2026-07-072026-07-07http://salesiana.dossiersoluciones.com/handle/123456789/110600We review the entanglement properties in collective models and their relationship with quantum phase transitions. Focusing on the concurrence which characterizes the two-spin entanglement, we show that for first-order transition, this quantity is singular but continuous at the transition point, contrary to the common belief. We also propose a conjecture for the concurrence of arbitrary symmetric states which connects it with a recently proposed criterion for bipartite entanglement.8 pages, 2 figures, published versionQuantum PhysicsStatistical Mechanicstext