In Type III seesaw model, there are tree level flavor changing neutral currents (FCNC) in the lepton sector, due to mixing of charged particles in the leptonic triplet introduced to realize seesaw mechanism, with the usual charged leptons. In this work we study these FCNC effects in a systematic way using available experimental data. Several FCNC processes have been studied before. The new processes considered in this work include: lepton flavor violating processes $τ\to P l$, $τ\to V l$, $V \to l \bar l'$, $P \to l \bar l'$, $M\to M' l \bar l'$ and muonium-antimuonium oscillation. Results obtained are compared with previous results from $l_i \to l_j l_k \bar l_l$, $l_i \to l_j γ$, $Z \to l \bar l'$ and $μ- e$ conversion. Our results show that the most stringent constraint on the $e$-to-$τ$ FCNC effect comes from $τ\to π^0 e$ decay. $τ\to ρ^0 μ$ and $τ\to π^0 μ$ give very stringent constraints on the $μ$-to-$τ$ FCNC effect, comparable with that obtained from $τ\to μ\bar μμ$ studied previously. The constraint on the $e$-to-$μ$ FCNC effect from processes considered in this work is much weaker than that obtained from processes studies previously, in particular that from $μ- e$ conversion in atomic nuclei. We find that in the canonical seesaw models the FCNC parameters, due to tiny neutrino masses, are all predicted to be much smaller than the constraints obtained here, making such models irrelevant. However, we also find that in certain special circumstances the tiny neutrino masses do not directly constrain the FCNC parameters. In these situations, the constraints from the FCNC studies can still play important roles.
We study the quark sector of the universal seesaw model with SU(2)$_L$ $\times$ SU(2)$_R$ $\times$ $U(1)$.The model incorporates the seesaw mechanism with the vector-like quarks (VLQs). The purpose of this work is to study the model with the effective theory. After integrating the heavy five VLQs, we derive the effective theory with four up-type quark and three down type quark. In this work, the FCNC of Z boson for top quark and top$^\prime$ quark is derived.
Realistic predictions are made for lepton flavour violating and flavour changing neutral current decays in the large tan beta regime of a SUSY-seesaw model. Lepton flavour violating neutral Higgs decays are discussed within this framework along with the highly constraining charged lepton decays l_i --> l_j + gamma. In the b-s system the important constraint from b --> s + gamma is studied in conjunction with the rare FCNC Bs --> mu mu (tau mu) decays and the recently measured Delta Ms.
Lepton polarization asymmetries for the flavor-changing neutral current (FCNC) dileptonic decays of Λb baryons are calculated using single-component analytic (SCA) and multicomponent numerical (MCN) form factors. We show that these polarization asymmetries are insensitive to the transition form factors and, thus, the effects of QCD in the nonperturbative regime. Therefore, these observables can provide somewhat model independent ways of extracting the Wilson coefficients.
After a quarter of century of intense search for new physics beyond the Standard Model (SM), two ideas stand out to naturally cope with (i) small neutrino masses and (ii) a light higgs boson : Seesaw and SUSY. The combination of these two ideas, i.e. SUSY seesaw exhibits a potentially striking signature: a strong (or even very strong) enhancement of lepton flavour violation (LFV), which on the contrary remains unobservable in the SM seesaw. Indeed, even when supersymmetry breaking is completely flavour blind, Renormalisation Group running effects are expected to generate large lepton flavour v…
The seesaw model of quark masses is studied systematically, focusing on its developments. A framework allowing the top quark mass to be of the order of the electroweak symmetry breaking scale, while the remaining light quarks have much smaller masses, due to the seesaw mechanism, is presented. The violation of the GIM mechanism is shown to be small and the tree level FCNC are suppressed naturally. In this model, there are many particles which could contribute to the FCNC in the one-loop level. Parameters of the model are constrained by using the experimental data on K^0-\bar{K}^0 mixing and ε_…
Branching ratios, lepton forward-backward asymmetries, and lepton polarization asymmetries for the flavor-changing neutral current (FCNC) dileptonic decays of the $Λ_b$ baryon to the ground state and a number of excited state $Λ$ baryons are calculated using form factors extracted using wave functions from a constituent quark model. The SM branching ratios for the transition to the ground state calculated using these quark model form factors are consistent with the recent measurement reported by the LHCb collaboration. It is shown that the lepton polarization asymmetries are largely insensitiv…
Flavor-changing neutral currents (FCNC) are studied on the basis of a ``democratic seesa'' mass matrix model, which yields a singular enhancement of the top-quark mass m_t and can give reasonable quark masses and CKM matrix elements. The most exciting aspect of the model is that the structure of the $6 \times 6$ right-handed fermion mixing matrix in the up-quark sector, $U^R_u$, shows an abnormal structure in contrast to that of $U^L_u$. This causes characteristic effects on the right-handed FCNC concerned with top quark. A single top-quark production at future $e^+ e^-$ colliders, $e^+ + e^- …
In the context of Supersymmetric Grand Unified theories with soft breaking terms arising at the Planck scale, it is generally possible to link flavor changing neutral current and CP violating processes occurring in the leptonic and hadronic sectors. We study the correlation between flavor changing squark and slepton mass insertions in models à la SU(5). We show that the constraints coming from lepton flavor violation exhibit a strong impact on CP-violating B decays.
