We study the fermionic Schwinger effect in two dimensional de Sitter spacetime. To do so we first present a method to semiclassically compute the number of pairs created per momentum mode for general time dependent fields. In addition the constant electric field is studied in depth. In this case solutions for the Dirac equation can be found and the number of pairs can be computed using the standard Bogoliubov method. This result is shown to agree with the semiclassical one in the appropriate limit. The solutions are also used to compute the expectation value of the induced current. Comparing these results to similar studies for bosons we find that while the results agree in the semiclassical limit they do not generally. Especially there is no occurrence of a strong current for small electric fields.Comment: 19 pages, 1 figure, V2:small changes and some references added, version accepted for publication in Phys. Rev.

We semiclassically investigate Schwinger pair production for pulsed rotating electric fields depending on time. To do so we solve the Dirac equation for two-component fields in a WKB-like approximation. The result shows that for two-component fields the spin distribution of produced pairs is generally not 1 : 1. As a result the pair creation rates of spinor and scalar quantum electro dynamics (QED) are different even for one pair of turning points. For rotating electric fields the pair creation rate is dominated by particles with a specific spin depending on the sense of rotation for a certain range of pulse lengths and frequencies. We present an analytical solution for the momentum spectrum of the constant rotating field. We find interference effects not only in the momentum spectrum but also in the total particle number of rotating electric fields.PACS numbers: 12.20. Ds, 11.15.Kc, 11.15.Tk IntroductionSince the first investigations of electron-positron pair creation in strong electric fields, also known as the Schwinger effect, there has been a lot of theoretical investigations of it. However it has not yet been possible to measure it directly due to the exponentially damped pair creation rate ∼ exp(−π/ ) where = E/E c is the field strength E normalized by the critical electric field [1-3]As laser powers in future may get closer to reaching this critical field strength, investigations of the effect are of interest. However there is the possibility that different strong field processes, such as QED cascades, will set in which might prevent reaching critical intensities [4][5][6][7][8][9][10][11][12][13][14].As pointed out in [15] it might be crucial for the detection of the Schwinger effect to evaluate if one can distinguish a QED cascade triggered by an electron which was produced in the Schwinger process from one which was triggered by vacuum impurities. To do so one first has to evaluate the properties of the pairs produced via the Schwinger effect. The simplest field configurations taken into account for cascade calculations are uniformly rotating electrical fields. These are approximative models for the electric fields in the anti-nodes of circularly polarized standing waves. The momentum spectrum of produced electron-positron pairs for rotating fields has been recently investigated numerically for pulsed fields with the help of the real-time Dirac-Heisenberg-Wigner (DHW) formalism [15] as well as analytically for constant rotating fields with help of the semiclassical WKB approximation for spinor QED [16]. Numerical methods usually need a lot of computation time. Semiclassical methods can help to give a better understanding of special features of the momentum spectrum, e.g. interference effects. For one-component fields depending solely on time there exist a lot of semiclassical investigations using e.g. the WKB-approximation [17][18][19][20][21][22][23][24][25][26] or the world-line instanton method [27][28][29]. In addition to that there are exact solutions for fields depending on lightcone variabl...