%0 Journal Article %T The equivariant cohomology rings of Peterson varieties %A Yukiko Fukukawa %A Megumi Harada %A Mikiya Masuda %J Mathematics %D 2013 %I arXiv %R 10.2969/jmsj/06731147 %X The main result of this note is an efficient presentation of the $S^1$-equivariant cohomology ring of Peterson varieties (in type $A$) as a quotient of a polynomial ring by an ideal $\mathcal{J}$, in the spirit of the well-known Borel presentation of the cohomology of the flag variety. Our result simplifies previous presentations given by Harada-Tymoczko and Bayegan-Harada. In particular, our result gives an affirmative answer to a conjecture of Bayegan and Harada that the defining ideal $\mathcal{J}$ is generated by quadratics. %U http://arxiv.org/abs/1310.8643v2