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SUMMARY:The Bethe Salpeter equation and unitarization of chiral perturbati
 on theory amplitudes
DTSTART;VALUE=DATE-TIME:20020502T103000Z
DTEND;VALUE=DATE-TIME:20020502T113000Z
DTSTAMP;VALUE=DATE-TIME:20261109T032805Z
UID:indico-event-1263@indico.ific.uv.es
DESCRIPTION:The Bethe-Salpeter equation restores exact elastic unitarity i
 n the $s-$ channel by summing up an infinite set of chiral loops. We use t
 his equation to show how a chiral expansion can be undertaken in the two p
 article irreducible amplitude and the propagators accomplishing exact elas
 tic unitarity at any step. Renormalizability of the amplitudes can be achi
 eved by allowing for an infinite set of counter-terms as is the case in or
 dinary Chiral Perturbation Theory. Crossing constraints can be imposed on 
 the parameters to a given order. Within this framework\, we study the $s-$
 wave meson-baryon scattering\, for the strangeness $S=0\,-1$ sectors\, in 
 a coupled channel formalism\, and the leading and next-to-leading contribu
 tions to the vector pion form factor. In the latter case\, Watson's theore
 m is automatically satisfied and obtain a quite accurate determination of 
 some of the ChPT $SU(2)-$low energy parameters (${\\bar l}_1 - {\\bar l}_2
  = -6.1\\er{0.1}{0.3} $ and ${\\bar l}_6= 19.14 \\pm 0.19$). Extensions to
  the study of $Kl_3$ and semi-leptonic B $\\to \\pi$ form-factors are also
  discussed.\n\nhttps://indico.ific.uv.es/event/1263/
LOCATION:Edf. Institutos de Investigación Sala Seminarios IFIC
URL:https://indico.ific.uv.es/event/1263/
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