Polarization-operator approach to electron-positron pair production in combined laser and Coulomb fields

Abstract

The optical theorem is applied to the process of electron-positron pair creation in the superposition of a nuclear Coulomb and a strong laser field. We derive new representations for the total production rate as two-fold integrals, both for circular laser polarization and for the general case of elliptic polarization, which has not been treated before. Our approach allows us to obtain by analytical means the asymptotic behaviour of the pair creation rate for various limits of interest. In particular, we consider pair production by two-photon absorption and show that, close to the energetic threshold of this process, the rate obeys a power law in the laser frequency with different exponents for linear and circular laser polarization. With the help of the upcoming x-ray laser sources our results could be tested experimentally.

Relativistic nonperturbative above-threshold phenomena in strong laser fields

“…For the collision scenarios outlined above, the latter is of the order of បω ~ 100 keV. While in the multiphoton and tunneling regimes, closed form expressions for the total pair creation rate can be derived by analytical means (see, e.g., [47]), for ATPP corresponding formulas are not known. We have there fore fitted an analytical curve to our numerical data.…”

“…The exponential behavior in Eq. (7) closely resembles the pair produc tion rate in the tunneling regime which scales as exp( ) in combined laser and nuclear fields [47]; note that E c /E = mc 2 /បωξ. ATPP at low laser fre quencies បω Ӷ mc 2 in the projectile frame is therefore heavily suppressed.…”

“…Because of the large projectile mass the two step Breit-Wheeler process via Compton scatter ing is suppressed. Starting with the early work of Yak ovlev [43], several theoreticians have studied nonlin ear Bethe−Heitler pair creation, with a focus on the tunneling and multiphoton regimes of interaction (see [44][45][46][47][48][49][50] and references therein). Relatively little work has been done on the intermediate above threshold regime where ξ ~ 1 [45,46].…”

Dynamic nuclear Stark shift in superintense laser fields

“…Rare exceptions study direct laserand x-ray-nucleus interactions in the context of β decay [26] or x-ray-driven gamma emission of nuclei [27]. On the other hand, effects such as laser-induced pair creation which previously had been neglected for the same reason of small interaction matrix elements, are now being studied, see for example [28,29,30,31,32,33,34]. The reason is that it can be expected that present and upcoming technology will allow to enter regimes where these traditionally neglected processes become possible.…”

Bound-freee+e−pair creation with a linearly polarized laser field and a nuclear field

“…Theoretically the process of free pair creation by com-bined Coulomb and laser fields has been investigated by several authors [17,18,19,20,21,22,23,24,25,26,27,28,29,30,31] with a focus on the tunneling regime. Also muon pair creation in laser-ion collisions has been calculated recently [32,33].…”