3,270 research outputs found

    Higgs mass prediction in the MSSM at three-loop level in a pure DR\overline{\text{DR}} context

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    The impact of the three-loop effects of order αtαs2\alpha_t\alpha_s^2 on the mass of the light CP-even Higgs boson in the MSSM is studied in a pure DR\overline{\text{DR}} context. For this purpose, we implement the results of Kant et al. into the C++ module Himalaya and link it to FlexibleSUSY, a Mathematica and C++ package to create spectrum generators for BSM models. The three-loop result is compared to the fixed-order two-loop calculations of the original FlexibleSUSY and of FeynHiggs, as well as to the result based on an EFT approach. Aside from the expected reduction of the renormalization scale dependence with respect to the lower order results, we find that the three-loop contributions significantly reduce the difference from the EFT prediction in the TeV-region of the SUSY scale MSM_S. Himalaya can be linked also to other two-loop DR\overline{\text{DR}} codes, thus allowing for the elevation of these codes to the three-loop level.Comment: 32 pages, 8 figures, 1 table [version submitted to EPJC

    The light CP-even MSSM Higgs mass resummed to fourth logarithmic order

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    We present the calculation of the light neutral CP-even Higgs mass in the MSSM for a heavy SUSY spectrum by resumming enhanced terms through fourth logarithmic order (N3^3LL), keeping terms of leading order in the top Yukawa coupling αt\alpha_t, and NNLO in the strong coupling αs\alpha_s. To this goal, the three-loop matching coefficient for the quartic Higgs coupling of the SM to the MSSM is derived to order αt2αs2\alpha_t^2\alpha_s^2 by comparing the perturbative EFT to the fixed-order expression for the Higgs mass. The new matching coefficient is made available through an updated version of the program Himalaya. Numerical effects of the higher-order resummation are studied using specific examples, and sources of theoretical uncertainty on this result are discussed.Comment: 26 pages, 3 figures, matches version published in EPJ

    A climate network perspective on the intertropical convergence zone

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    The intertropical convergence zone (ITCZ) is an important component of the tropical rain belt. Climate models continue to struggle to adequately represent the ITCZ and differ substantially in its simulated response to climate change. Here we employ complex network approaches, which extract spatiotemporal variability patterns from climate data, to better understand differences in the dynamics of the ITCZ in state-of-the-art global circulation models (GCMs). For this purpose, we study simulations with 14 GCMs in an idealized slab-ocean aquaplanet setup from TRACMIP – the Tropical Rain belts with an Annual cycle and a Continent Model Intercomparison Project. We construct network representations based on the spatial correlation patterns of monthly surface temperature anomalies and study the zonal-mean patterns of different topological and spatial network characteristics. Specifically, we cluster the GCMs by means of the distributions of their zonal network measures utilizing hierarchical clustering. We find that in the control simulation, the distributions of the zonal network measures are able to pick up model differences in the tropical sea surface temperature (SST) contrast, the ITCZ position, and the strength of the Southern Hemisphere Hadley cell. Although we do not find evidence for consistent modifications in the network structure tracing the response of the ITCZ to global warming in the considered model ensemble, our analysis demonstrates that coherent variations of the global SST field are linked to ITCZ dynamics. This suggests that climate networks can provide a new perspective on ITCZ dynamics and model differences therein

    Children's Planning Performance in the Zoo Map Task (BADS-C) : Is It Driven by General Cognitive Ability, Executive Functioning, or Prospection?

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    Preparation of this article was partially funded by the Swiss National Science Foundation (SNSF; 100014_152841) and the Natural Sciences and Engineering Council of Canada (NSERC; RGPIN-2015-03774).Peer reviewedPostprin

    Spiral Growth and Step Edge Barriers

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    The growth of spiral mounds containing a screw dislocation is compared to the growth of wedding cakes by two-dimensional nucleation. Using phase field simulations and homoepitaxial growth experiments on the Pt(111) surface we show that both structures attain the same characteristic large scale shape when a significant step edge barrier suppresses interlayer transport. The higher vertical growth rate observed for the spiral mounds on Pt(111) reflects the different incorporation mechanisms for atoms in the top region and can be formally represented by an enhanced apparent step edge barrier.Comment: 11 pages, 4 figures, partly in colo

