460 research outputs found

    An alternative view on the electroweak interactions

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    We discuss an alternative to the Higgs mechanism which leads to gauge invariant masses for the electroweak bosons. The key idea is to reformulate the gauge invariance principle which, instead of being applied as usual at the level of the action, is applied at the level of the quantum fields. In other words, we define gauge invariant quantum fields which are used to build the action. In that framework, the Higgs field is not necessarily a physical degree of freedom but can merely be a dressing field that does not propagate. If the Higgs boson is not propagating, the weak interactions must become strongly coupled below 1 TeV and have a non-trivial fixed point and would thus be renormalizable at the non-perturbative level. On the other hand, if a gauge invariant Higgs boson is introduced in the model, its couplings to the fermions and the electroweak bosons can be quite different from those expected in the standard model.Comment: 10 page

    Multiple ways to keep FFAT under control!

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    This is the final version. Available on open access from SAGE Publications via the DOI in this recordData availability: The research data supporting this publication are provided within this paper with reference to PMID: 35019937Peroxisomes and the ER are closely inter-connected organelles, which collaborate in the metabolism of lipids. In a recent research paper in the Journal of Cell Biology, we describe a novel mechanism by which peroxisome-ER membrane contact sites are regulated, via phosphorylation of the peroxisomal protein ACBD5. We found that the interaction between ACBD5 and the ER protein VAPB, which we have previously shown to form a tether complex at peroxisome-ER contacts, is controlled by phosphorylation of ACBD5 at two different sites of its FFAT motif – the VAPB binding site. We also identify the kinase GSK3-β as being responsible for direct phosphorylation of ACBD5 to negatively regulate interaction with VAPB, leading to reduced peroxisome-ER contacts. In this article we provide additional insights into how this work, in combination with other studies on phosphorylation of VAP interactors, suggests a complex system of both positive and negative regulation of the FFAT motif via phosphorylation.Biotechnology & Biological Sciences Research Council (BBSRC)UKRIMedical Research Council (MRC

    Observing Brane Inflation

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    Linking the slow-roll scenario and the Dirac-Born-Infeld scenario of ultra-relativistic roll (where, thanks to the warp factor, the inflaton moves slowly even with an ultra-relativistic Lorentz factor), we find that the KKLMMT D3/anti-D3 brane inflation is robust, that is, enough e-folds of inflation is quite generic in the parameter space of the model. We show that the intermediate regime of relativistic roll can be quite interesting observationally. Introducing appropriate inflationary parameters, we explore the parameter space and give the constraints and predictions for the cosmological observables in this scenario. Among other properties, this scenario allows the saturation of the present observational bound of either the tensor/scalar ratio r (in the intermediate regime) or the non-Gaussianity f_NL (in the ultra-relativistic regime), but not both.Comment: 31 pages, 12 figures; typo correcte

    High Scale Physics Connection to LHC Data

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    The existing data appears to provide hints of an underlying high scale theory. These arise from the gauge coupling unification, from the smallness of the neutrino masses, and via a non-vanishing muon anomaly. An overview of high scale models is given with a view to possible tests at the Large Hadron Collider. Specifically we discuss here some generic approaches to deciphering their signatures. We also consider an out of the box possibility of a four generation model where the fourth generation is a mirror generation rather than a sequential generation. Such a scenario can lead to some remarkably distinct signatures at the LHC.Comment: 23 pages, no figures. Based on invited lectures at the 46th Course at the International School of Subnuclear Physics- Erice -Sicily: 29 August -7 September, 200

