ELFT HÍRADÓ

[Andras LASZLO <laszlo.andras AT wigner.hu>]

---------- Forwarded message ----------
Date: Thu, 20 Apr 2023 11:08:27 +0200 (CEST)
From: Daniel Nogradi <nogradi AT bodri.elte.hu>
To: Daniel Nogradi <nogradi AT bodri.elte.hu>
Subject: ELTE particle physics seminar - 25 April


Date/Time: 25 April, Tuesday, 14:15

Location: ELTE TTK, second floor, 2.54 Novobatzky room

Speaker: Karoly Seller (ELTE)

Title:  Real effective potentials for phase transitions in models with extended 
scalar sectors

Abstract:

The effective potential obtained by loop expansion is usually not real in the 
range of field values explored by its minima during a phase transition. The 
appearance of complex values is due to the breakdown of conventional 
perturbation theory when applied to a non-convex classical potential. To solve 
this issue, we apply the "optimized perturbation theory" in a fixed gauge to 
the SM, and singlet scalar extensions of it, in order to calculate a one-loop 
effective potential that is real by construction. We test this computational 
scheme by comparing such a potential obtained in Landau gauge to that derived 
based on the Higgs pole mass.We use our effective potential to study the 
parameter dependence of the critical temperatures in a two-step phase 
transition of the form (0,0) -> (0,w') -> (v,w) that occurs for decreasing 
temperature in scalar extensions of the SM with two non-zero vacuum expectation 
values v and w.


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