Giacomo Ferrante - No room for monopole dark matter

Thursday Jul 9, 2026, 3:00 PM → 4:00 PM Europe/Rome

Aula G, 1st floor (Via della Vasca Navale, 84)

Magnetic monopoles are topological defects: solitons whose existence and stability follow from the vacuum structure of a spontaneously broken gauge theory. This makes monopoles from a dark gauge sector a natural and compelling dark matter candidate. Such monopoles are produced in the early universe during the thermal phase transition that leads to symmetry breaking in the dark sector. I will revisit the computation of their abundance in the simplest model admitting monopole solutions. I will explore the three regimes where the phase transition is second order, weakly first order, or supercooled, identifying the regions of parameter space where the monopole relic density matches that of dark matter. However, a dark sector featuring monopoles necessarily contains stable electrically-charged particles, namely massive vector bosons. I will show that the abundance of gauge bosons always greatly exceeds the monopole one. This result leads to the conclusion that dark monopoles cannot constitute a sizeable fraction of dark matter in the minimal model, contrarily to what has been claimed in the literature.

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