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Hong-shi Zong - One of the best experts on this subject based on the ideXlab platform.
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The chiral phase transition of QED(3) around the Critical Number of fermion flavors
Annals of Physics, 2014Co-Authors: Pei-lin Yin, Hong-tao Feng, Zhu-fang Cui, Hong-shi ZongAbstract:At zero temperature and density, the nature of the chiral phase transition in QED(3) with N-f massless fermion flavors is investigated. To this end, in Landau gauge, we numerically solve the coupled Dyson Schwinger equations for the fermion and boson propagator within the bare and simplified Ball Chiu vertices separately. It is found that, in the bare vertex approximation, the system undergoes a high-order continuous phase transition from the Nambu-Goldstone phase into the Wigner phase when the Number of fermion flavors N-f reaches the Critical Number N-f.c, while the system exhibits a typical characteristic of second-order phase transition for the simplified Ball-Chiu vertex. (C) 2014 Elsevier Inc. All rights reserved.
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Influence of finite chemical potential on the Critical Number of fermion flavors in QED 3 _
Physical Review D, 2006Co-Authors: Hong-tao Feng, Feng-yao Hou, Wei-min Sun, Hong-shi ZongAbstract:Based on the rainbow approximation of Dyson-Schwinger equation and the assumption that the inverse dressed fermion propagator at finite chemical potential is analytic in the neighborhood of $\ensuremath{\mu}=0$, A new method for calculating the dressed fermion propagator at finite chemical potential in ${\mathrm{QED}}_{3}$ is developed. From this the effects of the chemical potential on the Critical Number of the fermion flavors is evaluated.
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THE INFLUENCE OF THE GAUGE BOSON MASS ON THE Critical Number OF THE FERMION FLAVORS IN QED3
International Journal of Modern Physics A, 2005Co-Authors: Hong-tao Feng, Wei-min Sun, Hong-shi ZongAbstract:Using the Dyson–Schwinger equations for the propagators of fermion and gauge boson with a nonzero mass, we investigate the effects of the full vacuum polarization and vertex on the fermion propagators in QED3 with N fermion flavors. We find that the Critical Number of the fermion flavors is affected appreciably by the gauge boson mass and depend on the form of the full vertex function Ansatz.
Koji Kato - One of the best experts on this subject based on the ideXlab platform.
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Humidity effect on the Critical Number of friction cycles for wear particle generation in carbon nitride coatings
Wear, 2002Co-Authors: Dong F Wang, Koji KatoAbstract:Abstract Wear particle generation in carbon nitride coatings by a spherical diamond counterpart in repeated sliding contacts has been studied with an emphasis on the effect of relative humidity varying from 0.4 to 80%. An environmental scanning electron microscope (E-SEM), in which a pin-on-disk type apparatus was installed, has in situ provided direct evidence that when and where the wear particle generation do occur. The in situ examination of non-conductive carbon nitride coatings are therefore available free from surface charging with controllable relative humidity and a sliding speed of 50 mm/s varying normal load from 10 to 250 mN. Based on the in situ examination, the shape transition maps for generated wear particles have been obtained for carbon nitride coatings in various relative humidity. The results show that the Critical Number of friction cycles ( N c ) for detecting a cluster of wear particles is observed to be generally increasing with an increase in relative humidity. It also appears that the increase in relative humidity results in a decrease in peak-to-valley (P-V) values of contact tracks during the first friction cycle, which is essentially induced by a combined plastic deformation behavior of carbon nitride coated silicon surface. This further implies that the effective surface property such as hardness has been possibly changed by introducing water vapor into the contact interface between the carbon nitride coating and the spherical diamond counterpart, if assuming the contact pressure has a constant value.
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coating hardness effect on the Critical Number of friction cycles for wear particle generation in carbon nitride coatings
Diamond and Related Materials, 2002Co-Authors: Dong F Wang, Koji KatoAbstract:Wear particle generation in carbon nitride coatings by a spherical diamond counterpart in repeated sliding contacts has been studied with an emphasis on the effect of coating hardness, through varying two nitrogen incorporation conditions of ion acceleration energy (I.A.E.) and ion current density (I.C.D.). With a pin-on-disk type apparatus installed in the chamber of an environmental scanning electron microscope (E-SEM), the motivation of this paper is to show the direct evidence of when and where the wear particles of non-conductive carbon nitride coatings deposited onto silicon substrates do generate under controllable relative humidity, rather than infer that how wear particle generation do occur from post-testing observation. Based on the in situ examination, the shape transition maps for generated wear particles have been obtained for various nitrogen incorporation conditions. The results show that the Critical Number of friction cycles, Nc, for detecting a cluster of wear particles is observed to be generally decreasing with an increase in both ion acceleration energy and ion current density. However, the effect of ion acceleration energy seems to be somewhat bigger than that of ion current density, not only on the Critical Number of friction cycles, Nc, but also on the coating characteristics, such as surface roughness, nano-indentation hardness and internal stress. It is found further that the Critical Number of friction cycles, Nc, is showing a linearly increasing behavior with an increase in nano-indentation hardness, which is determined by both ion acceleration energy and ion current density during an ion beam assisted deposition process.
Hassan Firouzjahi - One of the best experts on this subject based on the ideXlab platform.
