Strong Constraints Research Articles

Starspot Coverage on Two New K-type Low-mass Eclipsing Binaries with Radius Inflation

Utilizing data from the Transiting Exoplanet Survey Satellite (TESS) and LAMOST, we present a photometric and spectroscopic investigation of two new K-type low-mass eclipsing binaries, TIC 56913729 and TIC 97729372. Our analysis yields masses and radii for TIC 56913729, M 1 = 0.7822 ± 0.0054M ⊙, R 1 = 0.7891 ± 0.0021R ⊙, and M 2 = 0.7532 ± 0.0052M ⊙, R 2 = 0.7648 ± 0.0021R ⊙. For TIC 97729372, the results are M 1 = 0.6410 ± 0.0058M ⊙, R 1 = 0.6537 ± 0.0069R ⊙ and M 2 = 0.6480 ± 0.0058M ⊙, R 2 = 0.6418 ± 0.0062R ⊙. In addition, by analyzing the out-of-eclipse starspot light variations, the lower limit of starspot coverage varies in different TESS sectors from 2% to 12%. We observed a clear radius inflation in the mass–radius diagram for both stars, when plotted against PARSEC and SPOT isochrones with 1 Gyr. Yet, this apparent discrepancy disappears when the comparison is made with either an older PARSEC isochrone (12 Gyr) or a SPOT isochrone (250 Myr) with high starspot coverage (F spot ∼ 85%), which is significantly higher than the typical starspot coverage deduced from light curves. Due to the lack of strong age constraints, we cannot firmly exclude that the observed radius inflation may be the result of a post-main-sequence evolutionary effect, although the spectral and kinematic properties of these stars are hardly compatible with 10–12 Myr old (Pop II) stars. It is more likely that the radius inflation is produced by the strong magnetic activity in these rapidly rotating stars, even if it is impossible to infer the actual total spot coverage, due to the age uncertainties.

Self-assembled properties of water cuboids

Although liquid water and ice are characterised by predominantly tetrahedral coordination, small water clusters often exhibit a cubic structural motif. In this article, the stability of hydrogen-bonded water nanostructures in the form of n 1×n 2×n 3 cuboids is investigated. The requirement for complete hydrogen bonding imposes a strong constraint on their structure. The equations of the donor–acceptor balance are derived, from which all possible forms of completely hydrogen-bonded cuboids are deduced. The flexible non-additive AMOEBA potential is used for geometric optimisation of the set of configurations with different directions of hydrogen (H-) bonds. It has been established that the majority of completely hydrogen-bonded structures are formed by one layer of fused cubes. The lowest energy configurations of the, in fact, bilayer structures are formed by trans-configurations of transverse pairs of molecules, although some H-bonds are broken in this case. It is noted that the structure of the cuboids may result from the assembly of short nanotubes and smaller cuboids. On the other hand, unrealised H-bonds at the corners of the cuboids make it possible to assemble larger bilayer structures.

Enhanced production of 60Fe in massive stars.

Massive stars are a major source of chemical elements in the cosmos, ejecting freshly produced nuclei through winds and core-collapse supernova explosions into the interstellar medium. Among the material ejected, long-lived radioisotopes, such as 60Fe (iron) and 26Al (aluminum), offer unique signs of active nucleosynthesis in our galaxy. There is a long-standing discrepancy between the observed 60Fe/26Al ratio by γ-ray telescopes and predictions from supernova models. This discrepancy has been attributed to uncertainties in the nuclear reaction networks producing 60Fe, and one reaction in particular, the neutron-capture on 59Fe. Here we present experimental results that provide a strong constraint on this reaction. We use these results to show that the production of 60Fe in massive stars is higher than previously thought, further increasing the discrepancy between observed and predicted 60Fe/26Al ratios. The persisting discrepancy can therefore not be attributed to nuclear uncertainties, and points to issues in massive-star models.

