21 research outputs found
O(1/N_f) Corrections to the Thirring Model in 2<d<4
The Thirring model, that is, a relativistic field theory of fermions with a
contact interaction between vector currents, is studied for dimensionalities
2<d<4 using the 1/N_f expansion, where N_f is the number of fermion species.
The model is found to have no ultraviolet divergences at leading order provided
a regularization respecting current conservation is used. Explicit O(1/N_f)
corrections are computed, and the model shown to be renormalizable at this
order in the massless limit; renormalizability appears to hold to all orders
due to a special case of Weinberg's theorem. This implies there is a universal
amplitude for four particle scattering in the asymptotic regime. Comparisons
are made with both the Gross-Neveu model and QED.Comment: 22 pages in plain TeX, with 7 figs included using psfig.tex (Minor
conceptual changes - algebra unaffected
On the stability of renormalizable expansions in three-dimensional gravity
Preliminary investigations are made for the stability of the expansion
in three-dimensional gravity coupled to various matter fields, which are
power-counting renormalizable. For unitary matters, a tachyonic pole appears in
the spin-2 part of the leading graviton propagator, which implies the unstable
flat space-time, unless the higher-derivative terms are introduced. As another
possibility to avoid this spin-2 tachyon, we propose Einstein gravity coupled
to non-unitary matters. It turns out that a tachyon appears in the spin-0 or -1
part for any linear gauges in this case, but it can be removed if non-minimally
coupled scalars are included. We suggest an interesting model which may be
stable and possess an ultraviolet fixed point.Comment: 32 pages. (A further discussion to avoid tachyons is included. To be
Published in Physical Review D.
Effective action of magnetic monopole in three-dimensional electrodynamics with massless matter and gauge theories of superconductivity
We compute one-loop effective action of magnetic monopole in
three-dimensional electrodynamics of massless bosons and fermions and find that
it contains an infrared logarithm. So, when the number of massless matter
species is sufficiently large, monopoles are suppressed and in the weak
coupling limit charged particles are unconfined. This result provides some
support to gauge theories of high-temperature superconductors. It also provides
a mechanism by which interlayer tunneling of excitations with one unit of the
ordinary electric charge can be suppressed while that of a doubly charged
object is allowed.Comment: 8 pages, LATEX, UCLA/93/TEP/41 (the last sentence of the paragraph
concerning applications at the end of the paper has been deleted; mailing
problems have been corrected
CPT, Strings, and Meson Factories
Spontaneous breaking of CPT is possible in string theory. We show that it can
arise at a level within reach of experiments at meson factories currently being
built or designed. For , , and -charm factories, we discuss the
likely experimental string signatures and provide estimates of the bounds that
might be attained in these machines.Comment: in press, Physical Review
Sub-Critical Closed String Field Theory in D Less Than 26
We construct the second quantized action for sub-critical closed string field
theory with zero cosmological constant in dimensions ,
generalizing the non-polynomial closed string field theory action proposed by
the author and the Kyoto and MIT groups for . The proof of gauge
invariance is considerably complicated by the presence of the Liouville field
and the non-polynomial nature of the action. However, we explicitly show
that the polyhedral vertex functions obey BRST invariance to all orders. By
point splitting methods, we calculate the anomaly contribution due to the
Liouville field, and show in detail that it cancels only if , in both the bosonized and unbosonized polyhedral vertex functions. We
also show explicitly that the four point function generated by this action
reproduces the shifted Shapiro-Virasoro amplitude found from matrix
models and Liouville theory in two dimensions. LATEX file.Comment: 28 pages, CCNY-HEP-93-