Sasakian immersions of Sasaki-Ricci solitons into Sasakian space forms

TL;DR

This paper investigates conditions under which Sasaki-Ricci solitons can be immersed into Sasakian space forms, revealing their Einstein properties and explicit constants, especially in the compact case with specific curvature bounds.

Contribution

It establishes that Sasaki-Ricci solitons immersed in Sasakian space forms are $ extit{ extbf{ exteta}-Einstein} $ with rational constants and characterizes their structure based on curvature conditions.

Findings

Sasaki-Ricci solitons immersed in space forms are $ extit{ extbf{ exteta}-Einstein}.

The $ extit{ extbf{ exteta}}$-Einstein constants are rational numbers.

For $c \\leq -3$, the solitons are locally equivalent to standard space forms.

Abstract

Let $(g,X)$ be a Sasaki-Ricci soliton on a Sasakian manifold $S$. We prove that if $(S,g)$ admits a local Sasakian immersion in a Sasakian space form $S(N,c)$ of constant $\phi$-sectional curvature $c$, then $S$ is $\eta$-Einstein and its $\eta$-Einstein constants are rational. Moreover, if $c\leq -3$, $S$ is locally equivalent to the Sasakian space form $S(n,c)$ and its $\eta$-Einstein constants are determined by $c$. Further results are obtained in the compact setting, i.e. when $c>-3$, under additional hypotheses.