Search

We explore the effect of neutron lifetime and its uncertainty on standard big bang nucleosynthesis (BBN). BBN describes the cosmic production of the light nuclides, 1 H , D, 3 H + 3 He , 4 He , and 7 Li + 7 Be , in the first minutes of cosmic time. The neutron mean life τ n has two roles in modern BBN calculations: (1) it normalizes the matrix element for weak n ↔ p interconversions, and (2) it sets the rate of free neutron decay after the weak interactions freeze-out. We review the history of the interplay between τ n measurements and BBN, and present a study of the sensitivity of the light element abundances to the modern neutron lifetime measurements. We find that τ n uncertainties dominate the predicted 4 He error budget, but these theory errors remain smaller than the uncertainties in 4 He observations, even with the dispersion in recent neutron lifetime measurements. For the other light element predictions, τ n contributes negligibly to their error budget. Turning the problem around, we combine present BBN and cosmic microwave background (CMB) determinations of the cosmic baryon density to predict a "cosmologically preferred" mean life of τ n (BBN + CMB) = 870 ± 16 s , which is consistent with experimental mean life determinations. We show that if future astronomical and cosmological helium observations can reach an uncertainty of σ obs (Y p) = 0.001 in the 4 He mass fraction Y p , this could begin to discriminate between the mean life determinations. [ABSTRACT FROM AUTHOR]

We revisit the viability of the CMSSM, searching for regions of parameter space that yield a neutralino dark matter density compatible with Planck measurements, as well as LHC constraints including sparticle searches and the mass of the Higgs boson, recent direct limits on spin-independent and -dependent dark matter scattering from the LUX-ZEPLIN (LZ) experiment, the indirect constraints from Fermi-LAT and H.E.S.S. on dark matter annihilations to photons in dwarf spheroidal galaxies and the Galactic Centre, and the IceCube limits on muons from annihilations to neutrinos in the Sun. For representative values of tan β and A 0 we map in detail the Planck-compatible strips in CMSSM parameter planes, which exhibit multiple distinctive features for large tan β , A 0 = 0 and μ > 0 , and identify portions of the strips that survive all the phenomenological constraints. We find that the most powerful constraint is that from m h , followed by the LZ limit on spin-independent scattering, whereas sparticle searches at the LHC and indirect dark matter searches are less restrictive. Most of the surviving CMSSM parameter space features a Higgsino-like dark matter particle with a mass ∼ 1000 - 1100 GeV, which could best be probed with future direct searches for dark matter scattering. [ABSTRACT FROM AUTHOR]

The abundance of magnesium in the interstellar medium is a powerful probe of star formation processes over cosmological time-scales. Magnesium has three stable isotopes, 24Mg, 25Mg, and 26Mg, which can be produced in both massive and intermediate-mass (IM) stars with masses between 2 and 8 M⊙. In this work, we use constraints on the cosmic star formation rate density (SFRD) and explore the role and mass range of IM stars using the observed isotopic ratios. We compare several models of stellar nucleosynthesis with metallicity-dependent yields and also consider the effect of rotation on the yields of massive stars and its consequences on the evolution of the Mg isotopes. We use a cosmic evolution model updated with new observational SFRD data and new reionization constraints coming from 2018 Planck Collaboration determinations. We find that the main contribution of 24Mg comes from massive stars whereas 25Mg and 26Mg come from IM stars. To fit the observational data on magnesium isotopic ratios, an additional IM SFRD component is preferred. Moreover, the agreement between model and data is further improved when the range of IM masses is narrowed towards higher masses (5–8 M⊙). While some rotation also improves the fit to data, we can exclude the case where all stars have high rotational velocities due to an overproduction of 26Mg. [ABSTRACT FROM AUTHOR]

