English (United Kingdom)

https://curated-unify.zendy.io/wp-json/zendy-region/v1/featured_content/oa?rat=en

https://curated-unify.zendy.io/wp-json/zendy-region/v1/highlighted_journal/

Global: Zendy Plus annual

Presents the access of premium content as premium feature

Premium Content

Presents the keyphrase highlighting as premium feature

Keyphrase Highlighting

Presents the summarisation as premium feature

Summarisation

Insights

Presents the pdf analysis as premium feature

PDF Analysis

Presents the zaia usage as premium feature

ZAIA

Global: Zendy Plus monthly

Global: Zendy Tools annual

Global: Zendy Tools monthly

Global: Zendy Free Plan

We introduce the notion of the Color Glass Condensate (CGC) density matrix$\hat\rho$. This generalizes the concept of probability density for thedistribution of the color charges in the hadronic wave function and isconsistent with understanding the CGC as an effective theory after integrationof part of the hadronic degrees of freedom. We derive the evolution equationsfor the density matrix and show that the JIMWLK evolution equation arises hereas the evolution of diagonal matrix elements of $\hat\rho$ in the color chargedensity basis. We analyze the behavior of this density matrix under high energyevolution and show that its purity decreases with energy. We show that theevolution equation for the density matrix has the celebratedKossakowsky-Lindblad form describing the non-unitary evolution of the densitymatrix of an open system. Additionally, we consider the dilute limit anddemonstrate that, at large rapidity, the entanglement entropy of the densitymatrix grows linearly with rapidity according to $d S_e / d y = \gamma$, where$\gamma$ is the leading BFKL eigenvalue. We also discuss the evolution of$\hat\rho$ in the saturated regime and relate it to the Levin-Tuchin law andfind that the entropy again grows linearly with rapidity, but at a slower rate.By analyzing the dense and dilute regimes of the full density matrix we areable to establish a duality between the regimes. Finally we introduce theWigner functional derived from this density matrix and discuss how it can beused to determine the distribution of color currents, which may be instrumentalin understanding dynamical features of QCD at high energy.

The Color Glass Condensate density matrix: Lindblad evolution, entanglement entropy and Wigner functional