Probing the $R$ -ratio on the lattice

Alexandrou, Constantia; Urbach, Carsten; Garofalo, Marco; Bacchio, Simone; Jansen, Karl; Gagliardi, Giuseppe; Hadjiyiannakou, Kyriakos; Kostrzewa, Bartosz; De Santis, Alessandro; Frezzotti, Roberto; Petschlies, Marcus; Finkenrath, Jacob; Lubicz, Vittorio; Simula, Silvano; Wenger, Urs; Dimopoulos, Petros; Sanfilippo, Francesco; Tantalo, Nazario

Preprint

PUBDB-2022-08032

Probing the $R$ -ratio on the lattice

Alexandrou, C. ; Bacchio, S. ; De Santis, A.Extern* ; Dimopoulos, P. ; Finkenrath, J. ; Frezzotti, R. ; Gagliardi, G. ; Garofalo, M. ; Hadjiyiannakou, K. ; Kostrzewa, B.Extern* ; Jansen, K.DESY* ; Lubicz, V. ; Petschlies, M. ; Sanfilippo, F. ; Simula, S. ; Tantalo, N. (Corresponding author) ; Urbach, C. ; Wenger, U.

2022

This record in other databases:

Report No.: arXiv:2212.08467

Abstract: We present a first-principles lattice QCD investigation of the $R$-ratio between the $e^+e^-$ cross-section into hadrons and that into muons. By using the method of Ref. [1], that allows to extract smeared spectral densities from Euclidean correlators, we compute the $R$-ratio convoluted with Gaussian smearing kernels of widths of about $600$ MeV and central energies from $220$ MeV up to $2.5$ GeV. Our theoretical results are compared with the corresponding quantities obtained by smearing the KNT19 compilation [2] of $R$-ratio experimental measurements with the same Gaussian kernels and, in the region around the $\rho$-resonance peak, a tension of about three standard deviations is observed.

Keyword(s): density, spectral ; correlation function, Euclidean ; muon ; GeV ; lattice ; lattice field theory ; tension ; hadron