Simultaneous softening of σ and ϱ mesons associated with chiral restoration

• Published in: Nuclear physics. A Vol. 721; pp. C641 - C644
• Main Authors: Yokokawa, K., Hatsuda, T., Hayashigaki, A., Kunihiro, T.
• Format: Journal Article
• Language: English
• Published: Elsevier B.V 30-06-2003
• ISSN: 0375-9474
• DOI: 10.1016/S0375-9474(03)01142-4

Unitarized π-π scattering amplitudes in nuclear matter are studied with special emphasis on its complex poles in the scalar (σ) and vector (ϱ) channels. Partial restoration of chiral symmetry is modeled by the decrease of an in-medium pion decay constant
gf
π
∗
. For large chiral restoration (
φ
π
∗
φ
π
⪡ 1
), σ and ϱ poles show a large and simultaneous softening dictated by the Lambert
W function. On the other hands, for small chiral restoration (
φ
π
∗
φ
π
≲ 1
, broadening (softening) is a dominant effect for ϱ (σ). In medium π-π cross sections associated with these spectral shifts are also studied.