The ratio π (πΈ) of the cross-sections for π+πββ hadrons and π+πββπ+πβ is an extremely interesting hadronic observable due to its phenomenological applications. For example, the experimental measurements of π (πΈ) are used in the dispersive calculations of the leading hadronic vacuum polarization contribution to the muon πβ2 and these are in significant tension with direct lattice calculations and with the muon πβ2 experiment. It is thus very important to probe π (πΈ) from first-principles and compare it with experiment. In this talk we discuss the first-ever lattice QCD determination of π (πΈ) smeared with Gaussians, of different widths π and central energies, by using the HLT method for extracting smeared spectral densities from Euclidean lattice correlators. Β Our theoretical results, compared with the KNT19 compilation of π (πΈ) smeared with the same Gaussian kernels, shows a tension (about three standard deviations) for πβΌ600 MeV and central energies around the π resonance peak. Future perspectives, both methodological and phenomenological, are also discussed.
Tuesday
30 Apr/24
16:00
-
18:00
(Europe/Zurich)
Smeared R-ratio from lattice QCD
Where:
4/2-037 at CERN