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A. V. Kuznetsov - One of the best experts on this subject based on the ideXlab platform.
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creation of electron positron pairs at excited landau levels by neutrino in a Strong Magnetic Field
International Journal of Modern Physics A, 2014Co-Authors: A. V. Kuznetsov, D. A. Rumyantsev, V. N. SavinAbstract:The process of neutrino production of electron–positron pairs in a Magnetic Field of arbitrary strength, where electrons and positrons can be created in the states corresponding to excited Landau levels, is analyzed. The mean value of the neutrino energy loss due to the process ν → νe-e+ is calculated. The result can be applied for calculating the efficiency of the electron–positron plasma production by neutrinos in the conditions of the Kerr black hole accretion disk considered by experts as the most possible source of a short cosmological gamma burst. The presented research can also be useful for further development of the calculation technique for an analysis of quantum processes in external active medium, and in part in the conditions of moderately Strong Magnetic Field, when taking account of the ground Landau level appears to be insufficient.
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creation of electron positron pairs at excited landau levels by neutrino in a Strong Magnetic Field
arXiv: High Energy Physics - Phenomenology, 2014Co-Authors: A. V. Kuznetsov, D. A. Rumyantsev, V. N. SavinAbstract:The process of neutrino production of electron positron pairs in a Magnetic Field of arbitrary strength, where electrons and positrons can be created in the states corresponding to excited Landau levels, is analysed. The mean value of the neutrino energy loss due to the process $\nu \to \nu e^- e^+$ is calculated. The result can be applied for calculating the efficiency of the electron-positron plasma production by neutrinos in the conditions of the Kerr black hole accretion disc considered by experts as the most possible source of a short cosmological gamma burst. The presented research can be also useful for further development of the calculation technic for an analysis of quantum processes in external active medium, and in part in the conditions of moderately Strong Magnetic Field, when taking account of the ground Landau level appears to be insufficient.
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Electron mass operator in a Strong Magnetic Field and dynamical chiral symmetry breaking.
Physical Review Letters, 2002Co-Authors: A. V. KuznetsovAbstract:The electron mass operator in a Strong Magnetic Field is calculated. The contribution of higher Landau levels of virtual electrons, along with the ground Landau level, is shown to be essential in the leading log approximation. The effect of the electron dynamical mass generation by a Magnetic Field is investigated. In a model with N charged fermions, it is shown that some critical number Ncr exists for any value of the electroMagnetic coupling constant �, such that the fermion dynamical mass is generated with a doublet splitting for N Ncr, thus leaving the chiral symmetry unbroken. Asymptotic properties of the QED diagrams and operators in Strong Magnetic Fields B ≫ Be, Be = m 2/e ≃ 4.41 � 10 13 G (e is the elementary charge) are of conceptual interest both from the standpoint of the searches of the perturbation theory applicability borders, and also in view of possible applications in astrophysics and in cosmology of the early Universe. The investigations of this type are being performed by many authors during a rather long time. For example, a history of calculations of the electron mass operator in a Strong Magnetic Field lasts more than 30 years already. However, as we show in this Letter, it is too early to put the final point in the problem. One-loop contribution into the electron mass operator in a Strong Magnetic Field was obtained for the first time by Jancovici [1] in the leading (double) log approximation. Later on, in the papers by Loskutov and Skobelev [2, 3] the attempts were performed to calculate the two-loop contribution and to summarize all the manyloop contributions in the same approximation. A correct formula for the electron mass operator in this approximation was obtained recently in the paper [4]. However, the double log approximation becomes invalid in asymptotically Strong Magnetic Fields [5], because of the crucial influence of the Strong Magnetic Field on the virtual photon polarization operator. This influence provides an appearance of the effective photon mass, m 2 = (2�/�)eB, which replaces the electron mass in one of the two logarithms. A correct expression for the electron mass operator in the leading (single) log approximation was obtained recently in our paper [6] by the summation of the rainbow Feynman diagrams, in the form:
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ELECTRON MASS OPERATOR IN A Strong Magnetic Field
Modern Physics Letters A, 2002Co-Authors: A. V. Kuznetsov, Nikolaevich Valerij Mikheev, M. V. OsipovAbstract:The electron mass operator in a Strong Magnetic Field is calculated by summation of the leading log contributions in all orders of the perturbation theory. An influence of the Strong Field on the virtual photon polarization operator is taken into account. The contribution of higher Landau levels of virtual electrons, along with the ground Landau level, is shown to be essential in the leading log approximation.
Juri Poutanen - One of the best experts on this subject based on the ideXlab platform.