Electroweak loop corrections to the matrix elements for the spin-independent scattering of cold dark matter particles on nuclei are generally small, typically below the uncertainty in the local density of cold dark matter. However, as shown in this paper, there are instances in which the electroweak loop corrections are relatively large, and change significantly the spin-independent dark matter scattering rate. An important example occurs when the dark matter particle is a wino, e.g., in anomaly-mediated supersymmetry breaking (AMSB) and pure gravity mediation (PGM) models. We find that the one-loop electroweak corrections to the spin-independent wino LSP scattering cross section generally interfere constructively with the tree-level contribution for AMSB models with negative Higgsino mixing, μ < 0 , and in PGM-like models for both signs of μ , lifting the cross section out of the neutrino fog and into a range that is potentially detectable in the next generation of direct searches for cold dark matter scattering. [ABSTRACT FROM AUTHOR]

After the results of Run I, can we still 'guarantee' the discovery of supersymmetry at the LHC? It is shown that viable dark matter candidates in CMSSM-like models tend to lie in strips (coannihilation, funnel, focus point) in parameter space. The role of grand unification in constructing supersymmetric models is discussed and it is argued that nonsupersymmetric GUTs such as SO(10) may provide alternative solutions to many of the standard problems addressed by supersymmetry. [ABSTRACT FROM AUTHOR]

Recent observations in the total luminosity density have led to significant progress in establishing the star formation rate (SFR) at high redshift. Concurrently observed gamma-ray burst rates have also been used to extract the SFR at high redshift. The SFR in turn can be used to make a host of predictions concerning the ionization history of the Universe, the chemical abundances, and supernova rates. We compare the predictions made using a hierarchical model of cosmic chemical evolution based on three recently proposed SFRs: two based on extracting the SFR from the observed gamma-ray burst rate at high redshift, and one based on the observed galaxy luminosity function at high redshift. Using the WMAP/Planck data on the optical depth and epoch of reionization, we find that only the SFR inferred from gamma-ray burst data at high redshift suffices to allow a single mode (in the initial mass function – IMF) of star formation which extends from z = 0 to redshifts >10. For the case of the SFR based on the observed galaxy luminosity function, the reionization history of the Universe requires a bimodal IMF which includes at least a coeval high- (or intermediate-) mass mode of star formation at high redshift (z > 10). Therefore, we also consider here a more general bimodal case which includes an early-forming high-mass mode as a fourth model to test the chemical history of the Universe. We conclude that observational constraints on the global metallicity and optical depth at high redshift favour unseen faint but active star-forming galaxies as pointed out in many recent studies. [ABSTRACT FROM AUTHOR]

We revisit the calculation of the electron, neutron, and proton electric dipole moments (EDMs) in the constrained minimal supersymmetric standard model (CMSSM). The relatively large mass of the Higgs boson, mH ≃ 125 GeV coupled with the (as yet) lack of discovery of any supersymmetric particle at the LHC, has pushed the supersymmetry breaking scale to several TeV or higher. Though one might expect this decoupling to have relaxed completely any bounds on the two CP violating phases in the CMSSM (θμ and θA), the impressive experimental improvements in the limits on the EDMs (particularly the electron EDM) still allow us to set constraints of order (0.01−0.1)π on θA and (0.001−0.1)π on θμ. We also discuss the impact of future improvements in the experimental limits on supersymmetric models. [ABSTRACT FROM AUTHOR]

Many supersymmetric models such as the constrained minimal supersymmetric extension of the Standard Model (CMSSM) feature a strip in parameter space where the lightest neutralino $$\chi $$ is identified as the lightest supersymmetric particle, the lighter stop squark $${\tilde{t}_1}$$ is the next-to-lightest supersymmetric particle (NLSP), and the relic $$\chi $$ cold dark matter density is brought into the range allowed by astrophysics and cosmology by coannihilation with the lighter stop squark $${\tilde{t}_1}$$ NLSP. We calculate the stop coannihilation strip in the CMSSM, incorporating Sommerfeld enhancement effects, and we explore the relevant phenomenological constraints and phenomenological signatures. In particular, we show that the $${\tilde{t}_1}$$ may weigh several TeV, and its lifetime may be in the nanosecond range, features that are more general than the specific CMSSM scenarios that we study in this paper. [ABSTRACT FROM AUTHOR]

