72 research outputs found
On a CFT limit of planar -deformed SYM theory
We show that an integrable four-dimensional non-unitary field theory that was
recently proposed as a certain limit of the -deformed
SYM theory is incomplete and not conformal -- not even in the planar limit. We
complete this theory by double-trace couplings and find conformal one-loop
fix-points when admitting respective complex coupling constants. These
couplings must not be neglected in the planar limit, as they can contribute to
planar multi-point functions. Based on our results for certain two-loop planar
anomalous dimensions, we propose tests of integrability.Comment: LaTeX, 3 pages, 1 Figur
A piece of cake: the ground-state energies in gamma_i-deformed N=4 SYM theory
In the non-supersymmetric gamma_i-deformed N=4 SYM theory, the scaling
dimensions of the operators tr[Z^L] composed of L scalar fields Z receive
finite-size wrapping and prewrapping corrections in the 't Hooft limit. In this
paper, we calculate these scaling dimensions to leading wrapping order directly
from Feynman diagrams. For L>=3, the result is proportional to the maximally
transcendental `cake' integral. It matches with an earlier result obtained from
the integrability-based Luescher corrections, TBA and Y-system equations. At
L=2, where the integrability-based equations yield infinity, we find a finite
rational result. This result is renormalization-scheme dependent due to the
non-vanishing beta-function of an induced quartic scalar double-trace coupling,
on which we have reported earlier. This explicitly shows that conformal
invariance is broken - even in the 't Hooft limit.Comment: 21 pages, LaTeX, BibTeX, pstricks, feynm
The complete one-loop dilatation operator of planar real beta-deformed N=4 SYM theory
We determine the missing finite-size corrections to the asymptotic one-loop
dilatation operator of the real -deformed SYM theory for
the gauge groups and in the 't Hooft limit. In the case,
the absence of the field components leads to a new kind of finite-size
effect, which we call prewrapping. We classify which states are potentially
affected by prewrapping at generic loop orders and comment on the necessity to
include it into the integrability-based description. As a further result, we
identify classes of -point correlation functions which at all loop orders in
the planar theory are given by the values of their undeformed counterparts.
Finally, we determine the superconformal multiplet structure and one-loop
anomalous dimensions of all single-trace states with classical scaling
dimension .Comment: Latex, feynmp, pstricks, 37 pages, 6 tables, v2: formulations
improved, references added, typos corrected, v3: typos corrected, matches
published versio
On-Shell Methods for the Two-Loop Dilatation Operator and Finite Remainders
We compute the two-loop minimal form factors of all operators in the SU(2)
sector of planar N=4 SYM theory via on-shell unitarity methods. From the UV
divergence of this result, we obtain the two-loop dilatation operator in this
sector. Furthermore, we calculate the corresponding finite remainder functions.
Since the operators break the supersymmetry, the remainder functions do not
have the property of uniform transcendentality. However, the leading
transcendentality part turns out to be universal and is identical to the
corresponding BPS expressions. The remainder functions are shown to satisfy
linear relations which can be explained by Ward identities of form factors
following from R-symmetry.Comment: 24 pages; v2: typos corrected, some formulations clarified, matches
published versio
The spectrum of tachyons in AdS/CFT
We analyze the spectrum of open strings stretched between a D-brane and an
anti-D-brane in planar AdS/CFT using various tools. We focus on open strings
ending on two giant gravitons with different orientation in
and study the spectrum of string excitations using the following approaches:
open spin-chain, boundary asymptotic Bethe ansatz and boundary thermodynamic
Bethe ansatz (BTBA). We find agreement between a perturbative high order
diagrammatic calculation in SYM and the leading finite-size
boundary Luscher correction. We study the ground state energy of the system at
finite coupling by deriving and numerically solving a set of BTBA equations.
While the numerics give reasonable results at small coupling, they break down
at finite coupling when the total energy of the string gets close to zero,
possibly indicating that the state turns tachyonic. The location of the
breakdown is also predicted analytically.Comment: 40 pages, lots of figures, v2: typos corrected, accepted for
publication in JHE
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