3,587 research outputs found
On Heterotic Orbifolds, M Theory and Type I' Brane Engineering
Horava--Witten M theory -- heterotic string duality poses special problems
for the twisted sectors of heterotic orbifolds. In [1] we explained how in M
theory the twisted states couple to gauge fields apparently living on M9 branes
at both ends of the eleventh dimension at the same time. The resolution
involves 7D gauge fields which live on fixed planes of the (T^4/Z_N) x
(S^1/Z_2) x R^{5,1} orbifold and lock onto the 10D gauge fields along the
intersection planes. The physics of such intersection planes does not follow
directly from the M theory but there are stringent kinematic constraints due to
duality and local consistency, which allowed us to deduce the local fields and
the boundary conditions at each intersection. In this paper we explain various
phenomena at the intersection planes in terms of duality between HW and type I'
superstring theories. The orbifold fixed planes are dual to stacks of D6
branes, the M9 planes are dual to O8 orientifold planes accompanied by D8
branes, and the intersections are dual to brane junctions. We engineer several
junction types which lead to distinct patterns of 7D/10D gauge field locking,
7D symmetry breaking and/or local 6D fields. Another aspect of brane
engineering is putting the junctions together; sometimes, the combined effect
is rather spectacular from the HW point of view and the quantum numbers of some
twisted states have to `bounce' off both ends of the eleventh dimension before
their heterotic identity becomes clear. Some models involve D6/O8 junctions
where the string coupling diverges towards the orientifold plane. We use the
heterotic-HW-I' duality to predict what should happen at such junctions.Comment: 118 pages, uses phyzzx, color printer advice
On the M-Theory Approach to (Compactified) 5D Field Theories
We construct M-theory curves associated with brane configurations of SU(N),
SO(N) and 5d supersymmetric gauge theories compactified on a circle.
From the curves we can account for all the existing different SU(N) field
theories with . This is the correct bound for . We
remark on the exceptional case SU(2). The bounds obtained for SO(N) and
are and , respectively.Comment: 18 pages, minor correction
Wilson Loops in the Large N Limit at Finite Temperature
Using a proposal of Maldacena we compute in the framework of the supergravity
description of N coincident D3 branes the energy of a quark anti-quark pair in
the large N limit of U(N) N=4 SYM in four dimensions at finite temperature.Comment: 7 pages, LaTeX2e, 5 eps figures; references added and corrected,
typos correcte
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