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Feb 15 – 18, 2022
America/Vancouver timezone
WNPPC2022 Booklet has been added. See also information about today's special guest: Dr. Eden Hennessey

Spontaneous Symmetry Breaking and its Effects

Feb 16, 2022, 8:48 AM



Mr Vahid Shokollahiabhari (University of Saskatchewan)


In physics, symmetry breaking is a phenomenon in which (infinitesimally) small
fluctuations acting on a system crossing a critical point decide the system’s fate, by
determining which branch of bifurcation is taken. To an outside observer unaware of the
fluctuations, the choice will appear arbitrary. This process is called symmetry breaking,
because such transitions usually bring the system from a symmetric but disordered state
into one or more definite states. Symmetry breaking can be distinguished into two
types, explicit symmetry breaking and spontaneous symmetry breaking, characterized
by whether the equations of motion fail to be invariant or the ground state fails to be
invariant. In spontaneous symmetry breaking, the equations of motion of the system
are invariant, but the system is not. This is because the background (spacetime) of
the system, its vacuum, is variant. The full effective potential can be expressed as
VEff = VTree + VCW + VCT + VT
where VTree is the tree-level potential, VCW is the one-loop Coleman-Weinberg
(CW) potential, VCT are counter-terms, and VT is the thermal contribution. Spontaneous
symmetry breaking can happen in two ways: In theories for which Coleman-
Weinberg potential breaks the symmetry (conformal symmetry), and symmetry breaking
which happens at tree-level potential (non-conformal symmetry). We are calculating
the loop-corrected effective potential at non-vanishing temperature for both
conformal and non-conformal in two Higgs doublet model (2HDM).

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Primary author

Mr Vahid Shokollahiabhari (University of Saskatchewan)


Dr Tom Steele (University of Saskatchewan) Prof. Robert Mann (University of Waterloo) Dr Zhi-Wei Wang (Lund University) Mr Dylan Pu (University of Waterloo)

Presentation materials