5,414 research outputs found
Neutrino degeneracy and cosmological nucleosynthesis, revisited
A reexamination of the effects of non-zero degeneracies on Big Bang Nucleosynthesis is made. As previously noted, non-trivial alterations of the standard model conclusions can be induced only if excess lepton numbers L sub i, comparable to photon number densities eta sub tau, are assumed (where eta sub tau is approx. 3 times 10(exp 9) eta sub b). Furthermore, the required lepton number densities (L sub i eta sub tau) must be different for upsilon sub e than for upsilon sub mu and epsilon sub tau. It is shown that this loophole in the standard model of nucleosynthesis is robust and will not vanish as abundance and reaction rate determinations improve. However, it is also argued that theoretically (L sub e) approx. (L sub mu) approx. (L sub tau) approx. eta sub b is much less than eta sub tau which would preclude this loophole in standard unified models
Stochastic Process Associated with Traveling Wave Solutions of the Sine-Gordon Equation
Stochastic processes associated with traveling wave solutions of the
sine-Gordon equation are presented. The structure of the forward Kolmogorov
equation as a conservation law is essential in the construction and so is the
traveling wave structure. The derived stochastic processes are analyzed
numerically. An interpretation of the behaviors of the stochastic processes is
given in terms of the equation of motion.Comment: 12 pages, 9 figures; corrected typo
Gravitational Lensing by Power-Law Mass Distributions: A Fast and Exact Series Approach
We present an analytical formulation of gravitational lensing using familiar
triaxial power-law mass distributions, where the 3-dimensional mass density is
given by . The deflection angle and magnification factor are
obtained analytically as Fourier series. We give the exact expressions for the
deflection angle and magnification factor. The formulae for the deflection
angle and magnification factor given in this paper will be useful for numerical
studies of observed lens systems. An application of our results to the Einstein
Cross can be found in Chae, Turnshek, & Khersonsky (1998). Our series approach
can be viewed as a user-friendly and efficient method to calculate lensing
properties that is better than the more conventional approaches, e.g.,
numerical integrations, multipole expansions.Comment: 24 pages, 3 Postscript figures, ApJ in press (October 10th
In Situ Characterisation of Permanent Magnetic Quadrupoles for focussing proton beams
High intensity laser driven proton beams are at present receiving much
attention. The reasons for this are many but high on the list is the potential
to produce compact accelerators. However two of the limitations of this
technology is that unlike conventional nuclear RF accelerators lasers produce
diverging beams with an exponential energy distribution. A number of different
approaches have been attempted to monochromise these beams but it has become
obvious that magnetic spectrometer technology developed over many years by
nuclear physicists to transport and focus proton beams could play an important
role for this purpose. This paper deals with the design and characterisation of
a magnetic quadrupole system which will attempt to focus and transport
laser-accelerated proton beams.Comment: 20 pages, 42 figure
On the spatial Markov property of soups of unoriented and oriented loops
We describe simple properties of some soups of unoriented Markov loops and of
some soups of oriented Markov loops that can be interpreted as a spatial Markov
property of these loop-soups. This property of the latter soup is related to
well-known features of the uniform spanning trees (such as Wilson's algorithm)
while the Markov property of the former soup is related to the Gaussian Free
Field and to identities used in the foundational papers of Symanzik, Nelson,
and of Brydges, Fr\"ohlich and Spencer or Dynkin, or more recently by Le Jan
On the temperature dependence of correlation functions in the space like direction in hot QCD
We study the temperature dependence of quark antiquark correlations in the
space like direction. In particular, we predict the temperature dependence of
space like Bethe-Salpeter amplitudes using recent Lattice gauge data for the
space like string potential. We also investigate the effect of the space like
string potential on the screening mass and discuss possible corrections which
may arise when working with point sources.Comment: 15 pages 8 figures (not included, will be sent on request),
(SUNY-NTG-94-3
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