Large long-distance standard model effects in FCNC semileptonic D decays can make observable these processes in future measurements. Eventual disagreements in this sector and/or the observation of lepton family violating (LFV) D decays would require an explanatio beyond the SM framework. In this paper we confront present experimental data on leptonic and semileptonic FCNC and LFV D meson decays with a version of the two-Higgs doublet model that allows these effects to occur at tree- level. The stringent bounds on the parameters of the model are obtained from D^0 --> l^+l'^- and D --> pi l^+l'^…
The observed flavor-changing neutral-current (FCNC) processes in the standard model (SM) arise from the loop diagrams involving the weak charged currents mediated by the $W$-gauge boson. Nevertheless, the top-quark FCNCs and lepton-flavor violating processes resulting from the same mechanism are highly suppressed. We investigate possible new physics effects that can enhance the suppressed FCNC processes, such as $t\to q(h,V)$ with $V=γ,Z,g$, $h\to \ell \ell'$, and $\ell\to \ell' γ$. To achieve the assumption that the induced-FCNCs are all from quantum loops, we consider the scotogenic mechanis…
Many extensions of the Standard Model(SM) generate contributions to Flavor Changing Neutral Current(FCNC) processes that must have sufficient flavor suppression to be consistent with experiments, if the new physics (NP) is associated with a scale of a TeV. Here we present a mechanism for suppressing the NP effects to FCNC processes. We consider the possibility that the source of NP contributions to FCNC processes share the same flavor symmetry underlying the SM source of FCNC processes which are the quark and lepton mass matrices. We call this the principle of shared flavor symmetry. In the fl…
We analyse the constraints and some of the phenomenological implications of a class of two Higgs doublet models where there are flavour-changing neutral currents (FCNC) at tree level but the potentially dangerous FCNC couplings are suppressed by small entries of the CKM matrix $V$. This class of models have the remarkable feature that, as a result of a discrete symmetry of the Lagrangian, the FCNC couplings are entirely fixed in the quark sector by $V$ and the ratio $v_2 /v_1$ of the vevs of the neutral Higgs. The discrete symmetry is extended to the leptonic sector, so that there are FCNC in …
We derive the necessary conditions to build a class of invisible axion models with Flavor Changing Neutral Currents at tree-level controlled by the fermion mixing matrices and present an explicit model implementation. A horizontal Peccei-Quinn symmetry provides a solution to the strong CP problem via the Peccei-Quinn mechanism and predicts a cold dark mater candidate, the invisible axion or familon. The smallness of active neutrino masses can be explained via a type I seesaw mechanism, providing a dynamical origin for the heavy seesaw scale. The possibility to avoid the domain wall problem sta…
We consider scenarios with a heavy $Z^\prime$ gauge boson with flavour non-universal quark and lepton couplings with the goal to illustrate how the cancellation of gauge anomalies generated by the additional U(1)$^\prime$ gauge symmetry would imply correlations between FCNC processes in the quark sector, in the lepton sector and most interestingly between quark flavour and lepton flavour violating processes. We present scenarios with only left-handed flavour-violating $Z^\prime$ couplings and those with also right-handed flavour-violating couplings. These are characterized by a small number of…
In this paper, we consider a single top quark production in association with a neutral gauge boson (Z boson or Photon) at the future electron-positron colliders. We utilize these channels to probe the top quark Flavour Changing Neutral Currents (FCNC) interactions in $tqZ$ and $tqγ$ vertices. We perform two separate analyses for top-Z-jet and top-$γ$-jet channels. The Standard Model Effective Field Theory (SMEFT) approach is employed to search for these anomalous couplings. We consider parton showering, hadronization and fast detector simulation in our study and use a cut-and-count technique t…
