  The rise of a trending topic on Twitter or Facebook leads to the temporal
emergence of a set of users currently interested in that topic. Given the
temporary nature of the links between these users, being able to dynamically
identify communities of users related to this trending topic would allow for a
rapid spread of information. Indeed, individual users inside a community might
receive recommendations of content generated by the other users, or the
community as a whole could receive group recommendations, with new content
related to that trending topic. In this paper, we tackle this challenge, by
identifying coherent topic-dependent user groups, linking those who generate
the content (creators) and those who spread this content, e.g., by
retweeting/reposting it (distributors). This is a novel problem on
group-to-group interactions in the context of recommender systems. Analysis on
real-world Twitter data compare our proposal with a baseline approach that
considers the retweeting activity, and validate it with standard metrics.
Results show the effectiveness of our approach to identify communities
interested in a topic where each includes content creators and content
distributors, facilitating users' interactions and the spread of new
information.
