34 research outputs found
Experience, Knowledge, and Democracy: Television through a Deweyan Lens
While there have been numerous studies regarding television and its influence on modern life conducted in the past sixty years, there has not yet been a critique of television grounded in the work of John Dewey. John Dewey died when television was still a new technology; however, I believe that Dewey would have been critical of television had he lived to further experience it. One need only look to Dewey’s writings regarding mass communication and media to see that he was critical of how communication technologies influence human society. Television programming is nearly ubiquitous today and it requires ongoing inquiry as its influence is widespread and continues to grow. This dissertation extends television studies by developing a Deweyan critique of the medium. I assert in this dissertation that Dewey’s philosophy, especially his notions of experience, knowledge, and democracy can inform a current critique of television
Vanishing Str M^2 in the presence of anomalous U_A(1)
We show that the presence of an anomalous factor in the gauge
group of string-derived models may have the new and important phenomenological
consequence of allowing the vanishing of in the
``shifted" vacuum, that results in the process of cancelling the anomalous . The feasibility of this effect seems to be enhanced by a vanishing
vacuum energy, and by a ``small" value of in the
original vacuum. In the class of free-fermionic models with vanishing vacuum
energy that we focus on, a necessary condition for this mechanism to be
effective is that in the original vacuum. A vanishing
ameliorates the cosmological constant problem and is a
necessary element in the stability of the no-scale mechanism.Comment: 7 pages, no figures, LaTe
On the One Loop Fayet-Iliopoulos Term in Chiral Four Dimensional Type I Orbifolds
We consider the generation of Fayet-Iliopoulos terms at one string loop in
some recently found N=1 open string orbifolds with anomalous U(1) factors with
nonvanishing trace of the charge. Low-energy field theory arguments lead one to
expect a one loop quadratically divergent Fayet-Iliopoulos term. We show that a
one loop Fayet-Iliopoulos term is not generated, due to a cancellation between
contributions of worldsheets of different topology. The vanishing of the one
loop Fayet-Iliopoulos term in open string compactifications is related to the
cancellation of twisted Ramond-Ramond tadpoles.Comment: 14 pages, LaTeX, 2 figures; references and a few minor comments
(including a relevant gamma matrix identity) adde
Consistency of Superspace Low Energy Equations of Motion of 4D Type II Superstring with Type II Sigma Model at Tree-Level
We derive the torsion constraints and show the consistency of equations of
motion of four-dimensional Type II supergravity in superspace, with Type II
sigma model. This is achieved by coupling the four-dimensional compactified
Type II Berkovits' superstring to an N=2 curved background and requiring that
the sigma-model has superconformal invariance at tree-level. We compute this in
a manifestly 4D N=2 supersymmetric way. The constraints break the target
conformal and SU(2) invariances and the dilaton will be a conformal,
compensator. For Type II superstring in four dimensions,
worldsheet supersymmetry requires two different compensators. One type is
described by chiral and anti-chiral superfields. This compensator can be
identified with a vector multiplet. The other Type II compensator is described
by twist-chiral and twist-anti-chiral superfields and can be identified with a
tensor hypermultiplet. Also, the superconformal invariance at tree-level
selects a particular gauge, where the matter is fixed, but not the
compensators. After imposing the reality conditions, we show that the Type II
sigma model at tree-level is consistent with the equations of motion for Type
II supergravity in the string gauge.Comment: 8 pages, changes in the title and abstract, references added,
accepted for publication in Physics Letters
Emission Spectrum of Fundamental Strings: An Algebraic Approach
We formulate a linear difference equation which yields averaged
semi-inclusive decay rates for arbitrary, not necessarily large, values of the
masses. We show that the rates for decays M \to m+\M' of typical heavy open
strings are independent of the masses and , and compute the ``mass
deffect''. For closed strings we find decay rates proportional to , where is the reduced mass of the decy products. Our
method yields exact interaction rates valid for all mass ranges and may provide
a fully microscopic basis, not limited to the long string approximation, for
the interactions in the Boltzmann equation approach to hot string gases.Comment: 35 pages, 3 figure
Covariant Computation of the Low Energy Effective Action of the Heterotic Superstring
We derive the low energy effective action of the heterotic superstring in
superspace. This is achieved by coupling the covariantly quantized
Green-Schwarz superstring of Berkovits to a curved background and requiring
that the sigma model has superconformal invariance at tree level and at one
loop in \a'. Tree level superconformal invariance yields the complete
supergravity algebra, and one-loop superconformal invariance the equations of
motion of the low energy theory. The resulting low energy theory is old-minimal
supergravity coupled to a tensor multiplet. The dilaton is part of the
compensator multiplet.Comment: 59 pages, LaTeX, with two figures (needs epsfig
The Ubiquitous Inflaton in String-Inspired Models
A string theory based inflationary model is developed where the inflaton
interacts with a multitude of massive string level states causing dissipation
of vacuum energy. Inflation terminates in a warm Universe without the need for
reheating.Comment: In Press Physical Review Letters 1999, modified titl
Dynamical Topology Change in String Theory
Exact string solutions are presented, providing backgrounds where a dynamical
change of topology is occuring. This is induced by the time variation of a
modulus field. Some lessons are drawn concerning the region of validity of
effective theories and how they can be glued together, using stringy
information in the region where the topology changes.Comment: LaTeX file, 17pp., CERN-TH.7219/94, LPTENS-94/11. (Discussions have
been clarified in several places
Three Generations in the Fermionic Construction
We obtain three generation SU(3)_c X SU(2)_L X U(1)_Y string models in all of
the exactly solvable (0,2) constructions sampled by fermionization. None of
these examples, including those that are symmetric abelian orbifolds, rely on
the Z_2 X Z_2 orbifold underlying the NAHE basis. We present the first known
three generation models for which the hypercharge normalization, k_1, takes
values smaller than that obtained from an SU(5) embedding, thus lowering the
effective gauge coupling unification scale. All of the models contain
fractional electrically charged and vectorlike exotic matter that could survive
in the light spectrum.Comment: harvmac, 51 page
Infrared Regularization of Superstring Theory and the One-Loop Calculation of Coupling Constants
Infrared regularized versions of 4-D N=1 superstring ground states are
constructed by curving the spacetime. A similar regularization can be performed
in field theory. For the IR regularized string ground states we derive the
exact one-loop effective action for non-zero U(1) or chromo-magnetic fields as
well as gravitational and axionic-dilatonic fields. This effective action is IR
and UV finite. Thus, the one-loop corrections to all couplings (gravitational,
gauge and Yukawas) are unabiguously computed. These corrections are necessary
for quantitative string superunification predictions at low energies. The
one-loop corrections to the couplings are also found to satisfy Infrared Flow
Equations.Comment: Version to appear in Nucl. Phys. B. (several parts have been
expanded, and extra results have been added.