    Характеристика экономических отношений на финансовом рынке Украины

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    Розглянуто проблеми, особливості функціонування та взаємодії учасників фінансового ринку України. Обґрунтовано наявність внутрішніх фінансових джерел формування ресурсного потенціалу вітчизняних банків, доведено їх пріоритетність для країни порівняно із зовнішніми джерелами. Окреслено причини, що зумовлюють дефіцит ресурсного потенціалу в банківській системі України. Ключові слова: заощадження, нагромадження, банки, економічне зростання, посередники, фінансовий ринок, ресурси, трансформація, інвестиційний потенціал.Рассмотрены проблемы, особенности функционирования и взаимодействия участников финансового рынка Украины. Обосновано наличие внутренних финансовых источников формирования ресурсного потенциала отечественных банков, доказана их приоритетность для страны по сравнению с внешними источниками. Очерчены причины, которые предопределяют дефицит ресурсного потенциала в банковской системе Украины. Ключевые слова: сбережения, накопления, банки, экономический рост, посредники, финансовый рынок, ресурсы, трансформация, инвестиционный потенциал.The present paper examines topical problems related to the specific aspects of economic relations in the financial market of Ukraine. The relevance and selection of the theme stem from the fact that financial market as a specific organization form of cash flows takes a leading place in the economic mechanism of market economy. Agents of this market are engaged in a whole range of complex economic relations which in their turn play a key role in securing a dynamic and sustainable economic growth of a country. Development of the financial market and creation of adequate flexible and adaptive economic relations between its players are critical for Ukraine. This is explained by specific aspects of the economic system formation and reforming, which are related to undergoing an intersystem transformation stage. The indicated circumstances predetermined the goal and objectives of the study pursued, which come to examination of economic relations in the financial market of Ukraine, identification of the interaction specificity of various financial intermediaries in the accumulation process of idle cash and its transformation into the investment capital of national economy. Based on the results of the analysis conducted, it is established that unlike countries with developed financial systems, where the majority of institutional participants of the capital market are proportionally developed, it is the banking sector that dominates in Ukraine and has a determinant role in financing the economic development of the state. The availability of domestic financial resources for forming the resource potential of banks is substantiated, and their priority versus external resources for Ukraine is proved. The comparison of gross savings and gross capital formation allowed identifying certain problems as to transformation of the former into investment resources in Ukraine. The paper outlines some causes of a poor resource potential of national banking institutions. Keywords: savings, accumulation, banks, economic growth, intermediaries, financial market, resources, transformation, investment potential

    Controlling contacts - Molecular mechanisms to regulate organelle membrane tethering

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    This is the final version. Available on open access from Wiley via the DOI in this recordData availability statement: Data sharing is not applicable to this article as no new data were created or analyzed in this study.In recent years, membrane contact sites (MCS), which mediate interactions between virtually all subcellular organelles, have been extensively characterized and shown to be essential for intracellular communication. In this review essay, we focus on an emerging topic: the regulation of MCS. Focusing on the tether proteins themselves, we discuss some of the known mechanisms which can control organelle tethering events and identify apparent common regulatory hubs, such as the VAP interface at the endoplasmic reticulum (ER). We also highlight several currently hypothetical concepts, including the idea of tether oligomerization and redox regulation playing a role in MCS formation. We identify gaps in our current understanding, such as the identity of the majority of kinases/phosphatases involved in tether modification and conclude that a holistic approach-incorporating the formation of multiple MCS, regulated by interconnected regulatory modulators-may be required to fully appreciate the true complexity of these fascinating intracellular communication systems

    A Supersymmetric Stueckelberg U(1) Extension of the MSSM

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    A Stueckelberg extension of the MSSM with only one abelian vector and one chiral superfield as an alternative to an abelian extension with Higgs scalars is presented. The bosonic sector contains a new gauge boson Z' which is a sharp resonance, and a new CP-even scalar, which combines with the MSSM Higgs bosons to produce three neutral CP-even massive states. The neutral fermionic sector has two additional fermions which mix with the four MSSM neutralinos to produce an extended 6x6 neutralino mass matrix. For the case when the LSP is composed mostly of the Stueckelberg fermions, the LSP of the MSSM will be unstable, which leads to exotic decays of sparticles with many leptons in final states. Prospects for supersymmetry searches and for dark matter are discussed.Comment: 10 page

    Finding a short and accurate decision rule in disjunctive normal form by exhaustive search

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    Greedy approaches suffer from a restricted search space which could lead to suboptimal classifiers in terms of performance and classifier size. This study discusses exhaustive search as an alternative to greedy search for learning short and accurate decision rules. The Exhaustive Procedure for LOgic-Rule Extraction (EXPLORE) algorithm is presented, to induce decision rules in disjunctive normal form (DNF) in a systematic and efficient manner. We propose a method based on subsumption to reduce the number of values considered for instantiation in the literals, by taking into account the relational operator without loss of performance. Furthermore, we describe a branch-and-bound approach that makes optimal use of user-defined performance constraints. To improve the generalizability we use a validation set to determine the optimal length of the DNF rule. The performance and size of the DNF rules induced by EXPLORE are compared to those of eight well-known rule learners. Our results show that an exhaustive approach to rule learning in DNF results in significantly smaller classifiers than those of the other rule learners, while securing comparable or even better performance. Clearly, exhaustive search is computer-intensive and may not always be feasible. Nevertheless, based on this study, we believe that exhaustive search should be considered an alternative for greedy search in many problems
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