We study a new mechanism for the production of dark matter in the Universe which does not rely on thermal equilibrium. Dark matter is populated from the thermal bath subsequent to inflationary reheating via a massive mediator whose mass is above the reheating scale TRH. To this end, we consider models with an extra U(1) gauge symmetry broken at some intermediate scale (Mint ≃ 1010-1012 GeV). We show that not only does the model allow for gauge coupling unification (at a higher scale associated with grand unification) but it can provide a dark matter candidate which is a standard model singlet but charged under the extra U(1). The intermediate scale gauge boson(s) which are predicted in several E6/SO(10) constructions can be a natural mediator between dark matter and the thermal bath. We show that the dark matter abundance, while never having achieved thermal equilibrium, is fixed shortly after the reheating epoch by the relation TRH³/Mint4. As a consequence, we show that the unification of gauge couplings which determines Mint also fixes the reheating temperature, which can be as high as TRH ≃ 1011 GeV. [ABSTRACT FROM AUTHOR]

ABSTRACT Standard big bang nucleosynthesis (BBN) at the baryon density determined by the microwave anisotropy spectrum predicts an excess of 7Li compared to observations by a factor of 4-5. In contrast, BBN predictions for D/H are somewhat below (but within 2σ of) the weighted mean of observationally determined values from quasar absorption systems. Solutions to the 7Li problem which alter the nuclear processes during or subsequent to BBN often lead to a significant increase in the deuterium abundance consistent with the highest values of D/H seen in absorption systems. Furthermore, the observed D/H abundances show considerable dispersion. Here, we argue that those systems with D/H ≃ 4 × 10−5 may be more representative of the primordial abundance and as a consequence, those systems with lower D/H would necessarily have been subject to local processes of deuterium destruction. This can be accounted for by models of cosmic chemical evolution able to destroy in situ deuterium due to the fragility of this isotope. [ABSTRACT FROM AUTHOR]

Taking into account the available accelerator and astrophysical constraints, the mass of the lightest neutral Higgs boson h in the minimal supersymmetric extension of the Standard Model with universal soft supersymmetry-breaking masses (CMSSM) has been estimated to lie between 114 and ~130 GeV. Recent data from ATLAS and CMS hint that mh ~ 125 GeV, though mh ~ 119 GeV may still be a possibility. Here we study the consequences for the parameters of the CMSSM and direct dark matter detection if the Higgs hint is confirmed, focusing on the strips in the (m1/2,m0) planes for different tan β and A0 where the relic density of the lightest neutralino ? falls within the range of the cosmological cold dark matter density allowed by WMAP and other experiments. We find that if mh ~ 125 GeV focus-point strips would be disfavoured, as would the low-tan β ῖ-? and t~1-? coannihilation strips, whereas the ῖ-? coannihilation strip at large tan β and A0 > 0 would be favoured, together with its extension to a funnel where rapid annihilation via direct-channel H/A poles dominates. On the other hand, if mh ~ 119 GeV more options would be open. We give parameterisations of WMAP strips with large tan β and fixed A0/m0 > 0 that include portions compatible with mh = 125 GeV, and present predictions for spin-independent elastic dark matter scattering along these strips. These are generally low for models compatible with mh = 125 GeV, whereas the XENON100 experiment already excludes some portions of strips where mh is smaller. [ABSTRACT FROM AUTHOR]

In many theories of unified interactions, there are additional degrees of freedom that may allow for the variation of the fundamental constants of nature. I will review the motivation for and theoretical relations between such variations. I will then review the various astrophysical and experimental constraints on the variations of constants and their dependence on spectroscopic data. [ABSTRACT FROM AUTHOR]

