8,061 research outputs found

    Observational Constraints on Varying Alpha in Λ(α)\Lambda(\alpha)CDM Cosmology

    Full text link
    In this work, we consider the so-called Λ(α)\Lambda(\alpha)CDM cosmology with Λα6\Lambda\propto\alpha^{-6} while the fine-structure "constant" α\alpha is varying. In this scenario, the accelerated expansion of the universe is driven by the cosmological "constant" Λ\Lambda (equivalently the vacuum energy), and the varying α\alpha is driven by a subdominant scalar field ϕ\phi coupling with the electromagnetic field. The observational constraints on the varying α\alpha and Λα6\Lambda\propto\alpha^{-6} models with various couplings BF(ϕ)B_F(\phi) between the subdominant scalar field ϕ\phi and the electromagnetic field are considered.Comment: 13 pages, 5 figures, 1 table, revtex4; v2: appendix removed, Commun. Theor. Phys. in press; v3: published version. arXiv admin note: text overlap with arXiv:1605.0457

    Three-generation neutrino oscillations in curved spacetime

    Get PDF
    Three-generation MSW effect in curved spacetime is studied and a brief discussion on the gravitational correction to the neutrino self-energy is given. The modified mixing parameters and corresponding conversion probabilities of neutrinos after traveling through celestial objects of constant densities are obtained. The method to distinguish between the normal hierarchy and inverted hierarchy is discussed in this framework. Due to the gravitational redshift of energy, in some extreme situations, the resonance energy of neutrinos might be shifted noticeably and the gravitational effect on the self-energy of neutrino becomes significant at the vicinities of spacetime singularities.Comment: 25 pages, 5 figures, 2 tables. Some changes are made according to referee's suggestions. The final version is to be published at Nuclear Physics

    Timing and Power Optimization Using Mixed-Dynamic-Static CMOS

    Get PDF
    An effective approach to timing and power optimization for single clocking and multiple clocking dynamic CMOS designs is presented in this thesis. For the single-clocking scheme dynamic CMOS sub-blocks can be replaced by static CMOS and mixed-dynamic-static CMOS for power minimization. For the multiple-clocking scheme the delay of data ready for use plays more important role than its clock pulse in timing optimization. Power minimization can be achieved by implementing dynamic CMOS sub-blocks with static or mixed-dynamic-static CMOS. In comparison with the benchmark 16-bit carry select adder in dynamic CMOS, the critical path delay is reduced by 41.1% using the single-clock optimization approach; the power and delay are reduced by 43% and 41.1% respectively using the multiple-clock optimization approach. In comparison with the benchmark 64-bit comparator in dynamic CMOS, the critical path delay is reduced by 49% using the single-clock optimization approach; the power and delay are reduced by 43.1% and 49% respectively using the multiple-clock optimization approach

    Short note on two output-dependent hidden Markov models

    Get PDF
    The purpose of this note is to study the assumption of mutual information independence", which is used by Zhou (2005) for deriving an output-dependent hidden Markov model, the so-called discriminative HMM (D-HMM), in the context of determining a stochastic optimal sequence of hidden states. The assumption is extended to derive its generative counterpart, the G-HMM. In addition, state-dependent representations for two output-dependent HMMs, namely HMMSDO (Li, 2005) and D-HMM, are presented
    corecore