@incollection{statphys23_0318,
	title = {Ageing in reaction-diffusion systems},
	address = {Genova, Italy},
	author = {F. Baumann and A. Gambassi and M. Henkel and M. Pleimling and J. Richert},
	booktitle = {Abstract Book of the XXIII IUPAP International Conference on Statistical Physics},
	editor = {Luciano Pietronero and Vittorio Loreto and Stefano Zapperi},
	month = {9-13 July},
	url = {http://st23.statphys23.org/webservices/abstract/preview_pop.php?ID_PAPER=318},
	year = {2007},
	biburl = {http://www.bibsonomy.org/bibtex/27c79694e052e4ae730305932dc4fd96e/statphys23},
	abstract = {The investigation of ageing phenomena in critical reaction-diffusion systems,
like for instance the (fermionic) contact process (directed percolation), has started only recently [1,2]. To some surprise it was found that the ageing exponents $a$ and $b$, that describe the scaling behaviour of the autoresponse and of the autocorrelation, are not equal, in contrast to critical systems
with detailed balance where the identity $a=b$ holds. As a consequences the definition of the fluctuation-dissipation ratio must differ in these systems from that used in critical magnetic systems. 

In this contribution we first look at the contact process from a field-theoretical point of view [3], confirming the above result that a and b do not agree. We then suggest an interpretation of the modified definition of the 
flucutation-dissipation ratio (which was already proposed in [2]) for this
specific system. We also look at a different type of reaction-diffusion system which allows for an exact solution [4]. Also in this case, the above inequality
of a and b is confirmed, but the relation between them is not identical to the relation found for the critical contact process. \\

1)  T. Enss, M. Henkel, A. Picone, U. Schollwoeck, J. Phys. A: Math. Gen. {\bf 37}, 10479.\\
2) J.J. Ramasco, M. Henkel, M.A. Santos, and C.A. da Silva Santos, J. Phys A: Math. Gen. {\bf 37}, 10497.\\
3) F. Baumann and A. Gambassi, J. Stat. Mech. P01002 (2007).\\
4) F. Baumann, M. Henkel, M. Pleimling, and J. Richert, J.Phys. A: Math. Gen. {\bf 38}, 6623 (2005).},
	keywords = {ageing directed fluctuation-dissipation percolation ratio reaction-diffusion statphys23 systems topic-4 }
}