Studying in-medium hadron properties with HADES

for theheaviest top quark result from this interaction. However, for the light u,d,squark flavors, an additional mechanism is introduced to account for the largeu,d,sconstituent masses. It is connected to the phenomenon of spontaneousbreaking of Chiral Symmetry (CS), a global symmetry of Quantum ChromoDynamics (QCD) exactly valid in the limit of massless quarks [1]. Conser-vation of the CS would lead to decoupling of left-handed and right-handedquark interactions and to mass degeneration of hadrons with opposite par-ities (as for example for J= 1 mesons ρ(770) and a1(1260)). The sponta-neous breaking of chiral symmetry is caused by a non-trivial feature of theQCD vacuum, namely the existence of a scalar quark condensate hqq¯ i. Theinteraction of current quarks with the condensate is responsible for the largeconstituent quark masses. The condensate’s expectation value can be esti-mated assuming SU(2) flavor symmetry, hqq¯ i = −(240MeV)