In the wake of exploring uncertainty in the full angular distribution of the $B\to K\pi +{\mu }^{+}{\mu }^{-}$ decay caused by the presence of the intermediate scalar $K_0^{*}$ meson, we perform the straightforward calculation of the $B(B_s)\to S$ ($S$ is a scalar meson) transition form factors in the full kinematical region within the covariant quark model. We restrict ourselves to the scalar mesons below 1 GeV: $a_0(980)$, $f_0(500)$, $f_0(980)$, and $K_0^{*}(800)$. As an application of the obtained results we calculate the widths of the semileptonic and rare decays $B(B_s)\to S\ell \overline{\nu }$, $B(B_s)\to S\ell \overline{\ell }$, and $B(B_s)\to S\nu \overline{\nu }$. We compare our results with those obtained in other approaches.

The NA62 experiment at CERN has the capability to collect data in a beam-dump mode, where 400 GeV protons are dumped on an absorber. In this configuration, New Physics particles, including dark photons, dark scalars, and axion-like particles, may be produced in the absorber and decay in the instrumented volume beginning approximately 80 m downstream of the dump. A search for these particles decaying in flight to hadronic final states is reported, based on an analysis of a sample of $$1.4 \times 10^{17}$$ 1.4 × 10 17 protons on dump collected in 2021. No evidence of a New Physics signal is observed, excluding new regions of parameter spaces of multiple models.

A bstract: Results from the study of the rare decays $$ {K}^{+}\to {\pi}^{+}\nu \overline{\nu} $$ K + → π + ν ν ¯ , K ⁺ → π ⁺ μ ⁺ μ ⁻ and K ⁺ → π ⁺ γγ at the NA62 experiment at CERN are interpreted in terms of improved limits for $$ \mathcal{B}\left({K}^{+}\to {\pi}^{+}X\right) $$ B K + → π + X and coupling parameters of hidden-sector models, where X is a mediator. World-leading limits are achieved for dark photon, dark scalar and axion-like particle models.

Nuclear gamma-resonance spectroscopy on ⁵⁷Fe nuclei, X-ray diffraction, and scanning electron microscopy have been used to study the narrow fractions of fly ash formed after combustion of the Ekibastuz coal. Two groups of samples of magnetic (ferrospheres) and non-magnetic type have been separated by granulometric and magnetic separation. A number of regularities associated with the granules size of fly ash have been established. According to the data of Mössbauer spectroscopy, a decrease in the magnetically ordered contribution has been identified with the growth of the particle size. After magnetic separation, iron in ferrospheres was found mainly in the structure of Fe₃O₄/γ-Fe₂O₃ and α-Fe₂O₃. The dominant phase was Fe₃O₄ (60–77%), the amount of which decreases with the growth of the grain size. With the growth of the particle size, the ratio of [Fe]^tetra/[Fe]^octa positions occupancy in Fe₃O₄ approaches 0.5; the structure of magnetite tends to the stoichiometric composition. α-Fe was found in the composition of ferrospheres, and a mechanism of its formation was proposed. The main components of the non-magnetic fractions of fly ash are mullite, hercynite, and silicate glass.