# EPS-HEP2021 conference

26-30 July 2021
Zoom
Europe/Berlin timezone

## NNLO QCD corrections to B-meson mixing

26 Jul 2021, 14:30
15m
Zoom

#### Zoom

Parallel session talk Flavour Physics and CP Violation

### Description

The flavor mixing parameter $\Delta \Gamma_{12}^s$ that governs the lifetime differences of neutral $B_s$ mesons suffers from large uncertainties related to the uncalculated perturbative corrections. In this talk I will present new results on the previously unknown NNLO QCD corrections to the $B_s - \bar{B}_s$ mixing process that lead to a reduction of theoretical errors on $\Delta \Gamma_{12}^s$. To this end, we perform a fully analytic evaluation of the current-current correlators at 3 loops, as well as the current-penguin and current-chromomagnetic correlators at 2 loops in the $\Delta B = 1$ effective Hamiltonian. Some interesting aspects of this calculation to be addressed in my talk involve higher-order matching between two effective field theories ($\mathcal{H}_{\textrm{eff}}^{\Delta B = 1}$ and $\mathcal{H}_{\textrm{eff}}^{\Delta B = 2}$), dedicated treatment of evanescent operators in the presence of dimensionally regulated IR divergences, asymptotic expansion of the amplitudes in $m_c/m_b$ up to $\mathcal{O}(m_c^2)$ and the analytic evaluation of the resulting 3-loop on-shell integrals with one mass scale.