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Boundary crossing in stochastic inflation with a Critical Number of fields
Physical Review D, 2019Co-Authors: Mahdiyar Noorbala, Hassan FirouzjahiAbstract:We study boundary crossing probability in the context of stochastic inflation. We prove that for a generic multi-field inflationary potential, the probability that the inflaton reaches infinitely far regions in the field space is Critically dependent on the Number of fields, being nonzero for more than two fields, and zero otherwise. We also provide several examples where the boundary crossing probability can be calculated exactly, most notably, for a particular landscape of a two-field model with a multi-well potential.
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Critical Number of Fields in Stochastic Inflation.
Physical review letters, 2017Co-Authors: Vincent Vennin, Hooshyar Assadullahi, Hassan Firouzjahi, Mahdiyar Noorbala, David WandsAbstract:Stochastic effects in generic scenarios of inflation with multiple fields are investigated. First passage time techniques are employed to calculate the statistical moments of the Number of inflationary e-folds, which give rise to all correlation functions of primordial curvature perturbations through the stochastic δN formalism. The Number of fields is a Critical parameter. The probability of exploring arbitrarily large-field regions of the potential becomes nonvanishing when more than two fields are driving inflation. The mean Number of e-folds can be infinite, depending on the Number of fields; for plateau potentials, this occurs even with one field. In such cases, correlation functions of curvature perturbations are infinite. They can, however, be regularized if a reflecting (or absorbing) wall is added at large energy or field value. The results are found to be independent of the exact location of the wall and this procedure is, therefore, well defined for a wide range of cutoffs, above or below the Planck scale. Finally, we show that, contrary to single-field setups, multifield models can yield large stochastic corrections even at sub-Planckian energy, opening interesting prospects for probing quantum effects on cosmological fluctuations.
Hong-tao Feng - One of the best experts on this subject based on the ideXlab platform.
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The chiral phase transition of QED(3) around the Critical Number of fermion flavors
Annals of Physics, 2014Co-Authors: Pei-lin Yin, Hong-tao Feng, Zhu-fang Cui, Hong-shi ZongAbstract:At zero temperature and density, the nature of the chiral phase transition in QED(3) with N-f massless fermion flavors is investigated. To this end, in Landau gauge, we numerically solve the coupled Dyson Schwinger equations for the fermion and boson propagator within the bare and simplified Ball Chiu vertices separately. It is found that, in the bare vertex approximation, the system undergoes a high-order continuous phase transition from the Nambu-Goldstone phase into the Wigner phase when the Number of fermion flavors N-f reaches the Critical Number N-f.c, while the system exhibits a typical characteristic of second-order phase transition for the simplified Ball-Chiu vertex. (C) 2014 Elsevier Inc. All rights reserved.
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Influence of finite chemical potential on the Critical Number of fermion flavors in QED 3 _
Physical Review D, 2006Co-Authors: Hong-tao Feng, Feng-yao Hou, Wei-min Sun, Hong-shi ZongAbstract:Based on the rainbow approximation of Dyson-Schwinger equation and the assumption that the inverse dressed fermion propagator at finite chemical potential is analytic in the neighborhood of $\ensuremath{\mu}=0$, A new method for calculating the dressed fermion propagator at finite chemical potential in ${\mathrm{QED}}_{3}$ is developed. From this the effects of the chemical potential on the Critical Number of the fermion flavors is evaluated.
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THE INFLUENCE OF THE GAUGE BOSON MASS ON THE Critical Number OF THE FERMION FLAVORS IN QED3
International Journal of Modern Physics A, 2005Co-Authors: Hong-tao Feng, Wei-min Sun, Hong-shi ZongAbstract:Using the Dyson–Schwinger equations for the propagators of fermion and gauge boson with a nonzero mass, we investigate the effects of the full vacuum polarization and vertex on the fermion propagators in QED3 with N fermion flavors. We find that the Critical Number of the fermion flavors is affected appreciably by the gauge boson mass and depend on the form of the full vertex function Ansatz.
Sadhan K. Adhikari - One of the best experts on this subject based on the ideXlab platform.
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Critical Number of atoms in an attractive Bose-Einstein condensate on an optical plus harmonic traps
Journal of Physics B: Atomic Molecular and Optical Physics, 2003Co-Authors: Sadhan K. AdhikariAbstract:The stability of an attractive Bose-Einstein condensate on a joint one-dimensional optical lattice and an axially-symmetric harmonic trap is studied using the numerical solution of the time-dependent mean-field Gross-Pitaevskii equation and the Critical Number of atoms for a stable condensate is calculated. We also calculate this Critical Number of atoms in a double-well potential which is always greater than that in an axially-symmetric harmonic trap. The Critical Number of atoms in an optical trap can be made smaller or larger than the corresponding Number in the absence of the optical trap by moving a node of the optical lattice potential along the axial direction of the harmonic trap. This variation of the Critical Number of atoms can be observed experimentally and compared with the present calculation.
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Collapse of attractive Bose-Einstein condensed vortex states in a cylindrical trap.
Physical review. E Statistical nonlinear and soft matter physics, 2001Co-Authors: Sadhan K. AdhikariAbstract:The quantized vortex states of a weakly interacting Bose-Einstein condensate of atoms with attractive interatomic interaction in an axially symmetric harmonic oscillator trap are investigated using the numerical solution of the time-dependent Gross-Pitaevskii equation obtained by the semi-implicit Crank-Nicholson method. The collapse of the condensate is studied in the presence of deformed traps with the larger frequency along either the radial or the axial direction. The Critical Number of atoms for collapse is calculated as a function of the vortex quantum Number L. The Critical Number increases with increasing angular momentum L of the vortex state but tends to saturate for large L.