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[Fizinfo] Stat Fiz Szeminarium

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  • From: StatFizSzeminar <statfiz AT>
  • To: fizinfo AT
  • Subject: [Fizinfo] Stat Fiz Szeminarium
  • Date: Wed, 13 Feb 2019 19:05:19 +0100

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ELTE TTK Fizikai Intézet

2019. február 20.



Zsolt Szép

MTA-ELTE Theoretical Physics Research Group

"Thermodynamics of the O(4) model from the
Phi-derivable approximation"

We investigate the effects of higher order truncations
of the two-particle irreducible (2PI) action on the
equilibrium FFT-based numerical solution of the model
and the description of the phase transition. We find
that the two-loop level truncation represents an
improvement over the Hartree-Fock truncation, but at
the next level of the truncation, the solution to the
coupled propagator and field equations is lost in some
temperature range. This feature is a result of the IR
sensitivity of the propagator equation and makes
impossible the direct determination of the critical
temperature in the chiral limit. Vertex resummation
provided by the 1/N expansion to next to leading order
in the 2PI effective action tames this problem to some
degree. At NLO in the 2PI-1/N expansion we determine
the critical exponents and the universal scaling function
and compare them with their lattice counterparts.

1117, Budapest, Pázmány P. sétány 1/A, Északi tömb 2.54

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