Supersymmetric Left-right Model Research Articles

Reconciling collider signals, dark matter, and the muon anomalous magnetic moment in the supersymmetric U(1)R × U(1)B−L model

We study the low-scale predictions of the supersymmetric model extended by U(1)R × U(1)B−L symmetry, obtained by breaking SO(10) symmetry at GUT scale via a left-right supersymmetric model. Two new singlet Higgs fields left({upchi}_R,{overline{upchi}}_Rright) are responsible for the U(1)R × U(1)B−L symmetry breaking to the standard model gauge group. We explore the phenomenology of this model by assuming universal and non-universal boundary conditions at the GUT scale and their effects in obtaining consistency among low-energy observables, dark matter experiments, muon magnetic moment measurements, and Z′ phenomenology. We examine different scenarios with both the lightest neutralino and sneutrino mass eigenstates as dark matter candidates. We explore the collider signals of various scenarios by including relevant benchmarks and exploring their significance versus standard model background. To complement our analysis, we perform recasting of several LHC analyses to verify the credibility of the benchmarks. We find that relaxing the universality conditions at MGUT can significantly improve the agreement of the model against the experimental bounds. While the muon anomalous magnetic moment is found to be the most challenging observable to fit within the model, we identify, allowing for non-universality at the GUT scale, points in the parameter space consistent within 2σ from the average measured value.

Higgs flavor phenomenology in a supersymmetric left-right model with parity

In this paper, we focus on the supersymmetric model with left-right (LR) symmetry, that is especially proposed in our previous work [1]. In this model, there are four Higgs doublets in order to realize the Standard Model (SM) fermion masses and the Cabibbo-Kobayashi-Maskawa matrix. The heavy Higgs doublets unavoidably have flavor changing couplings to the SM fermions and induce flavor-changing neutral currents at tree level. We study broader parameter space than the previous work with including the renormalization group corrections to the Yukawa couplings between the LR breaking scale, mathcal{O} (1013) GeV, and the supersymmetry breaking scales, mathcal{O} (100) TeV. The CP violating observable in K– overline{K} mixing, ϵK, strongly constrains the model, so that heavy Higgs mass should be heavier than mathcal{O} (100) TeV. We study the lepton flavor violating (LFV) processes setting heavy Higgs masses to be 170 TeV. The branching ratios of μ → 3e and the μ–e conversion can be larger than 10−16 that could be covered by the future experiments. We also study the degree of fine-tuning in the parameter region that predicts testable LFV processes.

Anatomy of heavy gauge bosons in a left-right supersymmetric model

We perform a detailed study of the various decay channels of the heavy charged and neutral gauge bosons ($W_R$ and $Z_R$ respectively) in a left-right supersymmetric (LRSUSY) framework. The decay branching ratios of the $W_R$ and $Z_R$ bosons depend significantly on the particle spectrum and composition of the SUSY states. We show several combinations of mass spectrum for the SUSY particles to facilitate the decay of these heavy gauge bosons into various combinations of final states. Finally, we choose two benchmark points and perform detailed collider simulations for these heavy gauge bosons in the context of the high energy and high luminosity run of the large hadron collider. We analyze two SUSY cascade decay channels -- mono-$W$ + $\slashed{E}_T$ and mono-$Z$ + $\slashed{E}_T$ along with the standard dilepton and dijet final states. Our results show that the existence of these heavy gauge bosons can be ascertained in the direct decay channels of dilepton and dijet whereas the other two channels will be required to establish the supersymmetric nature of this model.

Exploring the supersymmetric U(1)B−L×U(1)R model with dark matter, muon g−2 , and Z′ mass limits

We study the low scale predictions of supersymmetric standard model extended by $U(1)_{B-L}\times U(1)_{R}$ symmetry, obtained from $SO(10)$ breaking via a left-right supersymmetric model, imposing universal boundary conditions. Two singlet Higgs fields are responsible for the radiative $U(1)_{B-L}\times U(1)_{R}$ symmetry breaking, and a singlet fermion $S$ is introduced to generate neutrino masses through inverse seesaw mechanism. The lightest neutralino or sneutrino emerge as dark matter candidates, with different low scale implications. We find that the composition of the neutralino LSP changes considerably depending on the neutralino LSP mass, from roughly half $U(1)_R$ bino, half MSSM bino, to singlet higgsino, or completely dominated by MSSM higgsino. The sneutrino LSP is statistically much less likely, and when it occurs it is a 50-50 mixture of right-handed sneutrino and the scalar $\tilde S$. Most of the solutions consistent with the relic density constraint survive the XENON 1T exclusion curve for both LSP cases. We compare the two scenarios and investigate parameter space points and find consistency with the muon anomalous magnetic moment only at the edge of $2\sigma$ deviation from the measured value. However, we find that the sneutrino LSP solutions could be ruled out completely by strict reinforcement of the recent $Z^\prime $ mass bounds. We finally discuss collider prospects for testing the model.