Large Eruptive and Confined Flares in Relation to the Solar Active Region Evolution

Solar active regions (ARs) provide the required magnetic energy and the topology configuration for flares. Apart from conventional static magnetic parameters, the evolution of AR magnetic flux systems should have nonnegligible effects on magnetic energy store and the trigger mechanism of eruptions, which would promote the prediction for the flare using photospheric observations conveniently. Here we investigate 322 large (M- and X-class) flares from 2010 to 2019, almost the whole solar cycle 24. The flare occurrence rate is obviously higher in the developing phase, which should be due to the stronger shearing and complex configurations caused by affluent magnetic emergences. However, the probability of flare eruptions in decaying phases of ARs is obviously higher than that in the developing phase. The confined flares were in nearly equal counts to eruptive flares in developing phases, whereas the eruptive flares were half over confined flares in decaying phases. Yearly looking at flare eruption rates demonstrates the same conclusion. The relationship between sunspot group areas and confined/erupted flares also suggested that the strong field make constraints on the mass ejection, though it can contribute to flare productions. The flare indexes also show a similar trend. It is worth mentioning that all the X-class flares in the decaying phase were erupted, without the strong field constraint. The decaying of magnetic flux systems had facilitation effects on flare eruptions, which may be consequent on the splitting of magnetic flux systems.

The inflated, eccentric warm Jupiter TOI-4914 b orbiting a metal-poor star, and the hot Jupiters TOI-2714 b and TOI-2981 b

Recent observations of giant planets have revealed unexpected bulk densities. Hot Jupiters, in particular, appear larger than expected for their masses compared to planetary evolution models, while warm Jupiters seem denser than expected. These differences are often attributed to the influence of the stellar incident flux, but it has been unclear if they also result from different planet formation processes, and if there is a trend linking the planetary density to the chemical composition of the host star. In this work, we present the confirmation of three giant planets in orbit around solar analogue stars. TOI-2714 b (P ≃ 2.5 d, Rp ≃ 1.22 RJ, Mp = 0.72 MJ) and TOI-2981 b (P ≃ 3.6 d, RP ≃ 1.2 RJ, MP = 2 MJ) are hot Jupiters on nearly circular orbits, while TOI-4914 b (P ≃ 10.6 d, RP ≃ 1.15 RJ, Mp = 0.72 MJ) is a warm Jupiter with a significant eccentricity (e = 0.41 ± 0.02) that orbits a star more metal-poor ([Fe/H] = −0.13) than most of the stars known to host giant planets. Similarly, TOI-2981 b orbits a metal-poor star ([Fe/H] = −0.11), while TOI-2714 b orbits a metal-rich star ([Fe/H] = 0.30). Our radial velocity follow-up with the HARPS spectrograph allows us to detect their Keplerian signals at high significance (7, 30, and 23σ, respectively) and to place a strong constraint on the eccentricity of TOI-4914 b (18σ). TOI-4914 b, with its large radius (Rp ≃ 1.15 RJ) and low insolation flux (F⋆ < 2 × 108 erg s−1 cm−2), appears to be more inflated than what is supported by current theoretical models for giant planets. Moreover, it does not conform to the previously noted trend that warm giant planets orbiting metal-poor stars have low eccentricities. This study thus provides insights into the diverse orbital characteristics and formation processes of giant exoplanets, in particular the role of stellar metallicity in the evolution of planetary systems.

Probing Populations of Dark Stellar Remnants in the Globular Clusters 47 Tuc and Terzan 5 Using Pulsar Timing

We present a new method to combine multimass equilibrium dynamical models and pulsar timing data to constrain the mass distribution and remnant populations of Milky Way globular clusters (GCs). We first apply this method to 47 Tuc, a cluster for which there exists an abundance of stellar kinematic data and which is also host to a large population of millisecond pulsars. We demonstrate that the pulsar timing data allow us to place strong constraints on the overall mass distribution and remnant populations even without fitting on stellar kinematics. Our models favor a small population of stellar-mass black holes (BHs) in this cluster (with a total mass of 446−72+75M⊙ ), arguing against the need for a large (>2000 M ⊙) central intermediate-mass BH. We then apply the method to Terzan 5, a heavily obscured bulge cluster that hosts the largest population of millisecond pulsars of any Milky Way GC and for which the collection of conventional stellar kinematic data is very limited. We improve existing constraints on the mass distribution and structural parameters of this cluster and place stringent constraints on its black hole content, finding an upper limit on the mass in BHs of ∼4000 M ⊙. This method allows us to probe the central dynamics of GCs even in the absence of stellar kinematic data and can be easily applied to other GCs with pulsar timing data, for which data sets will continue to grow with the next generation of radio telescopes.

