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Effect of pion thermal width on the sigma spectrum

Tetsuo Nishikawa·Yoshimasa Hidaka·Munehisa Ohtani·Osamu Morimatsu
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Abstract

We study the effect of the thermal width of $π$ on the spectral function of $σ$. In order to take into account a finite thermal width of $π$, we replace the internal pion mass in the self-energy of $σ$ with that of the complex pole found in a previous paper. The obtained spectral function for $T\aplg 100 {\rm MeV}$ turns out to possess two broad peaks. Although a sharp peak at $σ\toππ$ threshold was observed in the one-loop calculation without the pion thermal width, the peak is shown to be smeared out. We also search for the poles of the $σ$ propagator and analyze the behavior of the spectral function with these poles.

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Tetsuo Nishikawa, Yoshimasa Hidaka, Munehisa Ohtani, Osamu Morimatsu. 2003-10-27. Effect of pion thermal width on the sigma spectrum. https://arxiv.org/abs/hep-ph/0310296

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