24,279 research outputs found
Scaling limit of a non-relativistic model
I calculate the structure function for scattering from the two-body bound
state in its lowest level in a non-relativistic model of confined scalar
``quarks'' of masses and . The scaling limit in exists and is non-vanishing only for the values
and which correspond to the fractions of
the momentum of the two-body system carried by each of the ``quarks.'' In the
scaling limit, the interference from scattering off of the two ``quarks''
vanishes. Thus the scaling limit of this model agrees with the parton picture.Comment: 10 pages, 3 figures not included, in LaTex, UMD 92-22
Variational Principle in the Algebra of Asymptotic Fields
This paper proposes a variational principle for the solutions of quantum
field theories in which the ``trial functions'' are chosen from the algebra of
asymptotic fields, and illustrates this variational principle in simple cases.Comment: 15 pages, Latex, no figure
A plan for the economic assessment of the benefits of improved meteorological forecasts
Benefit-cost relationships for the development of meteorological satellites are outlined. The weather forecast capabilities of the various weather satellites (Tiros, SEOS, Nimbus) are discussed, and the development of additional satellite systems is examined. A rational approach is development that leads to the establishment of the economic benefits which may result from the utilization of meteorological satellite data. The economic and social impacts of improved weather forecasting for industries and resources management are discussed, and significant weather sensitive industries are listed
The origins of nuclear astrophysics at Caltech
Shortly before the start of World War II, several theoretical
physicists, including Hans Bethe and Carl von Weizsacker, advanced the
idea that the sun derives it energy from nuclear reactions within its
core. C. C. Lauritsen and William Fowler, nuclear physicists at
Caltech's Kellogg Laboratory, were among the first experimentalists to
appreciate the application of nuclear physics to stellar interiors.
Post-war strategies for studying nuclear processes in the stars
included an innovative series of unofficial, weekly seminars with Mt.
Wilson astronomers at director Ira Bowen's house, the testing of
Bethe's carbon cycle in Kellogg, and the collaboration with a diverse
group of scientists ranging from cosmologist Fred Hoyle to astronomers
Margaret and Geoffrey Burbidge. The events leading up to the
publication of the 1957 paper by Fowler, Hoyle, Burbidge, and Burbidge,
in The Reviews of Modern Physics, now regarded as a watershed in the
history of nuclear astrophysics, are discussed. For his work in low-energy
nuclear astrophysics, Fowler won the 1983 Nobel Prize in
physics
Non-Invariant Ground States, Thermal Average, and generalized Fermionic Statistics
We present an approach to generalised fermionic statistics which relates the
existence of a generalised statistical behaviour to non-invariant ground
states. Considering the thermal average of an operatorial generalization of the
Heisenberg algebra, we get an occupation number which depends on the degree of
mixing between symmetric and antisymmetric sectors of the ground state. A
natural prescription is given for the construction of a supersymmetric
statistics. We also show that the structure of the vacuum, and therefore the
statistical behaviour of the system, can be accounted for in terms of a second
order phase transition.Comment: 11 pages, accepted in Physics Letters
Covariance of Time-Ordered Products Implies Local Commutativity of Fields
We formulate Lorentz covariance of a quantum field theory in terms of
covariance of time-ordered products (or other Green's functions). This
formulation of Lorentz covariance implies spacelike local commutativity or
anticommutativity of fields, sometimes called microscopic causality or
microcausality. With this formulation microcausality does not have to be taken
as a separate assumption.Comment: 6 pages, section on non-local theories removed, published versio
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