Dark matter in variations of constrained minimal supersymmetric standard models will be discussed. Particular attention will be given to the comparison between accelerator and direct detection constraints. [ABSTRACT FROM AUTHOR]

Abstract: The nature and identity of the dark matter of the Universe is one of the most challenging problems facing modern cosmology. Only 5% of the energy density of the Universe can be associated with known forms of matter. Problems for baryonic and neutrino dark matter imply the necessity to search beyond the standard model for dark matter candidates. Emphasis is placed on the prospects for supersymmetric dark matter. [Copyright &y& Elsevier]

Abstract: We consider the possibility that the soft supersymmetry-breaking parameters and of the MSSM are universal at some scale below the supersymmetric grand unification scale , as might occur in scenarios where either the primordial supersymmetry-breaking mechanism or its communication to the observable sector involve a dynamical scale below . We analyze the planes of such sub-GUT CMSSM models, noting the dependences of phenomenological, experimental and cosmological constraints on . In particular, we find that the coannihilation, focus-point and rapid-annihilation funnel regions of the GUT-scale CMSSM approach and merge when . We discuss sparticle spectra and the possible sensitivity of LHC measurements to the value of . [Copyright &y& Elsevier]

Abstract: We present an overview of the standard model of big bang nucleosynthesis (BBN), which describes the production of the light elements in the early universe. The theoretical prediction for the abundances of D, 3He, 4He, and 7Li is discussed. We emphasize the role of key nuclear reactions and the methods by which experimental cross section uncertainties are propagated into uncertainties in the predicted abundances. The observational determination of the light nuclides is also discussed. Particular attention is given to the comparison between the predicted and observed abundances, which yields a measurement of the cosmic baryon content. The spectrum of anisotropies in the cosmic microwave background (CMB) now independently measures the baryon density to high precision; we show how the CMB data test BBN, and find that the CMB and the D and 4He observations paint a consistent picture. This concordance stands as a major success of the hot big bang. On the other hand, 7Li remains discrepant with the CMB-preferred baryon density; possible explanations are reviewed. Finally, moving beyond the standard model, primordial nucleosynthesis constraints on early universe and particle physics are also briefly discussed. [Copyright &y& Elsevier]

Abstract: We discuss the interpretation of present and possible future experimental constraints on decay in the context of the constrained minimal extension of the Standard Model (CMSSM) with universal scalar masses. We emphasize the importance of including theoretical and other experimental uncertainties in calculating the likelihood function, which can affect significantly the inferred 95% confidence-level limit on the CMSSM parameters. The principal uncertainties are the meson decay constant, and . The latter induce uncertainties in the mass of the neutral Higgs boson that dominates the decay amplitude at large , reducing the CMSSM region excluded by present and possible future limits from the Fermilab Tevatron collider and the LHC. [Copyright &y& Elsevier]

Abstract: We reconsider the effects of the radiation from the decays of unstable particles on the production and destruction of the primordial light elements, with a view to reconciling the high primordial 7Li abundance deduced from big bang nucleosynthesis (BBN), as implied by the baryon-to-photon ratio now inferred from the anisotropies of the cosmic microwave background (CMB), with the lower abundance of 7Li observed in halo stars. The potential destruction of 7Li is strongly constrained by observations of deuterium (D), 3He and 6Li. We identify ranges for the unstable particle abundance and lifetime which would deplete 7Li while remaining consistent with the abundance of 6Li. However, in these regions either the D abundance is unacceptably low or the ratio 3He/D is unacceptably large. We conclude that late particle decay is unable to explain both the discrepancy of the calculated 7Li abundance and the observed 7Li plateau. In the context of supersymmetric theories with neutralino or gravitino dark matter, we display the corresponding light-element constraints on the model parameters. [Copyright &y& Elsevier]

