22,572 research outputs found
Projected Richardson varieties and affine Schubert varieties
Let be a complex quasi-simple algebraic group and be a partial flag
variety. The projections of Richardson varieties from the full flag variety
form a stratification of . We show that the closure partial order of
projected Richardson varieties agrees with that of a subset of Schubert
varieties in the affine flag variety of . Furthermore, we compare the
torus-equivariant cohomology and -theory classes of these two
stratifications by pushing or pulling these classes to the affine Grassmannian.
Our work generalizes results of Knutson, Lam, and Speyer for the Grassmannian
of type .Comment: 20 pages. To appear in Annales de l'institut fourie
Asymptotic properties of maximum likelihood estimators in models with multiple change points
Models with multiple change points are used in many fields; however, the
theoretical properties of maximum likelihood estimators of such models have
received relatively little attention. The goal of this paper is to establish
the asymptotic properties of maximum likelihood estimators of the parameters of
a multiple change-point model for a general class of models in which the form
of the distribution can change from segment to segment and in which, possibly,
there are parameters that are common to all segments. Consistency of the
maximum likelihood estimators of the change points is established and the rate
of convergence is determined; the asymptotic distribution of the maximum
likelihood estimators of the parameters of the within-segment distributions is
also derived. Since the approach used in single change-point models is not
easily extended to multiple change-point models, these results require the
introduction of those tools for analyzing the likelihood function in a multiple
change-point model.Comment: Published in at http://dx.doi.org/10.3150/09-BEJ232 the Bernoulli
(http://isi.cbs.nl/bernoulli/) by the International Statistical
Institute/Bernoulli Society (http://isi.cbs.nl/BS/bshome.htm
Status of the Zee-Babu model for neutrino mass and possible tests at a like-sign linear collider
We provide an updated scan of the allowed parameter space of the two-loop
Zee-Babu model for neutrino mass. Taking into account most recent experimental
data on as well as the mixing angle we obtain
lower bounds on the masses of the singly and doubly charged scalars of between
1 to 2 TeV, with some dependence on perturbativity and fine-tuning
requirements. This makes the scalars difficult to observe at LHC with 14 TeV
even with optimistic assumptions on the luminosity, and would require a
multi-TeV linear collider to see the scalar resonances. We point out, however,
that a sub-TeV linear collider in the like-sign mode may be able to observe
lepton flavour violating processes such as due to
contact interactions induced by the doubly charged scalar with masses up to
around 10 TeV. We investigate the possibility to distinguish the Zee-Babu model
from the Higgs triplet model using such processes.Comment: 12 pages, 7 figure
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