910 research outputs found

    Green Function on the q-Symmetric Space SU_q(2)/U(1)

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    Following the introduction of the invariant distance on the non-commutative C-algebra of the quantum group SU_q(2), the Green function and the Kernel on the q-homogeneous space M=SU(2)_q/U(1) are derived. A path integration is formulated. Green function for the free massive scalar field on the non-commutative Einstein space R^1xM is presented.Comment: Plain Latex, 19

    Surveying Standard Model Flux Vacua on T6/Z2×Z2T^6/Z_2\times Z_2

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    We consider the SU(2)LxSU(2)R Standard Model brane embedding in an orientifold of T6/Z2xZ2. Within defined limits, we construct all such Standard Model brane embeddings and determine the relative number of flux vacua for each construction. Supersymmetry preserving brane recombination in the hidden sector enables us to identify many solutions with high flux. We discuss in detail the phenomenology of one model which is likely to dominate the counting of vacua. While Kahler moduli stabilization remains to be fully understood, we define the criteria necessary for generic constructions to have fixed moduli.Comment: 30 pages, LaTeX, v2: added reference

    Diagonal deformations of thin center vortices and their stability in Yang-Mills theories

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    The importance of center vortices for the understanding of the confining properties of SU(N) Yang-Mills theories is well established in the lattice. However, in the continuum, there is a problem concerning the relevance of center vortex backgrounds. They display the so called Savvidy-Nielsen-Olesen instability, associated with a gyromagnetic ratio gm(b)=2g^{(b)}_m=2 for the off-diagonal gluons. In this work, we initially consider the usual definition of a {\it thin} center vortex and rewrite it in terms of a local color frame in SU(N) Yang-Mills theories. Then, we define a thick center vortex as a diagonal deformation of the thin object. Besides the usual thick background profile, this deformation also contains a frame defect coupled with gyromagnetic ratio gm(d)=1g^{(d)}_m=1, originated from the charged sector. As a consequence, the analysis of stability is modified. In particular, we point out that the defect should stabilize a vortex configuration formed by a pair of straight components separated by an appropriate finite distance.Comment: 20 pages, LaTe

    Alignment of a digital watershed and land use game to national education standards

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    Digital games, especially simulations, have supported student learning outcomes in the areas of science and agriculture in classrooms and nonformal settings. Simulations contribute robustly to student achievement in science, technology, engineering, and mathematics (STEM), and agriculture content areas, especially when they are aligned with national education standards. The People in Ecosystems Watershed Integration (PEWI) simulation is a digital game that was evaluated for fit to two national standards: the Next Generation Science Standards (NGSS) and the Agriculture, Food, and Natural Resources Standards (AFNR). The evaluation of alignment of PEWI to NGSS provided “extensive” evidence on a four‐point scale for meeting Criterion A: Explaining phenomenon/designing solutions; Criterion B: 3‐D learning, science and engineering practices, rated for three areas: (a) “extensive” for science and engineering practices, (b) “adequate” for disciplinary core ideas, and (c) “extensive” for cross‐cutting concepts. Additionally, PEWI aligned with nine high school–level NGSS student performance expectations categories. For AFNR Standards, the PEWI evaluation provided evidence for alignment to 10 standards and 17 indicators from the AFNR areas of Environmental Service Systems, Natural Resource Systems, and Plant Systems

    First near-relativistic solar electron events observed by EPD onboard Solar Orbiter

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    Context. Solar Orbiter, launched in February 2020, started its cruise phase in June 2020, in coincidence with its first perihelion at 0.51 au from the Sun. The in situ instruments onboard, including the Energetic Particle Detector (EPD), operate continuously during the cruise phase enabling the observation of solar energetic particles. Aims. In situ measurements of the first near-relativistic solar electron events observed in July 2020 by EPD are analyzed and the solar origins and the conditions for the interplanetary transport of these particles investigated. Methods. Electron observations from keV energies to the near-relativistic range were combined with the detection of type III radio bursts and extreme ultraviolet (EUV) observations from multiple spacecraft in order to identify the solar origin of the electron events. Electron anisotropies and timing as well as the plasma and magnetic field environment were evaluated to characterize the interplanetary transport conditions. Results. All electron events were clearly associated with type III radio bursts. EUV jets were also found in association with all of them except one. A diversity of time profiles and pitch-angle distributions was observed. Different source locations and different magnetic connectivity and transport conditions were likely involved. The July 11 event was also detected by Wind, separated 107 degrees in longitude from Solar Orbiter. For the July 22 event, the Suprathermal Electron and Proton (STEP) sensor of EPD allowed for us to not only resolve multiple electron injections at low energies, but it also provided an exceptionally high pitch-angle resolution of a very anisotropic beam. This, together with radio observations of local Langmuir waves suggest a very good magnetic connection during the July 22 event. This scenario is challenged by a high-frequency occultation of the type III radio burst and a nominally non-direct connection to the source; therefore, magnetic connectivity requires further investigation

    Application of Newtonian physics to predict the speed of a gravity racer

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    Gravity racing can be studied using numerical solutions to the equations of motion derived from Newton’s second law. This allows students to explore the physics of gravity racing and to understand how design and course selection influences vehicle speed. Using Euler’s method, we have developed a spreadsheet application that can be used to predict the speed of a gravity powered vehicle. The application includes the effects of air and rolling resistance. Examples of the use of the application for designing a gravity racer are presented and discussed. Predicted speeds are compared to the results of an official world record attempt

    Lower limit on the neutralino mass in the general MSSM

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    We discuss constraints on SUSY models with non-unified gaugino masses and R_P conservation. We derive a lower bound on the neutralino mass combining the direct limits from LEP, the indirect limits from gmuon, bsgamma, Bsmumu and the relic density constraint from WMAP. The lightest neutralino (mneutralino=6GeV) is found in models with a light pseudoscalar with MA<200GeV and a large value for tanÎČtan\beta. Models with heavy pseudoscalars lead to mneutralino>18(29)GeV for tan⁥ÎČ=50(10)\tan\beta=50(10). We show that even a very conservative bound from the muon anomalous magnetic moment can increase the lower bound on the neutralino mass in models with mu<0 and/or large values of tan⁥ÎČ\tan\beta. We then examine the potential of the Tevatron and the direct detection experiments to probe the SUSY models with the lightest neutralinos allowed in the context of light pseudoscalars with high tan⁥ÎČ\tan\beta. We also examine the potential of an e+e- collider of 500GeV to produce SUSY particles in all models with neutralinos lighter than the W. In contrast to the mSUGRA models, observation of at least one sparticle is not always guaranteed.Comment: 37 pages, LateX, 16 figures, paper with higher resolution figures available at http://wwwlapp.in2p3.fr/~boudjema/papers/bound-lsp/bound-lsp.htm
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