Physics Letters B 771 (2017) 180–188
Contents lists available at ScienceDirect
Physics Letters B
www.elsevier.com/locate/physletb
Rainbow tensor model with enhanced symmetry and extreme melonic
dominance
H. Itoyama
a,b
, A. Mironov
c,d,e,∗
, A. Morozov
d
a
Department of Mathematics and Physics, Graduate School of Science, Osaka City University, 3-3-138, Sugimoto, Sumiyoshi-ku, Osaka, 558-8585, Japan
b
Osaka City University Advanced Mathematical Institute (OCAMI), 3-3-138, Sugimoto, Sumiyoshi-ku, Osaka, 558-8585, Japan
c
I.E. Tamm Theory Department, Lebedev Physics Institute, Leninsky prospect, 53, Moscow 119991, Russia
d
ITEP, B. Cheremushkinskaya, 25, Moscow, 117259, Russia
e
Institute for Information Transmission Problems, Bolshoy Karetny per. 19, build. 1, Moscow 127051, Russia
a r t i c l e i n f o a b s t r a c t
Article history:
Received
21 March 2017
Received
in revised form 26 April 2017
Accepted
15 May 2017
Available
online 18 May 2017
Editor:
M. Cveti
ˇ
c
We introduce and briefly analyze the rainbow tensor model where all planar diagrams are melonic. This
leads to considerable simplification of the large N limit as compared to that of the matrix model: in
particular, what are dressed in this limit are propagators only, which leads to an oversimplified closed
set of Schwinger–Dyson equations for multi-point correlators. We briefly touch upon the Ward identities,
the substitute of the spectral curve and the AMM/EO topological recursion and their possible connections
to Connes–Kreimer theory and forest formulas.
© 2017 The Authors. Published by Elsevier B.V. This is an open access article under the CC BY license
(http://creativecommons.org/licenses/by/4.0/). Funded by SCOAP
3
.
1. Introduction
Tensor models are thought of as straightforward generalizations of matrix models from matrices to tensors [1], and are the most
natural objects to consider in the study of non-linear algebra [2]. For a variety of reasons, they did not long attract the attention they
deserve, though a lot of important work was performed by numerous research groups (see [3,4] and especially [5–10] for incomplete set
of references).
The
current surge of interest to tensor models [11,12,14,15] is partly explained by their simplified large N behavior as compared to
the matrix models: instead of all planar diagrams, what contribute in some cases are only melonic ones. This makes the Schwinger–
Dyson
equation (SDE) in the large N limit almost as simple as in the leading logarithmic approximation in QED: it is enough to
dress the propagator, while the vertices remain undressed. The only complication is that, in this limit, the SDE is no longer linear
and solved by a geometric progression: instead it turns into a higher order equation, but the semi-infinite Bogoliubov chain does not
arise.
In
this letter, we consider the rainbow tensor model which possesses these properties in extreme: it selects the melonic diagrams out
of all planar by symmetry, all others simply do not exist as its Feynman diagrams. In exchange, it clarifies to some extent what is the
price to pay for this “simplification”: already the SDE becomes much more involved when one considers a generic point in the moduli
space of external parameters (colorings). The model can be easily formulated for tensors of any rank D, but all its features are already
seen at the level of D = 3, which we use in most considerations to simplify the presentation. We mostly repeat in slightly different words
and with slightly different accents the elementary basic observations, which were already made in the above cited references, and try
to minimize deviations from the previously introduced notation. We concentrate on the matrix model aspects of the story and do not
consider time-dependence [11,12,14,15], relation to SYK model [16,17], holography [17].
We
also do not dwell upon intriguing similarity to arborescent calculus in knot theory [18]. It is, however, reflected in some of the
terminology below.
*
Corresponding author.
E-mail
address: mironov@itep.ru (A. Mironov).
http://dx.doi.org/10.1016/j.physletb.2017.05.043
0370-2693/
© 2017 The Authors. Published by Elsevier B.V. This is an open access article under the CC BY license (http://creativecommons.org/licenses/by/4.0/). Funded by
SCOAP
3
.