528 research outputs found
Asymptotically safe extensions of the Standard Model with flavour phenomenology
We investigate asymptotically safe extensions of the Standard Model with new
matter fields arising in the TeV energy range. The new sector contains singlet
scalars and vector-like fermions in representations which permit Yukawa
interactions with the Standard Model leptons. Phenomenological implications are
explored including charged lepton flavour violation, Drell-Yan processes and
lepton anomalous magnetic moments. For the latter, we find that BSM
contributions can be sizeable enough to explain the present experimental
discrepancies of the electron and muon anomalous magnetic moments with the
Standard Model.Comment: 4 pages, 4 figures. Contribution to the 2019 EW session of the 54th
Rencontres de Morion
Quasi-Two-Level Flying-Capacitor-Converter for Medium Voltage Grid Applications
Medium voltage converters are becoming more relevant in future grid applications. Especially more wind and PV generation systems will be have to added and integrated into the grid in order to achieve the required reduction in CO2 emissions. High power generation units will be integrated into the grid at medium voltage level. Furthermore meshed MV grids will require interties based on MV converter technology. Today\u27s standard medium voltage converters are either based on the MMC technology or us 3L/5L approaches operated at low switching frequencies and containing bulky filters. Both concepts still lead to relatively high costs and low efficiencies which are major reasons for the slow spread of power converters in medium voltage grid applications.. Future grid applications demand less distortion, higher reliability and lower costs for converter systems at each voltage level. The Quasi-Two-Level operation of the flying capacitor multilevel converter with silicone-carbide (SiC) based semiconductors is a method for achieving these requirements for medium voltage converters. This paper presents a new concept for minimizing capacitance and balancing the capacitors with fast switching semiconductors. Moreover, a novel approach for limiting the overvoltage stress caused by the Quasi-Two-Level modulation of a flying capacitor converter is presented
Can County Commissions Emerge as Players in Western Natural Resources Policy Development?
Many county commissioners in the western United States preside over rural and/or public lands-dominated counties. Their formal role in the development of natural resources public policy is poorly defined, but rapidly evolving. As part-time elected officials, they state needs for training in both policy process skills and technically oriented subject matter. A survey investigation of their nonformal learning environment was conducted. They desire more consistent involvement in issues dialogue and higher-quality interactions with various policy influencers. Commissioners overwhelmingly prefer consultation with county government officials--with more regularity, confidence, and credibility than with any other agency, consultant, or institution
Fixed Points in Supersymmetric Extensions of the Standard Model
We search for weakly interacting fixed points in extensions of the minimally
supersymmetric standard model (MSSM). Necessary conditions lead to three
distinct classes of anomaly-free extensions involving either new quark
singlets, new quark doublets, or a fourth generation. While interacting fixed
points arise prolifically in asymptotically free theories, their existence is
significantly constrained as soon as some of the non-abelian gauge sectors are
infrared free. Performing a scan over k different MSSM extensions
using matter field multiplicities and the number of superpotential couplings as
free parameters, we find mostly infrared conformal fixed points, and a small
subset with ultraviolet ones. All settings predict low-scale
supersymmetry-breaking and a violation of -parity. Despite of residual
interactions, the running of couplings out of asymptotically safe fixed points
is logarithmic as in asymptotic freedom. Some fixed points can be matched to
the Standard Model though the matching scale comes out too low. Prospects for
higher matching scales and asymptotic safety beyond the MSSM are indicated.Comment: 26 pages, 9 figure
A Highly Integrated 25-Level Cascaded H-Bridge Active Filter for the Mitigation of High Order Current Harmonics
The increasing share of power electronics in the conversion and distribution of electrical energy represents a novel challenge for energy quality and supply stability. It is to be expected that high-frequency current harmonics will increase significantly with the number of grid-connected power converters. To reduce the associated disadvantages, this paper presents a 25-Level Cascaded H-Bridge Active Filter for mitigating converter-induced current harmonics in the kilohertz range.~Compared to conventional active filters, the proposed use of a voltage-source active filter does not require high control bandwidth, tuning to specific frequencies or measurement and tracking of high frequency currents.~The highly integrated design on printed circuit boards allows a high number of voltage levels and a high power density at small additional effort and costs. A 12 kVA-demonstrator is used to mitigate the switching frequency current harmonics of a grid-connected two-level converter, verifying the effectiveness of the active filter configuration