Calcination-Controlled Synthesis of Carbon Dots@MgF2 Composites with Yellow, White, and Ultraviolet-Blue Thermally Activated Delayed Fluorescence for Multilevel Information Encryption.

It is attractive but challenging to develop carbon dot (CD) based materials with tunable thermally activated delayed fluorescence (TADF), especially in the long wavelength region. Here, by simply calcinating the mixture of m-phenylenediamine and MgF2 at 300-500 °C, a series of CDs@MgF2 composites exhibiting yellow, white, and ultraviolet-blue TADF with high photoluminescence quantum yields of up to 37.6% are prepared. Photophysical studies reveal that the yellow TADF with long lifetimes of 810-1106ms originates from the surface emission centers of CDs, while the ultraviolet-blue TADF with short lifetimes of 266-379ms is related to the carbon core emission centers. The combination of yellow and ultraviolet-blue TADF in a single material triggers dynamic afterglow with time-dependent colors from white to yellow. The MgF2 matrix offers multiple confinement of CDs through a rigid network, strong space constraint, and robust covalent/hydrogen bonding, thus preventing the triplet excitations from non-radiative transitions. The electron-withdrawing fluorine atoms induce substantial spin-orbit coupling and reduce the singlet-triplet energy gap, consequently facilitating the reverse intersystem crossing to enhance TADF efficiency. Importantly, the CDs@MgF2 composites possess outstanding optical stability against water, organic solvents, strong acids, bases, and oxidants. The fascinating TADF features enable the successful demonstration of multilevel information encryption using CDs@MgF2.

No Thick Atmosphere on the Terrestrial Exoplanet Gl 486b

A primary science goal for JWST is to detect and characterize the atmospheres of terrestrial planets orbiting M dwarfs (M-Earths). The existence of atmospheres on M-Earths is highly uncertain because their host stars’ extended history of high X-ray and ultraviolet irradiation may act to completely remove their atmospheres. We present two JWST secondary eclipse observations of the M-Earth Gl 486b (also known as GJ 486b) between 5 and 12 μm. We combined these observations with a precise analysis of the host star parameters to derive a planetary dayside temperature of T p = 865 ± 14 K. We compared this temperature to the maximum expected temperature for a zero albedo, zero heat redistribution bare rock and derived a temperature ratio of R=Tp,daysideTp,max=0.97±0.01 . This value is consistent with an airless body with a slight nonzero albedo or a thin atmosphere with <1% H2O or <1 ppm CO2. However, it is inconsistent with an Earth- or Venus-like atmosphere, and the spectrum shows no clear emission or absorption features. Additionally, our observations are inconsistent with the water-rich atmospheric scenario allowed by previous transit observations and suggest the transmission spectrum was instead shaped by stellar contamination. Given the potential for atmospheric escape throughout the system’s ≥6.6 Gyr lifetime, we conclude that the observations are likely best explained by an airless planet. This result is the most precise measurement yet of terrestrial exoplanet thermal emission with JWST, which places a strong constraint on the position of the “cosmic shoreline” between airless bodies and those with atmospheres.

Higgs-portal spin-1 dark matter with parity-violating interaction

We introduce the spin-1 U(1)X gauged field X with Z2 odd dark parity to evade the current strong constraints on kinetic mixing. Then, X becomes stable and a candidate for the dark matter. The lowest mass dimension of interaction is six, and the type is the Higgs portal. Two types of dim-6 operators are introduced. We consider the freeze-out dark matter scenario. With the limit of null momentum transfer, a parity odd operator is free from the direct detection constraints. Accordingly, the strong constraints on a parity even operator indicate turning on this parity odd operator to realize the dark matter relic density of the Universe. With the 1 TeV cut-off scale, our dark matter of around 400 GeV mass can explain the dark matter relic density and is allowed from the LUX-ZEPLIN experiment of the direct detection.

Is stochastic thermodynamics the key to understanding the energy costs of computation?

