I searched a lot to find a tutorial for drag & drop with jQuery alone (without UI), but due to the popularity of JQuery UI, all drag and drop features are based on JQuer
There are several plugins that you may use take a look at the following
http://wayfarerweb.com/jquery/plugins/animadrag/
http://threedubmedia.com/code/event/drag/demo/
it still jquery but no UI