2.0-//132.68.74.185//NONSGML kigkonsult.se iCalcreator 2.26.9//GREGORIANPUBLISHTechnion-Haifa University String Theory GroupTechnion-Haifa University String Theory Grouphttps://phsites.technion.ac.il/stringsAsia/JerusalemAsia/JerusalemAsia/Jerusalem2022-10-30T02:00:002023-10-29T02:00:00IST+03:00+02:002023-03-24T02:00:002024-03-29T02:00:00IDT+02:00+03:004nq1jjjk2i3p5qm94c8adn9ahh@google.com2023-02-04T01:49:36ZShota komatsu<p>Title: Landau diagrams in AdS and S-matrices from conformal correlators</p>
<p>Abstract: Quantum field theories in AdS generate conformalcorrelation functions on the boundary, and in the limit where AdS is nearly flat one should be able to extract an S-matrix from such correlators. We discuss a particularly simple position-space procedure to do so. It features a direct map from boundary positionsto (on-shell) momenta and thereby relates cross ratios to Mandelstam invariants. This recipe succeeds in several examples, includes the momentum-conserving delta functions, and can be shown to imply the two proposals based on Mellin space and on the OPE data.Interestingly the procedure does not always work: the Landau singularities of a Feynman diagram are shown to be part of larger regions, to be called `bad regionsâ€™, where the flat-space limit of the Witten diagram diverges. To capture these divergences we introducethe notion of Landau diagrams in AdS. As in flat space, these describe on-shell particles propagating over large distances in a complexified space, with a form of momentum conservation holding at each bulk vertex. As an application we recover the anomalousthreshold of the four-point triangle diagram at the boundary of a bad region.</p>Asia/Jerusalem2020-10-06T16:00:00Asia/Jerusalem2020-10-06T17:00:00en-USNeve Shalom0https://phsites.technion.ac.il/strings/event/shota-komatsu/