Tomsk Polytechnic University

About: Tomsk Polytechnic University is a education organization based out in Tomsk, Russia. It is known for research contribution in the topics: Combustion & Ignition system. The organization has 9190 authors who have published 13224 publications receiving 103735 citations.

Quantum imaging with incoherently scattered light from a free-electron laser

Abstract: The intensity correlations in incoherently scattered X-rays from a free-electron laser can be exploited to image 2D objects with a resolution close to or below the diffraction limit. The advent of accelerator-driven free-electron lasers (FEL) has opened new avenues for high-resolution structure determination via diffraction methods that go far beyond conventional X-ray crystallography methods1,2,3,4,5,6,7,8,9,10. These techniques rely on coherent scattering processes that require the maintenance of first-order coherence of the radiation field throughout the imaging procedure. Here we show that higher-order degrees of coherence, displayed in the intensity correlations of incoherently scattered X-rays from an FEL, can be used to image two-dimensional objects with a spatial resolution close to or even below the Abbe limit. This constitutes a new approach towards structure determination based on incoherent processes11,12, including fluorescence emission or wavefront distortions, generally considered detrimental for imaging applications. Our method is an extension of the landmark intensity correlation measurements of Hanbury Brown and Twiss13 to higher than second order, paving the way towards determination of structure and dynamics of matter in regimes where coherent imaging methods have intrinsic limitations14.

The influence of the surface microtexture on wettability properties and drop evaporation

Abstract: The influence of different microstructure of the surface of aluminum alloy on the free convection in the liquid and the evaporation of the water drop were studied experimentally. Various textures were created using laser surface treatment. The character of water drop evaporation on heated structured surfaces was compared with that on untreated rough surface. Velocity fields were measured using the Micro Particle Image Velocimetry (Micro PIV) method. A chemical analysis of sample surfaces in the cavity and in its vicinity was carried out. The effect of different textures on the wettability properties is shown. The evaporation rate of a drop depends on several competing factors: the diameter of the wetted drop spot, the drop height, the convection due to the surface thermocapillary forces, and the convection caused by the surface microstructures. The article also assesses the individual impact of these factors. The greatest intensification of convection and evaporation is associated with textures in the form of craters with a diameter of about 50–100 μm. The competing influence of several parameters leads to the need of their optimization. This paper demonstrates a general approach to such an optimization.

Search for the Higgs boson decaying to two muons in proton-proton collisions at √s=13 TeV

Abstract: A search for the Higgs boson decaying to two oppositely charged muons is presented using data recorded by the CMS experiment at the CERN LHC in 2016 at a center-of-mass energy s=13 TeV, corresponding to an integrated luminosity of 35.9 fb-1. Data are found to be compatible with the predicted background. For a Higgs boson with a mass of 125.09 GeV, the 95% confidence level observed (background-only expected) upper limit on the production cross section times the branching fraction to a pair of muons is found to be 3.0 (2.5) times the standard model expectation. In combination with data recorded at center-of-mass energies s=7 and 8 TeV, the background-only expected upper limit improves to 2.2 times the standard model value with a standard model expected significance of 1.0 standard deviation. The corresponding observed upper limit is 2.9 with an observed significance of 0.9 standard deviation. This corresponds to an observed upper limit on the standard model Higgs boson branching fraction to muons of 6.4×10-4 and to an observed signal strength of 1.0±1.0(stat)±0.1(syst).

High resolution ro-vibrational analysis of interacting bands ν4, ν7, ν10, and ν12 of 13C2H4

Abstract: High accurate, ~ 1 × 10 − 4 cm − 1 , ro-vibrational spectra of the C 2 13 H 4 molecule in the region of 600–1600 cm −1 were recorded with Bruker IFS 120/125 HR Fourier transform interferometers and analyzed in the Hamiltonian model which takes into account Coriolis resonance interactions between all four bands. More than 660, 3870, 2420, and 2550 transitions belonging to the ν 4 , ν 7 , ν 10 , and ν 12 bands were assigned in the experimental spectrum with the maximum values of quantum numbers J max . / K a max . , equal to 38/10, 43/21, 33/16 and 52/18, respectively. To make the ro-vibrational analysis physically more suitable, the initial values of the rotational and centrifugal distortion parameters of the studied bands were theoretically estimated by the use of isotopic relations. On that basis, a set of 55 vibrational, rotational, centrifugal distortion, and resonance interaction parameters was obtained from the fit. They reproduce values of 2934 initial “experimental” ro-vibrational energy levels obtained from nonsaturated unblended lines (more than 9500 assigned transitions of the ν 4 , ν 7 , ν 10 , and ν 12 bands) with the rms error d rms = 0.00014 cm − 1 . Ground state parameters of the C 2 13 H 4 molecule were improved as well.

Axions in gravity with torsion

Abstract: We study a scenario allowing a solution of the strong charge parity problem via the Peccei-Quinn mechanism, implemented in gravity with torsion. In this framework there appears a torsion-related pseudoscalar field known as the Kalb-Ramond axion. We compare it with the so-called Barbero-Immirzi axion recently proposed in the literature also in the context of the gravity with torsion. We show that they are equivalent from the viewpoint of the effective theory. The phenomenology of these torsion-descended axions is completely determined by the Planck scale without any additional model parameters. These axions are very light and very weakly interacting with ordinary matter. We briefly comment on their astrophysical and cosmological implications in view of the recent BICEP2 and Planck data.