29 research outputs found
The Holographic Dictionary for Beta Functions of Multi-trace Coupling Constants
Field theories with weakly coupled holographic duals, such as large N gauge
theories, have a natural separation of their operators into `single-trace
operators' (dual to single-particle states) and `multi-trace operators' (dual
to multi-particle states). There are examples of large N gauge theories where
the beta functions of single-trace coupling constants all vanish, but marginal
multi-trace coupling constants have non-vanishing beta functions that spoil
conformal invariance (even when all multi-trace coupling constants vanish). The
holographic dual of such theories should be a classical solution in anti-de
Sitter space, in which the boundary conditions that correspond to the
multi-trace coupling constants depend on the cutoff scale, in a way that spoils
conformal invariance. We argue that this is realized through specific bulk
coupling constants that lead to a running of the multi-trace coupling
constants. This fills a missing entry in the holographic dictionary.Comment: 31 pages. v2: added references. v3: added references, JHEP versio
The Thermal Free Energy in Large N Chern-Simons-Matter Theories
We compute the thermal free energy in large N U(N) Chern-Simons-matter
theories with matter fields (scalars and/or fermions) in the fundamental
representation, in the large temperature limit. We note that in these theories
the eigenvalue distribution of the holonomy of the gauge field along the
thermal circle does not localize even at very high temperatures, and this
affects the computation significantly. We verify that our results are
consistent with the conjectured dualities between Chern-Simons-matter theories
with scalar fields and with fermion fields, as well as with the strong-weak
coupling duality of the N=2 supersymmetric Chern-Simons-matter theory.Comment: 41 pages, 8 figures. v2: minor corrections, added references. v3:
added pdfoutpu
Three-Prong Distribution of Massive Narrow QCD Jets
We study the planar-flow distributions of narrow, highly boosted, massive QCD
jets. Using the factorization properties of QCD in the collinear limit, we
compute the planar-flow jet function from the one-to-three splitting function
at tree-level. We derive the leading-log behavior of the jet function
analytically. We also compare our semi-analytic jet function with parton-shower
predictions using various generators.Comment: 59 pages, 9 figure
d=3 Bosonic Vector Models Coupled to Chern-Simons Gauge Theories
We study three dimensional O(N)_k and U(N)_k Chern-Simons theories coupled to
a scalar field in the fundamental representation, in the large N limit. For
infinite k this is just the singlet sector of the O(N) (U(N)) vector model,
which is conjectured to be dual to Vasiliev's higher spin gravity theory on
AdS_4. For large k and N we obtain a parity-breaking deformation of this
theory, controlled by the 't Hooft coupling lambda = 4 \pi N / k. For infinite
N we argue (and show explicitly at two-loop order) that the theories with
finite lambda are conformally invariant, and also have an exactly marginal
(\phi^2)^3 deformation.
For large but finite N and small 't Hooft coupling lambda, we show that there
is still a line of fixed points parameterized by the 't Hooft coupling lambda.
We show that, at infinite N, the interacting non-parity-invariant theory with
finite lambda has the same spectrum of primary operators as the free theory,
consisting of an infinite tower of conserved higher-spin currents and a scalar
operator with scaling dimension \Delta=1; however, the correlation functions of
these operators do depend on lambda. Our results suggest that there should
exist a family of higher spin gravity theories, parameterized by lambda, and
continuously connected to Vasiliev's theory. For finite N the higher spin
currents are not conserved.Comment: 34 pages, 29 figures. v2: added reference
Correlation Functions of Large N Chern-Simons-Matter Theories and Bosonization in Three Dimensions
We consider the conformal field theory of N complex massless scalars in 2+1
dimensions, coupled to a U(N) Chern-Simons theory at level k. This theory has a
't Hooft large N limit, keeping fixed \lambda = N/k. We compute some
correlation functions in this theory exactly as a function of \lambda, in the
large N (planar) limit. We show that the results match with the general
predictions of Maldacena and Zhiboedov for the correlators of theories that
have high-spin symmetries in the large N limit. It has been suggested in the
past that this theory is dual (in the large N limit) to the Legendre transform
of the theory of fermions coupled to a Chern-Simons gauge field, and our
results allow us to find the precise mapping between the two theories. We find
that in the large N limit the theory of N scalars coupled to a U(N)_k
Chern-Simons theory is equivalent to the Legendre transform of the theory of k
fermions coupled to a U(k)_N Chern-Simons theory, thus providing a bosonization
of the latter theory. We conjecture that perhaps this duality is valid also for
finite values of N and k, where on the fermionic side we should now have (for
N_f flavors) a U(k)_{N-N_f/2} theory. Similar results hold for real scalars
(fermions) coupled to the O(N)_k Chern-Simons theory.Comment: 49 pages, 16 figures. v2: added reference