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SUMMARY:Topical Seminar: Extracting Scattering Amplitudes from Euclidean C
orrelators
DTSTART;VALUE=DATE-TIME:20240531T100000Z
DTEND;VALUE=DATE-TIME:20240531T110000Z
DTSTAMP;VALUE=DATE-TIME:20240618T182916Z
UID:indico-event-7635@indico.ific.uv.es
DESCRIPTION:\nScattering amplitudes can be extracted from time-ordered $n$
-point functions by means of the well known LSZ reduction formula\, even i
n non-perturbative Quantum Field Theories\, such as Quantum Chromodynamics
(QCD). However\, in the context of Lattice QCD\, one can access only Eucl
idean $n$-point functions sampled at discrete points and with finite (but
systematically improvable) precision and accuracy. This makes the problem
of analytically continuing back to Minkowski space-time ill-posed. I will
present here one particular strategy which allows to extract scattering am
plitudes from Euclidean correlators\, while avoiding analytic continuation
\, technically turning an ill-posed problem into a merely ill-conditioned
one.\n\nWorking in the axiomatic framework of the Haag-Ruelle scattering t
heory\, we show that scattering amplitudes can be approximated arbitrarily
well in terms of linear combinations of Euclidean correlators at discrete
time separations. The essential feature of the proposed approximants is t
hat one can calculate them\, at least in principle\, from Lattice-QCD data
. In this talk\, after reviewing the basic ideas behind Haag-Ruelle scatt
ering theory\, I will sketch the derivation of the approximations formulae
\, and discuss extensively how they can be used in practical numerical cal
culations. Also\, similarities and differences with other methods\, e.g. L
üscher's formalism\, will be reviewed.\n\n\n\nhttps://indico.ific.uv.es/e
vent/7635/
LOCATION:IFIC Primera-1-1-1 - Paterna. Seminario
URL:https://indico.ific.uv.es/event/7635/
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