Physics

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Physics

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    Electron–hole interaction in cylindrical quantum dots
    (Elsevier, 2022) Vram Mughnetsya ; Ashot Movsisyan ; Albert Kirakosyan
    The Coulomb interaction of electron and hole in a cylindrical quantum dot in the frame of the first perturbation theory and the effective mass approximation is studied. The analogue of Brus’s equation for Coulomb interaction of electron–hole pair in a spherical quantum dot is obtained for a cylindrical nanocrystal and an expression for the energy band gap shift is derived, which can be used for explaining of some experimental results obtained for MoS and 3C-SiC nanocrystals.
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    Tidal disruption effects near black holes and Lambda-gravity
    (Springer, 2022-08-26) A.Stepanian ; V.Gurzadya ; Sh.Khlghatyan
    The tidal disruption of stars in the vicinity of massive black holes is discussed in the context of Λ-gravity. The latter provides an explanation to the Hubble tension as a possible consequence of two Hubble flows, the local and global ones. The bunch of notions that play role for the considered tidal effect are obtained, along with the rate of the disrupted stars. The role of pulsars is emphasized due to their ability to penetrate up to the horizon of the massive black hole as for them the tidal radius can reach the horizon. Tidal disruption mechanism also can lead to segregation of stars by their mean density versus the distance from the black hole, the denser stars surviving at shorter distances. The interplay of the central gravity field and the repulsive Λ-term increase with radius, and its certain observational consequences are discussed.