The relationship between the thermodynamic and computational properties of physical systems has been a major theoretical interest since at least the 19th century. It has also become of increasing practical importance over the last half-century as the energetic cost of digital devices has exploded. Importantly, real-world computers obey multiple physical constraints on how they work, which affects their thermodynamic properties. Moreover, many of these constraints apply to both naturally occurring computers, like brains or Eukaryotic cells, and digital systems. Most obviously, all such systems must finish their computation quickly, using as few degrees of freedom as possible. This means that they operate far from thermal equilibrium. Furthermore, many computers, both digital and biological, are modular, hierarchical systems with strong constraints on the connectivity among their subsystems. Yet another example is that to simplify their design, digital computers are required to be periodic processes governed by a global clock. None of these constraints were considered in 20th-century analyses of the thermodynamics of computation. The new field of stochastic thermodynamics provides formal tools for analyzing systems subject to all of these constraints. We argue here that these tools may help us understand at a far deeper level just how the fundamental thermodynamic properties of physical systems are related to the computation they perform.

Multi-wavelength observations of the luminous fast blue optical transient AT2023fhn. Up to ∼200 days post-explosion

Luminous fast blue optical transients (LFBOTs) are a class of extragalactic transients notable for their rapid rise and fade times, blue colour, and accompanying luminous X-ray and radio emission. Only a handful have been studied in detail since the prototypical example AT\,2018cow. Their origins are currently unknown, but ongoing observations of previous and new events are placing ever stronger constraints on their progenitors. We aim to put further constraints on the LFBOT AT\,2023fhn, and LFBOTs as a class, using information from the multi-wavelength transient light curve, its host galaxy, and local environment. Our primary results were obtained by fitting galaxy models to the spectral energy distribution of AT\,2023fhn's host and local environment, and by modelling the radio light curve of AT\,2023fhn as due to synchrotron self-absorbed emission from an expanding blast wave in the circumstellar medium. We find that neither the host galaxy nor circumstellar environment of AT\,2023fhn are unusual compared with previous LFBOTs, but that AT\,2023fhn has a much lower X-ray to ultraviolet luminosity ratio than previous events. We argue that the variety in ultraviolet-optical to X-ray luminosity ratios among LFBOTs is likely due to viewing angle differences, and that the diffuse, yet young local environment of AT\,2023fhn - combined with a similar circumstellar medium to previous events - favours a progenitor system containing a massive star with strong winds. Plausible progenitor models in this interpretation therefore include the mergers of black holes and Wolf-Rayet stars or failed supernovae.

Black hole-neutron star mergers in Einstein-scalar-Gauss-Bonnet gravity

Gravitational wave observations of black hole-neutron star binaries, particularly those where the black hole has a lower mass compared to other observed systems, have the potential to place strong constraints on modifications to general relativity that arise at small curvature length scales. Here we study the dynamics of black hole-neutron star mergers in shift-symmetric Einstein-scalar-Gauss-Bonnet gravity, a representative example of such a theory, by numerically evolving the full equations of motion. We consider quasi-circular binaries with different mass-ratios that are consistent with recent gravitational wave observations, including cases with and without tidal disruption of the star, and quantify the impact of varying the coupling controlling deviations from general relativity on the gravitational wave signal and scalar radiation. We find that the main effect on the late inspiral is the accelerated frequency evolution compared to general relativity, and that—even considering Gauss-Bonnet coupling values approaching those where the theory breaks down—the impact on the merger gravitational wave signal is mild, predominately manifesting as a small change in the amplitude of the ringdown. We compare our results to current post-Newtonian calculations and find consistency throughout the inspiral. Published by the American Physical Society 2024

Theoretical constraints on models with vectorlike fermions

We provide a set of theoretical constraints on models in which the Standard Model field content is extended by vectorlike fermions and in some cases also by a real scalar singlet. Our approach is based on the study of electroweak vacuum stability, perturbativity of model couplings, and gauge couplings unification with the use of renormalization group equations. We show that careful analysis of these issues leads to strong constraints on the parameter space of the considered models. This, in turn, has important implications for phenomenology, as we show using examples of the double Higgs boson production, electroweak precision observables, and the electroweak phase transition. Published by the American Physical Society 2024

Reconciling concentration to virial mass relations

The concentration--virial mass (c-M) relation is a fundamental scaling relation within the standard cold dark matter (Lambda CDM) framework well established in numerical simulations. However, observational constraints of this relation are hampered by the difficulty of characterising the properties of dark matter haloes. Recent comparisons between simulations and observations have suggested a systematic difference of the c-M relation, with higher concentrations in the latter. In this work, we undertake detailed comparisons between simulated galaxies and observations of a sample of strong-lensing galaxies. We explore several factors of the comparison with strong gravitational lensing constraints, including the choice of the generic dark matter density profile, the effect of radial resolution, the reconstruction limits of observed versus simulated mass profiles, and the role of the initial mass function in the derivation of the dark matter parameters. Furthermore, we show the dependence of the c-M relation on reconstruction and model errors through a detailed comparison of real and simulated gravitational lensing systems. An effective reconciliation of simulated and observed c-M relations can be achieved if one considers less strict assumptions on the dark matter profile, for example, by changing the slope of a generic NFW profile or focusing on rather extreme combinations of stellar-to-dark matter distributions. A minor effect is inherent to the applied method: fits to the NFW profile on a less well-constrained inner mass profile yield slightly higher concentrations and lower virial masses.

