375 research outputs found
Deformation independent open brane metrics and generalized theta parameters
We investigate the consequences of generalizing certain well established
properties of the open string metric to the conjectured open membrane and open
Dp-brane metrics. By imposing deformation independence on these metrics their
functional dependence on the background fields can be determined including the
notorious conformal factor. In analogy with the non-commutativity parameter
in the string case, we also obtain `generalized' theta
parameters which are rank q+1 antisymmetric tensors (polyvectors) for open
Dq-branes and rank 3 for the open membrane case. The expressions we obtain for
the open membrane quantities are expected to be valid for general background
field configurations, while the open D-brane quantities are only valid for one
parameter deformations. By reducing the open membrane data to five dimensions,
we show that they, modulo a subtlety with implications for the relation between
OM-theory and NCYM, correctly generate the open string and open D2-data.Comment: 24 pages, LaTe
An M-theory solution generating technique and SL(2,R)
In this paper we generalize the O(p+1,p+1) solution generating technique
(this is a method used to deform Dp-branes by turning on a NS-NS B-field) to
M-theory, in order to be able to deform M5-brane supergravity solutions
directly in eleven dimensions, by turning on a non zero three form A. We find
that deforming the M5-brane, in some cases, corresponds to performing certain
SL(2,R) transformations of the Kahler structure parameter for the three-torus,
on which the M5-brane has been compactified. We show that this new M-theory
solution generating technique can be reduced to the O(p+1,p+1) solution
generating technique with p=4. Further, we find that it implies that the open
membrane metric and generalized noncommutativity parameter are manifestly
deformation independent for electric and light-like deformations. We also
generalize the O(p+1,p+1) method to the type IIA/B NS5-brane in order to be
able to deform NS5-branes with RR three and two forms, respectively. In the
type IIA case we use the newly obtained solution generating technique and
deformation independence to derive a covariant expression for an open D2-brane
coupling, relevant for OD2-theory.Comment: 24 pages, Latex. v2:Sections 3.2 and 3.3 improved. v3:Some
clarifications added. Version published in JHE
Reduction of open membrane moduli
We perform a general reduction of the open membrane metric in a worldvolume
direction of the M5-brane. Using reduction rules analogous to the bulk, we show
that the open membrane metric leads to the standard open string metric and open
string coupling constant on the D4-brane only for an ``electric'' reduction in
which case the open membrane metric has no off-diagonal components and the
Born-Infeld curvature tensor is a matrix of rank 2. Instead, if we perform a
general reduction, with nonzero off-diagonal components of the open membrane
metric, we obtain a rank 4 Born-Infeld tensor corresponding to a bound state of
an open string with an open D2--brane. Next, we identify and reduce a 3-form
open membrane ``noncommutativity'' tensor on the M5-brane. This open membrane
parameter only reduces to the open string noncommutativity tensor on the
D4-brane provided we constrain ourselves to an ``electric'' or a ``magnetic''
reduction.Comment: 15 pages, LaTeX, uses JHEP.cls and JHEP.bst style file
On the Problem of Multiple M2 Branes
A simplified version of 3d BL theory is considered, which allows any number N
of M2 branes in d=11. The underlying 3-algebra structure is provided by
degenerate U(N) Nambu bracket [X,Y,Z] = tr(X) [Y,Z] + tr(Y) [Z,X] + tr(Z)
[X,Y], the corresponding f^{abcd} is not totally antisymmetric and extended
supersymmetry of the action remains to be checked. All the fields, including
auxiliary non-propagating gauge fields, are in adjoint representation of SU(N)
and the only remnant of 3-algebra structure is an octuple of gauge singlets,
acquiring vacuum expectation value in transition to D2 branes in d=10.Comment: 12 page
On Berenstein-Douglas-Seiberg Duality
I review the proposal of Berenstein-Douglas for a completely general
definition of Seiberg duality. To give evidence for their conjecture I present
the first example of a physical dual pair and explicitly check that it
satisfies the requirements. Then I explicitly show that a pair of toric dual
quivers is also dual according to their proposal. All these computations go
beyond tilting modules, and really work in the derived category. I introduce
all necessary mathematics where needed.Comment: 22 pages, LaTe
Prognostic risk stratification with SPECT imaging: results from a 20,340 patient multicenter registry
Current Profiles of Molecular Nanowires; DFT Green Function Representation
The Liouville-space Green function formalism is used to compute the current
density profile across a single molecule attached to electrodes. Time ordering
is maintained in real, physical, time, avoiding the use of artificial time
loops and backward propagations. Closed expressions for molecular currents,
which only require DFT calculations for the isolated molecule, are derived to
fourth order in the molecule/electrode coupling.Comment: 21 page
AdS_3 OM theory and the self-dual string or Membranes ending on the Five-brane
We describe properties of the M-theory five-brane containing coincident
self-dual strings on its worldvolume. This is the five-brane description of Q
membranes ending on the five-brane. In particular, we consider a Maldacena-like
low energy limit in the six-dimensional worldvolume which yields a near
`horizon' description of the self-dual string using light open membranes, i.e.
OM theory, in an AdS_3 x S^3 geometry.Comment: 13 pages, latex, v2: corrected open membrane metric prefactor + typo
M2-branes on M-folds
We argue that the moduli space for the Bagger-Lambert A_4 theory at level k
is (R^8 \times R^8)/D_{2k}, where D_{2k} is the dihedral group of order 4k. We
conjecture that the theory describes two M2-branes on a Z_{2k} ``M-fold'', in
which a geometrical action of Z_{2k} is combined with an action on the branes.
For k=1, this arises as the strong coupling limit of two D2-branes on an O2^-
orientifold, whose worldvolume theory is the maximally supersymmetric SO(4)
gauge theory. Finally, in an appropriate large-k limit we show that one
recovers compactified M-theory and the M2-branes reduce to D2-branes.Comment: 16 pages, LaTeX, v2: typos corrected, included appendices on
Chern-Simons level quantization and monopole charge quantizatio
Light-like noncommutativity and duality from open strings/branes
In this paper we perform some non-trivial tests for the recently obtained
open membrane/D-brane metrics and `generalized' noncommutativity parameters
using Dp/NS5/M5-branes which have been deformed by light-like fields. The
results obtained give further evidence that these open membrane/D-brane metrics
and `generalized' noncommutativity parameters are correct. Further, we use the
open brane data and supergravity duals to obtain more information about
non-gravitational theories with light-like noncommutativity, or `generalized'
light-like noncommutativity. In particular, we investigate various duality
relations (strong coupling limits). In the light-like case we also comment on
the relation between open membrane data (open membrane metric etc.) in six
dimensions and open string data in five dimensions. Finally, we investigate the
strong coupling limit (high energy limit) of five dimensional NCYM with
\Theta^{12}=\Theta^{34}. In particular, we find that this NCYM theory can be UV
completed by a DLCQ compactification of M-theory.Comment: 24 pages, Latex. v2:Comments and references added. v3:Version
published in JHE
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