A constrained supersymmetric left-right model

We present a supersymmetric left-right model which predicts gauge coupling unification close to the string scale and extra vector bosons at the TeV scale. The subtleties in constructing a model which is in agreement with the measured quark masses and mixing for such a low left-right breaking scale are discussed. It is shown that in the constrained version of this model radiative breaking of the gauge symmetries is possible and a SM-like Higgs is obtained. Additional CP-even scalars of a similar mass or even much lighter are possible. The expected mass hierarchies for the supersymmetric states differ clearly from those of the constrained MSSM. In particular, the lightest down-type squark, which is a mixture of the sbottom and extra vector-like states, is always lighter than the stop. We also comment on the model's capability to explain current anomalies observed at the LHC.

Is the CMSeejjexcess a hint for light supersymmetry?

We discuss the impact of additional two-body decays of the right-handed neutrino into a light charged Higgs state on the dilepton plus dijet cross sections from resonant $W'$ production. We consider in particular a supersymmetric left-right symmetric model which predicts such a light charged Higgs boson. We demonstrate that the $eejj$ excess as measured by CMS can be explained best if the $W'$ also has decay modes into Higgsino-like charginos and neutralinos with masses of a few hundred GeV. Provided that this excess is confirmed, the model predicts also one right-handed neutrino with a mass below 200 GeV as well as a doubly charged Higgs boson which should be discovered at the LHC in the near future.

Doubly-charged Higgs and vacuum stability in left-right supersymmetry

We present an analysis of supersymmetric left-right symmetric models with Higgs fields lying in the adjoint representation of SU(2) R . These models feature a doubly-charged Higgs boson which gets its mass only at the loop level. We present, for the first time, a complete one-loop calculation of this mass and show that contributions that have been neglected so far can shift it by a few hundreds of GeV. We then combine this observation with LHC bounds deduced from extra charged gauge boson and doubly-charged Higgs boson searches. In particular, we point out that existing limits get substantially modified by the presence of singly-charged Higgs bosons that are also predicted in these models. In addition, we address constraints stemming from vacuum stability considerations and show how the considered class of models could be ruled out at the next LHC run in the absence of any signal.

Left-right supersymmetry after the Higgs boson discovery

We perform a thorough analysis of the parameter space of the minimal left-right supersymmetric model in agreement with the LHC data. The model contains left- and right-handed fermionic doublets, two Higgs bidoublets, two Higgs triplet representations, and one singlet, insuring a charge-conserving vacuum. We impose the condition that the model complies with the experimental constraints on supersymmetric particles masses and on the doubly-charged Higgs bosons, and require that the parameter space of the model satisfy the LHC data on neutral Higgs signal strengths at $2\sigma$. We choose benchmark scenarios by fixing some basic parameters and scanning over the rest. The LSP in our scenarios is always the lightest neutralino. We find that the signals for $H\to \gamma \gamma$ and $H \to VV^\star$ are correlated, while $H \to b \bar b$ is anti-correlated with all the other decay modes, and also that the contribution from singly-charged scalars dominate that of the doubly-charged scalars in $H\to \gamma \gamma$ and $H \to Z\gamma$ loops, contrary to Type-II seesaw models. We also illustrate the range for mass spectrum of the LRSUSY model in light of planned measurements of the branching ratio of $H\to \gamma \gamma$ to 10% level.

Supersymmetric left–right model with radiative neutrino mass and multipartite dark matter

The unifiable supersymmetric left-right model where the neutral fermion $n$ in the $SU(2)_R$ doublet $(n,e)_R$ is a dark-matter candidate, is shown to have the requisite particle content for the neutrino $\nu$ in the $SU(2)_L$ doublet $(\nu,e)_L$ to acquire a small radiative Majorana mass from dark matter, i.e. scotogenic from the Greek "scotos" meaning darkness. As a result, there are at least three coexisting stable dark-matter particles with different interactions. We study their possible phenomenological impact on present and future experiments.

