178 research outputs found
Characterizations of Student's t-distribution via regressions of order statistics
Utilizing regression properties of order statistics, we characterize a family
of distributions introduced by Akhundov, Balakrishnan, and Nevzorov (2004),
that includes the t-distribution with two degrees of freedom as one of its
members. Then we extend this characterization result to t-distribution with
more than two degrees of freedom.Comment: To appear in "Statistics
New Bound States of Top-anti-Top Quarks and T-balls Production at Colliders (Tevatron, LHC, etc.)
The present talk is based on the assumption that New Bound States (NBSs) of
top-anti-top quarks (named T-balls) exist in the Standard Model (SM): a) there
exists the scalar 1S - bound state of 6t+6\bar t - the bound state of 6
top-quarks with their 6 anti-top-quarks; b) the forces which bind these
top-quarks are very strong and almost completely compensate the mass of the 12
top-anti-top-quarks forming this bound state; c) such strong forces are
produced by the interactions of top-quarks via the virtual exchange of the
scalar Higgs bosons having the large value of the top-quark Yukawa coupling
constant g_t\simeq 1. Theory also predicts the existence of the NBS 6t + 5\bar
t, which is a color triplet and a fermion similar to the t'-quark of the fourth
generation. We have also considered "b-replaced" NBSs: n_b b + (6t + 6\bar t -
n_b t) and n'_b b + (6t + 5\bar t - n'_b t), etc. We have estimated the masses
of the lightest "b-replaced" NBS: M_{NBS}\simeq (300 - 400) GeV, and discussed
the larger masses of the NBSs. We have developed a theory of the scalar
T-ball's condensate, and predicted the existence of the three SM phases,
calculating the top-quark Yukawa coupling constant at the border of two phases
(with T-ball's condensate and without it) equal to: g_t \approx 1. The
searching for the Higgs boson H and T-balls at the Tevatron and LHC is
discussed.Comment: 43 pages, 20 figure
Quasi-fixed point scenario in the modified NMSSM
The simplest extension of the MSSM that does not contradict LEP II
experimental bound on the lightest Higgs boson mass at is the
modified Next-to-Minimal Supersymmetric Standard Model (MNSSM). We investigate
the renormalization of Yukawa couplings and soft SUSY breaking terms in this
model. The possibility of -quark and -lepton Yukawa coupling
unification at the Grand Unification scale is studied. The particle
spectrum is analysed in the vicinity of the quasi-fixed point where the
solutions of renormalization group equations are concentrated at the
electroweak scale.Comment: 19 pages, 3 figures, LaTeX2
Correlations of record events as a test for heavy-tailed distributions
A record is an entry in a time series that is larger or smaller than all
previous entries. If the time series consists of independent, identically
distributed random variables with a superimposed linear trend, record events
are positively (negatively) correlated when the tail of the distribution is
heavier (lighter) than exponential. Here we use these correlations to detect
heavy-tailed behavior in small sets of independent random variables. The method
consists of converting random subsets of the data into time series with a
tunable linear drift and computing the resulting record correlations.Comment: Revised version, to appear in Physical Review Letter
Adaptation dynamics of the quasispecies model
We study the adaptation dynamics of an initially maladapted population
evolving via the elementary processes of mutation and selection. The evolution
occurs on rugged fitness landscapes which are defined on the multi-dimensional
genotypic space and have many local peaks separated by low fitness valleys. We
mainly focus on the Eigen's model that describes the deterministic dynamics of
an infinite number of self-replicating molecules. In the stationary state, for
small mutation rates such a population forms a {\it quasispecies} which
consists of the fittest genotype and its closely related mutants. The
quasispecies dynamics on rugged fitness landscape follow a punctuated (or
step-like) pattern in which a population jumps from a low fitness peak to a
higher one, stays there for a considerable time before shifting the peak again
and eventually reaches the global maximum of the fitness landscape. We
calculate exactly several properties of this dynamical process within a
simplified version of the quasispecies model.Comment: Proceedings of Statphys conference at IIT Guwahati, to be published
in Praman
- …