Hyperheavenly spaces and their application in Walker and para-K\"ahler geometries: part II

TL;DR

This paper explores 4-dimensional spaces with null string congruences, focusing on algebraically degenerate self-dual Weyl tensors, and classifies para-K"ahler Einstein metrics within this framework.

Contribution

It provides a comprehensive classification of para-K"ahler Einstein metrics with algebraically degenerate self-dual Weyl spinors in spaces with null string congruences.

Findings

Classified various Petrov-Penrose types of such spaces

Derived all para-K"ahler Einstein metrics with algebraically degenerate self-dual Weyl spinor

Analyzed the structure of spaces admitting expanding self-dual null string congruences

Abstract

4-dimensional spaces equipped with congruences of null strings are considered. It is assumed that a space admits a congruence of expanding self-dual null strings and its self-dual part of the Weyl tensor is algebraically degenerate. Different Petrov-Penrose types of such spaces are analyzed. A special attention is paid to para-K\"ahler Einstein spaces. All para-K\"ahler Einstein metrics of spaces with algebraically degenerate self-dual Weyl spinor are found in all the generality.