Eur. Phys. J. C (2015) 75:202
DOI 10.1140/epjc/s10052-015-3423-8
Regular Article - Theoretical Physics
Twelve-dimensional effective action and T -duality
Kang-Sin Choi
a
Scranton Honors Program, Ewha Womans University, Seoul 120-750, Korea
Received: 1 December 2014 / Accepted: 17 April 2015 / Published online: 9 May 2015
© The Author(s) 2015. This article is published with open access at Springerlink.com
Abstract We propose a 12-dimensional supergravity
action which describes low-energy dynamics of F-theory.
Dimensional reduction leads the theory to become 11-
dimensional, IIA, and IIB supergravities. Self-duality of the
four-form field in IIB supergravity is understood. It is neces-
sary to abandon 12-dimensional Poincaré symmetry by mak-
ing one dimension compact, which is to be decompactified
in some region of parameter space, such that the physical
degrees of freedom are the same as those of 11-dimensional
supergravity. This makes T -duality explicit as a relation
between different compactification schemes.
1 Introduction
The ideas of Kaluza and Klein (KK) [1,2], generalized to
higher dimensions, are beautiful ones that translate the known
field degrees of freedom and their interactions into geometry
of extra dimensions. Most of the supergravity theories, which
one hopes to have an intimate connection to our world, can be
obtained by dimensional reduction of an 11-dimensional one
[3]. However, it does not directly give type IIB supergravity
in ten dimensions, although their relation is well understood
in the context of string theory.
Eleven-dimensional supergravity is a low-energy descrip-
tion of M-theory [4,5]. It has also been suggested that type
IIB superstring theory is obtained by a reduction of F -theory
on a torus, with its complex structure identified by the axion–
dilaton, and the latter is shown to be T -dual to M-theory [6].
Thus, the effective field theory of F-theory should be 12-
dimensional; however, it is not easy to write down the action.
One crucial difficulty might be that the 12-dimensional mini-
mal fermion with Lorentzian signature (11, 1), which must be
the case for F -theory, should have superpartner components
with spin higher than two in the four-dimensional language,
whose interacting theory would be inconsistent [7]. Another
a
e-mail: kangsin@ewha.ac.kr
obstacle is that, if F-theory is dual to M-theory, there should
be no surplus field degrees of freedom, although the former
is a higher-dimensional theory.
An important hint comes from a careful look at the deriva-
tion of F -theory [6,8,9]. Although it is T -dual to M-theory,
F-theory has one more dimension than the latter. Now, this
extra dimension is a dual dimension to one of the dimension
shared by the two theories. In other words, F -theory has two
redundant dimensions whose radii are inverse to each other.
Although we cannot maintain 12-dimensional Poincaré sym-
metry fully, each of the 10- and 11-dimensional theories
can be symmetric on its own. There is no contradiction if
we cannot see both at once. Therefore, it is natural to keep
both dimensions. In this picture, M-theory looks like a com-
pactification F-theory on a circle, as schematically shown in
Fig. 1.
We propose for the bosonic part a desired 12-dimensional
effective action, whose dimensional reductions lead to those
of all known supergravities in 11 and 10 dimensions, found
in the standard textbooks [10]. Since we follow and make
use of the duality relation between M- and F-theory from
the 11-dimensional supergravity, this theory shall provide
the effective field theory for F-theory.
Supergravity is powerful enough in the sense that many
of the new results here, like the existence of a three-brane
and generalized T -duality, are obtained without referring to
string theory. Of course, the effective field description of F-
theory is timely in realistic model building, because we have
so far borrowed descriptions, for instance of the gauge fields,
from M-theory [11–13].
2 The bosonic action of 12-dimensional supergravity
We start with the fundamental bosonic degrees of freedom of
11-dimensional supergravity: the graviton G
mn
and the rank
three antisymmetric tensor field C
mnp
. The latter is promoted
to a four-form field,
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