## Saturday, June 28, 2014 ... /////

### Bruno Zumino: 1923-2014

Sadly, Bruno Zumino, an Italian emeritus professor at UC Berkeley, died at age of 91 on June 22nd early after the midnight.

His 100 or so papers have won him 20,000 citations or so, a sign he was a top physicist.

His papers include six very different articles with over 1,000 citations per paper. They cover the eras both before the discovery of supersymmetry and after the discovery of supersymmetry.

The first class includes work on chiral Lagrangians and collaborators like Coleman and Callan. However, as his surname indicates, Zumino was most important for the research of supersymmetry. Along with his superpartner Julius (Zumon) Wess (who died in 2007, so SUSY was broken by 7 years in this case), they wrote down the first interacting quantum field theory, the Wess-Zumino model.

When I was already decided to write down that the Wess-Zumino model was the first interacting $d=4$ supersymmetric quantum field theory, at least in the Western world, I opened the Wikipedia page about that theory (click) and found the same sentence. Of course, it's no coincidence, the sentences were written by me in 2005 and there were only dozens of edits afterwards.

I still remember the minor surprise over 20 years ago when I checked that this theory including one scalar, one pseudoscalar, and one two-component fermionic spinor is indeed exactly invariant under supersymmetry even though it includes a Yukawa interaction as well as a quartic one. See Supersymmetric Lagrangians for a more technical review how to build similar Lagrangians.

The Wess-Zumino-Witten model is something else, an important two-dimensional conformal field theory with a group manifold as its target space. Similar CFTs are important building blocks of theories on the string theoretical world sheet.

Along with Deser, Brumino also wrote one of the first papers constructing a supersymmetric theory of gravity, i.e. supergravity.

RIP, Prof Zumino.