Speaker
Dr
Juan Leon
(Instituto de Física Fundamental (CSIC))
Description
LEON, Juan (Instituto de Fisica Fundamental (CSIC))
Creation and annihilation operators adding or subtracting well-defined
amounts of energy and momentum to the field canonically describe particles,
the elementary excitations of the fields, in QFT. These operators create
quanta completely delocalized in space, at odds with the idea of particles
as minute subdivisions of matter of finite mass and tiny size. In this talk,
I will show how QFT owns the tools to describe localized quanta using the
appropriate operators. Fock Space operators in unitarily inequivalent
representations describe both subatomic units, those with sharply defined
momentum and energy on the one side, and those well localized in space-time
on the other. This gives rise to explanations for a multitude of different
properties, from the absence of local number operators in the standard
formulation to the absence of local projectors for the vacuum state as the
raison d'etre for vacuum entanglement.
