Pi pi scattering in the rho meson channel at finite temperature

Dec, 1997
32 pages
Published in:
  • Nucl.Phys.A 630 (1998) 719-742
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Abstract:
We study ππ\pi\pi scattering in the I=1, JP=1J^P=1^- channel at finite temperature in the framework of the extended Nambu-Jona-Lasinio model that explicitly includes vector and axial-vector degrees of freedom in addition to the usual scalar and pseudoscalar sector. The S-matrix in the coupled channels qqˉq\bar q and ππ\pi \pi is constructed via ρ\rho-exchange in the ss-channel. The self-energy of the ρ\rho-meson contains both quark and pion loop contributions. The analytic structure of the S-matrix for T0T\geq 0 is investigated and the motion of the ρ\rho-pole as a function of coupling constant and temperature is followed in the complex s\sqrt{s}-plane. For numerical calculations, parameters are chosen in order that mπm_\pi, fπf_\pi and the experimental ππ\pi\pi phase shifts δ11\delta_1^1 at zero temperature are reproduced, and then the behavior of the ρ\rho-pole as well as the ππ\pi\pi cross section is investigated as a function of the temperature. We find that the position of the ρ\rho mass stays practically constant for 0T1300\leq T\leq 130 MeV, and then moves down in energy by about 200 MeV for 130 MeVT230\leq T\leq 230 MeV.
Note:
  • 25 pages, 12 figures, to appear in Nucl. Phys. A
  • 12.39.Ba
  • 21.65.+f
  • 24.85.+p
  • 25.75.-q
  • ππscattering
  • ϱ-meson
  • Finite temperature
  • Analytic structure
  • pi pi: elastic scattering
  • rho(770): exchange