Photon "mass" and atomic levels in a superstrong magnetic field

The structure of atomic levels originating from the lowest Landau level in a superstrong magnetic field is analyzed. The influence of the screening of the Coulomb potential on the values of critical nuclear charge is studied.Comment: Contribution to the proceedings of the LOWDIM Workshop devoted to Sergei Gaikovich Matinyan 80'th birthday; 6 pages, 2 figure

The rise and fall of the fourth quark-lepton generation

The existence of the fourth quark-lepton generation is not excluded by the electroweak precision data. However, the recent results on the 126 GeV higgs boson production and decay do not allow an extra generation at least as far as the perturbation theory can be used.Comment: Report at the conference QTHEP 2013, Repino, June 23-30 2013 and lecture at the 2013 Helmholz School Physics of Heavy Quarks and Hadrons, Dubna, July 15-28. An important acknowledgement is adde

Resonant scattering and recombination of pseudo-degenerate WIMPs

We consider the direct and indirect detection signatures of WIMPs \chi^0 in kinematic regimes with a heavier, but nearly degenerate, charged state \chi^{+-}. For small splittings of O(10) MeV, the scattering of WIMPs off nuclei may be dominated by inelastic recombination processes mediated by the formation of (\chi^- N) bound states, leading to a distinct signature for direct detection. These cross-sections are bound primarily by limits on the abundance of heavy isotopes, and may be considerably larger than the elastic scattering cross section in more conventional models. If the mass splitting is too large for recombination to occur, there may still be a significant resonant enhancement of loop-induced electromagnetic form-factors of the WIMP, which can enhance the elastic scattering cross-section. We also discuss how this regime affects the annihilation cross-section and indirect detection signatures, and note the possibility of a significant mono-energetic \gamma-signal, mediated by resonant processes near the (\chi^+\chi^-) bound state threshold.Comment: 22 pages, 6 figures; v2: typos corrected, to appear in Phys. Rev.

Modification of Coulomb law and energy levels of hydrogen atom in superstrong magnetic field

The screening of a Coulomb potential by superstrong magnetic field is studied. Its influence on the spectrum of a hydrogen atom is determined.Comment: Lectures at 39 ITEP Winter School and 11 Baikal Summer School; 12 pages, 5 figure

Is G a conversion factor or a fundamental unit?

By using fundamental units c, h, G as conversion factors one can easily transform the dimensions of all observables. In particular one can make them all ``geometrical'', or dimensionless. However this has no impact on the fact that there are three fundamental units, G being one of them. Only experiment can tell us whether G is basically fundamental.Comment: 2 page