Spatial 't Hooft loop in hot SUSY theories at weak coupling

The spatial 't Hooft loop measures the colour electric flux in SU(N)/Z(N) gauge theory. It is a closed loop of Dirac Z(N) flux and has strength k=1, 2,.., N-1. It is analyzed for generic k and small gauge coupling in the high temperature phase of {\cal N} =1, 2 and 4 SUSY theory up and including cubic order. In one loop order no qualitative difference with gluodynamics shows. However the two loop order shows a logarithmic divergence appear in the centre of the wall. This is because the gluinos become bosonic in the centre and acquire long wavelength excitations. We discuss the cure for this divergence, due to a gluino zero mode. The physics of Casimir scaling is explained. The cubic order can be obtained from gluodynamics by simple rescalings of the Debye masses and the Casimir parameter $k/N_c$.Comment: 8 figure

The thermal instanton determinant in compact form

The thermal instanton determinant for the gauge group $SU(2)$ can be reduced to a form involving two simple functions. Various boundary conditions can easily incorporated. Only a two dimensional integral has to be done numerically. As an example we compute the contribution to the free energy of $\mathcal{N}=1$ theory.Comment: 26 pages, 2 figures. This version contains a number of cosmetic improvements of the version appearing in PR

Minimalistic musings about the Standard Model

\hspace{2,0cm}{{\bf A tribute to Martinus Veltman 1931-2021}} Martinus ("Tini") Veltman 's early contributions to the Standard Model were essential for its succes. After some nostalgic reminiscences, I turn to the Standard Model with a minimalistic attitude, the point of view that beyond the SM there is only the Planck scale. Known since long, the gravitational force can be obtained as the gauge theory of local Poincar\'e symmetry, called gauge gravity. This gauge theory of gravity embodies {\it per se} a Palatini formulation. This causes the potential of non-minimally coupled Higgs inflation to have an intriguing improved large field behaviour. Some of its effects are experimentally accessible or refutable. The question of quantum corrections is discussed.Comment: submitted to Acta Physica Polonica. Some cosmetic changes and typos correcte

Domain Walls and Metastable Vacua in Hot Orientifold Field Theories

We consider "Orientifold field theories", namely SU(N) gauge theories with Dirac fermions in the two-index representation at high temperature. When N is even these theories exhibit a spontaneously broken Z2 centre symmetry. We study aspects of the domain wall that interpolates between the two vacua of the theory. In particular we calculate its tension to two-loop order. We compare its tension to the corresponding domain wall in a SU(N) gauge theory with adjoint fermions and find an agreement at large-N, as expected from planar equivalence between the two theories. Moreover, we provide a non-perturbative proof for the coincidence of the tensions at large-N. We also discuss the vacuum structure of the theory when the fermion is given a large mass and argue that there exist N-2 metastable vacua. We calculate the lifetime of those vacua in the thin wall approximation.Comment: 29 pages, 4 figures. v2: minor changes in the introduction section. to appear in JHE