We propose a supersymmetric (SUSY) SU(5) Grand Unified Theory (GUT) including a single right-handed neutrino singlet and an adjoint matter representation below the GUT scale and extend this model to include an A4 family symmetry and a gauged anomaly-free Abelian group. In our approach hierarchical neutrino masses result from a combined type I and type III seesaw mechanism, and the A4 symmetry leads to tri-bimaximal mixing which arises indirectly. The mixing between the single right-handed neutrino and the matter in the adjoint is forbidden by excluding an adjoint Higgs, leading to a diagonal heavy Majorana sector as required by constrained sequential dominance. The model also reproduces a realistic description of quark and charged lepton masses and quark mixings, including the Georgi-Jarlskog relations and the leptonic mixing sum rules s=r*cos(delta) and a=-r^2/4 with r=theta_C/3.
Properties of Dirac neutralinos and the corresponding EW scalar gauge bosons, as predicted by the N=1/N=2 hybrid supersymmetric model, and prospects for their discovery at colliders are discussed.
SUSY models with a gauge singlet easily allow for a strongly first order electroweak phase transition (EWPT). We discuss the wall profile, in particular transitional CP violation during the EWPT. We calculate CP violating source terms for the charginos in the WKB approximation and solve the relevant transport equations to obtain the generated baryon asymmetry.
The SU(5) GUT model extended with fermions in the adjoint $24_F$ representation predicts triplet fermions in the 100 GeV mass range, opening up the possibility of testing seesaw at LHC. However, once the model is supersymmerized, the triplet fermion mass is constrained to be close to the GUT scale for the gauge couplings to unify. We propose an extension of the SUSY SU(5) model where type II seesaw can be tested at LHC. In this model we add a matter chiral field in the adjoint $\hat{24}_F$ representation and Higgs chiral superfields in the symmetric $\hat{15}_H$ and $\hat{\bar{15}}_H$ represen…
SUSY models with a gauge singlet easily allow for a strong first order electroweak phase transition (EWPT) if the vevs of the singlet and Higgs fields are of comparable size. We discuss the profile of the stationary expanding bubble wall and CP-violation in the effective potential, in particular transitional CP-violation inside the bubble wall during the EWPT. The dispersion relations for charginos contain CP-violating terms in the WKB approximation. These enter as source terms in the Boltzmann equations for the (particle--antiparticle) chemical potentials and fuel the creation of a baryon asy…
Recent discovery of the SM-like Higgs boson with $m_h\simeq 125$ GeV motivates an extension of the minimal supersymmetric standard model (MSSM), which involves a singlet Higgs superfield with a sizable Yukawa coupling to the doublet Higgs superfields. We examine such singlet-extended SUSY models with a Peccei-Quinn (PQ) symmetry that originates from an anomalous $U(1)_A$ gauge symmetry. We focus on the specific scheme that the PQ symmetry is spontaneously broken at an intermediate scale $v_{\rm PQ}\sim \sqrt{m_{\rm SUSY}M_{\rm Pl}}$ by an interplay between Planck scale suppressed operators and…
We construct a supersymmetric (SUSY) $SU(5)$ model with the flavor symmetry $S_4\times Z_3\times Z_4$. Three generations of adjoint matter fields are introduced to generate the neutrino masses via the combined type I and type III see-saw mechanism. The first two generations of the the $\mathbf{10}$ dimensional representation in $SU(5)$ are assigned to be a doublet of $S_4$, the second family $\mathbf{10}$ is chose as the first component of the doublet, and the first family as the second component. Tri-bimaximal mixing in the neutrino sector is predicted exactly at leading order, charged lepton…
It is shown that in the next-to-leading approximation of N=4 SUSY the BFKL equation for two-gluon composite states in the adjoint representation of the gauge group can be reduced to a form which is invariant under Moebius transformation in the momentum space. The corresponding similarity transformation of its integral kernel is constructed in an explicit way.
