Cosmic Gamma Ray Constraints on the Indirect Effects of Dark Matter

The observed anomalous excess of high-energy cosmic ray (CR) positrons is widely discussed as possible indirect evidence for dark matter (DM). However, any source of cosmic positrons is inevitably the source of gamma radiation. The least model dependent test of CR anomalies interpretation via DM particles decays (or annihilation) is connected with gamma-ray background due to gamma overproduction in such processes. In this work, we impose an observational constraint on gamma ray production from DM. Then, we study the possible suppression of gamma yield in the DM decays into identical final fermions. Such DM particles arise in the multi-component dark atom model. The influence of the interaction vertices on the gamma suppression was also considered. No essential gamma suppression effects are found. However, some minor ones are revealed.Comment: The article was published in MDPI "Particle". The authors used to the article structure suggested by the journal (MDPI "Particles"

Hot Primordial Regions with Anomalous Hydrogenless Chemical Composition

We study primordial nucleosynthesis in hypothetical hot regions that could be formed by the primordial density inhomogeneities. It is shown that the regions that survived up to the present times acquire an abnormally high metallicity. This conclusion holds in a wide range of initial parameters of such regions. We considered the thermonuclear reaction rates and estimated abundances of deuterium and helium-3 and -4 inside these areas. It has been established that all baryons tend to form helium-4, which is the thermonuclear link in the chain of formation of heavier elements

Влияние температуры на длительность флуоресценции и электронные спектры безметалловых тетрапирролов в органическом полимере

Измерены спектрально-люминесцентные характеристики и длительность флуоресценции серии безметалловых тетрапирролов в твердых пленках поливинилбутираля при 293 и 77 К. Полученные результаты свидетельствуют об отсутствии коэффициента вязкости в изучаемом случае усиления флуоресценции, то есть для тетрапирролов, проявляющих усиливающий эффект в жидких растворах (тетраазапорфин и замещенный тетраазахлорин). Продолжительность флуоресценции в увеличение пленки при понижении температуры до 77 К незначительно увеличивалось. Анализ экспериментальных данных позволил оценить квантовые выходы внутренней конверсии и межкомбинационной конверсии тетраазапорфина и тетраазахлорина - фундаментальных структур тетрапиррольного ряда. Spectral and luminescent characteristics and the duration of fluorescence were measured for a series of metal-free tetrapyrroles in polyvinylbutyral solid fims at 293 and 77 K. The results provided evidence for the lack of a viscosity factor in the case of the fluorescence enhancement under study, i.e., for the tetrapyrroles showing the enhancement effect in liquid solutions (tetraazaporphine and substituted tetraazachlorin). The fl uorescence duration in the film increased insignifi cantly on lowering the temperature to 77 K. An analysis of the experimental data made it possible to estimate the quantum yields of internal conversion and intersystem crossing for tetraazaporphine and tetraazachlorin, which were the fundamental structures in the tetrapyrrole series