Universal Holographic Chiral Dynamics in an External Magnetic Field

In this work we further extend the investigation of holographic gauge theories in external magnetic fields, continuing earlier work. We study the phenomenon of magnetic catalysis of mass generation in 1+3 and 1+2 dimensions, using D3/D7- and D3/D5-brane systems, respectively. We obtain the low energy effective actions of the corresponding pseudo Goldstone bosons and study their dispersion relations. The D3/D7 system exhibits the usual Gell-Mann--Oakes--Renner (GMOR) relation and a relativistic dispersion relation, while the D3/D5 system exhibits a quadratic non-relativistic dispersion relation and a modified linear GMOR relation. The low energy effective action of the D3/D5 system is related to that describing magnon excitations in a ferromagnet. We also study properties of general Dp/Dq systems in an external magnetic field and verify the universality of the magnetic catalysis of dynamical symmetry breaking.Comment: 41 pages, 11 figures, references adde

Changes in the middle and upper atmosphere parameters during the January 2013 sudden stratospheric warming

We present the results of complex obser-vations of various parameters of the middle and upper atmosphere over Siberia in December 2012 – January 2013, during a major sudden stratospheric warming (SSW) event. We analyze variations in ozone concentration from microwave measurements, in stratosphere and lower mesosphere temperatures from lidar and satellite measurements, in the F2-layer critical frequency (foF2), in the total electron content (TEC), as well as in the ratio of concentrations of atomic oxygen to molecular nitrogen (O/N2) in the thermosphere. To interpret the observed disturbances in the upper atmosphere, the experimental measurements are compared with the results of model calculations obtained with the Global Self-consistent Model of Thermosphere—Ionosphere—Protonosphere (GSM TIP). The response of the upper atmosphere to the SSW event is shown to be a decrease in foF2 and TEC during the evolution of the warming event and a prolonged increase in O/N2, foF2, and TEC after the SSW maximum. For the first time, we observe the relation between the increase in stratospheric ozone, thermospheric O/N2, and ionospheric electron density for a fairly long time (up to 20 days) after the SSW maximum at midlatitudes

Influence of the High-Temperature Annealing on the Structure and Mechanical Properties of Vacuum–Arc Coatings from Mo/(Ti + 6 wt % Si)N

Scanning electron microscopy with energy dispersive element microanalysis, X-ray structural analysis, and microindentation were used to study the effect of the deposition conditions in a reactive nitrogen atmosphere on the growth morphology, phase composition, structure, and microhardness of vacuum–arc multilayer coatings produced by the evaporation of cathodes from Mo and (Ti + 6 wt % Si) both after their deposition and after high?temperature annealing. It has been established that the use of the composite cathode of Ti and Si allows the formation of the structure state inclined to ordering to form a two-phase compound from TiN and Ti5Si3 at high-temperature annealing. In this case the coating hard? ness increases to a value higher than 45 GPa

Cavitation erosion of Ti-6Al-4V alloy with vacuum-arc TiN and CrN coatings

The distilled-water cavitation erosion resistance of Ti-6Al-4V alloy with vacuum-arc TiN and CrN coatings is investigated. The results show that the coatings having high mechanical properties are capable to reduce appreciably the cavitation erosion of the alloy by prolonging the incubation period of fracture and by decreasing the mass loss. Preliminary ion-plasma nitriding of the alloy leads to the formation under the coating of a solid transition layer which enhances the coating alloy adhesion and so increases the alloy resistance to the cavitation erosion.Досліджено стійкість до кавітації в дистильованій воді сплаву Ti-6Al-4V з вакуумно-дуговими покриттями TiN і CrN. Показано, що покриття, які мають високі механічні властивості, істотно знижують кавітаційний знос сплаву, подовжуючи інкубаційний період руйнування і знижуючи втрату маси. Попереднє іонно-плазмове азотування сплаву призводить до формування під покриттям твердого перехідного шару, який покращує адгезію покриття до металу і тим самим збільшує його стійкість до кавітаційного руйнування.Исследована стойкость к кавитации в дистиллированной воде сплава Ti-6Al-4V с вакуумно-дуговыми покрытиями TiN и CrN. Показано, что покрытия, обладающие высокими механическими свойствами, существенно снижают кавитационный износ сплава, продлевая инкубационный период разрушения и снижая потерю массы. Предварительное ионно-плазменное азотирование сплава приводит к формированию под покрытием твердого переходного слоя, который улучшает адгезию покрытия к сплаву и тем самым увеличивает его стойкость к кавитационному разрушению

Deposition of TiN-based coatings using vacuum arc plasma in increased negative substrate bias voltage