We study the solution of the BFKL equation in the adjoint representation for the N=4 SUSY theory at NLO accuracy. Consistency with the large momentum transfer solution obtained by Fadin and Lipatov is found. We investigate, for large and small values of the momentum transfer, the growth with energy of the Green function, its collinear behaviour and the expansion in azimuthal angle Fourier components.
We present a generalization of the Next-to-Minimal Supersymmetric Standard Model (NMSSM), with an explicit mu-term and a supersymmetric mass for the singlet superfield, as a route to alleviating the little hierarchy problem of the Minimal Supersymmetric Standard Model (MSSM). Though this model does not address the mu-problem of the MSSM, we are able to generate masses for the lightest neutral Higgs boson up to 140 GeV with top squarks below the TeV scale, all couplings perturbative to the gauge unification scale, and with no need to fine tune parameters in the scalar potential. This model, whi…
Supersymmetry (SUSY) is an attractive extension of the Standard Model (SM) of particle physics which solves the SM hierarchy problem. Motivated by the theoretical $μ$-term problem of the Minimal Supersymmetric Model (MSSM), the Next-to MSSM (NMSSM) can also account for experimental deviations from the SM like the anomalous muon magnetic moment and the dark matter relic density. Natural SUSY, motivated by naturalness considerations, exhibits small fine tuning and a characteristic phenomenology with light higgsinos, stops and gluinos. We describe a scan in NMSSM parameter space motivated by Natu…
It has long been known that the broken supersymmetric (susy) phase of the singlet extended susy higgs model (SESHM) is at best metastable and the ground states of the model have vanishing vacuum energy and are exactly supersymmetric. If the SESHM is confirmed at the Large Hadron Collider (LHC), the numerical values of the parameters of the model have a bearing on key properties of the susy phase and might provide an estimate of the remaining time before a possible decay of our false vacuum. We provide some analysis of the model including a treatment of phases in the potential and soft higgs ma…
We show that inclusion of a TeV scale chiral superfield transforming in the adjoint representation of the color SU(3) to the MSSM particle content modifies the renormalization group running of some parameters in such a way that a 125 GeV mass of the light Higgs boson is accommodated more comfortably than in cMSSM / mSUGRA. Put differently, the introduction of a color adjoint TeV scale superfield helps resurrecting lighter choices for the stop and gluino which are otherwise disfavored in cMSSM / mSUGRA.
We calculate the eigenvalues of the next-to-leading kernel for the BFKL equation in the adjoint representation of the gauge group $SU(N_c)$ in the N=4 supersymmetric Yang-Mills model. These eigenvalues are used to obtain the high energy behavior of the remainder function for the 6-point scattering amplitude with the maximal helicity violation in the kinematical regions containing the Mandelstam cut contribution. The leading and next-to-leading singularities of the corresponding collinear anomalous dimension are calculated in all orders of perturbation theory. We compare our result with the kno…
A general analysis is made of the question whether the d=5 proton decay operators coming from exchange of colored Higgsinos can be completely eliminated in a natural way in supersymmetric grand unified models. It is shown that they can indeed be in SO(10) while at the same time naturally solving the doublet-triplet splitting problem, having only two light Higgs doublets, and using no more than a single adjoint Higgs field. Accomplishing all of this requires that the vacuum expectation value of the adjoint Higgs field be proportional to the generator I_{3R} rather than to B-L, as is usually ass…
We propose an $S_{4}$ flavor model based on supersymmetric (SUSY) SU(5) GUT. The first and third generations of \textbf{10} dimensional representations in SU(5) are all assigned to be $1_{1}$ of $S_{4}$. The second generation of \textbf{10} is to be $1_{2}$ of $S_{4}$. Right-handed neutrinos of singlet \textbf{1} and three generations of $\bar{\textbf{5}}$ are all assigned to be $3_{1}$ of $S_{4}$. The VEVs of two sets of flavon fields are allowed a moderate hierarchy, that is $\langleΦ^ν\rangle \sim λ_{c}\langleΦ^{e}\rangle$. Tri-Bimaximal (TBM) mixing can be produced at both leading order (L…
We propose a natural framework of SU(5) supersymmetric grand unified theory with the minimal particle contents, which does not contain dimension five proton decay operators. The suitable fermion mass hierarchy can be reproduced by higher dimensional operators of an adjoint Higgs field which breaks SU(5) gauge symmetry.
