3,035 research outputs found
Canonical Constraints on Leptonic Cp Violation using UHCR neutrino fluxes
It is shown that one can in principle constrain the CP-violating parameter
delta from measurements of four independant |V_{ij}|^2, or three of them and a
ratio, in the leptonic sector. To quantify our approach, using unitarity, we
derive simple expressions in terms of four independant |V_{ij}|^2 for
cos(delta) and an expression for sin^2(delta) from J^2. Thus, depending on the
values of |V_{ij}| and their accuracy, we can set meaningful limits on |delta|.
To illustrate numerically, if |V_{u1}|^2 is close to 0.1 with a 10% precision,
and if |V_{e3}^2 is larger than 0.005 and for values of |V_{e2}|^2 and
|V_{u3}|^2 that stay within +-0.1 of the current experimental data leads to a
bound pi/2 < |delta| < pi. Alternatively, a certain combination of parameters
with values of |V_{e3}|^2 larger than 0.01 leads to a closed bound of 73 <
|delta| < 103. In general, we find that it is better to use |V_{u1}|^2 or
|V_{t1}|^2 as the fourth independant |V_{ij}|^2 and that over most of the
parameter space, delta is least sensitive to |V_{e3}|^2. With just three
independant measurements (solar, atmospheric and reactor) it is impossible to
set limits on the CP phase. In this respect, we study the use of ultra high
energy cosmic (UHCR) neutrino fluxes as the additional fourth information. We
find that within the SM, neutrino fluxes of all three flavours will be very
similar but that pushing current neutrino data to their extreme values still
allowed, ratios of cosmic neutrino fluxes can differ by up to 20%; such large
discrepancies could imply negligibly small CP-violation. We also study a non
radiative neutrino decay model and find that the neutrino fluxes can differ by
a factor of up to 3 within this model and that an accuracy of 10% on the
neutrino fluxes is sufficient to set interestin limits on delta.Comment: 8 pages, 2 figures, 5 table
Extracting W Boson Couplings from the Production of Four Leptons
We consider the processes , including all possible charged lepton combinations, with
regard to measuring parameters characterizing the boson. We calculate at
what level these processes can be used to measure anamolous triple-boson
vertice coupling parameters for the cases of colliders at 500
and 1 center of mass energies.Comment: 13 pages,OCIP/C-93-
Applying dissipative dynamical systems to pseudorandom number generation: Equidistribution property and statistical independence of bits at distances up to logarithm of mesh size
The behavior of a family of dissipative dynamical systems representing
transformations of two-dimensional torus is studied on a discrete lattice and
compared with that of conservative hyperbolic automorphisms of the torus.
Applying dissipative dynamical systems to generation of pseudorandom numbers is
shown to be advantageous and equidistribution of probabilities for the
sequences of bits can be achieved. A new algorithm for generating uniform
pseudorandom numbers is proposed. The theory of the generator, which includes
proofs of periodic properties and of statistical independence of bits at
distances up to logarithm of mesh size, is presented. Extensive statistical
testing using available test packages demonstrates excellent results, while the
speed of the generator is comparable to other modern generators.Comment: 6 pages, 3 figures, 3 table
Generating-function method for tensor products
This is the first of two articles devoted to a exposition of the
generating-function method for computing fusion rules in affine Lie algebras.
The present paper is entirely devoted to the study of the tensor-product
(infinite-level) limit of fusions rules.
We start by reviewing Sharp's character method. An alternative approach to
the construction of tensor-product generating functions is then presented which
overcomes most of the technical difficulties associated with the character
method. It is based on the reformulation of the problem of calculating tensor
products in terms of the solution of a set of linear and homogeneous
Diophantine equations whose elementary solutions represent ``elementary
couplings''. Grobner bases provide a tool for generating the complete set of
relations between elementary couplings and, most importantly, as an algorithm
for specifying a complete, compatible set of ``forbidden couplings''.Comment: Harvmac (b mode : 39 p) and Pictex; this is a substantially reduced
version of hep-th/9811113 (with new title); to appear in J. Math. Phy
The 14C(n,g) cross section between 10 keV and 1 MeV
The neutron capture cross section of 14C is of relevance for several
nucleosynthesis scenarios such as inhomogeneous Big Bang models, neutron
induced CNO cycles, and neutrino driven wind models for the r process. The
14C(n,g) reaction is also important for the validation of the Coulomb
dissociation method, where the (n,g) cross section can be indirectly obtained
via the time-reversed process. So far, the example of 14C is the only case with
neutrons where both, direct measurement and indirect Coulomb dissociation, have
been applied. Unfortunately, the interpretation is obscured by discrepancies
between several experiments and theory. Therefore, we report on new direct
measurements of the 14C(n,g) reaction with neutron energies ranging from 20 to
800 keV
Ultracold Neutron Production in a Pulsed Neutron Beam Line
We present the results of an Ultracold neutron (UCN) production experiment in
a pulsed neutron beam line at the Los Alamos Neutron Scattering Center. The
experimental apparatus allows for a comprehensive set of measurements of UCN
production as a function of target temperature, incident neutron energy, target
volume, and applied magnetic field. However, the low counting statistics of the
UCN signal expected can be overwhelmed by the large background associated with
the scattering of the primary cold neutron flux that is required for UCN
production. We have developed a background subtraction technique that takes
advantage of the very different time-of-flight profiles between the UCN and the
cold neutrons, in the pulsed beam. Using the unique timing structure, we can
reliably extract the UCN signal. Solid ortho-D is used to calibrate UCN
transmission through the apparatus, which is designed primarily for studies of
UCN production in solid O. In addition to setting the overall detection
efficiency in the apparatus, UCN production data using solid D suggest that
the UCN upscattering cross-section is smaller than previous estimates,
indicating the deficiency of the incoherent approximation widely used to
estimate inelastic cross-sections in the thermal and cold regimes
Electric Dipole moments of charged leptons and lepton flavor violating interactions in the general two Higgs Doublet model
We calculate the electric dipole moment of electron using the experimental
result of muon electric dipole moment and upper limit of the BR(\mu -->
e\gamma) in the framework of the general two Higgs doublet model. Our
prediction is 10^{-32} e-cm, which lies in the experimental current limits.
Further, we obtain constraints for the Yukawa couplings \bar{\xi}^{D}_{N,\tau
e} and \bar{\xi}^{D}_{N,\tau\mu}. Finally we present an expression which
connects the BR(\tau\to \mu\gamma) and the electric dipole moment of
\tau-lepton and study the relation between these physical quantities.Comment: 8 pages, 4 Figures (required epsf sty
Fermion contribution to the static quantities of arbitrarily charged vector bosons
We present an analysis of the one-loop contribution from left- and
right-handed fermions to the static electromagnetic properties of an
arbitrarily charged no self-conjugate vector boson . Particular emphasis is
given to the case of a no self-conjugate neutral boson . Regardless the
electric charge of the boson, a fermionic loop can induce the two CP-even
form factors but only one CP-odd. As a result the corresponding electric dipole
moment is directly proportional to the magnetic quadrupole moment. The CP-odd
form factor might be severely suppressed since it requires the presence of both
left- and right-handed fermions. The behavior of the form factors is analyzed
for several scenarios of the fermion masses in the context of the decoupling
theorem.Comment: 12 pages, 3 figures, submitted to Journal of Physics
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