[seminar] P. Kroll, 23.1. (utorak) 14h (c.t.), seminar ZTF-a

[Anđelo Samsarov]

               SEMINAR  TEORIJSKE  FIZIKE


    (Zajednički seminari Fizičkog odsjeka PMF-a te Zavoda za teorijsku
     fiziku i Zavoda za eksperimentalnu fiziku IRB-a)

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     Twist-3 contributions to hard exclusive processes


      P. Kroll
      Fachbereich Physik, Universit¨at Wuppertal,
      D-42097 Wuppertal, Germany



    Datum:  utorak, 23. siječnja 2018.
    Vrijeme: 14 sati c.t.
    Mjesto: IRB, predavaona I krila


   Sažetak:

   After a brief introduction in the handbag physics for hard exlusive  
processes and generalized parton distribution (GPDs) I am going to  
talk on
deeply virtual electroproduction and wide-angle photoproduction of pions. I
will however begin with wide-angle Compton scattering as the gold-plated
process: parameter-free predictions for observables are found to be in fair
agreement with experiment. On the other, the same handbag mechanism
fails badly for wide-angle photoproduction of pions if the calculation  
is done to same (twist-2) accuracy as Compton scattering. An attempt  
to improve
the results by the inclusion of transversity GPDs which go along with the
twist-3 pion distribution amplitudes fails in the Wandzura-Wilczek  
approximation as well. For electroproduction of uncharged pions, on  
the othe hand, this twist-3 mechanism dominates and is in agreement  
with experiment. As the last topic of my talk I take up wide-angle  
pion photoproduction again
and will show that the full twist-3 contribution, i.e. both its 2- and  
3-particle part, improves the theoretical results considerably.






Voditelj seminara: Anđelo Samsarov (asamsarov at irb.hr)

http://thphys.irb.hr/Seminar/list.htm
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