We explore the novel possibility that the inflaton responsible for cosmological inflation is a gauge non-singlet in supersymmetric (SUSY) Grand Unified Theories (GUTs). For definiteness we consider SUSY hybrid inflation where we show that the scalar components of gauge non-singlet superfields, together with fields in conjugate representations, may form a D-flat direction suitable for inflation. We apply these ideas to SUSY models with an Abelian gauge group, a Pati-Salam gauge group and finally Grand Unified Theories based on SO(10) where the scalar components of the matter superfields in the …
A non-universal $U(1)_{X}$ extension to the Standard Model composed of two scalar doublets and two scalar singlets together with three additional quark singlets and two lepton singlets and three generations of right-handed and Majorana neutrinos is made to explain lepton mass hierarchy, neutrino masses via inverse seesaw mechanism and muon anomalous magnetic moment in an anomaly free framework. In the present model, exotic and Standard Model particles acquire mass thanks to vacuum expectation values at different scales, yet the electron and the lightest neutrino are tree level massless but mas…
I present two new renormalizable grand unified theories where the neutrino masses are generated through the type I and type III seesaw mechanisms. These theories can be considered as the simplest (SUSY) renormalizable grand unified theories based on the SU(5) gauge symmetry. Several phenomenological and cosmological aspects of these proposals are discussed.
The SUSY CP problem is one of serious problems in construction of realistic supersymmetric standard models. We consider the problem in a framework in which adjoint chiral multiplets are introduced and gauginos have Dirac mass terms induced by a U(1) gauge interaction in the hidden sector. This is realized in hidden sector models without singlet chiral multiplets, which are favored from a recent study of the Polonyi problem. We find that the dominant contributions to electron and neutron electric dipole moments (EDMs) in the model come from phases in the supersymmetric adjoint mass terms. When …
We propose new predictions from Grand Unified Theories (GUTs) (applicable to both supersymmetric (SUSY) and non-SUSY models) for the ratios of quark and lepton Yukawa couplings. These new predictions arise from splitting the masses of the messenger fields for the GUT scale Yukawa operators by Clebsch-Gordan factors from GUT symmetry breaking. This has the effect that these factors enter inversely in the predicted quark-lepton Yukawa coupling ratios, leading to new possible GUT predictions. We systematically construct the new predictions that can be realised in this way in SU(5) GUTs and Pati-S…
Low-energy supersymmetric models such as MSSM, NMSSM and MSSM with vectorlike fermion are consistent with perturbative unification. While the non-minimal extensions naturally explain Higgs mass and dark matter in the low energy region, it is unclear how seriously they are constrained in the ultraviolet region. Our study shows that $i)$, In the case of embedding MSSM into $\rm{SU}(5)$, the fit to SM fermion masses requires a singlet $S$, which leads to unviable embedding of NMSSM into $\rm{SU}(5)$ because such $S$ feeds singlet $N$ a mass of order unification scale as well. $ii)$, Similar resul…
We propose a set of 4 recurrence relations whose linear combination gives the number of group invariants, equivalently the dimension of the invariant subspace, in the tensor product of an arbitrary number of adjoint representations of the SU(3) Lie Group.
Null results from dark matter (DM) direct detection experiments and the 125 GeV Higgs both pose serious challenges to minimal supersymmetry. In this paper, we propose a simple extension of the MSSM that economically solves both problems: a "dark sector" consisting of a singlet and a pair of $SU(2)$ doublets. Loops of the dark sector fields help lift the Higgs mass to 125 GeV consistent with naturalness, while the lightest fermion in the dark sector can be viable thermal relic DM, provided that it is mostly singlet. The DM relic abundance is controlled by s-wave annihilation to tops and Higgsin…
We consider states in the adjoint representation of the Standard Model gauge group as messengers for mediation of supersymmetry (SUSY) breaking. These new messengers can shift the gauge coupling unification to the string scale at O(5x10^{17} GeV) if their masses are at O(10^{14} GeV). The predicted SUSY mass spectrum at the electroweak scale is significantly different from those in other gauge-mediated or supergravity models, resulting in robust mass relations. The gravitino mass is predicted to be about 1-10 GeV. The heavy messenger sector could provide a superheavy dark matter candidate.
