2,141 research outputs found

    Higher Order Stability of a Radiatively Induced 220 GeV Higgs Mass

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    The effective potential for radiatively broken electroweak symmetry in the single Higgs doublet Standard Model is explored to four sequentially subleading logarithm-summation levels (5-loops) in the dominant Higgs self-interaction couplant λ\lambda. We augment these results with all contributing leading logarithms in the remaining large but sub-dominant Standard Model couplants (t-quark, QCD and SU(2)U(1)SU(2)\otimes U(1) gauge couplants) as well as next to leading logarithm contributions from the largest of these, the t-quark and QCD couplants. Order-by-order stability is demonstrated for earlier leading logarithm predictions of an order 220 GeV Higgs boson mass in conjunction with fivefold enhancement of the value for λ\lambda over that anticipated from conventional spontaneous symmetry breaking.Comment: revtex, 6 pages. Analysis and text is expanded in revised versio

    Cold, anisotropically-interacting van der Waals molecule: TiHe

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    We have used laser ablation and helium buffer-gas cooling to produce the titanium-helium van der Waals molecule at cryogenic temperatures. The molecules were detected through laser-induced fluorescence spectroscopy. Ground-state Ti-He binding energies were determined for the ground and first rotationally excited states from studying equilibrium thermodynamic properties, and found to agree well with theoretical calculations based on newly calculated ab initio Ti-He interaction potentials, opening up novel possibilities for studying the formation, dynamics, and non-universal chemistry of van der Waals clusters at low temperatures

    Radiative Electroweak Symmetry-Breaking Revisited

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    In the absence of a tree-level scalar-field mass, renormalization-group methods permit the explicit summation of leading-logarithm contributions to all orders of the perturbative series within the effective potential for SU(2)×U(1)SU(2)\times U(1) electroweak symmetry. This improvement of the effective potential function is seen to reduce residual dependence on the renormalization mass scale. The all-orders summation of leading logarithm terms involving the dominant three couplings contributing to radiative corrections is suggestive of a potential characterized by a plausible Higgs boson mass of 216 GeV. However, the tree potential's local minimum at ϕ=0\phi =0 is restored if QCD is sufficiently strong.Comment: revtex, 4 pages, 1 eps figure embedded in manuscript. Updated version contains additional comments and corrects minor error

    Triviality and vacuum stability bounds in the three-loop neutrino mass model

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    We study theoretical constraints on the parameter space under the conditions from vacuum stability and triviality in the three-loop radiative seesaw model with TeV-scale right-handed neutrinos which are odd under the Z2Z_2 parity. In this model, some of the neutrino Yukawa coupling constants can be of the order of one. Requirement of strongly first order phase transition for successful electroweak baryogenes is also prefers order-one coupling constants in the scalar sector. Hence, it is important to clarify whether this model satisfies those theoretical conditions up to a given cutoff scale. It is found that the model can be consistent up to the scale above 10 TeV in the parameter region where the neutrino data, the lepton flavor violation data, the thermal relic abundance of dark matter as well as the requirement from the strongly first order phase transition are satisfied.Comment: 22 pages, 14 figure

    The Effective Potential, the Renormalisation Group and Vacuum Stability

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    We review the calculation of the the effective potential with particular emphasis on cases when the tree potential or the renormalisation-group-improved, radiatively corrected potential exhibits non-convex behaviour. We illustrate this in a simple Yukawa model which exhibits a novel kind of dimensional transmutation. We also review briefly earlier work on the Standard Model. We conclude that, despite some recent claims to the contrary, it can be possible to infer reliably that the tree vacuum does not represent the true ground state of the theory.Comment: 23 pages; 5 figures; v2 includes minor changes in text and additional reference

    Microfluidic genome-wide profiling of intrinsic electrical properties in Saccharomyces cerevisiae

