19 research outputs found
Orientifolding in N=2 Superspace
We discuss orientifold projections on superspace effective actions for
hypermultiplets. We present a simple and new mechanism that allows one to find
the Kahler potential and complex structure for the N=1 theory directly in terms
of the parent N=2 theory. As an application, we demonstrate our method for
Calabi-Yau orientifold compactifications of type IIB superstrings.Comment: 7 page
A Note on Twistor Gravity Amplitudes
In a recent paper, Witten proposed a surprising connection between
perturbative gauge theory and a certain topological model in twistor space. In
particular, he showed that gluon amplitudes are localized on holomorphic
curves. In this note we present some preliminary considerations on the
possibility of having a similar localization for gravity amplitudes.Comment: 14 pages, 6 figures. v2: minor changes, added referenc
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
Nonperturbative studies of supersymmetric matrix quantum mechanics with 4 and 8 supercharges at finite temperature
We investigate thermodynamic properties of one-dimensional U(N)
supersymmetric gauge theories with 4 and 8 supercharges in the planar large-N
limit by Monte Carlo calculations. Unlike the 16 supercharge case, the
threshold bound state with zero energy is widely believed not to exist in these
models. This led A.V. Smilga to conjecture that the internal energy decreases
exponentially at low temperature instead of decreasing with a power law. In the
16 supercharge case, the latter behavior was predicted from the dual black
0-brane geometry and confirmed recently by Monte Carlo calculations. Our
results for the models with 4 and 8 supercharges indeed support the exponential
behavior, revealing a qualitative difference from the 16 supercharge case.Comment: 16 pages, 7 figures, LaTeX2e, minor corrections in section 3, final
version accepted in JHE