An extension of the Standard Model with an additional Higgs singlet is analyzed. Bounds on singlet admixture for the 125 GeV h boson from electrow

We obtain the following analytical formula which describes the dependence of the electric potential of a pointlike charge on the distance away from it in the direction of an external magnetic field B: $\Phi${}(z)=e/|z|[1-exp{}(-6me2|z|)+exp{}(-(2/$\pi${})e3B+6me2|z|)]. The deviation from Coulomb's law becomes essential for B>3$\pi${}Bcr/$\alpha${}=3$\pi${}me2/e3$\approx${}6\ifmmode\times\else\texttimes\fi{}1016\,\,G. In such superstrong fields, electrons are ultrarelativistic except those which occupy the lowest Landau level (LLL) and which have the energy $\epsilon${}02=me2+pz2. The energy spectrum on which LLL splits in the presence of the atomic nucleus is found analytically. For B>3$\pi${}Bcr/$\alpha${} it differs substantially from the one obtained without accounting for the modification of the atomic potential.

We re-examine the physics of supercritical nuclei, specially focusing on the scattering phase $$\delta _{\varkappa }$$ and its dependence on the energy $$\

We found that spin-one new light particle exchanges are strongly bounded by high-energy and small momentum transfer $np$ elastic scattering data; the analogous bound for a scalar particle is considerably weaker, while for a pseudoscalar particle no bounds can be set. These bounds are compared with the bounds extracted from low-energy $n\mathrm{\text{−}}\mathrm{Pb}$ scattering experiments and from the bounds of ${\pi }^0$ and $K^{+}$ meson decays.

We propose a model-independent approach for the search of charged long-lived particles produced in ultraperipheral collisions at the LHC. The main idea is to improve event reconstruction at ATLAS and CMS with the help of their forward detectors. Detection of both scattered protons in forward detectors allows complete recovery of event kinematics. Though this requirement reduces the number of events, it greatly suppresses the background, including the large background from the pile-up.

The H→ZZ decay mode is usually considered as one of the most promising ways to discover new heavy neutral scalar H. We show that in the Georgi–Machacek model it is possible to get large enhancement of double SM-like Higgs boson production due to H decays while ZZ and WW decay channels could be highly suppressed