In the Kallen-Lehmann spectral representation (http://en.wikipedia.org/wiki/Källén–Lehmann_spectral_representation) the interacting propagator is given as a weighted sum over free propagators. The pole of the integracting propagator is, of course, given by [itex]p^2=m^2[/itex], m being the physical mass of the particle.(adsbygoogle = window.adsbygoogle || []).push({});

Could this spectral representation be used to find the mass shift [itex]\delta m^2 = m^2 - m_0^2[/itex] of a scalar field (m_0 is the bare mass of the noninteracting particle)?

Thanks

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# Spectral weight function and the mass shift of a scalar field

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