50 research outputs found
Topological DBI actions and nonlinear instantons
We consider Euclidean D4 and D6-branes filling the whole and
space, respectively. In both cases, with a constant background
B-field turned on for D4-branes, we propose actions which are the same as the
DBI actions up to some constant or total derivative terms. These extra terms
allow us to write the action as a square of nonlinear instanton equations. As
such, the actions can easily be supersymmetrized using the methods of
topological field theory.Comment: 9 pages, latex, added a reference, and minor modification
A 3d topological sigma model and D-branes
A 3d topological sigma model describing maps from a 3-manifold Y to a
Calabi-Yau 3-fold M is introduced. As the model is topological, we can choose
an arbitrary metric on M. Upon scaling up the metric, the path integral by
construction localizes on the moduli space of special Lagrangian submanifolds
of M. We couple the theory to dynamical gauge fields and discuss the case where
M has a mirror and the gauge group is U(1).Comment: 12 pages, JHEP latex, a reference adde
Dual Instantons in Anti-membranes Theory
We introduce two ansatzs for the 3-form potential of Euclidean 11d
supergravity on skew-whiffed AdS_4 X S^7 background which results in two scalar
modes with m^2=-2 on AdS_4. Being conformally coupled with a quartic
interaction it is possible to find the exact solutions of the scalar equation
on this background. These modes turn out to be invariant under SU(4) subgroup
of SO(8) isometry group, whereas there are no corresponding SU(4) singlet BPS
operators of dimensions one or two on the boundary ABJM theory. Noticing the
interchange of 8_s and 8_c representations under skew-whiffing in the bulk, we
propose the theory of anti-membranes should similarly be obtained from ABJM
theory by swapping these representations. In particular, this enables us to
identify the dual boundary operators of the two scalar modes. We deform the
boundary theory by the dual operators and examine the fermionic field equations
and compare the solutions of the deformed theory with those of the bulk.Comment: 14 pages, minor changes, added ref
Supersymmetry and gauge theory on Calabi-Yau 3-folds
We consider the dimensional reduction of supersymmetric Yang-Mills on a
Calabi-Yau 3-fold. We show by construction how the resulting cohomological
theory is related to the balanced field theory of the Kaehler Yang-Mills
equations introduced by Donaldson and Uhlenbeck-Yau.Comment: 11 page
Spectral Degeneracy in Supersymmetric Gluodynamics and One-Flavor QCD related to N=1/2 SUSY
In supersymmetric gluodynamics (N=1 super-Yang-Mills theory) we show that the
spectral functions induced by the nonchiral operator Tr G_{\alpha\beta}
\bar\lambda^2 are fully degenerate in the J^{PC}=1^{\pm -} channels. The above
operator is related to N=1/2 generalization of SUSY. Using the planar
equivalence, this translates into the statement of degeneracy between the
mesons produced from the vacuum by the operators (\bar \Psi \vec E\Psi + i\bar
\Psi \vec B \gamma^5\Psi) and (\bar \Psi \vec B\Psi - i\bar \Psi \vec E
\gamma^5\Psi) in one-flavor QCD, up to 1/N corrections. Here \Psi is the quark
field, and \vec E ,\vec B are chromoelectric/chromomagnetic fields,
respectively.Comment: Latex, 6 pages, two references adde
Nonanticommutative Deformation of N=4 SYM Theory: The Myers Effect and Vacuum States
We propose a deformation of SYM theoery induced by
nonanticommutative star product. The deformation introduces new bosonic terms
which we identify with the corresponding Myers terms of a stack of D3-branes in
the presence of a five-form RR flux. We take this as an indication that the
deformed lagrangian describes D3-branes in such a background. The vacuum states
of the theory are also examined. In a specific case where the U(1) part of the
gauge field is nonvanishing the (anti)holomorphic transverse coordinates of the
brane sit on a fuzzy two sphere. For a supersymmetric vacuum the
antiholomorphic coordinates must necessarily commute. However, we also
encounter non-supersymmetric vacua for which the antiholomorphic coordinates do
not commute.Comment: 14 pages, minor changes, refs. adde
N=1/2 Super Yang-Mills Theory on Euclidean AdS2xS2
We study D-branes in the background of Euclidean AdS2xS2 with a graviphoton
field turned on. As the background is not Ricci flat, the graviphoton field
must have both self-dual and antiself-dual parts. This, in general, will break
all the supersymmetries on the brane. However, we show that there exists a
limit for which one can restore half of the supersymmetries. Further, we show
that in this limit, the N=1/2 SYM Lagrangian on flat space can be lifted on to
the Euclidean AdS2xS2 preserving the same amount of supersymmetries as in the
flat case. We observe that without the C-dependent terms present in the action
this lift is not possible.Comment: 12 pages, latex file; v2: minor corrections, references adde
Instantons and Matter in N=1/2 Supersymmetric Gauge Theory
We extend the instanton calculus for N=1/2 U(2) supersymmetric gauge theory
by including one massless flavor. We write the equations of motion at leading
order in the coupling constant and we solve them exactly in the
non(anti)commutativity parameter C. The profile of the matter superfield is
deformed through linear and quadratic corrections in C. Higher order
corrections are absent because of the fermionic nature of the back-reaction.
The instanton effective action, in addition to the usual 't Hooft term,
includes a contribution of order C^2 and is N=1/2 invariant. We argue that the
N=1 result for the gluino condensate is not modified by the presence of the new
term in the effective action.Comment: 33 pages, harvmac; v2: minor changes, added references; v3: added
analysis of the instanton measure in section