15 research outputs found
Little IIB Matrix Model
We study the zero-dimensional reduced model of D=6 pure super Yang-Mills
theory and argue that the large N limit describes the (2,0) Little String
Theory. The one-loop effective action shows that the force exerted between two
diagonal blocks of matrices behaves as 1/r^4, implying a six-dimensional
spacetime. We also observe that it is due to non-gravitational interactions. We
construct wave functions and vertex operators which realize the D=6, (2,0)
tensor representation. We also comment on other "little" analogues of the IIB
matrix model and Matrix Theory with less supercharges.Comment: 17 pages, references adde
"Flip" of SL(2,R)-duality in five-dimensional supergravity
The dimensional reduction of the bosonic sector of five-dimensional minimal
supergravity to a Lorentzian four-dimensional spacetime leads to a theory with
a massless axion and a dilaton coupled to gravity and two U(1) gauge fields and
the dimensionally reduced equations of motion have SL(2,R)/SO(2)-duality
invariance. In our previous work, utilizing the duality invariance, we
formulated solution-generation techniques within five-dimensional minimal
supergravity. In this work, by choosing a timelike Killing vector, we consider
dimensional reduction to a four-dimensional Euclidean space, in which the field
equations have SL(2,R)/SO(1,1) invariance. In the timelike case, we develop a
new duality transformation technique, while in the spacelike case we have done
that in the previous work. As an example, by applying it to the Rasheed
solutions, we obtain rotating Kaluza-Klein black hole solutions in
five-dimensional minimal supergravity. In general, in contrast to the spacelike
case, the resulting dimensionally reduced solution includes the so-called NUT
parameter and therefore from a four-dimensional point of view, such a spacetime
is not asymptotically flat. However, it is shown that in some special cases, it
can describe ordinary Kaluza-Klein black holes.Comment: 16 page
New approach to solution generation using SL(2,R)-duality of a dimensionally reduced space in five-dimensional minimal supergravity and new black holes
The dimensional reduction of (the bosonic sector of) five-dimensional minimal
supergravity to four dimensions leads to a theory with a massless axion and a
dilaton coupled to gravity and two U(1) gauge fields (one of which has
Chern-Simons coupling), whose field equations have SL(2,R)-invariance.
Utilizing this SL(2,R)-duality, we provide a new formalism for solution
generation. As an example, applying it to the Rasheed solution, which are known
to describe dyonic rotating black holes (from the four-dimensional point of
view) of five-dimensional pure gravity, we obtain rotating Kaluza-Klein black
hole solutions in five-dimensional minimal supergravity. We also show that the
solutions have six charges: mass, angular momentum, Kaluza-Klein
electric/magnetic charges and electric/magnetic charges of the Maxwell field,
four of which are related by a constraint.Comment: 17 pages, a few references and comments added, to be published in PR
3-dimensional Gravity from the Turaev-Viro Invariant
We study the -deformed su(2) spin network as a 3-dimensional quantum
gravity model. We show that in the semiclassical continuum limit the
Turaev-Viro invariant obtained recently defines naturally regularized
path-integral la Ponzano-Regge, In which a contribution from
the cosmological term is effectively included. The regularization dependent
cosmological constant is found to be , where
. We also discuss the relation to the Euclidean Chern-Simons-Witten
gravity in 3-dimension.Comment: 11page
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.
Chiral Generations on Intersecting 5-branes in Heterotic String Theory
We show that there exist two 27 and one 27 bar of E6, net one D=4, N=1 chiral
matter supermultiplet as zero modes localized on the intersection of two
5-branes in the E8 x E8 heterotic string theory. The smeared intersecting
5-brane solution is used via the standard embedding to construct a heterotic
background, which provides, after a compactification of some of the transverse
dimensions, a five-dimensional Randall-Sundrum II like brane-world set-up in
heterotic string theory. As a by-product, we present a new proof of anomaly
cancellation between those from the chiral matter and the anomaly inflow onto
the brane without small instanton.Comment: 26 pages, 5 figures; references added, typo correcte
The Geroch group in the Ashtekar formulation
We study the Geroch group in the framework of the Ashtekar formulation. In
the case of the one-Killing-vector reduction, it turns out that the third
column of the Ashtekar connection is essentially the gradient of the Ernst
potential, which implies that the both quantities are based on the ``same''
complexification. In the two-Killing-vector reduction, we demonstrate Ehlers'
and Matzner-Misner's SL(2,R) symmetries, respectively, by constructing two sets
of canonical variables that realize either of the symmetries canonically, in
terms of the Ashtekar variables. The conserved charges associated with these
symmetries are explicitly obtained. We show that the gl(2,R) loop algebra
constructed previously in the loop representation is not the Lie algebra of the
Geroch group itself. We also point out that the recent argument on the
equivalence to a chiral model is based on a gauge-choice which cannot be
achieved generically.Comment: 40 pages, revte