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TZID:Europe/Paris
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BEGIN:VEVENT
UID:0-657@lptms.universite-paris-saclay.fr
DTSTART:20190402T110000Z
DTEND:20190402T123000Z
DTSTAMP:20190323T140524Z
URL:http://www.lptms.universite-paris-saclay.fr/seminars/seminaire-du-lptm
 s-kris-van-houcke/
SUMMARY:Séminaire du LPTMS: Kris Van Houcke - LPTMS\, salle 201\, 2ème é
 tage\, Bât 100\, Campus d'Orsay - 2 Avr 19 11:00
DESCRIPTION:Summation of diagrammatic series for a strongly correlated ferm
 ionic theory with zero convergence radius\nKris Van Houcke (École Normale
  Supérieure\, Paris)\nIn this talk I will mainly focus on the unitary Fer
 mi gas (spin 1/2 fermions with contact interactions in 3D\, which describe
 s cold atomic gases at a Feshbach resonance) in the normal phase. Thanks t
 o a diagrammatic Monte Carlo algorithm\, we accurately sample all skeleton
 \ndiagrams (built on dressed single-particle and pair propagators) up to o
 rder nine [1]. The diagrammatic series is divergent and there is no small 
 parameter so that a resummation method is needed. We compute the large-ord
 er asymptotics of the diagrammatic series\, based on a functional integral
  representation of the skeleton series and the saddle-point\nmethod. We sh
 ow that the radius of convergence is actually zero\, but the series is sti
 ll resummable\, by a generalised conformal-Borel transformation that incor
 porates the large-order asymptotics [2]. This yields new high-precision da
 ta\, not only for the equation of state\, but also for Tan's contact coeff
 icient and for the momentum distribution [3].\nI will also highlight some 
 recent developments in (determinant) diagrammatic Monte Carlo and present 
 new high-precision data for the Fermi polaron\, which is a single impurity
  atom immersed in a Fermi sea.\n\nReferences:\n\n[1] K. Van Houcke\, F. We
 rner\, T. Ohgoe\, N. V. Prokof'ev\, and B. V. Svistunov\, "Diagrammatic Mo
 nte Carlo algorithm for the resonant Fermi gas"\, Phys. Rev. B 99\, 035140
  (2019).\n[2] R. Rossi\, T. Ohgoe\, K. Van Houcke\, F. Werner\, "Resummati
 on of diagrammatic series with zero convergence radius for strongly correl
 ated fermions"\, Phys. Rev. Lett. 121\, 130405 (2018)\n[3] R. Rossi\, T. O
 hgoe\, E. Kozik\, N. Prokof'ev\, B. Svistunov\, K. Van Houcke\, F. Werner\
 , "Contact and momentum distribution of the unitary Fermi gas"\, Phys. Rev
 . Lett. 121\, 130406 (2018)
CATEGORIES:seminars
LOCATION:LPTMS\, salle 201\, 2ème étage\, Bât 100\, Campus d'Orsay\, 15 
 Rue Georges Clemenceau\, Orsay\, 91405\, France
GEO:48.698185;2.181768
X-APPLE-STRUCTURED-LOCATION;VALUE=URI;X-ADDRESS=15 Rue Georges Clemenceau\,
  Orsay\, 91405\, France;X-APPLE-RADIUS=100;X-TITLE=LPTMS\, salle 201\, 2è
 me étage\, Bât 100\, Campus d'Orsay:geo:48.698185,2.181768
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