...S.Ansoldi¹

E-mail address: ansoldi@trieste.infn.it

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... I. Guendelman²

E-mail address: guendel@bgumail.bgu.ac.il

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...E.Spallucci³

E-mail address: spallucci@trieste.infn.it

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... beam.⁴

This set-up is now a fully working project, PVLAS, at the I.N.F.N. Legnaro laboratories, taking data since May 1999: about this we refer the interested reader to [6] and references therein, as well as to [7] for a more direct connection with axion experiments.

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... diagonalized⁵

We will summarize here the final result about eigenvectors and the corresponding eigenvalues with all the relevant definitions, referring the reader to the mentioned appendix for the detailed computation.

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... get⁶

We now use the $\sim$ symbol to imply the same behavior in the ultraviolet limit.

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