The mass matrices of the charged leptons and neutrinos, previously derived in a minimal S_3-invariant extension of the Standard Model, were reparametrized in terms of their eigenvalues. We obtained explicit, analytical expressions for all entries in the neutrino mixing matrix, V_PMNS, the neutrino mixing angles and the Majorana phases as functions of the masses of charged leptons and neutrinos in excellent agreement with the latest experimental values. The resulting V_PMNS matrix is very close to the tri-bimaximal form of the neutrino mixing matrix. We also derived explicit analytical expressi…
We study the three body lepton flavor violating (LFV) decays $μ^- \to e^- e^+ e^-$, $τ^- \to l_i^- l_j^+ l_j^-$ and the semileptonic decay $τ\to μϕ$ in the flavor changing neutral current (FCNC) mediated $Z$ boson model. We also calculate the branching ratios for LFV leptonic B decays, $B_{d,s} \to μe$, $B_{d,s} \to τe$, $B_{d,s} \to τμ$ and the conversion of muon to electron in Ti nucleus. The new physics parameter space is constrained by using the experimental limits on $μ^- \to e^- e^+ e^-$ and $τ^- \to μ^- μ^+ μ^-$. We find that the branching ratios for $τ\to eee $ and $τ\to μϕ$ processes …
We discuss the impact of fermion mass matrices on some lepton number violating processes, namely baryogenesis via leptogenesis and neutrinoless double beta decay, and on some lepton flavor violating processes, namely radiative lepton decays in supersymmetric seesaw models.
In this work we analyse a non-minimal Lorentz-violating extension of the electroweak theory in the fermionic sector. Firstly we analyse the relation between the CKM rotation in the quark sector and possible contributions of this new coupling to flavour changing neutral currents (FCNC) processes. In sequel we look for non-diagonal terms through possible leptonic flavour violation (LFV) decays. Strong bounds are presented to the Lorentz violating parameters of both the quark and the leptonic sectors.
The observation of charged lepton flavour violation would be a smoking gun for new physics and could help in pinpointing the mechanism at the origin of neutrino masses and mixing. We present here our recent studies of lepton flavour violating Higgs decays in the inverse seesaw and its supersymmetric embedding, two examples of low-scale seesaw mechanisms. We predict branching ratios as large as $10^{-5}$ for the decays $h\rightarrow τμ$ and $h \rightarrow τe$ in the inverse seesaw, which can be probed in future colliders. Supersymmetric contributions can enhance the branching ratio of $h\righta…
The flavour-changing neutral currents (FCNC) are derived at tree level if the electroweak gauge group depends on the fermion family, which are absent in the standard model. We study the lepton flavour violation (LFV) through the FCNC interactions in a nonuniversal gauge interaction model where the third generation fermions are subjected to the separate SU(2)$_L$ gauge group.
One of the main purposes of SHiP experiment is to shed light on neutrino mass generation mechanisms like the so-called seesaw. We consider a minimal type-I seesaw neutrino mass mechanism model with two heavy neutral leptons (right-handed or sterile neutrinos) with arbitrary masses. Extremely high active-sterile mixing angle requires a correlation between the phases of the Dirac neutrino couplings. Actual experimental limits on the half-life of neutrinoless double beta decay $0νββ$-rate on the active-sterile mixing angle are not significative for SHiP.
Now the bounds on the lepton-flavor violating (LFV) decay modes of tau lepton are being improved by the Belle experiment in the KEK B factory. In this paper the LFV decay of tau lepton is discussed in the supersymmetric seesaw model, using the current neutrino oscillation data.
