Wednesday, January 16, 2013

1301.3205 (Ahmed Youssef et al.)

Resummation of infrared logarithms in de Sitter space via
Dyson-Schwinger equations: the ladder-rainbow approximation
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Ahmed Youssef, Dirk Kreimer
We study the infrared (large separations) behavior of a massless minimally coupled scalar QFT with a quartic self-interaction in de Sitter. We show that the perturbation series in the interaction strength $\lambda$ is secular, i.e it does not lead to a uniform approximation of the solution in the infrared region. Only a non-perturbative resummation can capture the correct IR behavior. We seek to justify this picture using the Dyson-Schwinger equations in the ladder-rainbow approximation. We are able to write down an ordinary differential equation obeyed by the two-point function and perform its asymptotic analysis. Opposing a widespread belief that IR divergences are regulated through a dynamical mass generation, our work suggest an even stronger IR decay than the power-law one resulting from a mass term.
View original: http://arxiv.org/abs/1301.3205

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