23 research outputs found
Exact Results in Quiver Quantum Mechanics and BPS Bound State Counting
We exactly evaluate the partition function (index) of N=4 supersymmetric
quiver quantum mechanics in the Higgs phase by using the localization
techniques. We show that the path integral is localized at the fixed points,
which are obtained by solving the BRST equations, and D-term and F-term
conditions. We turn on background gauge fields of R-symmetries for the chiral
multiplets corresponding to the arrows between quiver nodes, but the partition
function does not depend on these R-charges. We give explicit examples of the
quiver theory including a non-coprime dimension vector. The partition functions
completely agree with the mathematical formulae of the Poincare polynomials
(chi_y-genus) and the wall crossing for the quiver moduli spaces . We also
discuss exact computation of the expectation values of supersymmetric
(Q-closed) Wilson loops in the quiver theory.Comment: 40 pages, 7 figures; v2: minor corrections and references are added;
v3: references added, typos corrected, discrepancy in the non-coprime case
resolve
Shear viscosity of a highly excited string and the black hole membrane paradigm
Black hole membrane paradigm states that a certain viscous membrane seems to
be sitting on a stretched horizon of a black hole from the viewpoint of a
distant observer. We show that the shear viscosity of the fictitious membrane
can be reproduced by a highly excited string covering the stretched horizon
except for a numerical coefficient.Comment: 22 pages, no figure, minor correction
Transport coefficients of D1-D5-P system and the membrane paradigm
I discuss a correspondence between string theory and the black hole membrane
paradigm in the context of the D1-D5-P system. By using the Kubo formula, I
calculate transport coefficients of the effective string model induced by two
kinds of minimal scalars. Then, I show that these transport coefficients
exactly agree with the corresponding membrane transport coefficients of a
five-dimensional near-extremal black hole with three charges.Comment: 11 pages, no figure; v2: minor corrections, accepted for publication
in Physical Review
One-loop unitarity of scalar field theories on Poincare invariant commutative nonassociative spacetimes
We study scalar field theories on Poincare invariant commutative
nonassociative spacetimes. We compute the one-loop self-energy diagrams in the
ordinary path integral quantization scheme with Feynman's prescription, and
find that the Cutkosky rule is satisfied. This property is in contrast with
that of noncommutative field theory, since it is known that noncommutative
field theory with space/time noncommutativity violates unitarity in the above
standard scheme, and the quantization procedure will necessarily become
complicated to obtain a sensible Poincare invariant noncommutative field
theory. We point out a peculiar feature of the non-locality in our
nonassociative field theories, which may explain the property of the unitarity
distinct from noncommutative field theories. Thus commutative nonassociative
field theories seem to contain physically interesting field theories on
deformed spacetimes.Comment: 25 pages, 9 figures ; appendix and references adde
The Cutkosky rule of three dimensional noncommutative field theory in Lie algebraic noncommutative spacetime
We investigate the unitarity of three dimensional noncommutative scalar field
theory in the Lie algebraic noncommutative spacetime [x^i,x^j]=2i kappa
epsilon^{ijk}x_k. This noncommutative field theory possesses a SL(2,R)/Z_2
group momentum space, which leads to a Hopf algebraic translational symmetry.
We check the Cutkosky rule of the one-loop self-energy diagrams in the
noncommutative phi^3 theory when we include a braiding, which is necessary for
the noncommutative field theory to possess the Hopf algebraic translational
symmetry at quantum level. Then, we find that the Cutkosky rule is satisfied if
the mass is less than 1/(2^(1/2)kappa).Comment: 24 pages, 13 figures, a minor clarification, references adde