Rho is known for his works on the properties of hadrons in normal as well as extreme environments present in heavy nuclei, relativistic heavy-ion collisions and compact stars. In the early 1970s he started to study the
chiral symmetry of
Quantum Chromodynamics in nuclear medium. QCD was poorly understood at that time and he explained how chiral symmetry appears in nuclear structure. In 1979 he and
Gerald E. Brown implemented chiral symmetry in an effective theory of the
nucleon in the form of chiral bag model according to which quarks exist freely in a bag surrounded by a
pion cloud. In 1991 Rho and Brown derived a scaling property of hadrons in hot and dense medium, now known as
Brown-Rho scaling which predicted how the masses of the hadrons disappear in hot (
early universe) and dense (
neutron star) environments. The BR scaling has been tested experimentally in several electro-weak processes involving heavy nuclei. It has explained the
CERN heavy-ion experiments on
dilepton production and is expected to explain some features from the experiments at
RHIC. For the astro-hadron physics, it has possibilities to explain the
supernovae explosions and the structure of
compact stars. Rho is currently working on superdense hadronic QCD properties and astro-hadron physics. ==References==