Instruct: Identify the main and secondary category of Arxiv papers based on the titles and abstracts
Query: Exponential Lagrangian for the Gravitational Field and the problem of
  Vacuum Energy   We will analyze two particular features of an exponential gravitational
Lagrangian. On the one hand, while this choice of the Lagrangian density allows
for two free parameters, only one scale, the cosmological constant, arises as
fundamental when the proper Einsteinian limit is to be recovered. On the other
hand, the vacuum energy arising from $f(R)$ theories such that $f(0)\neq 0$
needs a cancellation mechanism, by which the present value of the cosmological
constant can be recast.

35
The categories of this paper are: mtrl-th
11
The categories of this paper are: hep-lat
36
The categories of this paper are: cmp-lg
32
The categories of this paper are: atom-ph
13
The categories of this paper are: quant-ph
37
The categories of this paper are: supr-con
9
The categories of this paper are: nlin
2
The categories of this paper are: math
31
The categories of this paper are: ao-sci
12
The categories of this paper are: nucl-th
20
The categories of this paper are: acc-phys
14
The categories of this paper are: math-ph
18
The categories of this paper are: econ
29
The categories of this paper are: funct-an
15
The categories of this paper are: nucl-ex
23
The categories of this paper are: solv-int