# The Horowitz-Polchinski solution The Horowitz-Polchinski solution is a classical solution to an effective field theory action of the low energy degrees of freedom that describes the critical behaviour (as temperature approaches the [[0439 Hagedorn transition|Hagedorn]] temperature) of highly excited free strings. ## Refs - OG: [[1997#Horowitz, Polchinski]] - all order in $\alpha'$: [[2023#Agia, Jafferis]] - discussed in [[2021#Chen, Maldacena, Witten]] ## Extensions - a fluid model for the transition: [[2022#Matsuo]] - [[2022#Chen]]