Monitoring the antibiotic darobactin modulating the β-barrel assembly factor BamA
The β-barrel assembly machinery (BAM) complex is an essential component of Escherichia coli that inserts and folds outer membrane proteins (OMPs). The natural antibiotic compound darobactin inhibits BamA, the central unit of BAM. Here, we employ dynamic single-molecule force spectroscopy (SMFS) to better understand the structure-function relationship of BamA and its inhibition by darobactin. The five N-terminal polypeptide transport (POTRA) domains show low mechanical, kinetic, and energetic stabilities. In contrast, the structural region linking the POTRA domains to the transmembrane β-barrel exposes the highest mechanical stiffness and lowest kinetic stability within BamA, thus indicating a mechano-functional role. Within the β-barrel, the four N-terminal β-hairpins H1-H4 expose the highest mechanical stabilities and stiffnesses, while the four C-terminal β-hairpins H5-H6 show lower stabilities and higher flexibilities. This asymmetry within the β-barrel suggests that substrates funneling into the lateral gate formed by β-hairpins H1 and H8 can force the flexible C-terminal β-hairpins to change conformations
What magic can perform: théâtralité et performativité dans Doctor Faustus de Christopher Marlowe
Dans un contexte dominé par l’iconoclasme de l’anglicanisme anglais et par la “ textualisation ” de la culture religieuse, Christopher Marlowe transforme sa pièce Doctor Faustus (1589), mise en scène dans les théâtres de la banlieue londonienne, en une réflexion sur les capacités performatives et “ incarnationnelles ” du théâtre. Cet article étudie comment l’inflexion métaphorique du langage théologique que les autorités ecclésiastiques avaient utilisé pour dénoncer les effets pervers de la représentation théâtrale permet au dramaturge anglais de formuler une conception de l’art littéraire comme création d’un monde et non plus comme imitation de la nature. Ainsi, Marlowe requalifie en termes théâtraux le concept de performativité : alors que, dans le théâtre du monde, la performativité de la prédestination divine vouait les croyants à une situation de détresse existentielle, la performativité artistique redonnait aux spectateurs la possibilité de créer leur propre monde, le monde du théâtre. C’est pourquoi le remaniement esthétique du lexique et de l’imaginaire théologique s’avère la réponse la plus profonde de Marlowe à la crise de “ l’absolutisme théologique ” : il fait du théâtre un espace de jeu où le traumatisme provoqué par cette crise pouvait être travaillé et éventuellement dépassée par sa resignification dramatique. C’est dire que, dans la version marlowienne du mythe faustien, l’autoaffirmation humaine se réalise surtout à travers le pouvoir cathartique de l’illusion théâtrale
Portals into Higgs Stability
We address the notorious metastability of the standard model (SM) and promote
it to a model building task: What are the new ingredients required to stabilize
the SM up to the Planck scale without encountering subplanckian Landau poles?
Using the SM extended by vector-like fermions, we chart out the corresponding
landscape of Higgs stability. We find that the gauge portal mechanism,
triggered by new SM charge carriers, opens up sizeable room for stability in a
minimally invasive manner. We also find models with Higgs criticality, and
Yukawa portals opening up at stronger coupling. Several models allow for
vector-like fermions in the TeV-range, which can be searched for at the LHC.
For nontrivial flavor structure severe FCNC constraints arise which complement
those from stability, and push lower fermion masses up to
.Comment: 18 pages, 16 figure
Vacuum Stability as a Guide for Model Building
We explain why vector-like fermions are natural candidates to lift the
Standard Model vacuum instability. Results are further discussed from the
viewpoint of criticality. Several models allow for vector-like quarks and
leptons in the TeV-range which can be searched for at the LHC.Comment: Proceedings Moriond EW 2023, 6 pages, 5 figure
Directions for model building from asymptotic safety
Building on recent advances in the understanding of gauge-Yukawa theories we explore possibilities to UV-complete the Standard Model in an asymptotically safe manner. Minimal extensions are based on a large avor sector of additional fermions coupled to a scalar singlet matrix field. We find that asymptotic safety requires fermions in higher representations of SU(3)C SU(2)L. Possible signatures at colliders are worked out and include R-hadron searches, diboson signatures and the evolution of the strong and weak coupling constants
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