We propose an extended version of the gauge-mediated SUSY breaking models where extra $SU(2)_L$ doublets and singlet field are introduced. These fields are assumed to be parity-odd under an additional matter parity. In this model, the lightest parity-odd particle among them would be dark matter in the Universe. In this paper, we discuss direct detection of the dark matter and the collider signatures of the model
The prediction for the Higgs mass in the dark matter selected high-scale SUSY is explored. We show the bounds on SUSY-breaking scale in models of SM $+\tilde{w}$ and SM $+\tilde{h}/\tilde{s}$ due to the observed Higgs mass at the LHC. We propose that effective theory below scale $\tilde{m}$ described by SM $+\tilde{w}$ is possibly realized in gauge mediation with multiple spurion fields that exhibit significant mass hierarchy, and that by SM $+\tilde{h}/\tilde{s}$ can be realized with direct singlet-messenger-messenger coupling for singlet Yukawa coupling $λ\sim(v/\tilde{m})^{1/2}g_{\text{SM}}…
It is shown that a supersymmetric SO(10) model extended with fermion singlets can accommodate the observed neutrino masses and mixings as well as generate the desired lepton asymmetry in concordance with the gravitino constraint. A necessary prediction of the model is near-TeV scale doubly-charged Higgs scalars which should be detectable at the LHC.
In this talk, I summarize a work done in collaboration with Otto Kong on the Zee neutrino mass model. We show that the MSSM with explicit R-parity violation actually contains the Zee model with the right-handed sleptons as the Zee singlet. We determine the conditions on the parameter space such that the neutrino mass matrix provides a viable texture that explains the atmospheric and solar data.
The ATLAS and CMS experiments at the LHC have found significant excess in the diphoton invariant mass distribution near 750 GeV. We interpret this excess in a predictive nonsupersymmetric SU(5) grand unified framework with a singlet scalar and light adjoint fermions. The 750 GeV resonance is identified as a gauge singlet scalar. Both its production and decays are induced by 24 dimensional adjoint fermions predicted within SU(5). The adjoint fermions are assumed to be odd under $Z_2$ symmetry which forbids their direct coupling to the standard model fermions. We show that the observed diphoton …
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…
We propose a model with $A_4$ flavor symmetry for leptons and quarks in the framework of supersymmetric SU(5) grand unified theory (GUT). The running masses of quarks and charged leptons at GUT scale ($\sim 10^{16}$ GeV) are realized by the adjoint 24-dimensional Higgs multiplet and additional gauge singlet scalar fields including flavons. In this paper, we focus on a result of the quark and charged lepton masses and quark mixing since our present model is known to reproduce recent experimental results of the neutrino mass and oscillation. Those results are showed numerically.
We study the possibility of spontaneous CP violation (SCPV) at the tree level in models with an extended Higgs sector. We show that the minimum equations for the complex phases of the vacuum expectation values (VEVs) have always a geometrical interpretation in terms of triangles. To illustrate our method we analyze the minimal supersymmetric (SUSY) model with R-parity violating couplings and sneutrino VEVs, where there is no SCPV. Then we study SUSY models with extra Higgs doublets and/or gauge singlets, and find that the simplest scenario with SCPV must include at least two singlet fields.
