Lambda Phenomena: the Lambda points of liquid Helium and chiral QCD

TL;DR

This paper explores the similarities between the superfluid transition in liquid Helium and the chiral phase transition in QCD, focusing on critical phenomena and universal scaling behaviors.

Contribution

It analyzes the critical behavior of QCD near the chiral limit and compares it with liquid Helium, highlighting implications for baryon number susceptibilities.

Findings

Finite specific heat at critical point in both systems

Implications for O(4) scaling in QCD

Potential universal features at phase transition

Abstract

The superfluid transition of liquid Helium shares an interesting phenomenon with the chiral limit of QCD: the specific heat is finite at the critical point, but has a cusp. From this follows an interesting mixture of universal and non-universal features at the critical point. Through the CP symmetry of chiral QCD, this has implications for the fourth order baryon number susceptibility and susceptibilities of higher orders. Investigations of such a scaling will show us whether O(4) scaling is an accurate description of baryon-free QCD when the pion mass is realistic.