The abstract looks perfectly fine - it is written so anyone working in this area would know what the paper is going to do. Writing it at a basic level would either require the abstract to be absurdly long or to leave unspecified what the paper contains.

I'm not in particle physics, but have read textbooks and papers in many areas of theoretical physics, and I understand enough of this abstract to know what it's going to do.

If MHV is an acronym you think should be expanded, it is not. There's well over 500,000 hits on google for MHV physics, and only 2900 hits for the expanded term. It is a widely used term in the field.