22,490 research outputs found

    Hydrogen at the rooftop: Compact CPV-hydrogen system to convert sunlight to hydrogen

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    Despite being highest potential energy source, solar intermittency and low power density make it difficult for solar energy to compete with the conventional power plants. Highly efficient concentrated photovoltaic (CPV) system provides best technology to be paired with the electrolytic hydrogen production, as a sustainable energy source with long term energy storage. However, the conventional gigantic design of CPV system limits its market and application to the open desert fields without any rooftop installation scope, unlike conventional PV. This makes CPV less popular among solar energy customers. This paper discusses the development of compact CPV-Hydrogen system for the rooftop application in the urban region. The in-house built compact CPV system works with hybrid solar tracking of 0.1° accuracy, ensured through proposed double lens collimator based solar tracking sensor. With PEM based electrolyser, the compact CPV-hydrogen system showed 28% CPV efficiency and 18% sunlight to hydrogen (STH) efficiency, for rooftop operation in tropical region of Singapore. For plant designers, the solar to hydrogen production rating of 217 kWhe/kgH2 has been presented with 15% STH daily average efficiency, recorded from the long term field operation of the syste

    Estimate of CP Violation for the LBNE Project and $\delta_{CP}

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    Measurements of CP violation (CPV) and the basic δCP\delta_{CP} parameter are the goals of the LBNE Project, which is being planned. Using the expected energy and baseline parameters for the LBNE Project, CPV and the dependence of CPV on δCP\delta_{CP} are estimated, to help in the planning of this project.Comment: 7 pages, 1 figur

    Group-theoretic restrictions on generation of CP-violation in multi-Higgs-doublet models

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    It has been known since decades that imposing a symmetry group G on the scalar sector of multi-Higgs-doublet models has consequences for CP-violation. In all examples of two- and three-Higgs-doublet models equipped with symmetries, one observes the following intriguing property: if G prevents explicit CP-violation (CPV), at least in the neutral Higgs sector, then it also prevents spontaneous CPV, and if G allows explicit CPV, then it allows for spontaneous CPV. One is led to conjecture that this is a general phenomenon. In this paper, we prove this conjecture for any rephasing symmetry group G and any number of doublets.Comment: 16 page

    EDMs vs. CPV in B_{s,d} mixing in two Higgs doublet models with MFV

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    We analyze the correlations between electric dipole moments (EDMs) of the neutron and heavy atoms and CP violation in B_{s,d} mixing in two Higgs doublet models respecting the Minimal Flavour Violation hypothesis, with flavour-blind CP-violating (CPV) phases. In particular, we consider the case of flavour-blind CPV phases from i) the Yukawa interactions and ii) the Higgs potential. We show that in both cases the upper bounds on the above EDMs do not forbid sizable non-standard CPV effects in B_s mixing. However, if a large CPV phase in B_s mixing will be confirmed, this will imply EDMs very close to their present experimental bounds, within the reach of the next generation of experiments, as well as BR(B_{s,d}-> mu^+ mu^-) typically largely enhanced over its SM expectation. The two flavour-blind CPV mechanisms can be distinguished through the correlation between S_psi K_S and S_psi phi that is strikingly different if only one of them is relevant. Which of these two CPV mechanisms dominates depends on the precise values of S_psi phi and S_psi K_S, as well as on the CKM phase (as determined by tree-level processes). Current data seems to show a mild preference for a hybrid scenario where both these mechanisms are at work.Comment: 9 pages, 8 figures. V2: minor modifications, few typos corrected, few refs adde
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