We compute the one-loop polarization tensor Π for the on-shell, massless mode in a thermalized SU(2) Yang-Mills theory being in its deconfining phase. Postulating that SU(2) CMB today = U(1) Y , we discuss Π's effect on the lowmomentum part of the black-body spectrum at temperatures ∼ 2 · · · 4 T CMB where T CMB ∼ 2.73 K. A table-top experiment is proposed to test the above postulate. As an application, we point out a possible connection with the stability of dilute, cold, and old innergalactic atomic hydrogen clouds. We also compute the two-loop correction to the pressure arising from the instantaneous massless mode in unitary-Coulomb gauge, which formerly was neglected, and present improved estimates for subdominant corrections.

Ultrashort flashes of THz light with low photon energies of a few meV, but strong electric or magnetic field transients have recently been employed to prepare various fascinating nonequilibrium states in matter. Here we present a new class of sources based on superradiant enhancement of radiation from relativistic electron bunches in a compact electron accelerator that we believe will revolutionize experiments in this field. Our prototype source generates high-field THz pulses at unprecedented quasi-continuous-wave repetition rates up to the MHz regime. We demonstrate parameters that exceed state-of-the-art laser-based sources by more than 2 orders of magnitude. The peak fields and the repetition rates are highly scalable and once fully operational this type of sources will routinely provide 1 MV/cm electric fields and 0.3 T magnetic fields at repetition rates of few 100 kHz. We benchmark the unique properties by performing a resonant coherent THz control experiment with few 10 fs resolution.

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Mothers in the puerperium are vulnerable to a wide spectrum of postpartum psychiatric disorders. One of the central psychological processes of the puerperium is the development of an emotional relationship with the baby. The bond to the infant as well as the interaction with the baby are two aspects of the mother-infant relationship that can be disturbed by mothers with postpartum psychiatric disorders. Dysfunctional maternal cognitions may also influence the development of an emotional bonding and the establishment of a positive interaction with the child. The aim of this study is to investigate differences in the self-perceived experience of bonding and the observed mother-child interaction of severely ill postpartum depressive and psychotic mothers. In addition the association between subjective experience of bonding and objective measurement of mother-child interaction will be described. Results show that depressive mothers perceived their bonding to the baby more negatively than psychotic mothers. No differences could be found in the objective interactional behaviour of the mothers in both groups, with the exception that the infants of psychotic mothers showed more eye contact avoidance towards their mothers. The subjective experience of motherhood clearly influences the maternal interactional behaviour with depressive mothers as well as with psychotic mothers.