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SUMMARY:Magnetic scattering: pairwise little group and pairwise helicity
DTSTART;VALUE=DATE-TIME:20211208T140000Z
DTEND;VALUE=DATE-TIME:20211208T153000Z
DTSTAMP;VALUE=DATE-TIME:20220116T101319Z
UID:indico-event-1087868@indico.cern.ch
DESCRIPTION:I discuss how to construct a Lorentz-invariant S-matrix for th
e scattering of electrically and magnetically charged particles. A key i
ngredient is a revision of our fundamental understanding of multi-particle
representations of the Poincaré group. Surprisingly\, the asymptotic st
ates for electric-magnetic scattering transform with an additional litt
le group phase\, associated with pairs of electrically and magnetically
charged particles. I will discuss the general construction of such states.
The resulting "pairwise helicity" is identified with the quantized "cros
s product" of charges e1 g2- e2 g1 for every charge-monopole pair\, an
d represents the extra angular momentum stored in the asymptotic electroma
gnetic field. We define a new kind ofpairwise spinor-helicity variable\,
which serves as an additional building block for electric-magnetic scatt
ering amplitudes. We then construct the most general 3-point S-matrix ele
ments\, as well as the full partial wave decomposition for the 2 -> 2 ferm
ion-monopole S-matrix. In particular\, we derive the famous helicity fl
ip in the lowest partial wave as a simple consequence of a generalized spi
n-helicity selection rule\, as well as the full angular dependence for th
e higher partial waves. We will also discuss a possible direction for reso
lving Callan's ``semiton" problem: the scattering amplitude of a positro
n on a GUT monopole which apparently does not have an allowed final stat
e. We will show that using entagled pairwise helicity spinors a simple pos
sible s-wave final state does exist.\n\nTH colloquia: https://cern.zoom.us
/j/67346292748?pwd=ZnRkQWh0ZXVFQTc5K256QW5NcEcrdz09\n\nhttps://indico.cern
.ch/event/1087868/
LOCATION:CERN zoom only
URL:https://indico.cern.ch/event/1087868/
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