516 research outputs found
Symmetry Scheme for Amino Acid Codons
Group theoretical concepts are invoked in a specific model to explain how
only twenty amino acids occur in nature out of a possible sixty four. The
methods we use enable us to justify the occurrence of the recently discovered
twenty first amino acid selenocysteine, and also enables us to predict the
possible existence of two more, as yet undiscovered amino acids.Comment: 18 pages which include 4 figures & 3 table
On the SO(9) structure of supersymmetric Yang-Mills quantum mechanics
In ten space-time dimensions the number of Majorana-Weyl fermions is not
conserved, not only during the time evolution, but also by rotations. As a
consequence the empty Fock state is not rotationally symmetric. We construct
explicitly the simplest singlet state which provides the starting point for
building up invariant SO(9) subspaces. The state has non-zero fermion number
and is a complicated combination of the 1360 elementary, gauge invariant,
gluinoless Fock states with twelve fermions. Fermionic structure of higher
irreps of SO(9) is also briefly outlined.Comment: 9 page
Possible Candidates for SUSY SO(10) Model with an Intermediate Scale
We study the possibility of an intermediate scale existing in supersymmetric
SO(10) grand unified theories: The intermediate scale is demanded to be around
10^{12} GeV so that neutrinos can obtain masses suitable for explaining the
experimental data on the deficit of solar neutrino with
Mikheev-Smirnov-Wolfenstein solution and the existence of hot dark matter. We
show that any Pati-Salam type intermediate symmetries are excluded by requiring
reasonable conditions and only is likely to be realized as an intermediate symmetry.Comment: LaTeX, 8 pages + 1 uuencoded eps figure (Error corrected
Z', new fermions and flavor changing processes, constraints on E models from --> eee
We study a new class of flavor changing interactions, which can arise in
models based on extended gauge groups (rank 4) when new charged fermions are
present together with a new neutral gauge boson. We discuss the cases in which
the flavor changing couplings in the new neutral current coupled to the
are theoretically expected to be large, implying that the observed
suppression of neutral flavor changing transitions must be provided by heavy
masses together with small - mixing angles.
Concentrating on E models, we show how the tight experimental limit on implies serious constraints on the mass and mixing
angle. We conclude that if the value of the flavor changing parameters is
assumed to lie in a theoretically natural range, in most cases the presence of
a much lighter than 1 TeV is unlikely.Comment: plain tex, 22 pages + 2 pages figures in PostScript (appended after
`\bye'), UM-TH 92-1
Mersenne Primes, Polygonal Anomalies and String Theory Classification
It is pointed out that the Mersenne primes and associated
perfect numbers play a significant role in string
theory; this observation may suggest a classification of consistent string
theories.Comment: 10 pages LaTe
Learning Physics from the Cosmic Microwave Background
The Cosmic Microwave Background (CMB) provides a precious window on
fundamental physics at very high energy scales, possibly including quantum
gravity, GUTs and supersymmetry. The CMB has already enabled defect-based
rivals to inflation to be discarded, and will be able to falsify many
inflationary models. In combination with other cosmological observations,
including those of high-redshift supernovae and large-scale structure, the CMB
is on the way to providing a detailed budget for the density of the Universe,
to be compared with particle-physics calculations for neutrinos and cold dark
matter. Thus CMB measurements complement experiments with the LHC and
long-baseline neutrino beams.Comment: 11 pages LaTeX using espcrc2.sty (included), 9 eps figures, invited
talk presented at 6th International Conference on Advanced Technology and
Particle Physics, October 1998, Como, Ital
Duality and the hadron spectrum
A form of exchange degeneracy for mesons and baryons is derived from duality and the absence of resonances in exotic channels. The implications of this structure for the hadron spectrum are discussed
Baryon and Lepton Number Assignment in Models
In models there are new particles whose baryon number is not uniquely
assigned. We point out that the baryon and lepton number assignment to these
particles can change the baryogenesis scenario significantly. We consider
left-right symmetric extension of the standard model in which quantum
number is gauged. The identification of with a generator of is
used to define the baryon and lepton numbers for the exotic particles in a way
that the electroweak baryon and lepton number anomaly corresponding to the
group vanishes, {\it i.e.}, there is no non-perturbative baryon or
lepton number violation during the electroweak phase transition. We study some
consequences of the new assignment.Comment: 14 pages, LaTeX file, 1 submitted Figure file(.eps
Maximal atmospheric neutrino mixing and the small ratio of muon to tau mass
We discuss the problem of the small ratio of muon mass to tau mass in a class
of seesaw models where maximal atmospheric neutrino mixing is enforced through
a -- interchange symmetry. We introduce into those models an
additional symmetry such that in the case of exact
invariance. The symmetry may be softly broken in the Higgs potential, and
one thus achieves in a technically natural way. We speculate
on a wider applicability of this mechanism.Comment: 10 pages, plain LaTeX, no figures, minor changes, final version for
J. Phys.
RADIOACTIVE WASTE DISPOSAL PROJECTS. IDAHO CHEMICAL PROCESSING PLANT TECHNICAL PROGRESS REPORT FOR JULY-SEPTEMBER 1959
The progress of extensive laboratory and pilot plant investigations on the fluidized bed process for the con version of radioactive liquid wastes to solids is reported. These studies are directed toward obtaining information on the dynamics of fluidized bed operation, the removal of volatile fission products and solids particles from gases, the development of equipment and operating techniques, and the various long term disposal aspects of all radioactive wastes. Laboratory studies on the removal of volatile ruthenium from a simulated calciner off-gas showed the removal efficiency of silica gel to decrease with successive wetting and drying cycles. Electrostatic precipitators were found to have a higher removal efficiency for solid particles (alumina) when a wetted wall rather than a dry wall type was used. Tests to determine the distribution of ruthenium in a pilot plant calciner were performed. Pilot plant data on particle growth in a fluidized bed were compared with theoretical equations. Operating experience with a NaK heat transfer system, and with liquid flow controllers is reported. The results of a series of qualitative tests to determine the likelihood of an explosive reaction should NaK leak into a fluidized bed calciner indicated that such a reaction is unlikely. A NaK leak that occurred at a welded junction was attributed to thermal overstressing of the metal and not due to corrosion. Calcium fluoride-impregnated Teflon was found to be a superior gasketing material, both chemically and mechanically, to pure Teflon. A literature survey on the chemistry of zirconium in a calcination process suggested the possibility of calcination in contact with silica and a laboratory unit is being installed to study the process. The hydraulics of a pulsed plate solids-liquid contactor and its associated equipment were determined. A preliminary investigation was started of the possibility of using metallizing techniques to surface coat solid particles and thereby reduce the leaching of fission products when contacted with ground water. Construction of a demonstrational fluidized bed calciner was approximately half completed; however, the national steel strike has slowed the construction schedule and the completion date cannot be estimated until the strike is settled. Process and equipment reviews of the facility and the results of thermal conductivity measurements on Idaho sands are reported. (auth
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