Boson pair production in arbitrarily polarized electric fields

Abstract

The momentum spectrum and number density of created bosons for two types of arbitrarily polarized electric fields are calculated and compared with those of created fermions, employing the equal-time Feshbach-Villars-Heisenberg-Wigner formalism which is confirmed that for an uniform and time-varying electric field it is completely equivalent to the quantum Vlasov equation in scalar QED. For an elliptically polarized field, it is found that the number density of created bosons is a square root of the number density of spin-up electrons times that of spin-down ones for a circularly polarized multicycle field. Moreover, the degree of spin polarization roughly grows as the Keldysh adiabaticity parameter increases for arbitrarily polarized multicycle fields. For a field constituted of two circularly polarized fields with a time delay, it is shown that momentum vortices also exist in boson pair creation and are induced only by the orbital angular momentum of particles. However, the vortices can reproduce the quantum statistic effect due to the effect of spin of particles. These results further deepen the understanding of some significant signatures in pair production.PACS numbers:

Advances in QED with intense background fields

“…As alternatives/improvements, one may for example construct spin-resolved phase-space distribution functions by inserting appropriate spin projection operators [408], or consider coarse-graining [409,410]. A good property of the choice (110) is that, for spatially homogeneous and linearly-polarized electric fields, it coincides with quantum Vlasov approach [405,399], see also [411]. Note that there are (infinitely) many other possible choices, reflecting the infinite ambiguity in defining particle number at non-asymptotic times -see Sec.…”

“…The Schwinger effect is modified if orientation of electric fields changes in time. Similarly to the linearlypolarised case, the time dependence results in enhancement of pair creation [757,758,663,678] and quantum interference that distorts momentum spectra [758,759,760,726,411]. A novel feature is that the Schwinger effect becomes spin (or chirality) dependent even without magnetic fields [761,762,408,763,764,765,678,411,766] and can produce spin current out of the vacuum [767,768].…”

Study of pair production in inhomogeneous two-color electric fields using the computational quantum field theory

“…Hebenstreit et al [24] found that the Wigner function in spinor QED could be reduced to the QVE for a spatially homogeneous and time-dependent electric field with one component. Li et al [28] generalized the above result to the scalar QED, and found that in this case the electric field could have three components. Blinne and Strobel [35] compared the semiclassical scattering method with the DHW formalism for rotating fields, and found that the numerical methods of these two approaches are complementary in terms of computation time as well as accuracy.…”

“…Furthermore, due to the equivalence between the QVE in spinor QED and the DHW formalism for a timedependent electric field with one component [24], the CQFT in spinor QED is also equivalent to the DHW formalism for this field, which indicates that the definition of quasi-particles in the DHW formalism is based on instantaneous energy eigenstates as well. Similarly, one can verify the equivalence between the CQFT and the Wigner function in scalar QED, and generalize it to the time-dependent electric field with three components because for this field the QVE and the Wigner function in scalar QED are equivalent [28]. Based on these results and given that both the CQFT presented here and the DHW formalism shown in [60] can calculate the pair production in a time-dependent electric field with three components, the equivalence between the CQFT in spinor QED and the DHW formalism can be further generalized to time-dependent electric fields with three components.…”

“…In addition to above-mentioned methods, the current widely used ones include the semiclassical scattering method related to the Wentzel-Kramers-Brillouin approach [7][8][9][10][11][12], the worldline instanton technique [13][14][15][16][17], the quantum Vlasov equation (QVE) [18][19][20][21][22], the Wigner function [23][24][25][26][27][28], the computational quantum field theory (CQFT) [29][30][31][32][33] and so on. Note that the QVE and the Wigner function can be collectively called quantum kinetic theory (QKT), and the Dirac-Heisenberg-Wigner (DHW) formalism is the Wigner function in spinor QED.…”