HQET sum rules for matrix elements of dimension-six four-quark operators for meson lifetimes within and beyond the Standard Model

22 May 2026, 10:15
15m

Speaker

Martin Lang (University of Siegen)

Description

Theory predictions of heavy-hadron lifetime ratios critically depend on precise determinations of the dimension-six spectator effects arising from the double insertion of the weak effective $|\Delta B| = 1$ Hamiltonian.
In the presence of beyond-standard-model (BSM) operators, the resulting $\Delta B = 0$ Hamiltonian features additional four-quark operators whose matrix elements need to be determined using non-perturbative methods.
We present for the first time results for the non-perturbative hadronic matrix elements of the four-quark operators relevant for the description of the meson lifetime ratio $\tau\left(B^+\right) / \tau\left(B_d\right)$, obtained using heavy-quark effective theory (HQET) sum rules with the full BSM effective Hamiltonian.
In addition, we recompute and update the bag parameters for the Standard Model operators.

Discipline Theory
Topic Heavy Quark Decays

Authors

Presentation materials