ELFT HÍRADÓ

[Somogyi Gábor <somogyi.gabor AT wigner.hu>]

Wigner FK RMI Elméleti Osztály Szemináriuma
Tisztelettel meghívjuk


          Burkhard Eden
          (Humboldt University, Berlin)


"The off-shell one and two-loop box recovered from intersection theory”


címmel tartandó szemináriumára.


Kivonat:



We advertise intersection theory for generalised hypergeometric functions as 
a means of evaluating Mellin-Barnes representations. As an example, we study 
two-parameter representations of the off-shell one- and two-loop box graphs 
in exactly four-dimensional configuration space. Closing the integration 
contours for the MB parameters we transform these into double sums. Polygamma 
functions in the MB representation of the double box and the occurrence of 
higher poles are taken into account by parametric differentiation. Summing 
over any one of the counters results into a p+1Fp that we replace by its 
Euler integral representation. The process can be repeated a second time and 
results in a two- or four-parameter Euler integral, respectively. We use 
intersection theory to derive Pfaffian systems of equations on related sets 
of master integrals and solve for the box and double box integrals 
reproducing the known expressions. Finally, we use a trick to re-derive the 
double box from a two-parameter Euler integral. This second computation 
requires only very little computing resources.


Helye: Wigner FK RMI III. ép. Tanácsterem
Ideje: 2026 február 20. péntek d.u. 2 óra

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                    Somogyi Gábor