Search for Light New Physics at 𝐵 Factories

Figure 1

(a) 90% CL upper limit on the Υ(3𝑆)→𝛾𝐴⁰,𝐴⁰→𝜇⁺𝜇⁻ (top) and Υ(2𝑆)→𝛾𝐴⁰,𝐴⁰→𝜇⁺𝜇⁻ branching fractions (middle) as a function of the 𝐴⁰ mass derived by BABAR. The limits on the product 𝐵(𝐴⁰→𝜇⁺𝜇⁻)𝑓²_Υ, are also shown (bottom). The 𝐽/𝜓 and 𝜓(2𝑆) regions (solid bands) are excluded from the search. (b) Product of branching fraction Υ(3𝑆)→𝛾𝐴⁰, 𝐴⁰→𝜏⁺𝜏⁻ (top) and the corresponding 90% CL upper limit (bottom) as a function of the 𝐴⁰ mass set by BABAR. The region corresponding to 𝜒_𝑏𝐽(2𝑃)→𝛾Υ(1𝑆) transitions (shaded band) is excluded.

(a)

(b)