17,044 research outputs found
Modelling the number counts of early-type galaxies by pure luminosity evolution
In this paper, we explore the plausible luminosity evolution of early-type
galaxies in different cosmological models by constructing a set of pure
luminosity evolution (PLE) models via the choices of the star formation rate
(SFR) parameters and formation redshift of galaxies, with the
observational constraints derived from the Hubble Space Telescope (HST)
morphological number counts for elliptical and S0 galaxies of the Medium Deep
Survey (MDS) and the Hubble Deep Field (HDF). We find that the number counts of
early-type galaxies can be explained by the pure luminosity evolution models,
without invoking exotic scenarios such as merging or introducing an additional
population. But the evolution should be nearly passive, with a high
assumed. The conclusion is valid in all of the three cosmological models we
adopted in this paper. We also present the redshift distributions for three
bins of observed magnitudes in F814w pass-band, to show at which redshift are
the objects that dominate the counts at a given magnitude. The predictions of
the redshift distribution of are also presented for comparison
with future data.Comment: Plain tex, 15pages, 9 eps figures, plus an extra figure fig2c.eps,
with the tex-macro mn.tex. MNRAS, accepte
Reconstruction of the Neutrino Mixing Matrix and Leptonic Unitarity Triangles from Long-baseline Neutrino Oscillations
We derive a new set of sum rules between the neutrino mass and mixing
parameters in vacuum and their effective counterparts in matter. The moduli of
nine genuine lepton mixing matrix elements can then be calculated in terms of
the matter-corrected ones, and the latter can directly be determined from a
variety of long-baseline neutrino oscillations. We show that it is possible to
reconstruct the leptonic unitarity triangles and CP violation in a similar
parametrization-independent way.Comment: 12 pages, 1 figur
Generalized Friedberg-Lee model for neutrino masses and leptonic CP violation from mu-tau symmetry breaking
Assuming the Majorana nature of massive neutrinos, we generalize the
Friedberg-Lee neutrino mass model to include CP violation in the neutrino mass
matrix M_\nu. The most general case with all the free parameters of M_\nu being
complex is discussed. We show that a favorable neutrino mixing pattern (with
\theta_12 \approx 35.3^\circ, \theta_23=45^\circ, \theta_13 \neq 0^\circ and
\delta=90^\circ) can naturally be derived from M_\nu, if it has an approximate
or softly-broken \mu-\tau symmetry. We also point out a different way to obtain
the nearly tri-bimaximal neutrino mixing pattern with \delta=0^\circ and
non-vanishing Majorana phases.Comment: 4 pages. Talk given by He Zhang at the 4th International Conference
on Flavor Physics, 24-28 September 2007, Beijing (to appear in the
proceedings
Model-independent Constraints on the Weak Phase (or ) and QCD Penguin Pollution in Decays
We present an {\it algebraic} isospin approach towards a more straightforward
and model-independent determination of the weak phase (or )
and QCD penguin pollution in decays. The world averages of
current experimental data allow us to impose some useful constraints on the
isospin parameters of transitions. We find that the magnitude of
(or ) extracted from the indirect CP violation in
mode is in agreement with the standard-model expectation from other indirect
measurements, but its four-fold discrete ambiguity has to be resolved in the
near future.Comment: 11 pages, 3 figures, 2 table
Robust fault detection for networked systems with communication delay and data missing
n this paper, the robust fault detection problem is investigated for a class of discrete-time networked systems with unknown input and multiple state delays. A novel measurement model is utilized to represent both the random measurement delays and the stochastic data missing phenomenon, which typically result from the limited capacity of the communication networks. The network status is assumed to vary in a Markovian fashion and its transition probability matrix is uncertain but resides in a known convex set of a polytopic type. The main purpose of this paper is to design a robust fault detection filter such that, for all unknown inputs, possible parameter uncertainties and incomplete measurements, the error between the residual signal and the fault signal is made as small as possible. By casting the addressed robust fault detection problem into an auxiliary robust H∞ filtering problem of a certain Markovian jumping system, a sufficient condition for the existence of the desired robust fault detection filter is established in terms of linear matrix inequalities. A numerical example is provided to illustrate the effectiveness and applicability of the proposed technique
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