1,606 research outputs found
Fourth SM Family Manifestations at CLIC
The latest electroweak precision data allow the existence of additional
chiral generations in the standard model. We study prospects of search for the
fourth standard model family fermions and quarkonia at and options of CLIC. It is shown that CLIC will be powerfull machine for
discovery and investigation of both fourth family leptons and quarkonia.
Moreover, the formation of the fourth family quarkonia will give a new
opportunity to investigate Higgs boson properties.Comment: 7 pages, 6 Table
The Fourth SM Family Neutrino at Future Linear Colliders
It is known that Flavor Democracy favors the existence of the fourth standard
model (SM) family. In order to give nonzero masses for the first three family
fermions Flavor Democracy has to be slightly broken. A parametrization for
democracy breaking, which gives the correct values for fundamental fermion
masses and, at the same time, predicts quark and lepton CKM matrices in a good
agreement with the experimental data, is proposed. The pair productions of the
fourth SM family Dirac and Majorana neutrinos at future
linear colliders with GeV, 1 TeV and 3 TeV are considered. The
cross section for the process
and the branching ratios for possible decay modes of the both neutrinos are
determined. The decays of the fourth family neutrinos into muon channels
provide cleanest signature at
colliders. Meanwhile, in our parametrization this channel is
dominant. bosons produced in decays of the fourth family neutrinos will be
seen in detector as either di-jets or isolated leptons. As an example we
consider the production of 200 GeV mass fourth family neutrinos at
GeV linear colliders by taking into account di-muon plus
four-jet events as signatures.Comment: 16 pages, 3 figures, 10 table
Role of Alpha Oscillations During Short Time Memory Task Investigated by Graph Based Partitioning
In this study, we investigate the clustering pattern of alpha band (8 Hz - 12 Hz) electroencephalogram (EEG) oscillations obtained from healthy individuals during a short time memory task with 3 different memory loads. The retention period during which subjects were asked to memorize a pattern in a square matrix is analyzed with a graph theoretical approach. The functional coupling among EEG electrodes are quantified via mutual information in the time-frequency plane. A spectral clustering algorithm followed by bootstrapping is used to parcellate memory related circuits and for identifying significant clusters in the brain. The main outcome of the study is that the size of the significant clusters formed by alpha oscillations decreases as the memory load increases. This finding corroborates the active inhibition hypothesis about alpha oscillations
Masses and decay constants of bound states containing fourth family quarks from QCD sum rules
The heavy fourth generation of quarks that have sufficiently small mixing
with the three known SM families form hadrons. In the present work, we
calculate the masses and decay constants of mesons containing either both
quarks from the fourth generation or one from fourth family and the other from
known third family SM quarks in the framework of the QCD sum rules. In the
calculations, we take into account two gluon condensate diagrams as
nonperturbative contributions. The obtained results reduce to the known masses
and decay constants of the and quarkonia when the fourth
family quark is replaced by the bottom or charm quark.Comment: 15 Pages, 9 Figures and 6 Table
Two-dimensional random walk in a bounded domain
In a recent Letter Ciftci and Cakmak [EPL 87, 60003 (2009)] showed that the
two dimensional random walk in a bounded domain, where walkers which cross the
boundary return to a base curve near origin with deterministic rules, can
produce regular patterns. Our numerical calculations suggest that the
cumulative probability distribution function of the returning walkers along the
base curve is a Devil's staircase, which can be explained from the mapping of
these walks to a non-linear stochastic map. The non-trivial probability
distribution function(PDF) is a universal feature of CCRW characterized by the
fractal dimension d=1.75(0) of the PDF bounding curve.Comment: 4 pages, 7 eps figures, revtex
Energies and wave functions for a soft-core Coulomb potential
For the family of model soft Coulomb potentials represented by V(r) =
-\frac{Z}{(r^q+\beta^q)^{\frac{1}{q}}}, with the parameters
Z>0, \beta>0, q \ge 1, it is shown analytically that the potentials and
eigenvalues, E_{\nu\ell}, are monotonic in each parameter. The potential
envelope method is applied to obtain approximate analytic estimates in terms of
the known exact spectra for pure power potentials. For the case q =1, the
Asymptotic Iteration Method is used to find exact analytic results for the
eigenvalues E_{\nu\ell} and corresponding wave functions, expressed in terms of
Z and \beta. A proof is presented establishing the general concavity of the
scaled electron density near the nucleus resulting from the truncated
potentials for all q. Based on an analysis of extensive numerical calculations,
it is conjectured that the crossing between the pair of states
[(\nu,\ell),(\nu',\ell')], is given by the condition \nu'\geq (\nu+1) and \ell'
\geq (\ell+3). The significance of these results for the interaction of an
intense laser field with an atom is pointed out. Differences in the observed
level-crossing effects between the soft potentials and the hydrogen atom
confined inside an impenetrable sphere are discussed.Comment: 13 pages, 5 figures, title change, minor revision
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