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compton scattering s matrix and cross section in Strong Magnetic Field
Physical Review D, 2016Co-Authors: Alexander A Mushtukov, Dmitrij I Nagirner, Juri PoutanenAbstract:Compton scattering of polarized radiation in a Strong Magnetic Field is considered. The recipe for calculation of the scattering matrix elements, the differential and total cross sections based on quantum electrodynamic (QED) second order perturbation theory is presented for the case of arbitrary initial and final Landau level, electron momentum along the Field and photon momentum. Photon polarization and electron spin state are taken into account. The correct dependence of natural Landau level width on the electron spin state is taken into account in general case of arbitrary initial photon momentum for the first time. A number of steps in calculations were simplified analytically making the presented recipe easy-to-use. The redistribution functions over the photon energy, momentum and polarization states are presented and discussed. The paper generalizes already known results and offers a basis for accurate calculation of radiation transfer in Strong B-Field, for example, in Strongly magnetized neutron stars.
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compton scattering s matrix and cross section in Strong Magnetic Field
Physical Review D, 2016Co-Authors: Alexander A Mushtukov, Dmitrij I Nagirner, Juri PoutanenAbstract:Compton scattering of polarized radiation in a Strong Magnetic Field is considered. The recipe for calculation of the scattering matrix elements, the differential and total cross sections based on quantum electrodynamic second-order perturbation theory is presented for the case of arbitrary initial and final Landau level, electron momentum along the Field and photon momentum. Photon polarization and electron spin state are taken into account. The correct dependence of natural Landau level width on the electron spin state is taken into account in a general case of arbitrary initial photon momentum for the first time. A number of steps in the calculations were simplified analytically making the presented recipe easy to use. The redistribution functions over the photon energy, momentum and polarization states are presented and discussed. The paper generalizes already known results and offers a basis for the accurate calculation of radiation transfer in a Strong B Field, for example, in Strongly magnetized neutron stars.
Zhongming Ren - One of the best experts on this subject based on the ideXlab platform.
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dual effects of 6 t Strong Magnetic Field on interdiffusion behavior of fe fesi diffusion couple
Materials Characterization, 2019Co-Authors: Lijun Fan, Yunbo Zhong, Tianxiang Zheng, Zhe Shen, Zhongming RenAbstract:Abstract Interdiffusion behavior of Fe-FeSi diffusion couple at 1050–1150 °C for up to 12 h under 6 T Strong Magnetic Field has been investigated, and the dual-effects of Strong Magnetic Field on interdiffusion behavior have been observed. Strong Magnetic Field significantly promotes diffusion of solid solution layer with the increased thickness about 425 μm and Si content about 6.3 wt% at 1100 °C for 12 h because of the increased frequency factor rather than the activation energy. The increased dislocation density was demonstrated by the broadening and shifting of X-ray diffraction peaks and the atomic scale observations with high resolution transmission electron microscope. The dislocation on the Fe20 wt%Si side increases lattice parameters of Fe3Si, and the suppressed diffusion of Fe3Si under Magnetic Field is primary due to the decreased frequency factor.
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preparation of c axis textured tib2 ceramics by a Strong Magnetic Field of 6 t assisted slip casting process
Materials Letters, 2018Co-Authors: Zhigang Yang, Kang Deng, Zhongming RenAbstract:Abstract Highly c-axis textured TiB 2 ceramics were prepared by slip-casting in a Strong Magnetic Field of 6 T and subsequent pressureless sintering. By analyzing the zeta potential and viscosity, the optimal slurries with good dispersibility and stability were prepared when the pH was about 10.5. In 6 T, c-axis of TiB 2 grain was oriented to parallel to the direction of Magnetic Field and its a or b-axis was perpendicular to the direction of Magnetic Field in TiB 2 ceramics. The degree of texture was 0.80 on the top surface perpendicular to the direction of Magnetic Field in the green body. After sintering without the Magnetic Field, the degree of texture reached 0.94. Sintering process promoted the improvement of degree of texture in TiB 2 ceramics by grain growth.
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preparation of c axis textured sic ceramics by a Strong Magnetic Field of 6 t assisted gel casting process
Ceramics International, 2016Co-Authors: Zhigang Yang, Yunbo Zhong, Zhongming Ren, Kang Deng, Qiuliang Wang, Yinming Dai, Hui WangAbstract:Abstract C-axis textured SiC ceramics were prepared by a Strong Magnetic Field of 6 T assisted gel-casting and subsequent pressureless sintering. The optimal suspension parameters for gel-casting were determined by analyzing the influences of pH value and dispersant content on the stability and dispersibility of suspensions. The effect of sintering conditions on the texture development and properties of SiC ceramics was discussed. It was found that the increasing sintering temperature or holding time promoted the densification process of SiC ceramics. The c-axis of SiC grain was aligned parallel to the Magnetic Field by applying a Strong Magnetic Field of 6 T. The degree of texture of SiC ceramics showed a slightly increasing trend with the increase of sintering temperature or holding time. When the samples were sintered at 1950 °C for 4 h or 6 h, the large elongated grains were formed in the samples, leading to the extremely evident anisotropic microstructure on different planes. Textured SiC ceramics exhibited the anisotropic bending strength.
