Speaker
Description
The mesonic $f_{PS} / m_V$ and $f_V / m_V$ ratios, with f the decay constant and m the meson mass, are calculated in mass perturbed conformal gauge theories to NNLO and N$^3$LO orders, respectively. Here NNLO and N$^3$LO refer to the non-relativistic effective theory expansion which is the applicable framework. The results are expanded a la Banks-Zaks in order to end up with scheme-independent predictions. These perturbative results are unambiguously reliable close to the upper end of the conformal window, $N_f = 16.5$ and it is shown that they might be reliable down to $N_f = 12$. An attempt is made to match these to previous non-perturbative lattice results in the range $2 \leq N_f \leq 10$ range. An abrupt change in the ratios is observed at around $N_f = 12 - 13$, which may signal the lower end of the conformal window.
| Topical area | Particle Physics Beyond the Standard Model |
|---|