We present SUSY_FLAVOR -- a Fortran 77 program that calculates important leptonic and semi-leptonic low-energy observables in the general R-parity conserving MSSM. For a set of input MSSM parameters, the code gives predictions for the K0-bar K0, D-bar D, B_d-bar B_d and B_s-bar B_s mixing parameters; B to X_s gamma, B_{s,d} to l+ l-, K0_L to pi nu-bar nu and K+ to pi+ nu-bar nu decay branching ratios; and the electric dipole moments of the leptons and the neutron. All these quantities are calculated at one-loop level (with some higher-order QCD corrections included) in the exact sfermion mass …
In this paper, the lepton flavor violating $τ\to \ell P(V)$ ($P,V= π^0, η, η^{\prime}, ρ^0, ω, ϕ$) and $τ\to 3\ell$ ($\ell = e, μ$) decays are studied in the framework of the type-III seesaw model, in which new triplet fermions with a zero hypercharge (Y=0) interact with ordinary lepton doublets via Yukawa couplings, and affect tree-level leptonic Z-boson couplings. We investigate the experimental bound from the leptonic Z decay to get contraint on the exsiting parameters space. We predict that the upper limits on the branching ratios of $τ\to \ell P(V)$ and $τ\to 3\ell$ can reach the experime…
We study phenomenological constraints on a simple $3-3-1$ model with flavor violating Yukawa couplings. Both triplets Higgs couple to leptons and quarks, which generates flavor violating signals in both lepton and quark sectors. We have shown that this model can allow for large Higgs lepton flavor-violating rate decay $h \rightarrow μτ$ and also can be reached to perfect agreements with other experimental constraints such as $τ\rightarrow μγ$ and $(g-2)_μ$. The contributions of flavor-changing neutral current (FCNC) couplings, Higgs-quark-quark couplings, to the mesons mixing are investigated.…
Based on the $SU(3)_{F}$ gauge family symmetry model which was proposed to explain the observed mass and mixing pattern of neutrinos, we investigate the symmetry breaking, the mixing pattern in quark and lepton sectors, and the contribution of the new gauge bosons to some flavour changing neutral currents (FCNC) processes at low energy. With the current data of the mass differences in the neutral pseudo-scalar $P^{0}-\bar{P}^{0}$ systems, we find that the $SU(3)_{F}$ symmetry breaking scale can be as low as 300TeV and the mass of the lightest gauge boson be about $100$TeV. Other FCNC processes…
FCNC processes are expected to offer us a deep insight into the physics at very short distance scales. We present a list of 20 goals in quark and lepton flavour physics that could be reached already in the next decade. This list includes also flavour conserving observables like electric dipole moments of the neutron and leptons and (g-2)_μ. Subsequently we will present some aspects of these goals by concentrating on supersymmetric flavour models. A much more extensive presentation of this material can be found in my recent EPS09 talk.
The canonical type-I seesaw model with three heavy Majorana neutrinos is one of the most natural extensions of the standard model (SM) to accommodate tiny Majorana masses of three ordinary neutrinos. At low-energy scales, Majorana neutrino masses and unitarity violation of lepton flavor mixing have been extensively discussed in the literature, which are respectively generated by the unique dimension-five Weinberg operator and one dimension-six operator in the seesaw effective field theory (SEFT) with the tree-level matching. In this work, we clarify that a self-consistent calculation of radiat…
We investigate a model with local U(1)$_{B-L}$ and discrete $Z_2$ symmetries where two types of weak isospin singlet neutrinos, vector-like charged lepton and exotic scalar fields are introduced. The linear seesaw mechanism is induced at one-loop level through Yukawa interactions associated with the standard model leptons and exotic fields. We also discuss lepton flavor violation and muon anomalous dipole magnetic moment induced by the new Yukawa interaction. In addition, our model has dark matter candidate which is the lightest $Z_2$ odd neutral particle. We calculate the relic density and co…
We propose a left-right symmetric framework with universal seesaw mechanism for the generation of masses of the Standard Model quarks and leptons. Heavy vector-like singlet quarks and leptons are required for generation of Standard Model-like quark and lepton masses through seesaw mechanism. A softly broken $Z_2$ symmetry distinguishes the lepton sector and the quark sector of the model. This leads to the presence of some lepton-specific interactions that can produce unique collider signatures which can be explored at the current Large Hadron Collider run and also future colliders.
