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UID:2518@qft.physik.hu-berlin.de
DTSTART;TZID=Europe/Berlin:20260619T120000
DTEND;TZID=Europe/Berlin:20260619T153000
DTSTAMP:20260618T085645Z
URL:https://qft.physik.hu-berlin.de/next-seminars/qft-colloquium-radu-roib
 an-penn-state-2/
SUMMARY:QFT-Colloquium Day - John Gracey (U. Liverpool) and Radu Roiban (Pe
 nn State) - 
DESCRIPTION:Announcing the special QFT Colloquia Day on Friday\, 19 June\, 
 starting at 12:00\, at room 1.221 (CSMB building)\, Zum Großen Windkanal 
 2\, 12489 Berlin.\n\n12:00 - Prof. John Gracey (University of Liverpool) :
  Topics in conformal field theories in d dimensions\n\n13:00 - Joint lunch
  break with coffee\, tea\, bagels and wraps\n\n14:30 - Prof. Radu Roiban (
 PennState - Eberly College of Science) :\n\n**************\nProf. John Gra
 cey\nTitle: Topics in conformal field theories in d dimensions\nAbstract: 
 We report on recent work in relation to properties of conformal field theo
 ries in spacetime dimensions d &gt\; 2.\nThe presentation is in two parts 
 where the focus in the first is on scalar cubic theories which are studied
  in relation to the Lee-Yang model and percolation theory.\nEstimates of c
 ritical exponents at the Wilson-Fisher fixed point derived from Schnetz's 
 six loop renormalization are produced. Applying resummation methods the ex
 ponent estimates are in good agreement with estimates from other methods s
 uch as Monte Carlo\, high T_c expansions\, functional renormalization grou
 p and the conformal bootstrap.\nThe second part concentrates on nonabelian
  gauge theories and in particular the Banks-Zaks-Caswell (BZC) fixed point
  in four dimensions which defines the conformal window.\nUsing the BZC exp
 ansion we compute several critical exponents to fourth order for SU(3) pro
 ducing estimates which\, with a suitable resummation\, are in reasonable a
 greement with lattice field theory across the full conformal window. An es
 timate of the location of the lower conformal window boundary is indicated
  and compared with those from other methods.\nThe situation with other col
 our groups and quark representations is also discussed.\n*************\n\n
 Prof. Radu Roiban\nTitle: Scattering as a probe of fundamental interaction
 s\nAbstract: Scattering amplitudes reveal a hidden simplicity in particle 
 interactions that is often obscured by individual Feynman diagrams. I wil
 l explain how modern methods use locality\, analyticity\, unitarity\, and 
 symmetry to reconstruct amplitudes from their singularity structure\, maki
 ng explicit the cancellations and simplifications that occur. Gravity prov
 ides particularly striking applications: amplitudes expose surprising rela
 tions between gauge theory and gravity\, known as the double copy\, provid
 e new ways to extract classical observables relevant to compact-object dyn
 amics\, and probe the high-energy structure of quantum gravity and supergr
 avity. Along the way\, these problems have driven the development of compu
 tational tools that play an important role in precision predictions across
  quantum field theory. The focus will be on the conceptual picture rather 
 than technical details.
CATEGORIES:Colloquia
LOCATION:IRIS building\, Room 1.221\, Zum Großen Windkanal 2\, Berlin\, 12
 489\, Germany
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 erlin\, 12489\, Germany;X-APPLE-RADIUS=100;X-TITLE=IRIS building\, Room 1.
 221:geo:0,0
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DTSTART:20260329T030000
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