Inflation, leptogenesis, and Yukawa quasiunification within a supersymmetric left-right model

A simple extension of the minimal left-right symmetric supersymmetric grand unified theory model is constructed by adding two pairs of superfields. This naturally violates the partial Yukawa unification predicted by the minimal model. After including supergravity corrections, we find that this extended model naturally supports hilltop F-term hybrid inflation along its trivial inflationary path with only a very mild tuning of the initial conditions. With a convenient choice of signs of the terms in the Kahler potential, we can reconcile the inflationary scale with the supersymmetric grand unified theory scale. All the current data on the inflationary observables are readily reproduced. Inflation is followed by non-thermal leptogenesis via the decay of the right-handed neutrinos emerging from the decay of the inflaton and any possible washout of the lepton asymmetry is avoided thanks to the violation of partial Yukawa unification. The extra superfields also assist us in reducing the reheat temperature so as to satisfy the gravitino constraint. The observed baryon asymmetry of the universe is naturally reproduced consistently with the neutrino oscillation parameters.

Chargino and neutralino production at the Large Hadron Collider in left-right supersymmetric models

Abstract We present a complete and extensive analysis of associated chargino and neutralino production in the framework of a supersymmetric theory augmented by left-right symmetry. This model provides additional gaugino and higgsino states in both the neutral and charged sectors, thus potentially enhancing new physics signals at the LHC. For a choice of benchmark scenarios, we calculate cross sections for 7, 8 and 14 TeV. We then simulate events expected to be produced at the LHC, and classify them according to the number of leptons in the final state. We devise methods to reduce the background and compare the signals with consistently simulated events for the Minimal Supersymmetric Standard Model. We pinpoint promising scenarios where left-right symmetric supersymmetric signals can be distinguished both from background and from the Minimal Supersymmetric Standard Model events.

New signals for doubly-charged scalars and fermions at the Large Hadron Collider

Several extensions of the Standard Model have light doubly-charged Higgs bosons in their particle spectrum. The supersymmetric versions of these models introduce fermionic superpartners of these doubly-charged Higgs bosons, the Higgsinos, which also remain light. In this work we analyze a new collider signal resulting from the pair production and decay of a light doubly-charged Higgsino to an even lighter doubly-charged Higgs boson. We focus on the minimal left-right supersymmetric model with automatic R-parity conservation, which predicts such a light doubly-charged Higgs boson and its Higgsino partner at the TeV scale, which are singlets of SU(2)_L. We investigate the distinctive signatures of these particles with four leptons and missing transverse energy in the final state at the Large Hadron Collider and show that the discovery reach for both particles can be increased in this channel.

Dark matter in a SUSY left-right model

Supersymmetric left-right models are well motivated extensions of the Minimal Supersymmetric Standard Model since they automatically contain the ingredients to explain the observed neutrino masses and mixings. Here we study a SUSY model in which the left-right symmetry is broken by triplets at a high scale leading to automatic R-parity conservation at low energies. The sparticle spectra in this model differ from the usual constrained MSSM expectations and these changes affect the relic abundance of the lightest neutralino. We discuss two examples: (1) the standard stau co-annihilation region, and (2) flavoured co-annihilation.

Dark matter and LHC phenomenology in a left-right supersymmetric model

Left-right symmetric extensions of the Minimal Supersymmetric Standard Model can explain neutrino data and have potentially interesting phenomenology beyond that found in minimal SUSY seesaw models. Here we study a SUSY model in which the left-right symmetry is broken by triplets at a high scale, but significantly below the GUT scale. Sparticle spectra in this model differ from the usual constrained MSSM expectations and these changes affect the relic abundance of the lightest neutralino. We discuss changes for the standard stau (and stop) co-annihilation, the Higgs funnel and the focus point regions. The model has potentially large lepton flavour violation in both, left and right, scalar leptons and thus allows, in principle, also for flavoured co-annihilation. We also discuss lepton flavour signals due to violating decays of the second lightest neutralino at the LHC, which can be as large as 20 fb$^{-1}$ at $\sqrt{s}=14$ TeV.

SpontaneousR-parity breaking, left-right symmetry, and consistent cosmology with transitory domain walls

Domain wall formation is quite generic in spontaneous Left-Right parity (D-parity) breaking models. Since they are in conflict with cosmology, we need some mechanisms to remove them. Planck scale suppressed effects have been considered to be quite successful for this purpose. We study this possibility in Minimal Supersymmetric Left-Right (SUSYLR) model originally proposed by Kuchimanchi et al \cite{Kuchimanchi:1993jg} where both D-parity and R-parity $(R_p = (-1)^{3(B-L)+2s})$ are spontaneously broken. We find that Planck scale suppressed terms allowed for the specific particle content of this model can successfully remove the domain walls provided the D-parity breaking scale is relatively low $(\leq 10^5-10^7 \text{GeV})$. However, demanding this theory to be part of a grand unified theory such as SO(10) forces the D-parity breaking scale to be very high $(\geq 10^{14} \text{GeV})$ and hence is in conflict with the constraint from domain wall removal. We also find another class of R-parity violating SUSYLR models where both these constraints can be simultaneously satisfied.

