A possible signature of new physics at BES-III

TL;DR

The paper discusses how recent leptonic decay measurements at CLEO-c and B factories hint at potential new physics, such as a charged Higgs boson, and emphasizes the importance of precise ratio measurements at BES-III to explore this further.

Contribution

It highlights the discrepancy between experimental decay constants and lattice QCD predictions, proposing BES-III measurements to investigate possible new particles.

Findings

Decay constant $f_{D_s}$ differs from lattice QCD by 4 sigma.

Measured decay ratio exceeds Standard Model prediction by 2 sigma.

Precise BES-III measurements can reveal signs of new physics.

Abstract

The recent observations of the purely leptonic decay $\Ds \to \mu^+ \nu_{\mu}$ and $\tau^+\nu_{\tau}$ at CLEO-c and $B$ factory may allow a possible contribution from a charged Higgs boson. One such measurement of the decay constant $f_{D_s}$ differs from the most precise unquenched lattice QCD calculation by 4 $\sigma$ level. Meanwhile, the measured ratio, ${\cal BR}(\Ds \to \mu^+ \nu_{\mu})$ / ${\cal BR}(\Dp \to \mu^+ \nu_{\mu})$, is larger than the standard model prediction at 2.0$\sigma$ level. We discuss that the precise measurement of the ratio ${\cal BR}(\Ds \to \mu^+ \nu_{\mu})$ / ${\cal BR}(\Dp \to \mu^+ \nu_{\mu})$ at BES-III will shed light on the presence of new intermediate particles by comparing the theoretical predictions, especially, the predictions of high precise unquenched lattice QCD calculation.