Search for sub-GeV Scalars in $e^{+}{e}^{-}$ collisions

Abstract

Light scalars that couple to leptons are common figures in beyond the Standard Model endeavors. Considering a scalar that has universal and couplings to leptons only, we compute this leptophilic scalar contribution to the $e^{-}{e}^{+}\to \ddot{I}{„}^{+}\ddot{I}{„}^{-}S$ production cross section with $S\to e^{+}{e}^{-}(\hat{I}{¼}^{+}\hat{I}{¼}^{-})$. We later compare the expected signal with recent data from the BELLE collaboration collected near the resonance $\hat{I}\yen (4S)$ with $\mathcal{L}=626f{b}^{-1}$ of integrated luminosity to place limits on the couplings-mass plane for the $4$~MeV-$6.5$~GeV mass range. We then extended this analysis to a more general one $e^{-}{e}^{+}\to {\ell }^{+}{\ell }^{-}S$ production cross section where $\ell =e,\hat{I}¼,\ddot{I}„$ with $S\to e^{+}{e}^{-}(\hat{I}{¼}^{+}\hat{I}{¼}^{-})$, showing that BELLE constitutes an excellent laboratory for light scalars, where can be derived constraints stronger than those derived stemming from the g-2 of the electron or muon.

8 pages, 4 figures