7,900 research outputs found
Masses and Interactions of q-Fermionic Knots
The q-electroweak theory suggests a description of elementary particles as
solitons labelled by the irreducible representations of SU_q(2). Since knots
may also be labelled by the irreducible representations of SU_q(2), we study a
model of elementary particles based on a one-to-one correspondence between the
four families of Fermions (leptons, neutrinos, (-1/3) quarks, (2/3) quarks) and
the four simplest knots (trefoils). In this model the three particles of each
family are identified with the ground and first two excited states of their
common trefoil. Guided by the standard electroweak theory we calculate
conditions restricting the masses of the fermions and the interactions between
them.
In its present form the model predicts a fourth generation of fermions as
well as a neutrino spectrum. The same model with q almost equal to 1 is
compatible with the Kobayashi-Maskawa matrix. Depending on the test of these
predictions, the model may be refined.Comment: 40 pages, 2 figures, latex forma
Light environment - A. Visible light. B. Ultraviolet light
Visible and ultraviolet light environment as related to human performance and safety during space mission
Are Bosonic Replicas Faulty?
Motivated by the ongoing discussion about a seeming asymmetry in the
performance of fermionic and bosonic replicas, we present an exact,
nonperturbative approach to zero-dimensional replica field theories belonging
to the broadly interpreted "beta=2" Dyson symmetry class. We then utilise the
formalism developed to demonstrate that the bosonic replicas do correctly
reproduce the microscopic spectral density in the QCD inspired chiral Gaussian
unitary ensemble. This disproves the myth that the bosonic replica field
theories are intrinsically faulty.Comment: 4.3 pages; final version to appear in PR
Analytical Results for a Single-Unit System Subject To Markovian Wear and Shocks
This thesis develops and analyzers a mathematical model for the reliability measures of a single-unit system subject to continuous wear due to its operating environment and randomly occurring shocks that inflict a random amount of damage to the unit. Assuming a Markovian operating environment and shock arrival mechanism, Laplace-Stieltjes transform expressions are obtained for the failure time distribution and all of its moments. Moreover, an analytical expression is derived for the long-run availability of the single-unit system when it is subject to an inspect-and-replace maintenance policy. The analytical results are illustrated, and their results compared with those of Monte Carlo-simulated failure data. The numerical results indicate that the reliability measures may be accurately computed via numerical inversion of the transform expressions in a straightforward manner when the input parameters are known a priori. In stark contrast to the simulation model which requires several hours to obtain the reliability measures, the analytical procedure computes the same measures in only a few seconds
Evolution of Lyman Alpha Galaxies: Stellar Populations at z ~ 0.3
We present the results of a stellar population analysis of 30 Lyman alpha
emitting galaxies (LAEs) at z ~ 0.3, previously discovered with the Galaxy
Evolution Explorer (GALEX). With a few exceptions, we can accurately fit model
spectral energy distributions to these objects, representing the first time
this has been done for a large sample of LAEs at z < 3, a gap of ~ 8 Gyr in the
history of the Universe. From the 26/30 LAEs which we can fit, we find an age
and stellar mass range of 200 Myr - 10 Gyr and 10^9 - 10^11 Msol, respectively.
These objects thus appear to be significantly older and more massive than LAEs
at high-redshift. We also find that these LAEs show a mild trend towards higher
metallicity than those at high redshift, as well as a tighter range of dust
attenuation and interstellar medium geometry. These results suggest that
low-redshift LAEs have evolved significantly from those at high redshift.Comment: Accepted for publication in the Astrophysical Journal. Replaced with
accepted version. Eight pages, four figures, in emulateapj forma
Collapse of Charge Gap in Random Mott Insulators
Effects of randomness on interacting fermionic systems in one dimension are
investigated by quantum Monte-Carlo techniques. At first, interacting spinless
fermions are studied whose ground state shows charge ordering. Quantum phase
transition due to randomness is observed associated with the collapse of the
charge ordering. We also treat random Hubbard model focusing on the Mott gap.
Although the randomness closes the Mott gap and low-lying states are created,
which is observed in the charge compressibility, no (quasi-) Fermi surface
singularity is formed. It implies localized nature of the low-lying states.Comment: RevTeX with 3 postscript figure
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