Minimal Length Effects on Schwinger Mechanism

In this paper,we investigate effects of the minimal length on the Schwinger mechanism using the quantum Geld theory(QFT) incorporating the minimal length.We Grst study the Schwinger mechanism for scalar Gelds in both usual QFT and the deformed QFT.The same calculations are then performed in the case of Dirac particles.Finally,we discuss how our results imply for the corrections to the Unruh temperature and the Hawking temperature due to the minimal length.     

An efficient, preconditioned, high-order solver for scattering by two-dimensional inhomogeneous media

We consider the problem of evaluating the scattering of TE polarized electromagnetic waves by two-dimensional penetrable inhomogeneities: building upon previous work [IEEE Trans. Antennas Propag. 48 (2000) 1862] we present a practical and general fast integral equation algorithm for this problem. The contributions introduced in this text include: (1) a preconditioner that significantly reduces the number of iterations required by the algorithm in the treatment of electrically large scatterers, (2) a new radial integration scheme based on Chebyshev polynomial approximation, which gives rise to increased accuracy, efficiency and stability, and (3) an efficient and stable method for the evaluation of scaled high-order Bessel functions, which extends the capabilities of the method to arbitrarily high frequencies. These enhancements give rise to an algorithm that is much more accurate and efficient than its previous counterpart, and that allows for treatment of much larger problems than permitted by the previous approach. In one test case, for example, the present algorithm results in far-field errors of 8.9×10⁻¹³ in a 2.12s calculation (on a 1.7 GHz PC) whereas the original algorithm gave rise to far-field errors of 1.1×10⁻⁸ in 88.91s on a 400 MHz PC. In another example, the present algorithm evaluates accurately the scattering by a cylinder of acoustical size κR=256, which is of the order of 20 times larger (400 times larger in square wavelengths) than the largest scatterers that could be treated by the previous approach. Yielding, at worst, third-order far field accuracy (or substantially better, for smooth scatterers) in fast computing times ( operations for an N point mesh) even for discontinuous and complex refractive index distributions (possibly containing severe geometric singularities such as corners and cusps), the proposed approach is the highest-order solver in existence for the problem under consideration.     

In Appreciation Julian Schwinger: From Nuclear Physics and Quantum Electrodynamics to Source Theory and Beyond

Julian Schwinger’s influence on twentieth-century science is profound and pervasive. He is most famous for his renormalization theory of quantum electrodynamics, for which he shared the Nobel Prize in Physics for 1965 with Richard Feynman and Sin-itiro Tomonaga. This triumph undoubtedly was his most heroic work, but his legacy lives on chiefly through subtle and elegant work in classical electrodynamics, quantum variational principles, proper-time methods, quantum anomalies, dynamical mass generation, partial symmetry, and much more. Starting as just a boy, he rapidly became one of the preeminent nuclear physicists in the world in the late 1930s, led the theoretical development of radar technology at the Massachusetts Institute of Technology during World War II, and soon after the war conquered quantum electrodynamics, becoming the leading quantum-field theorist for two decades, before taking a more iconoclastic route during the last quarter century of his life.     

Field theoretical approach to spin models

We developed a systematic non-perturbative method base on Dyson–Schwinger theory and the Φ-derivable theory for Ising model at broken phase. Based on these methods, we obtain critical temperature and spin spin correlation beyond mean field theory. The spectrum of Green function obtained from our methods become gapless at critical point, so the susceptibility become divergent at Tc. The critical temperature of Ising model obtained from this method is fairly good in comparison with other non-cluster methods. It is straightforward to extend this method to more complicate spin models for example with continue symmetry.     

Action Principle and Algebraic Approach to Gauge Transformations in Gauge Theories

The action principle is used to derive, by an entirely algebraic approach, gauge transformations of the full vacuum-to-vacuum transition amplitude (generating functional) from the Coulomb gauge to arbitrary covariant gauges and in turn to the celebrated Fock–Schwinger (FS) gauge for the Abelian (QED) gauge theory without recourse to path integrals or to commutation rules and without making use of delta functionals. The interest in the FS gauge, in particular, is that it leads to Faddeev–Popov ghosts-free non-Abelian gauge theories. This method is expected to be applicable to non-Abelian gauge theories including supersymmetric ones.     

Elastic Scattering of CH4 by Electron Impact

In this work we present a theoretical study on electrons scattering by CH₄ in the intermediate energy range. More specifically, we report integral and differential cross sections for electron scattering by CH₄ in the (10～300) eV range by the Schwinger multichannel method using plane waves as a trial basis set (SMC-PW). To include exchange effects we have used the Born-Ochkur model. Our aim is to study the numerical stability of the cross sections and our calculated results compared with experimental data and theoretical studies are encouraging.     

Gauge bosons at zero and finite temperature

Gauge theories of the Yang–Mills type are the single most important building block of the standard model of particle physics and beyond. They are an integral part of the strong and weak interactions, and in their Abelian version of electromagnetism. Since Yang–Mills theories are gauge theories their elementary particles, the gauge bosons, cannot be described without fixing a gauge. Therefore, to obtain their properties a quantized and gauge-fixed setting is necessary.     

Schwinger mechanism enhanced by the Nielsen–Olesen instability

We discuss gluon production by the Schwinger mechanism in collinear color-electric and magnetic fields which may be realized in pre-equilibrium stages of ultra-relativistic heavy-ion collisions. Fluctuations of non-Abelian gauge fields around a purely color-magnetic field contain exponentially growing unstable modes in a longitudinally soft momentum region, which is known as the Nielsen–Olesen instability. With a color-electric field imposed parallelly to the color-magnetic field, we can formulate this instability as the Schwinger mechanism. This is because soft unstable modes are accelerated by the electric fields to escape from the instability condition. Effects of instability remain in the transverse spectrum of particle modes, leading to an anomalously intense Schwinger particle production.     

Erratum to: “Theory of extreme correlations using canonical Fermions and path integrals” [Ann. Phys. 343 (2014) 164–199]

Erratum for paper “Theory of extreme correlations using canonical Fermions and path integrals”, B.S. Shastry, Ann. Phys. 343, 164–199 (2014) http://dx.doi.org/10.1016/j.aop.2014.02.005 AOP69618.