614 research outputs found

### Supersymmetric States in M5/M2 CFTs

We propose an exact, finite $N$ formula for the partition function over
$1/4^{th}$ BPS states in the conformal field theory on the world volume of $N$
coincident M5 branes and $1/8^{th}$ BPS states in the theory of $N$ coincident
M2 branes. We obtain our partition function by performing the radial
quantization of the Coulomb Branches of these theories, and rederive the same
formula from the quantization of supersymmetric giant and dual giant gravitons
in $AdS_7 \times S^4$ and $AdS_4 \times S^7$. Our partition function is
qualitatively similar to the analogous quantity in ${\cal N}=4$ Yang Mills. It
reduces to the sum over supersymmetric multi gravitons at low energies, but
deviates from this supergravity formula at energies that scale like a positive
power of $N$.Comment: 24 pages, harvmac; v2 reference adde

### Indices for Superconformal Field Theories in 3,5 and 6 Dimensions

We present a trace formula for a Witten type Index for superconformal field
theories in d=3,5 and 6 dimensions, generalizing a similar recent construction
in d=4. We perform a detailed study of the decomposition of long
representations into sums of short representations at the unitarity bound to
demonstrate that our trace formula yields the most general index (i.e. quantity
that is guaranteed to be protected by superconformal symmetry alone) for the
corresponding superalgebras. Using the dual gravitational description, we
compute our index for the theory on the world volume of N M2 and M5 branes in
the large N limit. We also compute our index for recently constructed Chern
Simons theories in three dimensions in the large N limit, and find that, in
certain cases, this index undergoes a large N phase transition as a function of
chemical potentials.Comment: a small typo corrected, 46 page

### Twisted Quantum Fields on Moyal and Wick-Voros Planes are Inequivalent

The Moyal and Wick-Voros planes A^{M,V}_{\theta} are *-isomorphic. On each of
these planes the Poincar\'e group acts as a Hopf algebra symmetry if its
coproducts are deformed by twist factors. We show that the *-isomorphism T:
A^M_{\theta} to A^V_{\theta} does not also map the corresponding twists of the
Poincar\'e group algebra. The quantum field theories on these planes with
twisted Poincar\'e-Hopf symmetries are thus inequivalent. We explicitly verify
this result by showing that a non-trivial dependence on the non-commutative
parameter is present for the Wick-Voros plane in a self-energy diagram whereas
it is known to be absent on the Moyal plane (in the absence of gauge fields).
Our results differ from these of (arXiv:0810.2095 [hep-th]) because of
differences in the treatments of quantum field theories.Comment: 12 page

### Supergravity at the boundary of AdS supergravity

We give a general analysis of AdS boundary conditions for spin-3/2
Rarita-Schwinger fields and investigate boundary conditions preserving
supersymmetry for a graviton multiplet in AdS_4. Linear Rarita-Schwinger fields
in AdS_d are shown to admit mixed Dirichlet-Neumann boundary conditions when
their mass is in the range $0 \leq |m| < 1/2l_{AdS}$. We also demonstrate that
mixed boundary conditions are allowed for larger masses when the inner product
is "renormalized" accordingly with the action. We then use the results obtained
for |m| = 1/l_{AdS} to explore supersymmetric boundary conditions for N = 1
AdS_4 supergravity in which the metric and Rarita-Schwinger fields are
fluctuating at the boundary. We classify boundary conditions that preserve
boundary supersymmetry or superconformal symmetry. Under the AdS/CFT
dictionary, Neumann boundary conditions in d=4 supergravity correspond to
gauging the superconformal group of the 3-dimensional CFT describing M2-branes,
while N = 1 supersymmetric mixed boundary conditions couple the CFT to N = 1
superconformal topologically massive gravity.Comment: 23 pages, RevTe

### The Kepler problem and non commutativity

We investigate the Kepler problem using a symplectic structure consistent
with the commutation rules of the noncommutative quantum mechanics. We show
that a noncommutative parameter of the order of $10^{-58} \text m^2$ gives
observable corrections to the movement of the solar system. In this way,
modifications in the physics of smaller scales implies modifications at large
scales, something similar to the UV/IR mixing.Comment: 10 page

### Elimination of IR/UV via Gravity in Noncommutative Field Theory

Models of particle physics with Noncommutative Geometry (NCG) generally
suffer from a manifestly non-Wilsonian coupling of infrared and ultraviolet
degrees of freedom known as the "IR/UV Problem" which would tend to compromise
their phenomenological relevance. In this Letter we explicitly show how one may
remedy this by coupling NCG to gravity. In the simplest scenario the Lagrangian
gets multiplied by a nonconstant background metric; in $\phi-4$ theory the
theorem that $\int d^4 x \phi \star \phi = \int d^4 x \phi^2$ is no longer true
and the field propagator gets modified by a factor which depends on both NCG
and the variation of the metric. A suitable limit of this factor as the
propagating momentum gets asymptotically large then eradicates the IR/UV
problem. With gravity and NCG coupled to each other, one might expect
anti-symmetric components to arise in the metric. Cosmological implications of
such are subsequently discussed.Comment: 6 pages; MPLA versio

### Emergence of supersymmetry on the surface of three dimensional topological insulators

We propose two possible experimental realizations of a 2+1 dimensional
spacetime supersymmetry at a quantum critical point on the surface of three
dimensional topological insulators. The quantum critical point between the
semi-metallic state with one Dirac fermion and the s-wave superconducting state
on the surface is described by a supersymmetric conformal field theory within
$\epsilon$-expansion. We predict the exact voltage dependence of the
differential conductance at the supersymmetric critical point.Comment: 8 pages, 2 figures; published versio

### The non-Abelian tensor multiplet in loop space

We introduce a non-Abelian tensor multiplet directly in the loop space
associated with flat six-dimensional Minkowski space-time, and derive the
supersymmetry variations for on-shell ${\cal{N}}=(2,0)$ supersymmetry.Comment: 11 pages, v2: cleaner presentation, mistakes are corrected (and an
erroneous section was removed

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