Semiconductor cavity QED: Bandgap induced by vacuum fluctuations

We consider theoretically a semiconductor nanostructure embedded in one-dimensional microcavity and study the modification of its electron energy spectrum by the vacuum fluctuations of the electromagnetic field. To solve the problem, a non-perturbative diagrammatic approach based on the Green's function formalism is developed. It is shown that the interaction of the system with the vacuum fluctuations of the optical cavity opens gaps within the valence band of the semiconductor. The approach is verified for the case of large photon occupation numbers, proving the validity of the model by comparing to previous studies of the semiconductor system excited by a classical electromagnetic field. The developed theory is of general character and allows for unification of quantum and classical descriptions of the strong light-matter interaction in semiconductor structures

Some Cosmological Implications of Hidden Sectors

We discuss some cosmological implications of extensions of the Standard Model with hidden sector scalars coupled to the Higgs boson. We put special emphasis on the conformal case, in which the electroweak symmetry is broken radiatively with a Higgs mass above the experimental limit. Our refined analysis of the electroweak phase transition in this kind of models strengthens the prediction of a strongly first-order phase transition as required by electroweak baryogenesis. We further study gravitational wave production and the possibility of low-scale inflation as well as a viable dark matter candidate.Comment: 23 pages, 8 figures; some comments added, published versio

BCS pairing in fully repulsive fermion mixtures

We consider a mixture of two neutral cold Fermi gases with repulsive interactions. We show that in some region of the parameter space of the system the effective attraction between fermions of the same type can appear due to the exchange of collective excitations. This leads to the formation of BCS pairing in the case where bare inter-atomic interactions are repulsive

Factorization of finite temperature graphs in thermal QED

We extend our previous analysis of gauge and Dirac fields in the presence of a chemical potential. We consider an alternate thermal operator which relates in a simple way the Feynman graphs in QED at finite temperature and charge density to those at zero temperature but non-zero chemical potential. Several interesting features of such a factorization are discussed in the context of the thermal photon and fermion self-energies.Comment: 4 page

Thermal Operator and Cutting Rules at Finite Temperature and Chemical Potential

In the context of scalar field theories, both real and complex, we derive the cutting description at finite temperature (with zero/finite chemical potential) from the cutting rules at zero temperature through the action of a simple thermal operator. We give an alternative algebraic proof of the largest time equation which brings out the underlying physics of such a relation. As an application of the cutting description, we calculate the imaginary part of the one loop retarded self-energy at zero/finite temperature and finite chemical potential and show how this description can be used to calculate the dispersion relation as well as the full physical self-energy of thermal particles.Comment: 17 pages, 13 figures. Added references, version to appear in Physical Review

Teaching Chemistry in a Spiral Progression Approach: Lessons from Science Teachers in the Philippines

As the Philippines moves towards implementing the K-12 curriculum, there has been a mismatch in teacher preparation in science. The present teacher education curriculum prepares science teachers to specialise in a specific field (e.g. integrated science, biology, chemistry, and physics). However, in the K-12 curriculum, they are required to teach all the sciences in a spiral progression approach. Hence, this study analysed the experiences of science teachers in teaching chemistry in the K-12 curriculum in order to identify their challenges and how they are overcoming them. Findings suggest that the teacher’s content, pedagogy, and assessment in chemistry are problematic; specifically, challenges such as instruction-related factors, teacher competence, in-service training sufficiency, job satisfaction, support from upper management, laboratory adequacy, school resources, assessment tools, and others influence teacher success in teaching chemistry. These identified challenges greatly affect the ultimate beneficiaries of education, which is the learner

The CP properties of the lightest Higgs boson with sbottom effects

In the framework of the recently proposed gluino-axion model, using the effective potential method and taking into account the top-stop as well as the bottom-sbottom effects, we discuss the CP--properties of the lightest Higgs boson, in particular its CP--odd composition, which can offer new opportunities at collider searches. It is found that although the CP-odd composition of the lightest Higgs increases slightly with the inclusion of the sbottom effects, it never exceeds %0.17 for all values of the renormalization scale Q ranging from top mass to TeV scaleComment: 24 pp, 12 eps fig