We explore generic features of the leptonic CP violation in the framework of the seesaw type I mechanism with similarity of the Dirac lepton and quarks mass matrices $m_D$. For this, we elaborate on the standard parametrization conditions which allow to simultaneously obtain the Dirac and Majorana phases. If the only origin of CP violation is the left-handed (LH) transformation which diagonalizes $m_D$ (similar to quarks), the leptonic CP violation is suppressed and the Dirac phase is close to $π$ or to $0$ with $\sin δ_{CP} \approx (\sin θ_{13}^q /\sin θ_{13}) \cos θ_{23} \sin δ_q \sim λ^2 \s…
The type-I seesaw model is probably the most straightforward and best studied extension of the Standard Model that can account for the tiny active neutrino masses determined from neutrino oscillation data. In this article, we calculate the complete set of one-loop corrections to charged lepton flavour violating processes within this model. We give the results both using exact diagonalisation of the neutrino mass matrix, and at at leading order in the seesaw expansion (i.e. $\mathcal{O}(v^2/M_R^2)$). Furthermore, we perform the matching onto the $SU(2)_L$ invariant Standard Model Effective Fiel…
We study phenomenological implications of a radiative inverse seesaw dark matter model. In this model, because neutrino masses are generated at two loop level with inverse seesaw, the new physics mass scale can be as low as a few hundred GeV and the model also naturally contain dark matter candidate. The Yukawa couplings linking the SM leptons and new particles can be large. This can lead to large lepton flavor violating effects. We find that future experimental data on $μ\to e γ$ and $μ- e$ conversion can further test the model. The new charged particles can affect significantly the $h \to γγ…
The inverse seesaw mechanism of neutrino mass, i.e. m_nu = (m_D^2/m_N^2)epsilon_L where epsilon_L is small, is discussed in the context of the U(1)_Sigma model. This is a gauge extension of the Standard Model of particle interactions with lepton triplets (Sigma^+,Sigma^),Sigma^-) as (Type III) seesaw anchors for obtaining small Majorana neutrino masses.
We analyse a possible connection between CP violations in the quark and lepton sectors, parametrised by the CKM and PMNS phases. If one assumes that CP breaking arises from complex Yukawa couplings, both in the quark and lepton sectors, the above connection is not possible in general, since Yukawa couplings in the two sectors have independent flavour structures. We show that both the CKM and PMNS phases can instead be generated by a vacuum phase in a class of two Higgs doublet models, and in this case a connection may be established. This scenario requires the presence of scalar FCNC at tree l…
We discuss a supersymmetric inverse seesaw model in which lepton flavour violating decays can be enhanced either by flavour violating slepton contributions or by the non-unitarity of the charged current mixing matrix. As an example we calculate Br(mu -> e gamma) taking into account both heavy lepton exchange as well as supersymmetric diagrams in a minimal supergravity framework. We find that the for the same parameters the rate can be enhanced with respect to seesaw model expectations, with or without supersymmetry.
We study the constraints on a minimal supersymmetric seesaw model imposed by neutrino data, charged lepton flavor violation, thermal leptogenesis and perturbativity. We show that it is possible to constrain the three heavy Majorana neutrino masses as well as the complex Yukawa coupling matrix. Our results provide a first step towards a seesaw benchmark model for further phenomenological studies and model building.
The Majorana nature of neutrinos is strongly motivated from the theoretical and phenomenological point of view. A plethora of neutrino mass models, known collectively as Seesaw models, exist that could generate both a viable neutrino mass spectrum and mixing pattern. They can also lead to rich, new phenomenology, including lepton number non-conservation as well as new particles, that may be observable at collider experiments. It is therefore vital to search for such new phenomena and the mass scale associated with neutrino mass generation at high energy colliders. In this review, we consider a…
The type II seesaw mechanism introduces a hypercharged Higgs triplet to explain the observed neutrino masses and mixing. Among three triplet components, the doubly charged Higgs boson can be the lightest and decay mainly to same-sign di-leptons. Furthermore, the heavier singly charged or neutral Higgs boson produces a doubly charged Higgs boson through its fast gauge decay. This leads to a novel signature of same-sign tetra-leptons resulting from a pair production of same-sign doubly charged Higgs bosons caused by the nearly degenerate neutral scalar mixing which can be sizable for an appropri…
We study the implications of the global $U(1)_R$ symmetry present in minimal lepton flavor violating implementations of the seesaw mechanism for neutrino masses. Our discussion is done in the context of explicit minimal type-I seesaw scenarios, where depending on the R-charge assignment different models can be constructed. We study the charged lepton flavor violating phenomenology of a concrete realization paying special attention to $μ\to eγ$ and $μ\to 3e$.