Supersymmetric left-right models with gauge coupling unification and fermion mass universality

We explore the unification of gauge couplings and fermion masses in two different types of supersymmetric left-right models, one with Higgs triplets and the other with both Higgs triplets as well as bitriplets. The minimal versions of these models do not give rise to the desired unification and some extra fields have to be added. After such a modification, it is possible in one model to get gauged $B-L$ symmetry to be unbroken down to TeV scale. We also identify the parameter space at the electroweak scale which gives rise to fermion mass unification at a high scale $M_{G}$. Type I seesaw emerges as the natural explanation of the small neutrino masses in both the models.

Higgs bosons in a minimalR-parity conserving left-right supersymmetric model

We revisit the Higgs sector of the left-right supersymmetric model. We study the scalar potential in a version of the model in which the minimum is the charge conserving vacuum state, without R-parity violation or additional non-renormalizable terms in the Lagrangian. We analyze the dependence of the potential and of the Higgs mass spectrum on the various parameters of the model, pinpointing the most sensitive ones. We also show that, contrary to previous expectations, the model can predict light neutral flavor-conserving Higgs bosons, while the flavor-violating ones are heavy, and within the limits from K0-K0bar, D0-D0bar and B0-B0bar mixings. We study variants of the model in which at least one pair of doubly-charged Higgs bosons is light, and show that the parameter space for such Higgs masses and mixings is very restrictive, thus making the model more predictive.

Neutrino masses and lepton-flavor-violating τ decays in the supersymmetric left-right model

In the supersymmetric left-right model, the light neutrino masses are given by the Type- II seesaw mechanism. A duality property of this mechanism indicates that there exist eight possible Higgs triplet Yukawa couplings which result in the same neutrino mass matrix. In this paper, we work out the one-loop renormalization group equations for the effective neutrino mass matrix in the supersymmetric left-right model. The stability of the Type- II seesaw scenario is briefly discussed. We also study the lepton-flavor-violating processes (τ→μγ and τ→eγ) by using the reconstructed Higgs triplet Yukawa couplings.

TeV scale left-right symmetry with spontaneousD-parity breaking

The different scenarios of spontaneous breaking of D-parity have been studied in both non-supersymmetric and supersymmetric version of the left-right symmetric models(LRSM). We explore the possibility of a TeV scale $SU(2)_R$ breaking scale $M_R$ and hence TeV scale right handed neutrinos from both minimization of the scalar potential as well as the coupling constant unification point of view. We show that although minimization of the scalar potential allows the possibility of a TeV scale $M_R$ and tiny neutrino masses in LRSM with spontaneous D-parity breaking, the gauge coupling unification at a high scale $\sim 10^{16}$ GeV does not favour a TeV scale symmetry breaking except in the supersymmetric left-right (SUSYLR) model with Higgs doublet and bidoublet. The phenomenology of neutrino mass is also discussed.

LHC and lepton flavour violation phenomenology of a left-right extension of the MSSM

We study the phenomenology of a supersymmetric left-right model, assuming minimal supergravity boundary conditions. Both left-right and (B-L) symmetries are broken at an energy scale close to, but significantly below the GUT scale. Neutrino data is explained via a seesaw mechanism. We calculate the RGEs for superpotential and soft parameters complete at 2-loop order. At low energies lepton flavour violation (LFV) and small, but potentially measurable mass splittings in the charged scalar lepton sector appear, due to the RGE running. Different from the supersymmetric 'pure seesaw' models, both, LFV and slepton mass splittings, occur not only in the left- but also in the right slepton sector. Especially, ratios of LFV slepton decays, such as Br(${\tilde\tau}_R \to \mu \chi^0_1$)/Br(${\tilde\tau}_L \to \mu \chi^0_1$) are sensitive to the ratio of (B-L) and left-right symmetry breaking scales. Also the model predicts a polarization asymmetry of the outgoing positrons in the decay $\mu^+ \to e^+ \gamma$, A ~ [0,1], which differs from the pure seesaw 'prediction' A=1$. Observation of any of these signals allows to distinguish this model from any of the three standard, pure (mSugra) seesaw setups.