Abstract: We discuss the prospects for detecting supersymmetric particles in variants of the minimal supersymmetric extension of the Standard Model (MSSM), in light of laboratory and cosmological constraints. We first assume that the lightest supersymmetric particle (LSP) is the lightest neutralino χ, and present scatter plots of the masses of the two lightest visible supersymmetric particles when the input scalar and gaugino masses are constrained to be universal (CMSSM), when the input Higgs scalar masses are non-universal (NUHM), and when the squark and slepton masses are also non-universal and the MSSM is regarded as a low-energy effective field theory valid up to the GUT scale (LEEST) or just up to 10 TeV (LEEST10). We then present similar plots in various scenarios when the LSP is the gravitino. We compare the prospects for detecting supersymmetry at linear colliders (LCs) of various energies, at the LHC, and as astrophysical dark matter. We find that, whilst a LC with a centre-of-mass energy has some chance of discovering the lightest and next-to-lightest visible supersymmetric particles, would be required to ‘guarantee’ finding supersymmetry in the neutralino LSP scenarios studied, and an even higher might be required in certain gravitino dark matter scenarios. Direct dark matter experiments could explore part of the low-mass neutralino LSP region, but would not reveal all the models accessible to a low-energy LC. [Copyright &y& Elsevier]

Examines whether the fundamental parameters in physics are truly constant. Quantities usually assumed to be constant that could potentially vary; History of time-varying constants; Details of the theory of Big Bang nucleosynthesis.

We consider the possibility that the gravitino might be the lightest supersymmetric particle (LSP) in the constrained minimal extension of the Standard Model (CMSSM). In this case, the next-to-lightest supersymmetric particle (NSP) would be unstable, with an abundance constrained by the concordance between the observed light-element abundances and those calculated on the basis of the baryon-to-entropy ratio determined using CMB data. We modify and extend previous CMSSM relic neutralino calculations to evaluate the NSP density, also in the case that the NSP is the lighter stau, and show that the constraint from late NSP decays is respected only in a limited region of the CMSSM parameter space. In this region, gravitinos might constitute the dark matter. [Copyright &y& Elsevier]

Specific models of supersymmetry breaking predict relations between the trilinear and bilinear soft supersymmetry breaking parameters A0 and B0 at the input scale. In such models, the value of tanβ can be calculated as a function of the scalar masses m0 and the gaugino masses m1/2, which we assume to be universal. The experimental constraints on sparticle and Higgs masses, b→sγ decay and the cold dark matter density ΩCDMh2 can then be used to constrain tanβ in such specific models of supersymmetry breaking. In the simplest Polonyi model with A0=(3-√ of 3 )m0=B0+m0, we find 11≲tanβ≲20 (tanβ=4.15) for μ>0 (μ<0). We also discuss other models with A0=B0+m0, finding that only the range -1.9≲A0/m0≲2.5 is allowed for μ>0, and the range 1.25≲A0/m0≲4.8 for μ<0. In these models, we find no solutions in the rapid-annihilation ‘funnels’ or in the ‘focus-point’ region. We also discuss the allowed range of tanβ in the no-scale model with A0=B0=0. In all these models, most of the allowed regions are in the χ-τ1 coannihilation ‘tail’. [Copyright &y& Elsevier]

We re-examine the parameter space of the constrained minimal supersymmetric extension of the Standard Model (CMSSM), taking account of the restricted range of ΩCDMh2 consistent with the WMAP data. This provides a significantly reduced upper limit on the mass of the lightest supersymmetric particle LSP: mχ≲500 GeV for tanβ≲45 and μ>0, or tanβ≲30 and μ<0, thereby improving the prospects for measuring supersymmetry at the LHC, and increasing the likelihood that a 1-TeV linear e+e- collider would be able to measure the properties of some supersymmetric particles. [Copyright &y& Elsevier]