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preparation of textured porous al2o3 ceramics by slip casting in a Strong Magnetic Field and its mechanical properties
Crystal Research and Technology, 2015Co-Authors: Zhigang Yang, Yunbo Zhong, Zhongming Ren, Qiuliang Wang, Yinming Dai, Weidong Xuan, Hui WangAbstract:The textured porous Al2O3 ceramics were prepared by slip casting in a Strong Magnetic Field of 6 T and subsequently sintering. The c axis of Al2O3 grain was oriented parallel to the direction of the Magnetic Field and the textured porous microstructure with plate-shape grains was formed. The porosity of textured porous Al2O3 ceramic was 30.37% and the relative density reached 66.29% when the sintering temperature is 1600°C. The textured porous Al2O3 green body showed the linear shrinkage anisotropy. The bending strength of the textured porous Al2O3 ceramics depended on the alignment direction of plate-shape grains.
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dendrite fragmentation and columnar to equiaxed transition during directional solidification at lower growth speed under a Strong Magnetic Field
Acta Materialia, 2012Co-Authors: Annie Gagnoud, Zhongming Ren, Yves Fautrelle, Yudong Zhang, Rene Moreau, Claude EslingAbstract:Abstract The effects of Strong Magnetic Fields on the columnar-to-equiaxed transition (CET) have been investigated experimentally. Six alloys have been directionally solidified at low growth speeds (1–10 μm s−1) under Magnetic Fields up to 10 T. Experimental results show that the application of a Strong Magnetic Field causes a dendrite fragmentation and then the CET. The thermoelectric Magnetic force acting on cells/dendrites and equiaxed grains in the mushy zone has been studied numerically. Numerical results reveal that the value of the thermoelectric Magnetic force increases as the Magnetic Field intensity and the temperature gradient increase. A torque is created on cells/dendrites and equiaxed grains. This torque breaks cells/dendrites and drives the rotation of equiaxed grains. The rotation of equiaxed grains in the mushy zone will further destroy cells/dendrites. Thus, with the increase of the Magnetic Field intensity and the temperature gradient, the volume fraction of equiaxed grains in front of columnar dendrites increases. When the Magnetic Field intensity and the temperature gradient reach a critical value, the growth of columnar dendrites is blocked and the CET then occurs. The present work may initiate a new method of inducing the CET via an applied Strong Magnetic Field during directional solidification.
Igor Shovkovy - One of the best experts on this subject based on the ideXlab platform.
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Comment on "Electron mass operator in a Strong Magnetic Field and dynamical chiral symmetry breaking".
Physical Review Letters, 2003Co-Authors: V. P. Gusynin, V. A. Miransky, Igor ShovkovyAbstract:This is a comment on the paper ``Electron Mass Operator in a Strong Magnetic Field and Dynamical Chiral Symmetry Breaking" by A. V. Kuznetsov and N. V. Mikheev [Phys. Rev. Lett. 89 (2002) 011601]. We show that the main conclusions of the paper are incorrect.
Binoy Krishna Patra - One of the best experts on this subject based on the ideXlab platform.
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cumulative effects of bhatnagar gross krook collision term Strong Magnetic Field and quasiparticle description on charge and heat transport of a hot quark matter
arXiv: High Energy Physics - Phenomenology, 2020Co-Authors: Salman Ahamad Khan, Binoy Krishna PatraAbstract:Our aim is to explore the effect of modelling the collision terms by Bhatnagar-Gross-Krook (BGK), to ensure that each collision conserves particle number, momentum and energy, on the charge and heat transport of a hot quark matter in a Strong Magnetic Field (B), unlike the conservation of particle on the average of a cycle in collision terms of relaxation type. In addition, we explore the effect of the quasiparticle description of partons on the transport process with medium masses calculated by perturbative thermal QCD in the backgroung of Strong B. The modified collision term enhances both conductivities, which are itself increasing with both temperature and strength of Magnetic Field (B). The effect of the collision term is more pronounced in the high temperature region. As a consequence, the Lorenz number, $L$ $(=\kappa/\sigma_{el}T)$ becomes independent of $B$ and gets reduced and decreases monotonically with the temperature, resulting a weak violation of the Wiedemann-Franz Law, compared to the nearly constancy with collision terms of relaxation type. Whereas the Knudsen number ($\Omega$) gets amplified, compared to the relaxation collision term and it increases with both $T$ and $B$, but the increase with $B$ is meager. However, in the quasiparticle descriptionof partons, the characteristic dependence of conductivities on $T$ become interesting: both $\sigma_{el}$ and $\kappa$ gets reduced by an order of magnitude and $\sigma_{el}$ ($\kappa$) decreases (increases) with $T$ monotonically. Hence, $L$ gets increased, compared to the noninteracting description and decreases rapidly with $T$ but increases with $B$. On the contrary, $\Omega$ becomes smaller and shows a decreasing trend {\em especially} with $T$.
