\noindent Fourth meeting of the series of informal ``particle physics and cosmology'' meetings between theorists of the Institut de Physique Théorique and experimentalists of the Service de Physique de Particules/IRFU. \\ \par \noindent Theme: Anti-Hydrogen and The Physics of Heavy Ion Collisions \\ \par \noindent Titles of the topics to be discussed and program: see the web page of the Rencontres at this link: \\ http://ipht.cea.fr/en/Phocea-SPhT/ast\_visu\_spht.php?id\_ast=475