We present detailed calculations of the χ˜t˜1 coannihilation channels that have the largest impact on the relic χ˜ density in the constrained minimal supersymmetric extension of the Standard Model (CMSSM), in which scalar masses m0, gaugino masses m1/2 and the trilinear soft supersymmetry-breaking parameters A0 are each assumed to be universal at some input grand unification scale. The most important t˜1t˜1&ast; and t˜1t˜1 annihilation channels are also calculated, as well as t˜1ℓ˜ coannihilation channels. We illustrate the importance of these new coannihilation calculations when A0 is relatively large. While they do not increase the range of m1/2 and hence mχ allowed by cosmology, these coannihilation channels do open up new ‘tails’ of parameter space extending to larger values of m0. [Copyright &y& Elsevier]

Without assuming that Higgs masses have the same values as other scalar masses at the input GUT scale, we combine constraints on the minimal supersymmetric extension of the Standard Model (MSSM) coming from the cold dark matter density with the limits from direct searches at accelerators such as LEP, indirect measurements such as b→sγ decay and the anomalous magnetic moment of the muon. The requirement that Higgs masses-squared be positive at the GUT scale imposes important restrictions on the MSSM parameter space, as does the requirement that the LSP be neutral. We analyze the interplay of these constraints in the (μ,mA), (μ,m1/2), (m1/2,m0) and (mA,tanβ) planes. These exhibit new features not seen in the corresponding planes in the constrained MSSM in which universality is extended to Higgs masses. [Copyright &y& Elsevier]

We derive a general formalism for constructing a four-dimensional effective action for the radion field in 5 dimensions, taking into account the possible dependence of the scale factor on the internal coordinate. First and second variations of the action with respect to the size of the extra dimension reveals two types of algebraic constraints on the combination of brane and bulk Lagrangians that extremize the action, and provide an effective mass for the radion field. We derive a compact formula for the radion mass squared in terms of brane and bulk potentials for the case of a bulk scalar field. We further specialize these constraints for several, five-dimensional realizations of brane world models. [Copyright &y& Elsevier]

We consider the decay of the inflaton in Starobinsky-like models arising from either an R + R 2 theory of gravity or N = 1 no-scale supergravity models. If Standard Model matter is simply introduced to the R + R 2 theory, the inflaton (which appears when the theory is conformally transformed into the Einstein frame) couples to matter predominantly in Standard Model Higgs kinetic terms. This will typically lead to a reheating temperature of ∼3 × 10 9 GeV. However, if the Standard Model Higgs is conformally coupled to curvature, the decay rate may be suppressed and vanishes for conformal coupling ξ = 1 / 6 . Nevertheless, the inflaton decays through the conformal anomaly, leading to a reheating temperature of the order of 10 8 GeV. The Starobinsky potential may also arise in no-scale supergravity. In this case, the inflaton decays if there is a direct coupling of the inflaton to matter in the superpotential or to gauge fields through the gauge kinetic function. We also discuss the relation between the theories and demonstrate the correspondence between the no-scale models and the conformally coupled R + R 2 theory (with ξ = 1 / 6 ). [ABSTRACT FROM AUTHOR]

Discusses astrophysical 7Li as a product of Big Bang nucleosynthesis and galactic cosmic-ray spallation. Abundances of beryllium (Be) and boron (B) in a number of hot population II halo stars; Observed Be and Li (Lithium) and extracted Big Bang abundances of 7Li; Observed B and Li and extracted Big Bang abundance of 2Li; The stellar models of Pinsonneault et al; More.

Investigates the difficulties with a primordial origin of variations of D/H in quasar absorption systems. Examination of large-scale inhomogeneity in the baryon content of the universe; Implications of large-scale baryon inhomogeneity; Method used in the investigation; Findings of the investigation.

