Constraining Light Bosons with Radiative $Υ(1S)$ Decays

Abstract

Light bosons can be found in large classes of theories beyond the Standard Model. These light bosons may not be ruled out by current experiments and, indeed, may even provide an explanation for some anomalous experimental results. The radiative decays of quarkonium ($c \bar c, b \bar b$) states offer a promising opportunity to investigate such light bosons. Specifically, we investigate the reach that current CLEO data can have on models with light scalar and pseudoscalar bosons.

Figures (16)

• Figure 1: Plots of $F_A$ and $F_S$ [Eq. (\ref{['eq:qcd_corr']})] as functions of $x=2E_\gamma/m_\Upsilon$.
• Figure 2: The cross section for $e^+e^-\to\gamma\mu^+\mu^-$ in the standard model with different cuts on the photon's angle with the beamline.
• Figure 3: Lower bound on observable values of ${\cal B}(\Upsilon\to A\gamma){\cal B}(A\to\mu^+\mu^-)$ for a range of pseudoscalar masses with several values of cut on photon angle. It is seen that taking $-0.85 < \cos\theta_\gamma < 0.85$ generates a slightly stronger limit than either of the other two cuts.
• Figure 4: Lower bound on observable values of $g_d$ for a range of pseudoscalar masses with the photon cut near its optimum: $-0.85 < \cos\theta_\gamma < 0.85$.
• Figure 5: ${\cal B}(S\to\mu^+\mu^-)$ as a function of $m_S$ for several values of $r=\lambda_u/\lambda_d$, obtained from Eqs. (\ref{['eq:chiral_br']}) and (\ref{['eq:pert_spec_br']}).