We study two different initial conditions for fermions for the problem of pair production of fermions coupled to a classical electromagnetic field with backreaction in \oneplusone boost-invariant coordinates. Both of these conditions are consistent with fermions initially in a vacuum state. We present results for the proper time evolution of the electric field $E$, the current, the matter energy density, and the pressure as a function of the proper time for these two cases. We also determine the interpolating number density as a function of the proper time. We find that when we use a "first order adiabatic" vacuum initial condition or a "free field" initial condition for the fermion field, we obtain essentially similar behavior for physically measurable quantities. The second method is computationally simpler, it is twice as fast and involves half the storage required by the first method.
Particle-antiparticle pairs can be produced by background electric fields via the Schwinger mechanism provided they are unconfined. If, as in QED in (3+1)-$d$ these particles are massive, the particle production rate is exponentially suppressed below a threshold field strength. Above this threshold, the energy for pair creation must come from the electric field itself which ought to eventually relax to the threshold strength. Calculating this relaxation in a self-consistent manner, however, is difficult. Chu and Vachaspati addressed this problem in the context of capacitor discharge in massles…
Within the framework of the recently proposed Taylor-Lagrange regularization procedure, we reanalyze the calculation of radiative corrections in $QED$ at next to leading order. Starting from a well defined local bare Lagrangian, the use of this regularization procedure enables us to manipulate fully finite elementary amplitudes in the ultra-violet as well as infra-red regimes, in physical $D=4$ space-time dimensions and for physical massless photons, as required by gauge invariance. We can thus separately calculate the electromagnetic form factors of the electron and the cross-section for real…
The three-loop QED contributions to the $g-2$ of charged leptons with two internal fermion loops and a class of Kampé de Fériet series
利用Mellin-Barnes（MB）表象技术，重新讨论了具有两个内部闭合费米子环的带电轻子（在$g-2$文献中有时称为$A^{(6)}_3\left(\frac{m_1}{m_2}, \frac{m_1}{m_3}\right)$）的三圈QED质量对$g-2$的贡献.μ子和$τ$轻子反常磁矩$A^{(6)}_{3,μ}$和$A^{(6)}_{3,τ}$的结果被推广到它们的精确表达式，它们被认为是轻子质量比的级数展开。对电子$A^{(6)}_{3,e}$反常磁矩的贡献也以封闭形式明确给出。除此之外，我们表明，不同的系列表示来自MB表示集体收敛的所有可能的质量值。这种意想不到的行为是有关的事实，这些系列发挥双重超几何级数，属于一类的Kampé de Fériet系列，我们证明了具有相同的简单收敛性和解析延拓性质的Appell $F_1$双重超几何级数。
The Maxwell equations imply that, under the background of non-zero $\boldsymbol{B}$, varying $θ$ term produces $\boldsymbol{E} \cdot \boldsymbol{B}$. An interesting example is the Witten effect where a magnetic monopole becomes a dyon which, however, should disappear in the exact massless limit of the fermion. Underlying mechanism of this phenomenon has been understood by Callan by the presence of an effective axion-like degree of freedom around the monopole, which is roughly the phase of the fermions. The configuration of this axion cancels the effect of the $θ$ term. Now, the chiral anomaly …
We study neutral Fermions pair creation with anomalous magnetic moment from the vacuum by time-independent magnetic-field inhomogeneity as an external background. We show that the problem is technically reduced to the problem of charged-particle creation by an electric step, for which the nonperturbative formulation of strong-field QED is used. We consider a magnetic step given by an analytic function and whose inhomogeneity may vary from a "gradual" to a "sharp" field configuration. We obtain corresponding exact solutions of the Dirac-Pauli equation with this field and calculate pertinent qua…
