5,688 research outputs found
String and M-theory: answering the critics
Using as a springboard a three-way debate between theoretical physicist Lee
Smolin, philosopher of science Nancy Cartwright and myself, I address in
layman's terms the issues of why we need a unified theory of the fundamental
interactions and why, in my opinion, string and M-theory currently offer the
best hope. The focus will be on responding more generally to the various
criticisms. I also describe the diverse application of string/M-theory
techniques to other branches of physics and mathematics which render the whole
enterprise worthwhile whether or not "a theory of everything" is forthcoming.Comment: Update on EPSRC. (Contribution to the Special Issue of Foundations of
Physics: "Forty Years Of String Theory: Reflecting On the Foundations",
edited by Gerard 't Hooft, Erik Verlinde, Dennis Dieks and Sebastian de Haro.
22 pages latex
Putting String/Fivebrane Duality to the Test
According to string/fivebrane duality, the Green-Schwarz factorization of the
spacetime anomaly polynomial into means that just
as is the anomaly polynomial of the string worldsheet so
should be the anomaly polynomial of the fivebrane worldvolume. To test
this idea we perform a fivebrane calculation of and find perfect
agreement with the string one--loop result.Comment: 14 pages, CERN TH-6614/92, CTP-TAMU 60/9
Reducing - duality to - duality
The infrared limit of Yang-Mills theory with compact gauge group
compactified on a two-torus is governed by an effective superconformal
field theory. We conjecture that this is a certain orbifold involving the
maximal torus of . Yang-Mills -duality makes predictions for all
correlators of this effective conformal field theory. These predictions are
shown to be implied by the standard -duality of the conformal field theory.
Consequently, Montonen-Olive duality between electric and magnetic states
reduces to the standard two-dimensional duality between momentum and winding
states.Comment: 13 pages, harvmac, no figures. (Some Comments added. Some references
added.
D=6, N=1 String Vacua and Duality
We review the structure string vacua with emphasis on the
different connections due to T-dualities and S-dualities. The topics discussed
include: Anomaly cancellation; K3 and orbifold heterotic
compactifications; T-dualities between and
heterotic vacua; non-perturbative heterotic vacua and small instantons; N=2
Type-II/Heterotic duality in D=4 ; F-theory/heterotic duality in D=6; and
heterotic/heterotic duality in six and four dimensions.Comment: 52 pages, plain Latex. To appear in the proceedings of the APCTP
Winter School on Duality, Mt. Sorak (Korea), February 199
Freudenthal Dual Lagrangians
The global U-dualities of extended supergravity have played a central role in
differentiating the distinct classes of extremal black hole solutions. When the
U-duality group satisfies certain algebraic conditions, as is the case for a
broad class of supergravities, the extremal black holes enjoy a further
symmetry known as Freudenthal duality (F-duality), which although distinct from
U-duality preserves the Bekenstein-Hawking entropy. Here it is shown that, by
adopting the doubled Lagrangian formalism, F-duality, defined on the doubled
field strengths, is not only a symmetry of the black hole solutions, but also
of the equations of motion themselves. A further role for F-duality is
introduced in the context of world-sheet actions. The Nambu-Goto world-sheet
action in any (t, s) signature spacetime can be written in terms of the F-dual.
The corresponding field equations and Bianchi identities are then related by
F-duality allowing for an F-dual formulation of Gaillard-Zumino duality on the
world-sheet. An equivalent polynomial "Polyakov- type" action is introduced
using the so-called black hole potential. Such a construction allows for
actions invariant under all groups of type E7, including E7 itself, although in
this case the stringy interpretation is less clear.Comment: 1+16 pages, 1 Table, updated to match published versio
A Comment on String Solitons
We derive an exact string-like soliton solution of D=10 heterotic string
theory. The solution possesses instanton structure in the
eight-dimensional space transverse to the worldsheet of the soliton.Comment: 4 page
Real Special Geometry
We give a coordinate-free description of real manifolds occurring in certain
four dimensional supergravity theories with antisymmetric tensor fields. The
relevance of the linear multiplets in the compactification of string and
five-brane theories is also discussed.Comment: 10 pgs (TeX with Harvmac), CERN-TH.7211/94, UCLA/94/TEP/14,
POLFIS-TH.01/9
On the Dirac-Born-Infeld Action for D-branes
In this note, we consider the reformulation of the Dirac-Born-Infeld action
for a Dirichlet p-brane in Brink-Di Vecchia-Howe-Tucker form, i.e., including
an independent non-propagating world-volume metric. When p>2, the action
becomes non-polynomial. A closed expression is derived for p=3. For selfdual
field-strengths, the DBI action is reproduced by an action with a simple F^2
term. We speculate on supersymmetrization of the D_3-brane action. We also give
the governing equations for arbitrary p, and derive an implicit expression for
the D_4-brane lagrangian.Comment: Plain TeX, 7 pages, TeX file and one postscript figure in compressed
tar archiv
Vacuum interpolation in supergravity via super p-branes
We show that many of the recently proposed supersymmetric p-brane solutions
of d=10 and d=11 supergravity have the property that they interpolate between
Minkowski spacetime and a compactified spacetime, both being supersymmetric
supergravity vacua. Our results imply that the effective worldvolume action for
small fluctuations of the super p-brane is a supersingleton field theory for
, as has been often conjectured in the past.Comment: 8p
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