Designing Robust Single Atom Catalysts by Three-in-One Strategy: Sub-1-nm Space Confining, Bimetallic Bonding and Reaction-Induced Forming Active Sites.

It is imperative to design robust single atom catalysts (SACs) that maintain the stability of the active component under diverse reaction conditions and prevent aggregation or deactivation. Confining the single atom active site within sub-nanometer (sub-1-nm) spaces has proven effective in enhancing the stability and activity of the catalyst, owing to the strong constraints and regulations imposed on atomic behavior at this scale. Bimetallic bond atomic sites, comprising two distinct metal compositions, often exhibit unique electronic structures and catalytic properties. Designing SACs under reaction-induced conditions, such as varying temperatures, pressures, and atmospheres, can facilitate a deeper understanding of the formation and migration behavior of active sites in real reactions, as well as the optimization mechanisms for performance enhancement. The objective of this review is to promote a robust SAC design strategy that encapsulates bimetallic bonding active sites within sub-1-nm spaces and investigates catalyst preparation and performance under reaction-induced conditions. This design strategy is anticipated to bolster the catalytic activity and stability of the catalyst while also offering fresh perspectives and optimization avenues for the catalytic processes involved in practical chemical reactions.

An adaptive snow ablation-inspired particle swarm optimization with its application in geometric optimization

In response to the shortcomings of particle swarm optimization (PSO), such as low execution efficiency and difficulty in overcoming local optima, this paper proposes a multi-strategy PSO method incorporating snow ablation operation (SAO), known as SAO-MPSO. Firstly, Cubic initialization is performed on particles to obtain a good initial environment. Subsequently, SAO and PSO are combined in parallel, and a balanced search mechanism led by multiple sub-populations is devised, significantly improving the search efficiency of overall population. Finally, the degree day method of SAO is introduced, and particles are endowed with memory of environmental changes to prevent premature convergence of PSO, while balancing the exploration and exploitation (ENE) capabilities in later phases. All adaptive parameters are used throughout this method in place of fixed parameters to improve the robustness and adaptability. For a comprehensive analysis of SAO-MPSO, its good ENE ability is verified on CEC 2020 and CEC 2022 and this method is compared with existing improved PSO versions on both test sets. The results show that SAO-MPSO has certain advantages in the comparison of similar improved algorithms. In order to further validate the strength of SAO-MPSO in dealing with nonlinear optimization problems (OPs) with strong constraints, firstly, based on the ball Wang-Ball (BWB) curve, a combined BWB (CBWB) curve is constructed, and a construction method for CBWB curves that satisfy G1 and G2 continuity is derived. Then, with the energy minimization and scale parameters of the CBWB curve as the optimization objective and variables respectively, a shape optimization model that satisfies G2 continuity is established. Finally, three numerical optimization examples based on this model are solved using SAO-MPSO and compared with 10 other methods. The results show that the energy obtained by SAO-MPSO is the smallest, which verifies the effectiveness of this method applied to shape OPs of CBWB curve.

Constraints on dark matter from dynamical heating of stars in ultrafaint dwarfs. I. MACHOs and primordial black holes

We place limits on dark matter made up of compact objects significantly heavier than a solar mass, such as MACHOs or primordial black holes (PBHs). In galaxies, the gas of such objects is generally hotter than the gas of stars and will thus heat the gas of stars even through purely gravitational interactions. Ultrafaint dwarf galaxies (UFDs) maximize this effect. Observations of the half-light radius in UFDs thus place limits on MACHO dark matter. We build upon previous constraints with an improved heating rate calculation including both direct and tidal heating, and consideration of the heavier mass range above 104M⊙. Additionally we find that MACHOs may lose energy and migrate in to the center of the UFD, increasing the heat transfer to the stars. UFDs can constrain MACHO dark matter with masses between about 10M⊙ and 108M⊙ and these are the strongest constraints over most of this range. Published by the American Physical Society 2024

"Timely help" or "one disaster after another": The impact of potential and transition interim CEO succession on corporate performance.

