** Publicis rises 5 pct after posting 0.8 pct Q1organic growth v contraction expected by analysts
** Traders also cite Q1 organic sales of 2.1 bln euros asbeing slightly ahead of consensus
** Best day for stock since December 2013, among most tradedby average volumes on Stoxx 600
** Peers also higher: Havas rises 4.5 pct, WPP up 2 pct
(RM: alasdair.pal.thomsonreuters.com@reuters.net)