We revisit minimal non-supersymmetric models of SU(5) Grand Unification with the type II seesaw mechanism as the origin of neutrino masses. Imposing the requirement of gauge coupling unification and the proton lifetime bounds, we perform a Bayesian fit and obtain robust quantitative information on the mass scales of the beyond the Standard Model particles. We then study lepton-flavour-violating (LFV) processes induced by the type II scalar triplet and its SU(5) partners, showing that the interplay of upcoming searches for different LFV observables can provide additional information on the mass…
We study the anomalous production of a single top quark in association with a Higgs boson at the LHC originating from flavor changing neutral current (FCNC) interactions in $tqg$ and $tqH$ vertices. We derive the discovery potentials and $68\%$ C.L. upper limits considering leptonic decay of the top quark and the Higgs boson decay into a $b\bar{b}$ pair with 10 fb$^{-1}$ integrated luminosity of data in proton-proton collisions at the center-of-mass energy of 14 TeV. We propose a charge ratio for the lepton in top quark decay in terms of lepton $p_{T}$ and $η$ as a strong tool to observe the s…
We study the potential impacts of a new type of particle collider -- an $eμ$ collider -- on the search for new physics beyond the Standard Model. As our first attempt for exploring its physics potential, we demonstrate that the the $eμ$ collision experiment can be highly efficient in searching for lepton-number-violating Flavor Changing Neutral Current phenomena.
In a version of the 3-3-1 model proposed by Duong and Ma the introduction of the scalar sextet for giving mass to the charged leptons is avoided by adding a singlet charged lepton. We show that in this case the $τ$ lepton gains mass through a seesaw--like mechanism. Besides we show how to generate neutrino masses at the tree and at the 1-loop level with the respective Maki-Nakagawa-Sakata leptonic mixing matrices.
Within low-scale seesaw mechanisms, such as the inverse and linear seesaw, one expects (i) potentially large lepton flavor violation (LFV) and (ii) sizeable non-standard neutrino interactions (NSI). We consider the interplay between the magnitude of non-unitarity effects in the lepton mixing matrix, and the constraints that follow from LFV searches in the laboratory. We find that NSI parameters can be sizeable, up to percent level in some cases, while LFV rates, such as that for μ-> e γ, lie within current limits, including the recent one set by the MEG collaboration. As a result the upcoming …
In minimal supersymmetric seesaw models, the contribution to lepton flavour violation from Z-penguins is usually negligible. In this study, we consider the supersymmetric inverse seesaw and show that, in this case, the Z-penguin contribution dominates in several lepton flavour violating observables due to the low scale of the inverse seesaw mechanism. Among the observables considered, we find that the most constraining one is the muon to electron conversion rate which is already restricting the otherwise allowed parameter space of the model. Moreover, in this framework, the Z-penguins exhibit …
In leptogenesis scenario, the decays of heavy Majorana neutrinos generate lepton family asymmetries, $Y_e, Y_μ$ and $Y_τ$. They are sensitive to CP violating phases in seesaw models. The time evolution of the lepton family asymmetries are derived by solving Boltzmann equations. By taking a minimal seesaw model, we show how each family asymmetry varies with a CP violating phase. For instance, we find the case that the lepton asymmetry is dominated by $Y_μ$ or $Y_τ$ depending on the choice of the CP violating phase. We also find the case that the signs of lepton family asymmetries $Y_μ$ and $Y_τ…
The sensitivity of beam dump experiments to heavy neutral leptons depends on the relative strength of their couplings to individual lepton flavours in the Standard Model. We study the impact of present neutrino oscillation data on these couplings in the minimal type I seesaw model and find that it significantly constrains the allowed heavy neutrino flavour mixing patterns. We estimate the effect that the DUNE experiment will have on these predictions. We then discuss implication that this has for the sensitivity of the NA62 experiment when operated in the beam dump mode and provide sensitivity…
We study the LHC potential for discovering TeV-scale SU(2)_L 5-plet fermions introduced recently to explain small neutrino masses. We show that the Drell-Yan production and the decays of new exotic Sigma leptons are testable at the LHC. Their production is abundant due to nontrivial electroweak gauge charges. For 1 fb^-1 of integrated luminosity at the present LHC sqrt{s}=7 TeV, there can be 270 Sigma-Sigmabar pairs produced for M_Sigma = 400 GeV. Besides producing same-sign dilepton events, they could lead, due to a chosen small mixing between heavy and light leptons, to ~10 golden decays Sig…
We study the lepton electric dipole moments in the framework of the supersymmetric type II seesaw model where the exchange of heavy SU(2)_W triplets generates small neutrino masses. We show that the CP violating phase of the bilinear soft supersymmetry breaking term associated with the SU(2)_W triplets contributes to lepton electric dipole moments mainly through threshold corrections to the gaugino masses at the seesaw scale. As a consequence, the ratio of the electric dipole moments of the muon and the electron is the same as the ratio of their masses in a wide region of parameter space.
