28.11.2012 Views

Exact Solutions and Scalar Fields in Gravity - Instituto Avanzado de ...

Exact Solutions and Scalar Fields in Gravity - Instituto Avanzado de ...

Exact Solutions and Scalar Fields in Gravity - Instituto Avanzado de ...

SHOW MORE
SHOW LESS

Create successful ePaper yourself

Turn your PDF publications into a flip-book with our unique Google optimized e-Paper software.

144 EXACT SOLUTIONS AND SCALAR FIELDS IN GRAVITY<br />

We have here the follow<strong>in</strong>g dimensions:<br />

The Lagrangian (11) <strong>and</strong> the presently known exact<br />

solutions <strong>in</strong> MAG have been reviewed <strong>in</strong> [3].<br />

3. THE TRIPLET ANSATZ<br />

In the follow<strong>in</strong>g we will briefly review the results of Obukhov et al.<br />

[4]. Start<strong>in</strong>g from the most general gauge Lagrangian <strong>in</strong> (11), we<br />

now <strong>in</strong>vestigate the special case with<br />

Thus we consi<strong>de</strong>r a general weak part, i.e., we do not impose that one<br />

of the weak coupl<strong>in</strong>g constants vanishes right from the beg<strong>in</strong>n<strong>in</strong>g. However,<br />

the strong gravity part of (11) is truncated for simplicity. Its only<br />

surviv<strong>in</strong>g piece is given by the square of the dilation part of the segmental<br />

curvature In this case, the result of Obukhov et<br />

al. [4] reads as follows: Effectively, the curvature may be consi<strong>de</strong>red<br />

as Riemannian, torsion <strong>and</strong> nonmetricity may be represented by a<br />

1-form<br />

With the aid of the Riemannian curvature we <strong>de</strong>note Riemannian<br />

quantities by a til<strong>de</strong>, the field equation (4) looks like the E<strong>in</strong>ste<strong>in</strong><br />

equation with an energy-momentum source that <strong>de</strong>pends on torsion <strong>and</strong><br />

nonmetricity. Therefore, the field equation (5) becomes a system of differential<br />

equations for torsion <strong>and</strong> nonmetricity alone. In the vacuum<br />

case (i. e. these differential equations reduce to<br />

The four constants <strong>and</strong> which appear <strong>in</strong> (18) <strong>and</strong> (14),<br />

<strong>de</strong>pend uniquely on the parameters of the MAG Lagrangian (13):

Hooray! Your file is uploaded and ready to be published.

Saved successfully!

Ooh no, something went wrong!