    The mitochondrial genomes of sponges provide evidence for multiple invasions by Repetitive Hairpin-forming Elements (RHE)

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    Background: The mitochondrial (mt) genomes of sponges possess a variety of features, which appear to be intermediate between those of Eumetazoa and non-metazoan opisthokonts. Among these features is the presence of long intergenic regions, which are common in other eukaryotes, but generally absent in Eumetazoa. Here we analyse poriferan mitochondrial intergenic regions, paying particular attention to repetitive sequences within them. In this context we introduce the mitochondrial genome of Ircinia strobilina (Lamarck, 1816; Demospongiae: Dictyoceratida) and compare it with mtDNA of other sponges. Results: Mt genomes of dictyoceratid sponges are identical in gene order and content but display major differences in size and organization of intergenic regions. An even higher degree of diversity in the structure of intergenic regions was found among different orders of demosponges. One interesting observation made from such comparisons was of what appears to be recurrent invasions of sponge mitochondrial genomes by repetitive hairpin-forming elements, which cause large genome size differences even among closely related taxa. These repetitive hairpin-forming elements are structurally and compositionally divergent and display a scattered distribution throughout various groups of demosponges. Conclusion: Large intergenic regions of poriferan mt genomes are targets for insertions of repetitive hairpin- forming elements, similar to the ones found in non-metazoan opisthokonts. Such elements were likely present in some lineages early in animal mitochondrial genome evolution but were subsequently lost during the reduction of intergenic regions, which occurred in the Eumetazoa lineage after the split of Porifera. Porifera acquired their elements in several independent events. Patterns of their intra-genomic dispersal can be seen in the mt genome of Vaceletia sp

    Optical echo in photonic crystals

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    The dynamics of photonic wavepacket in the effective oscillator potential is studied. The oscillator potential is constructed on a base of one dimensional photonic crystal with a period of unit cell adiabatically varied in space. The structure has a locally equidistant discrete spectrum. This leads to an echo effect, i.e. the periodical reconstruction of the packet shape. The effect can be observed in a nonlinear response of the system. Numerical estimations for porous-silicon based structures are presented for femtosecond Ti:Sapphire laser pump.Comment: 4 page

    Assessing the effect of dynamics on the closed-loop protein-folding hypothesis

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    The closed-loop (loop-n-lock) hypothesis of protein folding suggests that loops of about 25 residues, closed through interactions between the loop ends (locks), play an important role in protein structure. Coarse-grain elastic network simulations, and examination of loop lengths in a diverse set of proteins, each supports a bias towards loops of close to 25 residues in length between residues of high stability. Previous studies have established a correlation between total contact distance (TCD), a metric of sequence distances between contacting residues (cf. contact order), and the log-folding rate of a protein. In a set of 43 proteins, we identify an improved correlation ( r 2 = 0.76), when the metric is restricted to residues contacting the locks, compared to the equivalent result when all residues are considered ( r 2 = 0.65). This provides qualified support for the hypothesis, albeit with an increased emphasis upon the importance of a much larger set of residues surrounding the locks. Evidence of a similar-sized protein core/extended nucleus (with significant overlap) was obtained from TCD calculations in which residues were successively eliminated according to their hydrophobicity and connectivity, and from molecular dynamics simulations. Our results suggest that while folding is determined by a subset of residues that can be predicted by application of the closed-loop hypothesis, the original hypothesis is too simplistic; efficient protein folding is dependent on a considerably larger subset of residues than those involved in lock formation. </jats:p

    Guiding of cold atoms by a red-detuned laser beam of moderate power

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    We report measurements on the guiding of cold 87^{87}Rb atoms from a magneto-optical trap by a continuous light beam over a vertical distance of 6.5 mm. For moderate laser power (<<85 mW) we are able to capture around 40% of the cold atoms. Although the guide is red-detuned, the optical scattering rate at this detuning (\approx70 GHz) is acceptably low. For lower detuning (<<30 GHz) a larger fraction was guided but radiation pressure starts to push the atoms upward, effectively lowering the acceleration due to gravity. The measured guided fraction agrees well with an analytical model.Comment: final version, 6 pages, incl. 6 figure
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