Back in time: The first black holes formed in the Universe

• Francesco Crescimbeni

Black holes have transformed our understanding of the Universe, shaping astronomy, cosmology, and fundamental physics. Yet their origin remains an open question. Some may have formed in the earliest moments after the Big Bang, including extremely light black holes that could still exist today. If so, they might help solve key problems in cosmology. From the first instants of cosmic history to the present, I will explore their formation and evolution, and how gravitational waves have opened a new window into their possible detection.

Dicussion

Hadronic molecules, compact tetraquarks and open relationships

• Andrea Carducci

The exotic hadron X(3872), first observed in 2003, remains one of the most intriguing states in heavy hadron spectroscopy. Its mass, extremely close to the DD* threshold, narrow width, and unusual decay patterns challenge the conventional quark–antiquark charmonium interpretation. Two main scenarios have been proposed to explain its structure: a shallow bound hadronic molecule or a compact tetraquark configuration with tightly correlated diquark–antidiquark constituents. In this presentation, we examine the theoretical and phenomenological arguments supporting each interpretation. We discuss how the proximity to threshold naturally suggests a loosely bound state governed by universal properties of near-threshold systems, while production rates in high-energy collisions and certain decay features may favor a more compact structure. Particular attention is devoted to prompt production, isospin violation, and the analogy with open relationships.

Discussion