Two-loop self-dual Euler-Heisenberg Lagrangians (II): Imaginary part and Borel analysis

We analyze the structure of the imaginary part of the two-loop Euler-Heisenberg QED effective Lagrangian for a constant self-dual background. The novel feature of the two-loop result, compared to one-loop, is that the prefactor of each exponential (instanton) term in the imaginary part has itself an asymptotic expansion. We also perform a high-precision test of Borel summation techniques applied to the weak-field expansion, and find that the Borel dispersion relations reproduce the full prefactor of the leading imaginary contribution.Comment: 28 pp, 6 eps figure

Физика газового разряда и ее современные приложения: учебное пособие

Курс лекций по физике газового разряда предназначен для студентов первого года обучения в магистратуре, обладающих знаниями по физике и математике в объеме программы бакалавриата факультета физико-математических наук РУДН. Он направлен на углубленное изучение кинетических процессов, протекающих в плазменных средах, основных типов устройств, реализующих газовый разряд, явлений, возникающих в приэлектродных областях, плазмохимических процессов применительно к современным технологиям. Учебное пособие выполнено в рамках инновационной образовательной программы Российского университета дружбы народов, комплекс экспортоориентированных инновационных образовательных программ по приоритетным направлениям науки и технологий

CP--Violating Invariants in Supersymmetry

I study the weak basis CP-violating invariants in supersymmetric models, in particular those which cannot be expressed in terms of the Jarlskog--type invariants, and find basis--independent conditions for CP conservation. With an example of the K-anti-K mixing, I clarify what are the combinations of supersymmetric parameters which are constrained by experiment.Comment: matches the PRD versio

Electric field gradients in MgB2_2 synthesized at high pressure: 111^111Cd TDPAC study and ab initio calculation

We report the high-pressure synthesis of novel superconductor MgB$_2$ and some related compounds. The superconducting transition temperature of our samples of MgB$_2$ is equal to 36.6 K. The MgB$_2$ lattice parameters determined via X-ray diffraction are in excellent agreement with results of our ab initio calculations. The time-differential perturbed angular correlation (TDPAC) experiments demonstrate a small increase in quadrupole frequency of $^111$Cd probe with decreasing temperature from 293 to 4.2 K. The electric field gradient (EFG) at the B site calculated from first principles is in fair agreement with EFG obtained from $^11$B NMR spectra of MgB$_2$ reported in the literature. It is also very close to EFG found in our $^111$Cd TDPAC measurements, which suggests that the $^111$Cd probe substitutes for boron in the MgB$_2$ lattice.Comment: 10 pages, 3 figure

Extraction of Kaon Formfactors from K^- -> mu^- nu_mu gamma Decay at ISTRA+ Setup

The radiative decay K->mu nu gamma has been studied at ISTRA+ setup in a new kinematical region. About 22K events of K^- -> mu^- nu_mu gamma have been observed. The sign and value of Fv-Fa have been measured for the first time. The result is Fv-Fa=0.21(4)(4).Comment: 11 pages, 21 figures, submitted to Phys. Lett.

Influence of Plasma Treatment on Physical Properties of Thin SnO2 Films Obtained from SnCl4 Solutions with Additions of NH4F and NH4OH

This paper considers the effect of oxygen and hydrogen plasma on SnO2 films synthesized from solutions of tin tetrachloride containing NH4F and NH4OH additives. It was found that the treatment of samples with oxygen plasma for 5 min led to a decrease in transparency by 1.11 and 1.17 times. On the transmission spectra, a decrease in the transmittance at a wavelength of 450 nm to 38.1% (1.24 times) in samples obtained from solutions with the addition of NH4F and up to 29.9% (1.53 times) in samples obtained from solutions with the addition of NH4OH is observed. The formation of tin oxide (II) under the influence of the reducing properties of hydrogen plasma is assumed. At the same time, the formation of metal tin from tin dioxide is not observed here. Due to the decreasing of transmission coefficient in the long-wave region of the spectrum. There is an increase in surface resistance after treatment with oxygen plasma, due to filling oxygen vacancies. Treatment of hydrogen plasma films leads to a decrease in surface resistance. Perhaps due to the increase in oxygen vacancies under the influence of hydrogen plasma. Within five minutes, the oxygen and hydrogen plasma had a more active effect on the films obtained from the solution with the addition of ammonium hydroxide, which is associated with a higher porosity of the sample. Consequently, irrespective of the time of plasma exposure with increasing the surface of contact between ionized gases and the film material, the interaction efficiency will increase

Search for Heavy Neutrino in K->mu nu_h(nu_h-> nu gamma) Decay at ISTRA+ Setup

Heavy neutrino nu_h with m_h < 300MeV/c^2 can be effectively searched for in kaon decays. We put upper limits on mixing matrix element |U_mu_h}|^2 for radiatively decaying nu_h from K->mu nu_h (nu_h -> nu gamma) decay chain in the following parameter region: 30MeV/c^2 < m_h < 80MeV/c^2; 10^{-11}sec < tau_h < 10^{-9}sec. For the whole region |U_{mu h}|^2 < 5 x 10^{-5} for Majorana type of nu_h and | U_{\mu h}|^2 < 8 x 10^{-5} for the Dirac case.Comment: Published in Phys. Lett.

Lebedev physical institute radiation complex – current status and new concepts

Multipurpose radiation complex is the result of long- term permanent development of new instrumentation at the Lebedev Physical Institute. This is stand-alone large facility designed for fundamental and applied research that had been started from the high current racetrack microtron project in the mid of seventies and has been completed by commissioning of far infrared FEL nowadays. Current status of the radiation complex including research as well as linac and FEL performance improvement is discussed in paper presented followed by new ideas in further facility development and application