A Quantum Phase Transition in the Cosmic Ray Energy Distribution

TL;DR

This paper proposes that the 'knee' in cosmic ray energy distribution at around 1 PeV is a second order quantum phase transition, involving a shift from boson-dominated to fermion-dominated cosmic rays.

Contribution

It introduces the idea that the cosmic ray energy 'knee' is a quantum phase transition, linking nuclear physics models to cosmic ray behavior at high energies.

Findings

Identifies the 'knee' as a second order phase transition with specific heat discontinuity.

Suggests a transition from boson-dominated to fermion-dominated cosmic rays.

Estimates the transition energy based on nuclear photo-disintegration processes.

Abstract

We here argue that the "knee" of the cosmic ray energy distribution at $E_c \sim 1$ PeV represents a second order phase transition of cosmic proportions. The discontinuity of the heat capacity per cosmic ray particle is given by $\Delta c=0.450196\ k_B$. However the idea of a deeper critical point singularity cannot be ruled out by present accuracy in neither theory nor experiment. The quantum phase transition consists of cosmic rays dominated by bosons for the low temperature phase E<E_c and dominated by fermions for high temperature phase $E > E_c$. The low temperature phase arises from those nuclei described by the usual and conventional collective boson models of nuclear physics. The high temperature phase is dominated by protons. The transition energy $E_c$ may be estimated in terms of the photo-disintegration of nuclei.