[Vuejs]-Is it possible to refer to a global bus in the template of a component?

You can initialize the bus to a data property like this:

data: {
    eventBus: bus
}

then you can do it in the template like this :

<div v-for="c in aList" v-on:click="eventBus.$emit('casedetails',c._source)">something</div>

but i prefer the first approach you are doing is better

If you have one global bus for all of your Vue components, you can add it to the prototype of Vue like so:

Vue.prototype.$bus = new Vue();

Then, each Vue instance will have a reference to that bus via this.$bus, which would be directly accessible in any template:

<div v-on:click="$bus.$emit(c._source)">something</div>