398 research outputs found
Exceptional Indices
Recently a prescription to compute the superconformal index for all theories
of class S was proposed. In this paper we discuss some of the physical
information which can be extracted from this index. We derive a simple
criterion for the given theory of class S to have a decoupled free component
and for it to have enhanced flavor symmetry. Furthermore, we establish a
criterion for the "good", the "bad", and the "ugly" trichotomy of the theories.
After interpreting the prescription to compute the index with non-maximal
flavor symmetry as a residue calculus we address the computation of the index
of the bad theories. In particular we suggest explicit expressions for the
superconformal index of higher rank theories with E_n flavor symmetry, i.e. for
the Hilbert series of the multi-instanton moduli space of E_n.Comment: 33 pages, 11 figures, v2: minor correction
Singular points in N=2 SQCD
We revisit the study of singular points in N=2 SQCD with classical gauge
groups. Using a technique proposed recently by Gaiotto, Seiberg and Tachikawa
we find that the low-energy physics at the maximally singular point involves
two superconformal sectors coupled to an infrared free SU(2) gauge group. When
one softly breaks extended supersymmetry to N=1 adding a mass term for the
chiral multiplet in the adjoint representation, a finite number of vacua remain
and the theory becomes confining. Our analysis allows to identify the
low-energy physics at these distinguished points in the moduli space. In some
cases, which we will describe in detail, two sectors coupled to an infrared
free SU(2) gauge group emerge as before. For USp and SO gauge groups one of
these sectors is always free, contrary to the SU case.Comment: 22 pages, 2 figure
More Three Dimensional Mirror Pairs
We found a lot of new three dimensional N = 4 mirror pairs generalizing
previous considerations on three dimensional generalized quiver gauge theories.
We recovered almost all previous discovered mirror pairs with these
constructions. One side of these mirror pairs are always the conventional
quiver gauge theories. One of our result can also be used to determine the
matter content and weakly coupled gauge groups of four dimensional N = 2
generalized quiver gauge theories derived from six dimensional A_N and D_N
theory, therefore we explicitly constructed four dimensional S-duality pairs.Comment: 33 pages, 18 figures version2 minor correction
On 4d rank-one N=3 superconformal field theories
We study the properties of 4d N=3 superconformal field theories whose rank is
one, i.e. those that reduce to a single vector multiplet on their moduli space
of vacua. We find that the moduli space can only be of the form C^3/Z_k for
k=1,2,3,4,6, and that the supersymmetry automatically enhances to N=4 for
k=1,2. In addition, we determine the central charges a and c in terms of k, and
construct the associated 2d chiral algebras, which turn out to be exotic N=2
supersymmetric W-algebras.Comment: 24 page
T-Branes and Monodromy
We introduce T-branes, or "triangular branes," which are novel non-abelian
bound states of branes characterized by the condition that on some loci, their
matrix of normal deformations, or Higgs field, is upper triangular. These
configurations refine the notion of monodromic branes which have recently
played a key role in F-theory phenomenology. We show how localized matter
living on complex codimension one subspaces emerge, and explain how to compute
their Yukawa couplings, which are localized in complex codimension two. Not
only do T-branes clarify what is meant by brane monodromy, they also open up a
vast array of new possibilities both for phenomenological constructions and for
purely theoretical applications. We show that for a general T-brane, the
eigenvalues of the Higgs field can fail to capture the spectrum of localized
modes. In particular, this provides a method for evading some constraints on
F-theory GUTs which have assumed that the spectral equation for the Higgs field
completely determines a local model.Comment: 110 pages, 5 figure
Pulsating Strings in Lunin-Maldacena Backgrounds
We consider pulsating strings in Lunin-Maldacena backgrounds, specifically in
deformed Minkowski spacetime and deformed AdS_5xS^5. We find the relation
between the energy and the oscillation number of the pulsating string when the
deformation is small. Since the oscillation number is an adiabatic invariant it
can be used to explore the regime of highly excited string states. We then
quantize the string and look for such a sector. For the deformed Minkowski
background we find a precise match with the classical results if the
oscillation number is quantized as an even number. For the deformed AdS_5xS^5
we find a contribution which depends on the deformation parameter.Comment: 16 pages, 2 figures, typos fixe
Light-like polygonal Wilson loops in 3d Chern-Simons and ABJM theory
We study light-like polygonal Wilson loops in three-dimensional Chern-Simons
and ABJM theory to two-loop order. For both theories we demonstrate that the
one-loop contribution to these correlators cancels. For pure Chern-Simons, we
find that specific UV divergences arise from diagrams involving two cusps,
implying the loss of finiteness and topological invariance at two-loop order.
Studying those UV divergences we derive anomalous conformal Ward identities for
n-cusped Wilson loops which restrict the finite part of the latter to
conformally invariant functions. We also compute the four-cusp Wilson loop in
ABJM theory to two-loop order and find that the result is remarkably similar to
that of the corresponding Wilson loop in N=4 SYM. Finally, we speculate about
the existence of a Wilson loop/scattering amplitude relation in ABJM theory.Comment: 37 pages, many figures; v2: references added, minor changes; v3:
references added, sign error fixed and note adde
An Extremal Chiral Primary Three-Point Function at Two-loops in ABJ(M)
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Counting Exceptional Instantons
We show how to obtain the instanton partition function of N=2 SYM with
exceptional gauge group EFG using blow-up recursion relations derived by
Nakajima and Yoshioka. We compute the two instanton contribution and match it
with the recent proposal for the superconformal index of rank 2 SCFTs with E6,
E7 global symmetry.Comment: 16 pages, references adde
Tailoring Three-Point Functions and Integrability II. Weak/strong coupling match
We compute three-point functions of single trace operators in planar N=4 SYM.
We consider the limit where one of the operators is much smaller than the other
two. We find a precise match between weak and strong coupling in the
Frolov-Tseytlin classical limit for a very general class of classical
solutions. To achieve this match we clarify the issue of back-reaction and
identify precisely which three-point functions are captured by a classical
computation.Comment: 36 pages. v2: figure added, references adde
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