The problem is when you use event propagation to register the event handlers, it is normally attached to the body
or some elements which is much higher up in the hierarchy. So by the time the events attached to accordion headers will be executed resulting in collapsing/expanding the tab.
Since you are creating the checkbox dynamically, the solution is to add the click event handler preventing propagation to the checkbox after it is created.
Ex:
var chk = $('<input />', { type: 'checkbox'});
chk.click(function(e){
e.stopPropagation();
});
chk.appendTo(accordionHeader)