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landau damping in a Strong Magnetic Field dissociation of quarkonia
Nuclear Physics, 2020Co-Authors: Mujeeb Hasan, Binoy Krishna Patra, Bhaswar Chatterjee, Partha BagchiAbstract:Abstract In this article we have investigated the effects of Strong Magnetic Field on the properties of quarkonia immersed in a thermal medium of quarks and gluons and then studied the quasi-free dissociation of quarkonia due to the Landau-damping. Thermalising the Schwinger propagator for quarks in the lowest Landau levels and the Feynman propagator for gluons in real-time formalism, we have calculated the resummed retarded and symmetric propagators, which in turn give the real and imaginary components of dielectric permittivity, respectively. Finally the inverse Fourier transform of the permittivities encrypt the effect of hot QCD medium in the presence of Strong Magnetic Field into both real and imaginary parts of heavy quark potential. We have found that the Magnetic Field largely affects the large-distance interaction, as a result, the real part of potential becomes more attractive and the magnitude of imaginary part too becomes larger, compared to its counterpart in the absence of Magnetic Field. The real part of the potential is thereafter solved numerically by the Schrodinger equation to obtain the energy eigenvalues and energy eigenfunctions of the charmonium states. We have noticed that in the presence of Strong Magnetic Field, the size ( r 2 ) of J / ψ and ψ ′ are swelled whereas χ c gets shrunk, unless the temperature is very high. Similarly the Magnetic Field affects the binding of J / ψ and χ c differently, i.e. it decreases the binding of J / ψ but increases for χ c . On contrary the Magnetic Field increases the width of the resonances, unless the temperature is sufficiently high. We have finally studied the dissociation due to the Landau damping and found that the dissociation temperatures become higher in the presence of Magnetic Field. For example, with e B = 6 m π 2 the J / ψ is dissociated at 2 T c , and with e B = 4 m π 2 the χ c is dissociated at 1.1 T c in comparison, with eB = 0 the J / ψ is dissociated at T = 1.6 T c and χ c is dissociated at T = 0.8 T c . However, with the further increase of Magnetic Field the dissociation temperatures decrease.
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landau damping in a Strong Magnetic Field dissociation of quarkonia
arXiv: High Energy Physics - Phenomenology, 2018Co-Authors: Mujeeb Hasan, Binoy Krishna Patra, Bhaswar Chatterjee, Partha BagchiAbstract:We have investigated the effects of Strong Magnetic Field on the properties of quarkonia immersed in a thermal medium of quarks and gluons and studied its quasi-free dissociation due to the Landau-damping. Thermalizing the Schwinger propagator in the lowest Landau levels for quarks and the Feynman propagator for gluons in real-time formalism, we have calculated the resummed retarded and symmetric propagators, which in turn give the real and imaginary components of dielectric permittivity, respectively. The Magnetic Field affects the large-distance interaction more than the short-distance interaction, as a result, the real part of potential becomes more attractive and the magnitude of imaginary part too becomes larger, compared to the thermal medium in absence of Strong Magnetic Field. As a consequence the average size of $J/\psi$'s and $\psi^\prime$'s are increased but $\chi_c$'s get shrunk. Similarly the Magnetic Field affects the binding of $J/\psi$'s and $\chi_c$'s discriminately, i.e. it decreases the binding of $J/\psi$ and increases for $\chi_c$. However, the further increase in Magnetic Field results in the decrease of binding energies. On contrary the Magnetic Field increases the width of the resonances, unless the temperature is sufficiently high. We have finally studied how the presence of Magnetic Field affects the dissolution of quarkonia in a thermal medium due to the Landau damping, where the dissociation temperatures are found to increase compared to the thermal medium in absence of Magnetic Field. However, further increase of Magnetic Field decreases the dissociation temperatures. For example, $J/\psi$'s and $\chi_c$'s are dissociated at higher temperatures at 2 $T_c$ and 1.1 $T_c$ at a Magnetic Field $eB \approx 6~{\rm{and}}~4~m_\pi^2$, respectively, compared to the values 1.60 $T_c$ and 0.8 $T_c$ in the absence of Magnetic Field, respectively.