2020 Impact factor 4.590
Particles and Fields

Eur. Phys. J. C 18, 665-672
DOI: 10.1007/s100520100582

What if the mass difference $\Delta M_s$ is around 18 inverse picoseconds?

A. Ali1 and D. London2

1  Deutsches Elektronen Synchrotron DESY, 22603 Hamburg, Germany
2  Laboratoire René J.-A. Lévesque, Université de Montréal, C.P. 6128, succ. centre-ville, Montréal, QC, H3C 3J7 Canada

(Received: 14 December 2000 / Published online: 23 January 2001 -© Springer-Verlag 2001)

Present experiments in pursuit of the mass difference in the Bs0- $\overline{B_s^0}$ system have put a lower bound on this quantity of $\Delta M_s > 14.9 {\rm ps}^{-1}$ (at 95% C.L.). The same experiments also yield a local minimum in the log-likelihood function around $\Delta M_s = 17.7 {\rm ps}^{-1}$, which is $2.5\sigma$ away from being zero. Motivated by these observations, we investigate the consequences of a possible measurement of $\Delta M_s = 17.7 \pm 1.4 {\rm ps}^{-1}$, in the context of both the standard model and supersymmetric models with minimal flavor violation. We perform a fit of the quark mixing parameters in these theories and estimate the expected ranges of the CP asymmetries in B decays, characterized by $\alpha$, $\beta$ and $\gamma$, the interior angles of the CKM-unitarity triangle. Based on this study, we argue that, if indeed $\Delta M_s$ turns out to be in its currently-favored range, this would disfavor a large class of supersymmetric models. Indeed, of all the models examined here, the best fit to the data occurs for the standard model.

© Società Italiana di Fisica, Springer-Verlag 2001