app/views/catalog/_index.html.erb
<% content_for(:sidebar) do %>
<%= render 'search_sidebar' %>
<% end %>
<% unless has_search_parameters? %>
<%# if there are no input/search related params, display the "home" partial -%>
<%= render 'home' %>
<%= render 'shared/sitelinks_search_box' %>
<% else %>
<%= render 'search_results' %>
<% end %>