A new superstring-motivated framework for a treatment of SU(N) SUSY GUTs is argued. We show that all the present difficulties of the minimal supersymmetric SU(5) model can successfully be overcome with a new renormalizable reflection-invariant superpotential with two-adjoint scalars, one of which is interpreted as a massive string mode essentially decoupled from the low-energy particle spectra. This superpotential is proved to properly fix a mass ratio of the basic adjoint scalar moduli, while its gauge-type reflection symmetry essentially protects the model from gravitational smearing. The si…
An anomaly free non-universal $U(1)_{X}$ extension to the Minimal Supersymmetric Standard Model is proposed, where additional two $SU(2)$ doublet superfields and four singlet superfields complement the scalar sector of the model. The fermion sector is extended by considering additional superfields containing three quark singlets, two charged lepton singlet superfields and six neutral leptons. A tree-level massless electron is found so radiative corrections are considered to match the mass spectrum with both SUSY and non-SUSY contributions. Likewise, a massless neutrino is found and analytic ex…
NMSPEC is a Fortran code that computes the sparticle and Higgs masses, as well as Higgs decay widths and couplings in the NMSSM, with soft SUSY breaking terms specified at MGUT. Exceptions are the soft singlet mass m_s^2 and the singlet self coupling kappa, that are both determined in terms of the other parameters through the minimization equations of the Higgs potential. We present a first analysis of the NMSSM parameter space with universal SUSY breaking terms at MGUT -- except for m_s and A_kappa -- that passes present experimental constraints on sparticle and Higgs masses. We discuss in so…
The evidence for a new singlet scalar particle from the 750 GeV diphoton excess, and the absence of any other signal of new physics at the LHC so far, suggest the existence of new coloured scalars. To study this possibility, we propose a supersymmetry inspired simplified model, extending the Standard Model with a singlet scalar and with heavy scalar fields carrying both colour and electric charges -- the `squarks'. To allow the latter to decay, and to generate the dark matter of the Universe, we also add a neutral fermion to the particle content. We show that this model provides a two-paramete…
We determine the allowed parameter space and the particle spectra of the minimal SUSY standard model (MSSM) and nonminimal SUSY standard model (NMSSM) imposing correct electroweak gauge-symmetry breaking and recent experimental constraints. The parameters of the models are evolved with the SUSY RGEs assuming universality at the GUT scale. Applying the new unbounded from below (UFB) constraints we can exclude the LSP singlinos and light scalar and pseudoscalar Higgs singlets of the NMSSM. This exclusion removes the experimental possibility to distinguish between the MSSM and NMSSM via the recen…
We consider neutralino dark matter within the framework of SUSY GUTs with non-universal gaugino masses. In particular we focus on the case of SU(5) with a SUSY breaking F-term in the 1, 24, 75 and 200 dimensional representations. We discuss the 24 case in some detail, and show that the bulk dark matter region cannot be accessed. We then go on to consider the admixture of the singlet SUSY breaking F-term with one of the 24, 75 or 200 dimensional F-terms, and show that in these cases it becomes possible to access the bulk regions corresponding to low fine-tuned dark matter. Our results are prese…
The MSSM with a light right-handed stop and supersymmetric models with a singlet whose vev is comparable to that of the SU(2)_W Higgs allow for a strongly first-order electroweak phase transition even for a mass of the lightest Higgs around 100 GeV. After a short review of the standard model situation we discuss these supersymmetric models. We also compare perturbative calculations based on the dimensionally reduced 3-dimensional action with lattice results and present an analytic procedure based on an analogue of the stochastic vacuum model of QCD to estimate the nonperturbative contributions…
In the minimal supersymmetric standard model (MSSM) extended by a singlet superfield, when the coupling between the singlet sector and the MSSM sector is tiny, the singlet sector can be a quasi dark sector with supersymmetry (SUSY). We investigate the cosmological phenomena in this scenario and obtain the following observations: (i) In the parameter space solving the small cosmological scale anomalies via self-interacting singlino dark matter (SIDM), a first-order phase transition (FOPT) can readily happen but requires rather light dark matter below MeV; (ii) The corresponding parameter space …
The Higgs mass implies fine-tuning for minimal theories of weak scale supersymmetry (SUSY). Non-decoupling effects can boost the Higgs mass when new states interact with the Higgs, but new sources of SUSY breaking that accompany such extensions threaten naturalness. We show that two singlets with a Dirac mass can increase the Higgs mass while maintaining naturalness in the presence of large SUSY breaking in the singlet sector. We explore the modified Higgs phenomenology of this scenario, which we call the "Dirac NMSSM."