The succession mode of interim CEO is highly uncertain. The smooth transition function of interim CEO is particularly important in the process of enterprise reform. We divide interim CEOs into potential successors and transition successors. Then we empirically analyze the heterogeneous impact and mechanism of interim CEOs on firm performance. The results show that compared with transition CEO, potential CEO has less negative impact on corporate performance. Interim CEO has a negative impact on enterprise performance by reducing agency efficiency. The mechanism analysis of this paper are as follows. For the potential CEO, strong incentive constraints can effectively mitigate the negative impact of the succession on corporate performance. For a transitional CEO, superior personal capabilities coupled with an effective oversight mechanism represent more optimal solutions. In today's corporate landscape, the frequencies of executive changes and interim successions are on the rise annually. Our research is tailored to aid enterprises in navigating these transitions seamlessly and in expediting their recovery processes.

Can agricultural water rights trading promote intensive and economical utilization of water resources in China based on the difference-in-differences model?

IntroductionImproving the level of intensive and economical utilization of water resources is an important step towards water and food security.MethodsBased on China’s provincial panel data from 2015 to 2021, this study uses a difference-in-differences (DID) model to examine the effect of agricultural water rights trading on intensive and economical utilization of water resources.ResultsThe results show that agricultural water rights trading can significantly promote an intensive and economical utilization of water resources at the 1% level, and the results remain valid even after a series of robustness tests. Further analysis indicates that agricultural water rights trading can promote better utilization of water resources by significantly reducing agricultural water consumption at the 1% level and reducing the proportion of agricultural water consumption at the 5% level to optimize water use structure. Moreover, in regions with scarce water resources, strong water resource constraints, more farmland water conservancy projects, and greater economic development, the promoting effect of agricultural water rights trading on the intensive and economical use of water resources is more significant.DiscussionThis study provides evidence of the impact of China’s agricultural water rights trading policy and offers new ideas and experiences to improve China’s water resource utilization efficiency. The contributions of this work are mainly threefold. First, this paper clearly distinguishes the intensive conservation of water resources, presents an evaluation index system, and complements the existing literature on measuring the intensive and economical utilization of water resources. Second, the path of agricultural water rights trading is analyzed to improve the level of intensive and economical utilization of water resources, thus enriching related research on transmission mechanisms. Third, the heterogeneity of the influence of different regional conditions on the level of intensive and economical utilization of water resources is discussed to improve relevant policies.

A 17 MeV pseudoscalar and the LSND, MiniBooNE and ATOMKI anomalies

In the absence of any new physics signals at the Large Hadron Collider (LHC), anomalous results at low energy experiments have become the subject of increased attention. We focus on three such results from the LSND, MiniBooNE (MB), and ATOMKI experiments. A 17 MeV pseudoscalar mediator (a′) can account for two (8Be and 4He) out of the three cases in which excess events have been seen in pair creation transitions in ATOMKI. We incorporate this mediator in a gauge invariant extension of the Standard Model (SM) with a second Higgs doublet and three singlet (seesaw) neutrinos (Ni, i = 1, 2, 3). N1,2 participate in an interaction in MB and LSND which, with a′ as mediator, leads to the production of e+e− pairs. The Ni also lead to mass-squared differences for SM neutrinos in agreement with global oscillation data. We first show that such a model offers a natural joint solution to the MB and LSND excesses, providing excellent fits to their data. Next, using the values of the couplings to the quarks and electrons which are required to explain pair creation nuclear transition data for 8Be and 4He in ATOMKI, we show that these values still lead to fits for MB and LSND data. However, once ATOMKI is incorporated, we find that strong constraints from the decays K+ → π+a′ (a′ → e+e−) and π+ → e+νee+e− come into play. While our solution is in conformity with the bounds on the former decay, it remains in tension with 90% CL bounds on the latter. We also discuss other constraints from both collider and non-collider experiments and from electroweak precision data, stability and unitarity. We compute the contributions to the electron and muon g – 2 up to two loops for our model. We discuss tests of the model in upcoming experiments.