294 research outputs found

    Finite temperature behaviour of the ISS-uplifted KKLT model

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    We study the static phase structure of the ISS-KKLT model for moduli stabilisation and uplifting to a zero cosmological constant. Since the supersymmetry breaking sector and the moduli sector are only gravitationally coupled, we expect negligible quantum effects of the modulus upon the ISS sector, and the other way around. Under this assumption, we show that the ISS fields end up in the metastable vacua. The reason is not only that it is thermally favoured (second order phase transition) compared to the phase transition towards the supersymmetric vacua, but rather that the metastable vacua form before the supersymmetric ones. This nice feature is exclusively due to the presence of the KKLT sector. We also show that supergravity effects are negligible around the origin of the field space. Finally, we turn to the modulus sector and show that there is no destabilisation effect coming from the ISS sector.Comment: 23 pages, 3 figures, mistake corrected, one plot updated, physical conclusions unchange

    Poly-instanton Inflation

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    We propose a new inflationary scenario in type IIB Calabi-Yau compactifications, where the inflaton is a K\"ahler modulus parameterising the volume of an internal four-cycle. The inflaton potential is generated via poly-instanton corrections to the superpotential which give rise to a naturally flat direction due to their double exponential suppression. Given that the volume mode is kept stable during inflation, all the inflaton-dependent higher dimensional operators are suppressed. Moreover, string loop effects can be shown to be negligible throughout all the inflationary dynamics for natural values of the underlying parameters. The model is characterised by a reheating temperature of the order Trh106T_{\rm rh}\simeq 10^6 GeV which requires Ne54N_e \simeq 54 e-foldings of inflation. All the inflationary observables are compatible with current observations since the spectral index is ns0.96n_s \simeq 0.96, while the tensor-to-scalar ratio is r105r\simeq 10^{-5}. The volume of the Calabi-Yau is of order 10310^3 in string units, corresponding to an inflationary scale around 101510^{15} GeVComment: 20 pages, 4 figure

    Inflation with racetrack superpotential and matter field

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    Several models of inflation with the racetrack superpotential for the volume modulus coupled to a matter field are investigated. In particular, it is shown that two classes of racetrack inflation models, saddle point and inflection point ones, can be constructed in a fully supersymmetric framework with the matter field F-term as a source of supersymmetry breaking and uplifting. Two models of F-term supersymmetry breaking are considered: the Polonyi model and the quantum corrected O'Raifeartaigh model. In the former case, both classes of racetrack inflation models differ significantly from the corresponding models with non-supersymmetric uplifting. The main difference is a quite strong dominance of the inflaton by the matter field. In addition, fine-tuning of the parameters is relaxed as compared to the original racetrack models. In the case of the racetrack inflation models coupled to the O'Raifeartaigh model, the matter field is approximately decoupled from the inflationary dynamics. In all of the above models the gravitino mass is larger than the Hubble scale during inflation. The possibility of having the gravitino much lighter than the Hubble scale is also investigated. It is very hard to construct models with light gravitino in which the volume modulus dominates inflation. On the other hand, models in which the inflationary dynamics is dominated by the matter field are relatively simple and seem to be more natural.Comment: 40 pages, 13 figures, references added, typos corrected, version to be publishe

    Universal flow diagram for the magnetoconductance in disordered GaAs layers

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    The temperature driven flow lines of the diagonal and Hall magnetoconductance data (G_{xx},G_{xy}) are studied in heavily Si-doped, disordered GaAs layers with different thicknesses. The flow lines are quantitatively well described by a recent universal scaling theory developed for the case of duality symmetry. The separatrix G_{xy}=1 (in units e^2/h) separates an insulating state from a spin-degenerate quantum Hall effect (QHE) state. The merging into the insulator or the QHE state at low temperatures happens along a semicircle separatrix G_{xx}^2+(G_{xy}-1)^2=1 which is divided by an unstable fixed point at (G_{xx},G_{xy})=(1,1).Comment: 10 pages, 5 figures, submitted to Phys. Rev. Let

    Occupational exposures to solvents and metals are associated with fixed airflow obstruction

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    peer-reviewedOur study is the first to investigate the associations between exposures to solvents and metals using lifetime work history calendars and fixed airflow obstruction (AO). We have shown that increasing cumulative exposure-unit years to chlorinated solvents is associated with fixed AO. We found that women were at increased risk of fixed AO with increasing cumulative exposed-unit-years to chlorinated solvents but not men

    The environmental impacts of land transformation in the coastal perimeter of the Mar Menor lagoon (Spain)