The abundance of nitrogen in the interstellar medium is a powerful probe of star formation processes over cosmological time-scales. Since nitrogen can be produced both in massive and intermediate-mass stars with metallicity-dependent yields, its evolution is challenging to model, as evidenced by the differences between theoretical predictions and observations. In this work, we attempt to identify the sources of these discrepancies using a cosmic evolution model. To further complicate matters, there is considerable dispersion in the abundances from observations of damped Lya absorbers (DLAs) at z ~ 2-3. We study the evolution of nitrogen with a detailed cosmic chemical evolution model and find good agreement with these observations, including the relative abundances of (N/O) and (N/Si). We find that the principal contribution of nitrogen comes from intermediate-mass stars, with the exception of systems with the lowest N/H, where nitrogen productionmight possibly be dominated by massive stars. This last result could be strengthened if stellar rotationwhich is important at lowmetallicity can produce significant amounts of nitrogen. Moreover, these systems likely reside in host galaxies with stellar masses below 108.5M☉. We also study the origin of the observed dispersion in nitrogen abundances using the cosmological hydrodynamical simulations Horizon-AGN. We conclude that this dispersion can originate from two effects: difference in the masses of the DLA host galaxies, and difference in their position inside the galaxy. [ABSTRACT FROM AUTHOR]

We show that a minimal scenario, utilizing only the graviton as an intermediate messenger between the inflaton, the dark sector and the Standard Model (SM), is able to generate simultaneously the observed relic density of dark matter (DM), the baryon asymmetry through leptogenesis, as well as a sufficiently hot thermal bath after inflation. We assume an inflaton potential of the form V(ϕ) ∝ ϕk about the minimum at the end of inflation. The possibility of reheating via minimal gravitational interactions has been excluded by constraints on dark radiation for excessive gravitational waves produced from inflation. We thus extend the minimal model in several ways: i) we consider non-minimal gravitational couplings — this points to the parameter range of DM masses M N 1 ≃ 2–10 PeV, and right-handed neutrino masses M N 2 ≃ (5–20) × 1011 GeV, and TRH ≲ 3 × 105 GeV (for k ≤ 20); ii) we propose an explanation for the PeV excess observed by IceCube when the DM has a direct but small Yukawa coupling to the SM; and iii) we also propose a novel scenario, where the gravitational production of DM is a two-step process, first through the production of two scalars, which then decay to fermionic DM final states. In this case, the absence of a helicity suppression enhances the production of DM and baryon asymmetry, and allows a great range for the parameters including a dark matter mass below an MeV where dark matter warmness can be observable by cosmic 21-cm lines, even when gravitational interactions are responsible for reheating. We also show that detectable primordial gravitational wave signals provide the opportunity to probe this scenario for TRH ≲ 5 × 106 GeV in future experiments, such as BBO, DECIGO, CE and ET. [ABSTRACT FROM AUTHOR]

The article focuses on finding recruitment options published in the journal IEE Review. The "Careers and Education" section of the IEE website at vww.iee.org includes an engineering jobs database that features jobs advertised in lEE Review and lEE Review Careers, as well as some that only appear online. The fields covered include electrical engineering, electronic engineering, control engineering, computing, IT and networking, manufacturing engineering, production engineering, power engineering and telecommunications engineering.

The article focuses on the recognition of people in education who are doing their bit to recruit the next generation engineers. Awards are presented every year to up to 12 teachers who have encouraged students to develop an interest in subjects related to electrical and electronic engineering or manufacturing. As well as a cash prize, presented at a celebration dinner where winners receive a year's free Institution of Electrical Engineers membership. The awards aren't restricted to any particular subject area, but nominees should have displayed high quality in their teaching and encouraged pupils to set themselves high standards in their choices.

The article discusses the preparation and auditing requirements for in-house training schemes in a medium-sized company that employs a number of engineers. The implications for the accreditation of such a program are discussed. The basic requirements include mentoring support, the opportunity for candidates to build a suitable portfolio, evidence of their competence, plus the assessment of competence against the standards for registration. Companies benefit from attracting keeping and developing high caliber recruits, while employees benefit from a structured pathway to professional registration.

