Statut  Confirmé 
Série  IPNX 
Domaines  hepph 
Date  Jeudi 22 Juin 2017 
Heure  11:00 
Institut  IPN 
Salle  Salle A201 
Nom de l'orateur  Ghosh 
Prenom de l'orateur  Shayan 
Addresse email de l'orateur  
Institution de l'orateur  Indian institute of Science, Bangalore 
Titre  Analytic solutions to massive twoloop sunset diagrams, and applications to Chiral Perturbation Theory 
Résumé  In this talk, we begin by showing how it is possible to obtain full analytic results for the twoloop three distinct mass scale sunset diagrams that appear in the expressions for the masses and decay constants of the pion, kaon and eta particles in twoloop SU(3) chiral perturbation theory. We then talk about two applications of these results: a) how it allows one to obtain small quark mass ratios to arbitrarily high powers, and b) how it allows one to make fits to lattice data to extract greater information about low energy constants. We then change track and discuss in more detail the MellinBarnes method used in our calculations, and demonstrate how this method can be extended using analytic continuation to obtain results for Feynman diagrams whose mass value parameters are such that it is impossible to use a direct calculation. We show how such methods of analytic continuation can also be helpful in contexts where a direct calculation does yield results, and thus set the stage for more widespread application of this technique. 
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