The role of long distance contribution to the $B\to K^{(\ast)} \ell^+ \ell^-$ in the Standard Model

TL;DR

This paper examines the impact of long-distance effects, including light quark loops and charming penguins, on the $B o K^{(*)} \, \ell^+ \ell^-$ decay spectrum within the Standard Model, especially at low $q^2$ values.

Contribution

It highlights the importance of including long-distance contributions, such as light quark loops and charming penguins, for accurate $q^2$ spectrum predictions in rare $B$ decays.

Findings

Long-distance effects significantly influence the $q^2$ spectrum at low invariant mass.

Light quark loops and charming penguins are essential for precise Standard Model calculations.

These contributions may affect interpretations of lepton flavor universality tests.

Abstract

We investigate rare semileptonic $B \to K^\ast\ell^+\ell^-$ by looking at the long distance contributions. Our analysis is limited to the very small values of physical accessible range of invariant mass of the leptonic couple $q^2$. We show that the light quarks loop has to be accounted for, along with the charming penguin contribution, in order to accurately compute the $q^2$-spectrum in the Standard Model. Such a long distance contribution may also play a role in the analysis of the lepton flavour universality violation in this process.