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    Methods to analyze the intrinsic physical properties of cells – for example, size, density, rigidity, or electrical properties – are an active area of interest in the microfluidics community. Although the physical properties of cells are determined at a fundamental level by gene expression, the relationship between the two remains exceptionally complex and poorly characterized, limiting the adoption of intrinsic separation technologies. To improve our current understanding of how a cell's genotype maps to a measurable physical characteristic and quantitatively investigate the potential of using these characteristics as biomarkers, we have developed a novel screen that combines microfluidic cell sorting with high-throughput sequencing and the haploid yeast deletion library to identify genes whose functions modulate one such characteristic – intrinsic electrical properties. Using this screen, we are able to establish a high-content electrical profile of the haploid yeast gene deletion strains. We find that individual genetic deletions can appreciably alter the electrical properties of cells, affecting [approximately] 10% of the 4432 gene deletion strains screened. Additionally, we find that gene deletions affecting electrical properties in specific ways (i.e. increasing or decreasing effective conductivity at higher or lower electric field frequencies) are strongly associated with an enriched subset of fundamental biological processes that can be traced to specific pathways and complexes. The screening approach demonstrated here and the attendant results are immediately applicable to the intrinsic separations community.Singapore-MIT AllianceNational Science Foundation (U.S.) (NSF IDBR grant DBI-0852654)National Institutes of Health (U.S.) (NIH grant EB005753

    Targeting EZH2 Reprograms Intratumoral Regulatory T Cells to Enhance Cancer Immunity.

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    Regulatory T cells (Tregs) are critical for maintaining immune homeostasis, but their presence in tumor tissues impairs anti-tumor immunity and portends poor prognoses in cancer patients. Here, we reveal a mechanism to selectively target and reprogram the function of tumor-infiltrating Tregs (TI-Tregs) by exploiting their dependency on the histone H3K27 methyltransferase enhancer of zeste homolog 2 (EZH2) in tumors. Disruption of EZH2 activity in Tregs, either pharmacologically or genetically, drove the acquisition of pro-inflammatory functions in TI-Tregs, remodeling the tumor microenvironment and enhancing the recruitment and function of CD8+ and CD4+ effector T cells that eliminate tumors. Moreover, abolishing EZH2 function in Tregs was mechanistically distinct from, more potent than, and less toxic than a generalized Treg depletion approach. This study reveals a strategy to target Tregs in cancer that mitigates autoimmunity by reprogramming their function in tumors to enhance anti-cancer immunity

    On Traversable Lorentzian Wormholes in the Vacuum Low Energy Effective String Theory in Einstein and Jordan Frames

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    Three new classes (II-IV) of solutions of the vacuum low energy effective string theory in four dimensions are derived. Wormhole solutions are investigated in those solutions including the class I case both in the Einstein and in the Jordan (string) frame. It turns out that, of the eight classes of solutions investigated (four in the Einstein frame and four in the corresponding string frame), massive Lorentzian traversable wormholes exist in five classes. Nontrivial massless limit exists only in class I Einstein frame solution while none at all exists in the string frame. An investigation of test scalar charge motion in the class I solution in the two frames is carried out by using the Plebanski-Sawicki theorem. A curious consequence is that the motion around the extremal zero (Keplerian) mass configuration leads, as a result of scalar-scalar interaction, to a new hypothetical "mass" that confines test scalar charges in bound orbits, but does not interact with neutral test particles.Comment: 18 page

    The chromatin remodeling factor ISW-1 integrates organismal responses against nuclear and mitochondrial stress

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    Age-associated changes in chromatin structure have a major impact on organismal longevity. Despite being a central part of the ageing process, the organismal responses to the changes in chromatin organization remain unclear. Here we show that moderate disturbance of histone balance during C. elegans development alters histone levels and triggers a stress response associated with increased expression of cytosolic small heat-shock proteins. This stress response is dependent on the transcription factor, HSF-1, and the chromatin remodeling factor, ISW-1. In addition, we show that mitochondrial stress during developmental stages also modulates histone levels, thereby activating a cytosolic stress response similar to that caused by changes in histone balance. These data indicate that histone and mitochondrial perturbations are both monitored through chromatin remodeling and involve the activation of a cytosolic response that affects organismal longevity. HSF-1 and ISW-1 hence emerge as a central mediator of this multi-compartment proteostatic response regulating longevity.Peer reviewe

    Near-brane SU(6) origin Higgs in Scherk-Schwarz breaking of five-dimensional SU(6) GUT

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    The symmetry breaking of five-dimensional SU(6) GUT is realized by Scherk-Schwarz mechanisms through trivial and pseudo nontrivial orbifold S1/Z2 breakings to produce dimensional deconstruction 5D SU(6) \rightarrow4D SU(6). The latter also induces near-brane weakly-coupled SU(6) Baby Higgs to further break the symmetry into SU(3)C \otimes SU(3)H \otimes U(1)C. The model successfully provides a scenario of the origin of (Little) Higgs from GUT scale, produces the (intermediate and light) Higgs boson with the most preferred range and establishes coupling unification and compactification scale correctly.Comment: 23 pages, 5 figure
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