻子味破坏。我们发现，在大气中微子异常所建议的参数空间范围内，如果τ-中微子Yukawa耦合与顶夸克的耦合一样大，那么在$^{48}_{22}Ti$上的μ-> e γ、τ-> μ γ分支比和μ-e转换率的下界分别为10^{-14}、10^{-9}和10^{-16}。这些反应速率可能在近期实验可达到的范围内。
We show how approximate Minimal Flavour Violation (MFV) can emerge from an SU(5) Supersymmetric Grand Unified Theory (SUSY GUT) supplemented by an S4 x U(1) family symmetry, which provides a good description of all quark and lepton (including neutrino) masses, mixings and CP violation. Assuming a SUSY breaking mechanism which respects the family symmetry, we calculate in full explicit detail the low energy mass insertion parameters in the super-CKM basis, including the effects of canonical normalisation and renormalisation group running. We find that the very simple family symmetry S4 x U(1) i…
We discuss the characteristic low energy phenomenological implications of an SU(5) Supersymmetric Grand Unified Theory (SUSY GUT) whose flavour structure is controlled by the family symmetry S4 x U(1), which provides a good description of all quark and lepton masses, mixings as well as CP violation. Although the model closely mimics Minimal Flavour Violation (MFV) as shown in arXiv:1511.07886, here we focus on the differences. We first present numerical estimates of the low energy mass insertion parameters, including canonical normalisation and renormalisation group running, for well-defined r…
We present a data-driven analysis of a concrete Supersymmetric (SUSY) Grand Unified Theory (GUT) of flavour, based on $SU(5)\times S_4$, which predicts charged fermion and neutrino mass and mixing, and where the mass matrices of both the Standard Model and the Supersymmetric particles are controlled by a common symmetry at the GUT scale. This framework also predicts non-vanishing non-minimal flavour violating effects, motivating a sophisticated data-driven parameter analysis to uncover the signatures and viability of the model. This computer-intensive Markov-Chain-Monte-Carlo (MCMC) based anal…
我们构建了一个基于S4 x SU（5）的超对称（SUSY）风味大统一理论（GUT），以及一个额外的（全球或本地）阿贝尔对称性，并研究它的次领先阶（NLO）的准确性。该模型包括一个成功的描述夸克和轻子的质量和混合角在领先的顺序（LO）结合Gatto-Sartori-Tonin（GST）关系和Georgi-Jarlskog（GJ）关系。我们研究了真空对准所产生的F-项的非线性光学和这样的修正被证明有一个可以忽略不计的影响费米子的质量和混合在LO实现的结果。三双峰（TB）的中微子部门的混合预测非常准确的非线性光学修正的顺序为0.1%。包括带电轻子混合修正意味着小的偏差TB混合所描述的一个精确的总和规则，准确的最大大气混合和反应堆混合角接近三度。
We propose a 6d model with a SUSY $SU(5)$ gauge symmetry. After compactification, it explains the origin of the $S_4$ Family Symmetry with CSD3 vacuum alignment, as well as $SU(5)$ breaking with doublet-triplet splitting. The model naturally accounts for all quark and lepton (including neutrino) masses and mixings, incorporating the highly predictive Littlest Seesaw structure. It spontaneously breaks CP symmetry, resulting in successful CP violation in the quark and lepton sectors, while solving the Strong CP problem. It also explains the Baryon Asymmetry of the Universe (BAU) through leptogen…
We consider supersymmetric grand unified theories with soft supersymmetry-breaking scalar masses $m_0$ specified above the GUT scale (super-GUTs) and patterns of Yukawa couplings motivated by upper limits on flavour-changing interactions beyond the Standard Model. If the scalar masses are smaller than the gaugino masses $m_{1/2}$, as is expected in no-scale models, the dominant effects of renormalization between the input scale and the GUT scale are generally expected to be those due to the gauge couplings, which are proportional to $m_{1/2}$ and generation-independent. In this case, the input…
