[xwiki-users] Logging configuration

Hi, I use XWiki 6.3 on ubuntu 14.04 LTS using Tomcat 7 and MySQL (XWiki .deb version). I want to know how to log some specific stuff like user creation or registration, pages modification, login/logout, forbidden acces to a page... I understand that i can do it with the administration interface of the wiki or by editing the logback.xml file. But i can't find any information on which "Logger" i have to configure to log specific events. For example, i found that if i set the "com.xpn.xwiki.user.impl.xwiki.MyFormAuthenticator" to INFO level, i can see failed and successful login in the catalina.out file. But for other specific action i don't know! I tried some logger but with no result for what i want to log. Thanks for help.