Bottomonium spectroscopy with mixing of eta_b states and a light CP-odd Higgs

TL;DR

This paper proposes that the observed eta_b(1S) mass discrepancy is due to mixing with a light CP-odd Higgs, affecting the bottomonium spectrum and decay predictions.

Contribution

It introduces a model where eta_b states mix with a light CP-odd Higgs, explaining mass shifts and predicting new decay channels.

Findings

Predicted eta_b spectrum shifts due to mixing.

Branching ratios into tau+ tau- depend on Higgs mass.

Mass range of the CP-odd Higgs consistent with experimental constraints.

Abstract

The mass of the eta_b(1S), measured recently by BABAR, is significantly lower than expected from QCD predictions for the Upsilon(1S) - eta_b(1S) hyperfine splitting. We suggest that the observed eta_b(1S) mass is shifted downwards due to a mixing with a CP-odd Higgs scalar A with a mass m_A in the range 9.4 - 10.5 GeV compatible with LEP, CLEO and BABAR constraints. We determine the resulting predictions for the spectrum of the eta_b(nS) - A system and the branching ratios into tau^+ tau^- as functions of m_A.