Impossibility of obtaining a CP-violating Euler-Heisenberg effective theory from a viable modification of QED

In this paper, we examine the CP-violating term of the Euler-Heisenberg action. We focus in the aspects related with the generation of such a term from a QED-like model in terms of the effective action approach. In particular, we show that the generation of the CP-violating term is closely related with both of vector and axial fermionic bilinears. Although, these anomalous models are not a "viable" extension of QED, we argue that the CP-violating term in the photon sector is obtained only from this class of models, and not from any fundamental field theory.Comment: 6 page

Induced CP-violation in the Euler–Heisenberg Lagrangian

Abstract In this paper, we examine the behaviour of the Euler–Heisenberg effective action in the presence of a novel axial coupling among the gauge field and the fermionic matter. This axial coupling is responsible to induce a CP-violating term in the extended form of the Euler–Heisenberg effective action, which is generated naturally through the analysis of the box diagram. However, this anomalous model is not a viable extension of QED, and we explicitly show that the induced CP-violating term in the Euler–Heisenberg effective Lagrangian is obtained only by adding an axial coupling to the ordinary QED Lagrangian. In order to perform our analysis, we use a parametrization of the vector and axial coupling constants, $$g_{v}$$ g v and $$g_{a}$$ g a , in terms of a new coupling $$\beta$$ β . Interestingly, this parametrization allows us to explore a hidden symmetry under the change of $$g_{v}\leftrightarrow g_{a}$$ g v ↔ g a in some diagrams. This symmetry is explicitly observed in the analysis of the box diagram, where we determine the $$\lambda _i$$ λ i coefficients of $${\mathcal {L}}_{\mathrm{ext.}}^\mathrm{\small EH}=\lambda _{1}{\mathcal {F}}^{2}+\lambda _{2}{\mathcal {G}}^{2}+ \lambda _{3}{\mathcal {F}}{\mathcal {G}}$$ L ext . E H = λ 1 F 2 + λ 2 G 2 + λ 3 F G , specially the coefficient $$\lambda _3$$ λ 3 related with the CP-violating term due to the axial coupling. As a phenomenological application of the results, we compute the relevant cross section for the light by light scattering through the extended Euler–Heisenberg effective action

Recombinant expression and purification of 'virus-like' bacterial encapsulin protein cages

Ultracentrifugation, particularly the use of sucrose or cesium chloride density gradients, is a highly reliable and efficient technique for the purification of virus-like particles and protein cages. Since virus-like particles and protein cages have a unique size compared to cellular macromolecules and organelles, the rate of migration can be used as a tool for purification. Here we describe a detailed protocol for the purification of recently discovered virus-like assemblies called bacterial encapsulins from Thermotoga maritima and Brevibacterium linens