We are pleased to invite you to the Skoltech Colloquium!
Guest Speaker: Professor Dmitri M. Gitman, Head of Nuclear Physics Department, Institut of Physics, The University of São Paulo.
When: April 17; 4:00pm.
Where: Institute of Gene Biology RAS, Vavilova street 34/5, Conference room, 1st floor.
What: Quantum Field Theory in strong external backgrounds.
Abstract: QFT with an external background is an effective model when a part of a quantized field is strong enough to be treated as a given (external) classical one. Such a model is frequently used to describe quantum processed in the presence of different strong backgrounds like strong electromagnetic fields, gravitational fields, and so on. Especially interesting are backgrounds that violate the quantum vacuum stability, creating real particles from the vacuum. In our works a nonperturbative approach to such QFT’s models was elaborated. It is based on using exact solutions of relativistic wave equations in the corresponding backgrounds. QFT with an external background can be considered as a consistent model only if the back reaction of created particles is relatively small. We discuss this consistency on the example of two important cases of external fields in QED: a constant macroscopic electromagnetic field and the Coulomb field of a point like charge Ze. To find the corresponding consistency restrictions on the macroscopic field and its duration, we calculate the change of mean energy density of quantized matter fields for an arbitrary constant electric field E, which is acting during a large but a finite time T. In the case of the external Coulomb field, we dispute the common opinion that the Dirac equation with such a field with Z>137 it inconsistent. Defining rigorously self-adjoint extensions of Dirac operator with the Coulomb field for arbitrary Z, one can see that all they have nonsingular spectra and complete sets of orthonormalized wave functions. Recently, the graphene physics attracts a lot attention due to numerous applications in nanotechnology. It turns out the at certain conditions this physics can be effectively described by the so-called Dirac model, which is a QFT with essentially unstable vacuum under the action of the the external electric field. Applying our approach to study the electric conductivity in the graphene, we obtain results that match which existing experimentally observations and explain unusual behavior of this conductivity due to generation of charge carriers from the vacuum by the electric field.
Transfers:
Shuttle bus Hypercube → Institute of Gene Biology RAS at 3:10 pm
Shuttle bus MSM (Karacorum) → Institute of Gene Biology RAS at 3:20 pm
How to get to Institute of Gene Biology RAS:
Address: Vavilova street 34/5 (ул. Вавилова 34/5)
Map: http://www.genebiology.ru/institute/way.shtml
Join us on Facebook: https://www.facebook.com/pages/Skoltech-Colloquium/667982569920574
Past schedule and video: https://www.skoltech.ru/en/colloquium/past-schedule/
If you like to participate and for further information or questions, please Liliya Abaimova
We look forward to seeing you.
