The 43rd International Symposium on Lattice Field Theory (Lattice 2026)

Towards the two pion contribution to the R-ratio: the $\pi\pi$ spectrum in finite-volume from ETMC gauge ensemble at the physical point

Not scheduled

20m

University of Maryland, College Park

Poster presentation Hadronic and nuclear spectrum and interactions

Speaker

Antonio Smecca (INFN - Sezione di Roma Tre)

Description

We present a lattice QCD study of the finite-volume $I=1$, P-wave two-pion spectrum at physical quark masses using twisted-mass fermions. We determine the six lowest-lying energy levels in a spatial box of approximately 5.1 fm, and compare our preliminary results with the corresponding finite-volume spectrum obtained from the Gounaris-Sakurai parametrization of the timelike pion electromagnetic form factor. The long-term goal of this study is to combine the finite-volume energies with the vacuum-to-two-pion electromagnetic matrix elements in order to determine the two-pion contribution to the hadronic R-ratio in e+e- annihilation, a quantity for which different experimental determinations are not fully consistent.