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    Assigned to WIT Press all rights under copyright that may exist in and to the Work and any associated written or multimedia components or other enhancements accompanying the Work.The distinctive environment of the lagoon has long been attractive for visitors. A surge in touristic activities has taken place in the area since the early 1960s, characterised by intense urban development along the lagoon s perimeter to accommodate the growing seasonal population. This phenomenon has particularly affected La Manga, a sandy bar which is 20 km in length. La Manga acts as a barrier between the lagoon and the Mediterranean Sea, crossed by five, more or less functional channels called golas . The urbanization process has changed the water flow system between the inside and seawater through the channels. The changes have affected coastal dynamics, the longitudinal profile of the coast and the lagoon s ecosystem. The coastal lagoon is also highly threatened by other pollution variables derived from agricultural lands. The water derived from the Tajo-Segura transfer generated a profound land transformation of the adjacent agricultural areas, which changed from extensive dry crop farming to intensively irrigated crops, disturbing the lagoon dramatically. This paper analyzes both land transformations around the coastal perimeter of the Mar Menor during the last 50 years and shows the environmental impact with its consequences on the ecosystem. Although numerous biological studies have been carried out in the Mar Menor, a better understanding of the consequences of land transformation in the perimeter of the lagoon is still necessary to understand the lagoon s situation. The results of territorial management in the Mar Menor lagoon need to be addressed in order to develop successful strategies in the area to protect this valuable ecosystem and its services.García-Ayllon Veintimilla, S.; Miralles García, JL. (2014). The environmental impacts of land transformation in the coastal perimeter of the Mar Menor lagoon (Spain). International Journal of Design and Nature and Ecodynamics. 9(2):109-128. doi:10.2495/DNE-V9-N2-109-128S1091289

    Non-Minimal Sneutrino Inflation, Peccei-Quinn Phase Transition and non-Thermal Leptogenesis

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    We consider a phenomenological extension of the minimal supersymmetric standard model which incorporates non-minimal chaotic inflation, driven by a quartic potential associated with the lightest right-handed sneutrino. Inflation is followed by a Peccei-Quinn phase transition based on renormalizable superpotential terms, which resolves the strong CP and mu problems of the minimal supersymmetric standard model provided that one related parameter of the superpotential is somewhat small. Baryogenesis occurs via non-thermal leptogenesis, which is realized by the inflaton decay. Confronting our scenario with the current observational data on the inflationary observables, the baryon assymetry of the universe, the gravitino limit on the reheating temperature and the upper bound on the light neutrino masses, we constrain the effective Yukawa coupling involved in the decay of the inflaton to relatively small values and the inflaton mass to values lower than 10^12 GeV.Comment: 21 pages including 3 figures; Final versio

    Contributions to the cross shock electric field at supercritical perpendicular shocks: Impact of the pickup ions

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    A particle-in-cell code is used to examine contributions of the pickup ions (PIs) and the solar wind ions (SWs) to the cross shock electric field at the supercritical, perpendicular shocks. The code treats the pickup ions self-consistently as a third component. Herein, two different runs with relative pickup ion density of 25% and 55% are presented in this paper. Present preliminary results show that: (1) in the low percentage (25%) pickup ion case, the shock front is nonstationary. During the evolution of this perpendicular shock, a nonstationary foot resulting from the reflected solar wind ions is formed in front of the old ramp, and its amplitude becomes larger and larger. At last, the nonstationary foot grows up into a new ramp and exceeds the old one. Such a nonstationary process can be formed periodically. hen the new ramp begins to be formed in front of the old ramp, the Hall term mainly contributed by the solar wind ions becomes more and more important. The electric field Ex is dominated by the Hall term when the new ramp exceeds the old one. Furthermore, an extended and stationary foot in pickup ion gyro-scale is located upstream of the nonstationary/self-reforming region within the shock front, and is always dominated by the Lorentz term contributed by the pickup ions; (2) in the high percentage (55%) pickup ion case, the amplitude of the stationary foot is increased as expected. One striking point is that the nonstationary region of the shock front evidenced by the self-reformation disappears. Instead, a stationary extended foot dominated by Lorentz term contributed by the pickup ions, and a tationary ramp dominated by Hall term contributed by the solar wind ions are clearly evidenced. The significance of the cross electric field on ion dynamics is also discussed.Comment: 11 pages, 6 figs and 1 table. This paper will be published in the journal: Astrophysics and Space Scienc

    Search for direct production of charginos and neutralinos in events with three leptons and missing transverse momentum in √s = 7 TeV pp collisions with the ATLAS detector

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    A search for the direct production of charginos and neutralinos in final states with three electrons or muons and missing transverse momentum is presented. The analysis is based on 4.7 fb−1 of proton–proton collision data delivered by the Large Hadron Collider and recorded with the ATLAS detector. Observations are consistent with Standard Model expectations in three signal regions that are either depleted or enriched in Z-boson decays. Upper limits at 95% confidence level are set in R-parity conserving phenomenological minimal supersymmetric models and in simplified models, significantly extending previous results
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