Physics Letters B 750 (2015) 294–297
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Physics Letters B
www.elsevier.com/locate/physletb
Application of Kawaguchi Lagrangian formulation to string theory
Ryoko Yahagi
∗
, Akio Sugamoto
Physics Department, Ochanomizu University, 2-1-1 Ohtsuka Bunkyo-ku, Tokyo 112-8610, Japan
a r t i c l e i n f o a b s t r a c t
Article history:
Received
12 August 2015
Received
in revised form 11 September
2015
Accepted
11 September 2015
Available
online 19 September 2015
Editor:
M. Cveti
ˇ
c
Keywords:
Lagrangian
formalism
Kawaguchi
geometry
Field
theory
String
theory
Duality
String-scalar duality proposed by Y. Hosotani and membrane-scalar duality by A. Sugamoto are
reexamined in the context of Kawaguchi Lagrangian formulation. The characteristic feature of this
formulation is the indifferent nature of fields and parameters. Therefore even the exchange of roles
between fields and parameters is possible. In this manner, dualities above can be proved easily. Between
Kawaguchi metrics of the dually related theories, a simple relation is found. As an example of the
exchange between fermionic fields and parameters, a replacement of the role of Grassmann parameters
of the 2-dimensional superspace by the 9th component of Neveu–Schwarz–Ramond (NSR) fermions is
studied in superstring model. Compactification is also discussed in this model.
© 2015 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
Recently, one of the authors (RY) proposed in collaboration with
Ootsuka, Ishida and Tanaka, a covariant Lagrangian formalism for
field theories with the aid of Kawaguchi geometry [1]. Kawaguchi
space [2], also known as areal space, is defined by a set of a man-
ifold
M and an areal metric called Kawaguchi metric K . In case of
field theories, M includes fields y
i
(i = 1, ···, n) and parameters
x
μ
(μ = 0, 1, ···, D − 1) of space and time, on the equal footing,
and is called extended configuration space. We label them as Z
a
(a = 0, ···, n + D − 1). Kawaguchi metric K is a kind of Lagrangian
density, depending on the coordinates of point in M and its deriva-
tives,
K = K (Z
a
, dZ
a
1
a
2
···a
D
), where (1)
dZ
a
1
a
2
···a
D
≡ dZ
a
1
∧ dZ
a
2
∧···∧dZ
a
D
. (2)
Integral of K over a given “sheet” S (or a higher dimensional sub-
manifold
depending on the theory) gives an area (or volume) of
the “sheet”. This gives an action of field theories:
*
Corresponding author.
E-mail
addresses: yahagi@hep.phys.ocha.ac.jp (R. Yahagi),
sugamoto.akio@ocha.ac.jp (A. Sugamoto).
Action =
S
K
= the area or volume of a sub-manifold S. (3)
To guarantee the reparametrization invariance, the homogeneity
condition is imposed on the Kawaguchi metric, namely
K (Z,λdZ
a
1
a
2
···a
D
) = λK (Z , dZ
a
1
a
2
···a
D
). (4)
In the formulation, fields and parameters are not identified.
If we assign {y
i
} as fields and {x
μ
} as parameters among {Z
a
},
the fields become functions of the parameters, such as σ : y
i
=
y
i
(x
0
, ···, x
D−1
). After the parametrization σ is fixed, we have
σ
∗
dx
0···μ−1
∧ dy
i
∧ dx
μ+1···D−1
dx
0···D−1
= ∂
μ
y
i
(x), (5)
and the usual description of field theories appears. This operation
σ
∗
is sometimes called pullback of a parametrization σ . However
it is important to note that there are a number of different ways
for the parametrization.
In
[1], it is proved that every known action can be an area
(a volume) of a certain subspace, so that every field theory can be
reformulated à la Kawaguchi. Nambu–Goto action is the prototype
of this formulation. The equal treatment of fields and parameters
http://dx.doi.org/10.1016/j.physletb.2015.09.034
0370-2693/
© 2015 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
.