The paper presents the results of the study on the influence of a high substrate bias voltage from 300 up to 1300 V on the titanium nitride coating deposition under nitrogen pressure of 2 Pa. The deposition rate, phase and chemical composition, adhesion and mechanical properties of coatings, macroparticle number and size distribution were investigated.Представлені результати дослідження впливу високої напруги зсуву підкладки від 300 до 1300 В на осадження покриттів нітриду титану при тиску азоту 2 Па. Вивчені швидкість осадження, фазовий і хімічний склад, адгезія і механічні властивості покриттів, кількість і розподіл за розмірами макрочасток.Представлены результаты исследования влияния высокого напряжения смещения подложки от 300 до 1300 В на осаждение покрытий нитрида титана при давлении азота 2 Па. Изучены скорость осаждения, фазовый и химический составы, адгезия и механические свойства покрытий, количество и распределение по размерам макрочастиц

High Precision Mass Measurements in Ψ\Psi and Υ\Upsilon Families Revisited

High precision mass measurements in $\Psi$ and $\Upsilon$ families performed in 1980-1984 at the VEPP-4 collider with OLYA and MD-1 detectors are revisited. The corrections for the new value of the electron mass are presented. The effect of the updated radiative corrections has been calculated for the $J/\Psi(1S)$ and $\Psi(2S)$ mass measurements.Comment: 5 pages, 1 table, submitted to Phys. Lett.

Complete measurement of three-body photodisintegration of 3He for photon energies between 0.35 and 1.55 GeV

The three-body photodisintegration of 3He has been measured with the CLAS detector at Jefferson Lab, using tagged photons of energies between 0.35 GeV and 1.55 GeV. The large acceptance of the spectrometer allowed us for the first time to cover a wide momentum and angular range for the two outgoing protons. Three kinematic regions dominated by either two- or three-body contributions have been distinguished and analyzed. The measured cross sections have been compared with results of a theoretical model, which, in certain kinematic ranges, have been found to be in reasonable agreement with the data.Comment: 22 pages, 25 eps figures, 2 tables, submitted to PRC. Modifications: removed 2 figures, improvements on others, a few minor modifications to the tex

A Kinematically Complete Measurement of the Proton Structure Function F2 in the Resonance Region and Evaluation of Its Moments

We measured the inclusive electron-proton cross section in the nucleon resonance region (W < 2.5 GeV) at momentum transfers Q**2 below 4.5 (GeV/c)**2 with the CLAS detector. The large acceptance of CLAS allowed for the first time the measurement of the cross section in a large, contiguous two-dimensional range of Q**2 and x, making it possible to perform an integration of the data at fixed Q**2 over the whole significant x-interval. From these data we extracted the structure function F2 and, by including other world data, we studied the Q**2 evolution of its moments, Mn(Q**2), in order to estimate higher twist contributions. The small statistical and systematic uncertainties of the CLAS data allow a precise extraction of the higher twists and demand significant improvements in theoretical predictions for a meaningful comparison with new experimental results.Comment: revtex4 18 pp., 12 figure

Measurement of the Deuteron Structure Function F2 in the Resonance Region and Evaluation of Its Moments

Inclusive electron scattering off the deuteron has been measured to extract the deuteron structure function F2 with the CEBAF Large Acceptance Spectrometer (CLAS) at the Thomas Jefferson National Accelerator Facility. The measurement covers the entire resonance region from the quasi-elastic peak up to the invariant mass of the final-state hadronic system W~2.7 GeV with four-momentum transfers Q2 from 0.4 to 6 (GeV/c)^2. These data are complementary to previous measurements of the proton structure function F2 and cover a similar two-dimensional region of Q2 and Bjorken variable x. Determination of the deuteron F2 over a large x interval including the quasi-elastic peak as a function of Q2, together with the other world data, permit a direct evaluation of the structure function moments for the first time. By fitting the Q2 evolution of these moments with an OPE-based twist expansion we have obtained a separation of the leading twist and higher twist terms. The observed Q2 behaviour of the higher twist contribution suggests a partial cancellation of different higher twists entering into the expansion with opposite signs. This cancellation, found also in the proton moments, is a manifestation of the "duality" phenomenon in the F2 structure function

eta-prime photoproduction on the proton for photon energies from 1.527 to 2.227 GeV

Differential cross sections for the reaction gamma p -> eta-prime p have been measured with the CLAS spectrometer and a tagged photon beam with energies from 1.527 to 2.227 GeV. The results reported here possess much greater accuracy than previous measurements. Analyses of these data indicate for the first time the coupling of the etaprime N channel to both the S_11(1535) and P_11(1710) resonances, known to couple strongly to the eta N channel in photoproduction on the proton, and the importance of j=3/2 resonances in the process.Comment: 6 pages, 3 figure