We propose a simple grand unified theory (GUT) scenario in which supersymmetry (SUSY) is spontaneously broken in visible sector. Our model is based on the GUT model that has been proposed to solve almost all problems in conventional GUT scenarios. In the previous work, the problems can be solved by a natural assumption in a supersymmetric vacuum. In this paper, we consider an extension of the model (i.e. omitting one singlet field) and break SUSY spontaneously without new sector. Our model does not have hidden sector and predicts high-scale SUSY where sfermion masses are of order 100-1000 TeV …
We present a model in which the same modulus field breaks both SUSY and a simple GUT gauge group down to the SM gauge group. The modulus is stabilized by the inverted hierarchy mechanism in a perturbative region so that the model is calculable. This is the first example of this kind in the literature. All mass scales (other than the Planck scale) are generated dynamically. In one of the models doublet-triplet splitting is achieved naturally by the sliding singlet mechanism while another model requires fine tuning. The gauge mediation contribution to the right handed slepton (mass)$^2$ is negat…
In this paper we present the renormalization group equations to one-loop order for all the parameters of two supersymmetric left-right theories that are softly broken. Both models are based upon the gauge group SU(3)^c x SU(2)_L x SU(2)_R x U(1)_{B - L} and both contain an arbitrary number of bidoublets as well as singlets; however, one model uses doublets to break SU(2)_R and the other uses triplets.
We propose a scenario for realizing inflation in the framework of supersymmetric B-L extension of the Standard Model. We find that one of the associated right-handed sneutrinos (the superpartner of the Standard Model singlet fermion) can provide a new non-trivial inflationary trajectory at tree level (therefore breaking B-L during inflation). As soon as the inflation ends, the right-handed sneutrino falls into the supersymmetric vacuum, with a vanishing vacuum expectation value, so that B-L symmetry is restored. In this class of models, the B-L gauge symmetry will be radiatively broken at a Te…
Radiative neutrino mass generation within supersymmetric (SUSY) construction is studied. The mechanism is considered where the lepton number violation is originating from the soft SUSY breaking terms. This requires MSSM extensions with states around the TeV scale. We present several explicit realizations based on extensions either by MSSM singlet or SU(2)_w triplet states. Besides some novelties of the proposed scenarios, various phenomenological implications are also discussed.
We extend the noncommutative (NC) standard model to incorporate singlet particles as cold dark matter. In the NC space-time, the singlet particles can be coupled to the U(1) gauge field in the adjoint representation. We Study the relic density of the singlet particles due to the NC induced interaction. Demanding either the singlet fermion or the singlet scalar to serve as cold dark matter and the NC induced interactions to be relevant to the dark matter production, we obtain the corresponding relations between the NC scale and the dark matter masses, which are consistent with some existing bou…
Following the recent results from Daya Bay and RENO, which measure the lepton mixing angle theta^l_13 ~ 0.15, we revisit a supersymmetric S4 x SU(5) model, which predicts tri-bimaximal (TB) mixing in the neutrino sector with theta^l_13 being too small in its original version. We show that introducing one additional S4 singlet flavon into the model gives rise to a sizable theta^l_13 via an operator which leads to the breaking of one of the two Z2 symmetries preserved in the neutrino sector at leading order. The results of the original model for fermion masses, quark mixing and the solar mixing …
