Physics Letters B 795 (2019) 528–532
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Physics Letters B
www.elsevier.com/locate/physletb
Bosonic Fradkin-Tseytlin equations unfolded. Irreducible case
O.V. Shaynkman
I.E. Tamm Theory Department, Lebedev Physical Institute, Leninski prospect 53, 119991, Moscow, Russia
a r t i c l e i n f o a b s t r a c t
Article history:
Received
27 May 2019
Accepted
31 May 2019
Available
online 5 June 2019
Editor:
M. Cveti
ˇ
c
We factorize 4d Fradkin-Linetsky higher spin conformal algebra by maximal ideal I
1
− α and construct
irreducible infinite-dimensional modules M
α
of 4d conformal algebra that are parameterized by real
number α. It is shown that independently of α unfolded system of equations corresponding to each M
α
describes collection of Fradkin-Tseytlin equations for all spins s = 1, ..., ∞ with zero multiplicity.
© 2019 The Author. 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
Conformal higher spin theory, i.e. theory of interacting confor-
mal
fields of all spins, is an interesting object from both AdS/CFT
correspondence and possible connection to AdS higher spin theory
points of view. It was discussed in a quite amount of papers (some
of which are [1–9]) starting from the pioneering work by Fradkin
and Tseytlin [10], where Lagrangians and corresponding equations
of motion (Fradkin-Tseytlin equations) describing free dynamics of
conformal fields of all spins were constructed. Then in paper [11]
infinite
dimensional algebras were introduced that were argued to
be proper candidates for the role of conformal higher spin algebra.
The
construction of [11]was as follows. Consider Weyl star
product algebra of two-component oscillators a, b,
¯
a,
¯
b
[b
β
, a
α
]
∗
= δ
α
β
, [
¯
b
˙
β
,
¯
a
˙
α
]
∗
= δ
˙
α
˙
β
, α,
˙
α = 1, 2, (1.1)
with the standard star product defined for symbols of operators
f (a, b,
¯
a,
¯
b) and g(a, b,
¯
a,
¯
b) by formula f ∗ g = f exp(
←→
)g , where
←→
=
1
2
←−
∂
∂b
·
−→
∂
∂a
−
←−
∂
∂a
·
−→
∂
∂b
+
←−
∂
∂
¯
b
·
−→
∂
∂
¯
a
−
←−
∂
∂
¯
a
·
−→
∂
∂
¯
b
.
(1.2)
As was shown in [12], [13], bilinear combinations of oscillators
with respect to star product commutator [ f , g]
∗
form sp(8) al-
gebra,
which reduces to 4d conformal subalgebra u(2, 2) when
restricted by two additional conditions
1. Centralization by helicity operator Z = i/2(a
α
b
α
−
¯
a
˙
α
¯
b
˙
α
);
[
f , Z]
∗
= 0
2. Reality condition f
(a, b,
¯
a,
¯
b) =−
¯
f (i
¯
a, i
¯
b, ia, ib).
E-mail address: shayn@lpi.ru.
(1.3)
The idea of Fradkin and Linetsky was to bring all polynomials (not
only bilinear) into the play but still keep conditions (1.3)imposed
and, thus, get infinite-dimensional extension of u(2, 2), which they
called iu(2, 2).
Let
us note that algebra iu(2, 2) is isomorphic to AdS
5
higher
spin algebra that was discussed in several papers [14–19]. In [17]
it
was denoted as cu(1, 0|8) where 8 indicates the number of os-
cillators
used and pair 1,0 points out that it has trivial structure
in spin 1 Yang-Mills sector. Algebra isu(2, 2) (i.e. iu(2, 2) factorized
by all star powers of Z ) was originally (in [11]) denoted as hsc(4),
where hsc means higher spin conformal and 4 indicates that it
extends 4-dimensional conformal algebra. It is isomorphic to the
minimal AdS
5
higher spin algebra denoted as hu
0
(1, 0|8) in [17].
As was discussed in [20–22]one can associate the minimal Ad S
5
higher spin algebra with the quotient of universal enveloping Ad S
5
Lie algebra over the kernel of its singleton representation.
By
analogy with the Ad S case the procedure of construction
of full nonlinear conformal higher spin theory could be separated
into two steps:
(1) Reformulate
linear equations of motion in unfolded (first or-
der)
form with higher spin algebra been gauge symmetry al-
gebra
of the system.
(2) Deform
nonlinearly both equations of motion and gauge sym-
metries
in the self consistent way.
Although
the second step requires a big amount of guess, the first
step is rather straightforward. In paper [23]unfolded formulation
of Fradkin-Tseytlin equations corresponding to reducible algebra
iu(2, 2) was given and in paper [24]the spectrum of spins de-
scribed
by this system was obtained. At the present paper we
https://doi.org/10.1016/j.physletb.2019.05.050
0370-2693/
© 2019 The Author. 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
.