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 Flavour Hierarchy and See-Saw Neutrinos from Bulk Masses in 5d Orbifold GUTs
在基于5维S^1/（Z_2 x Z '_2）轨道结构的超对称大统一理论（GUTs）中，标准模型（SM）物质和Higgs场可以用5维超多重态来实现。这些超多重态可以自然地具有大的质量，导致零模在两个膜之一的局部化，或者导致最低非零模的质量的指数抑制。我们证明了这些动力学特征允许在5维中构造一个优雅的3代SU（5）模型，该模型解释了费米子质量和CKM矩阵元素之间的几何层次。此外，如果U（1）_x（其中SU（5）x U（1）_x \subset SO（10））在体中被测量，但在SM膜处被轨道作用破坏，则右手中微子质量标度相对于M_GUT自然被抑制。再加上我们在带电费米子扇区的构造，通过通常的跷跷板机制，这导致了一个现实的轻中微子质量尺度和大中微子混合角。
Flavour physics, supersymmetry and grand unification
夸克味物理数据的整体拟合不支持标准模型，标准偏差为3.6，并指出介子-反介子混合振幅中新的CP破坏物理。Tevatron数据要求一个新的Bs-Bs-bar混合阶段，Bd-Bd-bar混合中的新物理学阐明了由B（B-> tau nu）驱动的幺正三角形上的张力。在超对称GUT模型中，大的大气中微子混合角会影响b -> s跃迁.我提出了一个SO（10）GUT模型，它容纳了大的Bs-Bs-bar混合相，同时遵守所有其他的实验约束的最新分析结果。
We point out that the hypothesis of a SU(5)-like supersymmetric Grand Unified Theory (GUT) implies a generic relation within the flavour structure of up-type squarks. Contrary to other well-known SU(5) relations between the down-quark and charged lepton sectors, this relation remains exact in the presence of any corrections and extra operators. Moreover it remains valid to a good precision at the electroweak scale, and opens thus new possibilities for testing SU(5)-like GUTs. We derive the low-energy effective theory of observable light up-type squarks, that also constitutes a useful tool for …
Grand Unified Theories (GUTs) can feature predictions for the ratios of quark and lepton Yukawa couplings at high energy, which can be tested with the increasingly precise results for the fermion masses, given at low energies. To perform such tests, the renormalization group (RG) running has to be performed with sufficient accuracy. In supersymmetric (SUSY) theories, the one-loop threshold corrections (TC) are of particular importance and, since they affect the quark-lepton mass relations, link a given GUT flavour model to the sparticle spectrum. To accurately study such predictions, we extend…
A $Z'$ gauge boson with mass around the (few) TeV scale is a popular example of physics beyond the Standard Model (SM) and can be a fascinating remnant of a Grand Unified Theory (GUT). Recently, $Z'$ models with non-universal couplings to the SM fermions due to extra vector-like states have received attention as potential explanations of the present $R_K$, $R_{K^{\ast}}$ anomalies; this includes GUT model proposals based on the $\mathrm{SO}(10)$ group. In this paper we further develop GUT models with a flavour non-universal low scale $Z'$ and clarify several outstanding issues within them. Fir…
We revisit mixing sum rule relations in the lepton and quark sectors under the assumption that the 1-3 elements of the flavour mixing matrices ($V^u_L,V^d_L,V^e_L,V^ν_L$) are zero in the flavour basis. We consider the exact relations resulting from the validity of this "zero 1-3 flavour mixing hypothesis" and analyse their implications based on the current experimental data, including effects from RG running. In particular, we analyse how the existing precise measurement of $θ_{13}^\mathrm{PMNS}$ allows to derive predictions for $θ_{23}^\mathrm{PMNS}$ in models with constrained $θ_{12}^\mathrm…
