2,536 research outputs found
Sequential procedure for test of uniformity in multinomial models
In this thesis we deal with a sequential procedure for testing uniformity in a given multinomial distribution using inverse sampling. From a decision theoretic point of view, we devise an efficient stopping rule that satisfies a pre-determined P*-condition. Dirichlet distribution Type II will be primarily used for developing the inverse-type sequential procedure based on the decision theoretic point of view. We assume a non-zero cell probability (parameter) for given multinomial models. In particular, we will be focusing on the equal cell probability configuration (EPC) among all feasible cell configurations. One of the main goals is to find optimal sample sizes that resulted from a desirable probability level, the probability of correct decision P{CD}, in testing uniformity in multinomial models. As an illustration, wheel of fortune will be considered to fit the developed model. Finally, the developed procedure will be discussed via Monte Carlo experimentation
Signatures of Self-Interacting Dark Matter in the Matter Power Spectrum and the CMB
We consider a self-interacting dark matter model in which the massive dark
photon mediating the self-interaction decays to light dark fermions to avoid
over-closing the universe. We find that if the model is constrained to explain
the dark matter halos inferred for spiral galaxies and galaxy clusters
simultaneously, there is a strong indication that dark matter is produced
asymmetrically in the early universe. It also implies the presence of dark
radiation, late kinetic decoupling for dark matter, and a suppressed linear
power spectrum due to dark acoustic damping. The Lyman- forest power
spectrum measurements put a strong upper limit on the damping scale and the
model has little room to reduce the abundances of satellite galaxies. Future
observations in the matter power spectrum and the CMB, in tandem with the
impact of self-interactions in galactic halos, makes it possible to measure the
gauge coupling and masses of the dark sector particles even when signals in
conventional dark matter searches are absent.Comment: 5 pages, 7 figures, published version in PL
Competition between the inter-valley scattering and the intra-valley scattering on magnetoconductivity induced by screened Coulomb disorder in Weyl semimetals
Recent experiments on Weyl semimetals reveal that charged impurities may play
an important role. We use a screened Coulomb disorder to model the charged
impurities, and study the magneto-transport in a two-node Weyl semimetal. It is
found that when the external magnetic field is applied parallel to the electric
field, the calculated longitudinal magnetoconductivity shows positive in the
magnetic field, which is just the negative longitudinal magnetoresistivity
(LMR) observed in experiments. When the two fields are perpendicular to each
other, the transverse magnetoconductivities are measured. It is found that the
longitudinal (transverse) magnetoconductivity is suppressed (enhanced)
sensitively with increasing the screening length. This feature makes it hardly
to observe the negative LMR in Weyl semimetals experimentally owing to a small
screening length. Our findings gain insight into further understanding on
recently actively debated magneto-transport behaviors in Weyl semimetals.
Furthermore we studied the relative weight of the inter-valley scattering and
the intra-valley scattering. It shows that the former is as important as the
latter and even dominates in the case of strong magnetic fields and small
screening length. We emphasize that the discussions on inter-valley scattering
is out of the realm of one-node model which has been studied.Comment: 14 pages, 5 figure
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