We provide a simple solution to the $μ/B_μ$ problem in the gauge-mediated Next-to-Minimal Supersymmetric Standard Model. In this model the messenger sector contains one pair of $3+\bar 3$ and one pair of $2+\bar 2$ messengers. These two messenger pairs couple to different gauge singlets in the hidden sector in which supersymmetry (SUSY) is broken. Such a gauge-mediation structure can naturally arise in many backgrounds. Because of the two effective SUSY breaking scales $\frac{< F_i>}{< M_i>}$ in the messenger sector, the renormalization group evolutions of the soft SUSY breaking parameters can…
The bulk matter Randall-Sundrum (RS) model is a setup where Standard Model (SM) matter and gauge fields reside in the bulk of 5D warped spacetime while the Higgs field is confined on the IR brane. The wavefunctions of the 1st and 2nd generation matter particles are localized towards the UV brane and those of the 3rd generation towards the IR brane, so that the hierarchical structure of the Yukawa couplings arises geometrically without hierarchy in fundamental parameters. This paper discusses an experimental test of this model in the case where the Kaluza-Klein scale is far above the collider s…
We suggest a supersymmetric (SUSY) explanation of neutrino masses and mixing, where nonrenormalizable interactions in the hidden sector generate lepton number violating Majorana mass terms for both right-chiral sneutrinos and neutrinos. It is found necessary to start with a superpotential including an array of gauge singlet chiral superfields. This leads to nondiagonal $ΔL = 2$ mass terms and almost diagonal SUSY breaking $A$-terms. As a result, the observed pattern of bilarge mixing can be naturally explained by the simultaneous existence of the seesaw mechanism and radiatively induced masses…
Consider a gauge singlet superfield S coupled to a pair of adjoint fields in a SUSY-GUT. If the tree-level vacuum is flat in S, the vev <S> which defines the GUT scale will be determined via dimensional transmutation at a scale M where the soft-breaking (mass)^2 vanishes as a result of running from $M_{Pl} = (8 πG_N)^{-1/2}$. Because of the large number of adjoint fields $N_A$ coupled to S, one finds that M can be generically close to $M_{GUT} = 2 \times 10^{16} GeV$: $M \simeq M_{Pl} \exp[-16 π^2 \log(3/2) / (N_A+4) λ^2]$, where $λ$ is a Yukawa $\sim$ 0.7. This work examines the symmetries an…
Quantum Restoration of the U(1)_Y Symmetry in Dynamically Broken SUSY-GUT's
我们提出了一个在大统一尺度下强相互作用的超对称超色SU（3）_H规范理论，其中超夸克凝聚在经典水平上将SU（5）_GUT破缺为SU（3）_C x SU（2）_L，而没有不破缺的U（1）_Y.然而，我们发现，破缺的U（1）_Y对称性通过量子力学效应恢复，因此在电弱尺度下仍然存在标准模型的规范对称性。强相互作用的动力学也自然产生一对无质量的希格斯双重态。除了这些Higgs二重态，我们还有一对无质量的单线态，它们对规范耦合常数的重整化群方程有贡献，从而影响了大统一理论。我们讨论这个问题的一个简单的解决方案。
We develop a model of sneutrino inflation that is charged under $U(1)_{B-L}$ gauge symmetry in no-scale supergravity framework. The model provides an interesting modification of tribrid inflation. We impose $U(1)_R$ symmetry on the renormalizable level while allow Planck suppressed non-renormalizable operators that break R-symmetry. This plays a crucial role in realizing a Starobinsly-like inflation scenario from one hand. On the other hand it plays essential role, as well as SUSY breaking effects, in deriving the neutrino masses from TeV inverse seesaw mechanism. Thus we provide an interpreta…
We consider an N=1 supersymmetric U(N) gauge theory with an adjoint chiral multiplet. By developing a self-consistent Hartree-Fock approximation to the leading order which is reminiscent of that of the BCS/NJL in the superconductivity/chiral symmetry, we show that the N=1 supersymmetry is spontaneously broken, giving a mixed Majorana-Dirac mass term for gaugino due to the nonvanishing D-term VEV and F-term one induced by D-term.
We study a new supersymmetric mechanism for lepton flavor violation in a minimal extension of the MSSM with low-mass heavy singlet neutrinos, which is fully independent of the flavor structure of the soft SUSY breaking sector. We find that l -> l' gamma processes are forbidden in the SUSY limit, whilst the processes l -> l'l1 l2 and mu -> e conversion in nuclei can be enhanced well above the observable level, via large neutrino Yukawa-coupling effects.