Minimal Resonant Leptogenesis and Lepton Flavour Violation
我们讨论了最小的非超对称模型的共振leptogenesis，基于近似味对称。作为一个说明性的例子，我们考虑一个共振τ-leptogenesis模型，兼容的通用右手中微子质量在大统一体尺度，所需的重中微子质量分裂产生辐射。特别是，我们明确地证明，如何最小数量的三个重马约拉纳中微子是必要的，以获得成功的leptogenesis和实验可测试的速率轻子味违反的过程中，如μ--> e γ和μ--> e转换的核。
In this dissertation, the Minimal Supersymmetric Standard Model (MSSM) is studied as a low-energy theory stemming from the $SU(5)$ Grand Unified Theory (GUT). We investigate the possibility of satisfying the minimal $SU(5)$ boundary condition $\mathbf{Y}^d=\mathbf{Y}^{e\,T}$ for the full $3\!\times\!3$ down-quark and lepton Yukawa matrices at the GUT scale within the $R$-parity conserving MSSM. We give numerical evidence in favour of the statement: There exist regions in the parameter space of the R-parity conserving MSSM for which the unification of the down-quark and lepton Yukawa matrices t…
We propose a mechanism for sufficient suppression of dimension-5 operators for proton decay in a supersymmetric SO(10) model. This mechanism is analogue to the double seesaw mechanism in studying neutrino masses. Only an intermediate VEV instead of an intermediate scale is required so that gauge coupling unification is maintained. The VEV is generated by introducing an anomalous U(1) symmetry whose breaking is at higher scale. The proton decay amplitudes are suppressed by this VEV over the GUT scale. We use $\textbf{45+54}$ in breaking GUT symmetry. $\textbf{120}$ is included so that fermion s…
Analysis of enhanced tan(beta) corrections in MFV GUT scenarios
我们分析了一个最小超对称标准模型（MSSM）采取最小味违反（MFV）结构在大统一尺度。考虑到重整化群方程演化过程中的全味结构，我们在电弱尺度下对参数进行了估计。我们主要集中在衰变Bs -> μ μ及其与其他观测值的相关性，如b -> s γ，b -> s l l，Δ M_Bs和μ子的异常磁矩。我们限制我们的分析，在参数空间中的区域一致的暗物质的约束。我们发现，BR（Bs -> mu mu）可以超过目前的实验限制的区域中的参数空间，这是允许的所有其他的约束，从而提供了一个额外的约束超对称参数。这甚至在受约束的MSSM中也成立。假设测量值为BR（Bs -> mu mu）~ 10^-7，我们分析了预测的MSSM谱和超对称粒子的味道破坏衰变模式，发现超对称粒子很小。
我们推导出了对量delta_{XY} ^{ij}，X，Y=L，R的新的约束条件，这些约束条件使MSSM中的带电slepton质量矩阵的味非对角项参数化。考虑电子的质量和反常磁矩，我们得到了电子的束缚|delta^{13}_{LL} delta^{13}_{RR}|对于tan β =50，<0.1，这涉及约束较差的元素delta^{13}_{RR}。我们改进了衰变τ-> mu gamma，τ-> e gamma和mu -> e gamma的预测，包括两个回路的校正，如果tan β很大，则会增强。从软超对称性破缺项的PMNS矩阵的有限重整化导出并应用于带电希格斯轻子顶点。我们发现，BR（τ-> e γ）的实验范围严重限制了PMNS元素U_{e3}的MSSM环路校正的大小，这对于正确解释未来的U_{e3}测量是很重要的。随后，我们用大统一理论分析来面对delta^{ij}_{LL}的新值。此外，我们还考虑了5维汤川项的影响，这是修复前两代汤川统一所必需的。如果普遍超对称破缺发生在GUT尺度以上，我们发现5维Yukawa耦合的味结构受到mu -> e γ的严格约束。
We explore possible signatures for charged lepton flavour violation (LFV), sparticle discovery at the LHC and dark matter (DM) searches in grand unified theories (GUTs) based on SU(5), flipped SU(5) (FSU(5)) and SU(4)$_c \times $SU(2)$_L \times $SU(2)$_R$ (4-2-2). We assume that soft supersymmetry-breaking terms preserve the group symmetry at some high input scale, and focus on the non-universal effects on different matter representations generated by gauge interactions at lower scales, as well as the charged LFV induced in Type-1 see-saw models of neutrino masses. We identify the different me…
