Moscow State University

About: Moscow State University is a education organization based out in Moscow, Russia. It is known for research contribution in the topics: Catalysis & Laser. The organization has 66747 authors who have published 123358 publications receiving 1753995 citations. The organization is also known as: MSU & Lomonosov Moscow State University.

Search for dark photons produced in 13 TeV $pp$ collisions

Abstract: Searches are performed for both promptlike and long-lived dark photons, A^{'}, produced in proton-proton collisions at a center-of-mass energy of 13 TeV, using A^{'}→μ^{+}μ^{-} decays and a data sample corresponding to an integrated luminosity of 1.6 fb^{-1} collected with the LHCb detector. The promptlike A^{'} search covers the mass range from near the dimuon threshold up to 70 GeV, while the long-lived A^{'} search is restricted to the low-mass region 214

Space-time parity violation and magnetoelectric interactions in antiferromagnets

Abstract: The properties of antiferromagnetic materials with violated space-time parity are considered. Particular attention is given to the bismuth ferrite BiFeO3 ferroelectric magnet. This material is distinguished from other antiferromagnets in that the inversion center is absent in its crystal and magnetic structures. This circumstance gives rise to diversified and unusual properties, namely, to the appearance of a spatially modulated spin structure and to the unique possibility of the linear magnetoelectric effect coexisting with a weak ferromagnetic moment. The magnetic-induced phase transitions accompanied by the suppression of the modulated spin structure and appearance of a number of new and unusual effects are considered. These are the linear magnetoelectric effect and the appearance of a toroidal moment and a weak ferromagnetic moment of the magnetoelectric nature.

The contribution of deep-sea macrohabitat heterogeneity to global nematode diversity

Abstract: The great variety of geological and hydrological conditions in the deep sea generates many different habitats. Some are only recently explored, although their true extent and geographical coverage are still not fully established. Both continental margins and mid-oceanic seafloors are much more complex ecologically, geologically, chemically and hydrodynamically than originally thought. As a result, fundamental patterns of species distribution first observed and explained in the context of relatively monotonous slopes and abyssal plains must now be re-evaluated in the light of this newly recognized habitat heterogeneity. Based on a global database of nematode genus composition, collected as part of the Census of Marine Life, we show that macrohabitat heterogeneity contributes significantly to total deep-sea nematode diversity on a global scale. Different deep-sea settings harbour specific nematode assemblages. Some of them, like coral rubble zones or nodule areas, are very diverse habitats. Factors such as increased substrate complexity in the case of nodules and corals seem to facilitate the co-existence of a large number of genera with different modes of life, ranging from sediment dwelling to epifaunal. Furthermore, strong biochemical gradients in the case of vents or seeps are responsible for the success of particular genera, which are not prominent in more typical soft sediments. Many nematode deep-sea genera are cosmopolitan, inhabiting a variety of deep-sea habitats and oceans, whereas only 21% of all deep-sea genera recorded are restricted to a single habitat. In addition to habitat heterogeneity, regional differences are important in structuring nematode assemblages. For instance, seeps from different regions yield different genera that thrive on the sulphidic sediments. This study also shows that many areas and habitats remain highly under-sampled, affecting our ability to understand fully the contribution of habitat heterogeneity versus regional differences to global nematode diversity.

The Hubble Flow around the Centaurus A/M83 Galaxy Complex

Abstract: We present Hubble Space Telescope ACS images and color-magnitude diagrams for 24 nearby galaxies in and near the constellation of Centaurus with radial velocities VLG < 550 km s-1. Distances are determined based on the luminosities of stars at the tip of the red giant branch that range from 3.0 to 6.5 Mpc. The galaxies are concentrated in two spatially separated groups around Cen A (NGC 5128) and M83 (NGC 5236). The Cen A group itself has a mean distance of 3.76 ± 0.05 Mpc, a velocity dispersion of 136 km s-1, a mean harmonic radius of 192 kpc, and an estimated orbital/virial mass of (6.4-8.1) × 1012 M⊙. This elliptical-dominated group is found to have a relatively high mass-to-light ratio: M/LB = 125 M⊙/L⊙. For the M83 group we derived a mean distance of 4.79 ± 0.10 Mpc, a velocity dispersion of 61 km s-1, a mean harmonic radius of 89 kpc, and an estimated orbital/virial mass of (0.8-0.9) × 1012 M⊙. This spiral-dominated group is found to have a relatively low M/LB = 34 M⊙/L⊙. The radius of the zero-velocity surface around Cen A lies at R0 = 1.40 ± 0.11 Mpc, implying a total mass within R0 of MT = (6.0 ± 1.4) × 1012 M⊙. This value is in good agreement with the Cen A orbital/virial mass estimates and provides confirmation of the relatively high M/LB of this elliptical-dominated group. The centroids of both groups, as well as surrounding field galaxies, have very small peculiar velocities, <25 km s-1, with respect to the local Hubble flow with H0 = 68 km s-1 Mpc-1.

Measurements of Higgs boson production and couplings in the four-lepton channel in pp collisions at center-of-mass energies of 7 and 8 TeV with the ATLAS detector

Abstract: The final ATLAS Run 1 measurements of Higgs boson production and couplings in the decay channel H -> ZZ* -> l(+)l(-)l(+)l'(-), where l, l' = e or mu, are presented. These measurements were performed using pp collision data corresponding to integrated luminosities of 4.5 and 20.3 fb(-1) at center-of-mass energies of 7 and 8 TeV, respectively, recorded with the ATLAS detector at the LHC. The H -> ZZ* -> 4l signal is observed with a significance of 8.1 standard deviations, with an expectation of 6.2 standard deviations, at m(H) = 125.36 GeV, the combined ATLAS measurement of the Higgs boson mass from the H -> gamma gamma and H -> ZZ* -> 4l channels. The production rate relative to the Standard Model expectation, the signal strength, is measured in four different production categories in the H -> ZZ* -> 4l channel. The measured signal strength, at this mass, and with all categories combined, is 1.44(-0.33)(+0.40). The signal strength for Higgs boson production in gluon fusion or in association with (tt) over bar or (bb) over bar pairs is found to be 1.7(-0.4)(+0.5), while the signal strength for vector-boson fusion combined with WH/ZH associated production is found to be 0.3(-0.9)(+1.6).