We re-examine the extremely metal-poor dwarf galaxy AGC 198691 using a high quality spectrum obtained by the LBT's MODS instrument. Previous spectral observations obtained from KOSMOS on the Mayall 4-m and the Blue channel spectrograph on the MMT 6.5-m telescope did not allow for the determination of sulfur, argon, or helium abundances. We report an updated and full chemical abundance analysis for AGC 198691, including confirmation of the extremely low "direct" oxygen abundance with a value of 12 + log (O/H) = 7.06 ± 0.03. AGC 198691's low metallicity potentially makes it a high value target for helping determine the primordial helium abundance (Y p). Though complicated by a Na  i night sky line partially overlaying the He  i λ5876 emission line, the LBT/MODS spectrum proved adequate for determining AGC 198691's helium abundance. We employ the recently expanded and improved model of Aver et al. incorporating higher Balmer and Paschen lines, augmented by the observation of the infrared helium emission line He  i λ10830 obtained by Hsyu et al. Applying our full model produced a reliable helium abundance determination, consistent with the expectation for its metallicity. Although this is the lowest metallicity object with a detailed helium abundance, unfortunately, due to its faintness [EW(Hβ) < 100 Å] and the compromised He  i λ5876, the resultant uncertainty on the helium abundance is too large to allow a significant improvement on the measurement of Y p. [ABSTRACT FROM AUTHOR]

Successful models of pure gravity mediation (PGM) with radiative electroweak symmetry breaking can be expressed with as few as two free parameters, which can be taken as the gravitino mass and $$\tan \beta $$ . These models easily support a 125-126 GeV Higgs mass at the expense of a scalar spectrum in the multi-TeV range and a much lighter wino as the lightest supersymmetric particle. In these models, it is also quite generic that the Higgs mixing mass parameter, $$\mu $$ , which is determined by the minimization of the Higgs potential is also in the multi-TeV range. For $$\mu >0$$ , the thermal relic density of winos is too small to account for the dark matter. The same is true for $$\mu <0$$ unless the gravitino mass is of order 500 TeV. Here, we consider the origin of a multi-TeV $$\mu $$ parameter arising from the breakdown of a Peccei-Quinn (PQ) symmetry. A coupling of the PQ-symmetry breaking field, $$P$$ , to the MSSM Higgs doublets, naturally leads to a value of $$\mu \sim \langle P \rangle ^2 /M_P \sim {\mathcal O}(100)$$ TeV and of the order that is required in PGM models. In this case, axions make up the dark matter or some fraction of the dark matter with the remainder made up from thermal or non-thermal winos. We also provide solutions to the problem of isocurvature fluctuations with axion dark matter in this context. [ABSTRACT FROM AUTHOR]

We consider the effects of non-universalities among sfermion generations in models of Pure Gravity Mediation (PGM). In PGM models and in many models with strongly stabilized moduli, the gravitino mass may be O(100) TeV, whereas gaugino masses, generated through anomalies at one loop, remain relatively light O(1) TeV. In models with scalar mass universality, input scalar masses are generally very heavy ( $$m_0 \simeq m_{3/2}$$ ), resulting in a mass spectrum resembling that in split supersymmetry. However, if one adopts a no-scale or partial no-scale structure for the Kähler manifold, sfermion masses may vanish at the tree level. It is usually assumed that the leading order anomaly mediated contribution to scalar masses appears at two loops. However, there are at least two possible sources for one-loop scalar masses. These may arise if Pauli-Villars fields are introduced as messengers of supersymmetry breaking. We consider the consequences of a spectrum in which the scalar masses associated with the third generation are heavy (order $$m_{3/2}$$ ) with one-loop scalar masses for the first two generations. A similar spectrum is expected to arise in GUT models based on $$E_7/\mathrm{SO}(10)$$ where the first two generations of scalars act as pseudo-Nambu-Goldstone bosons. Explicit breaking of this symmetry by the gauge couplings then generates one-loop masses for the first two generations. In particular, we show that it may be possible to reconcile the $$g_\mu - 2$$ discrepancy with potentially observable scalars and gauginos at the LHC. [ABSTRACT FROM AUTHOR]