[institut] [phys4phys] Group for Gravitation, Particles and Fields seminar, Friday, 30th of October, 2026

[Igor Prlina]

Dear colleagues,

You are cordially invited to the seminar of the Group for Gravitation, 
Particles and Fields, which will be held on Friday, 30th of October, 
2026, at 11:00 at the Institute of Physics Belgrade, lecture hall 360.

The talk entitled:

Model of fundamental decoherence and nonunitarity in quantum 
electrodynamics

will be given by Miloš Petrašinović.

Abstract: This talk will present a phenomenological model of fundamental 
decoherence in quantum electrodynamics, based on the assumption that the 
off-shell virtual particles can lead to a loss of quantum coherence. 
This mechanism is introduced by modifying internal electron and photon 
propagators with exponential factors that depend on the square of the 
four-momentum. Deviations from standard propagation are governed by the 
characteristic scales Λₑ and Λγ. The electron–photon interaction retains 
its vector form, while the photon is described by a massive Proca field.

Decoherence is modeled as an interruption of coherent propagation along 
an internal line of a Feynman diagram. The probability of this process 
is related to the modification of the propagator, and the resulting 
state is described by the density matrix of a thermalized ensemble. The 
corresponding statistical distribution is specified by the choice of 
fluctuation energy and by constraints on the mean four-momentum and the 
mean squared four-momentum. On this basis, statistical contributions 
from diagrams with a single interrupted internal line are formulated.

Particular attention will be devoted to isolating the contributions 
arising from the modified propagators and exploring how they can be 
probed through the electron's anomalous magnetic moment, the Lamb shift, 
and scattering probabilities. This establishes a framework for examining 
the physical implications of the model and possible experimental 
constraints on its characteristic scales.

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Time: October 30, 2026 11:00 Belgrade

Institute of Physics Belgrade, lecture hall 360, 2nd floor

BigBlueButton platform link: 
https://gravityserver.ipb.ac.rs/b/mar-ae0-f4q-qww

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Best regards,
Igor Prlina
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