We report in Table 14 and Figure 3 the up-to-date upper limits on the τ LFV branching fractions in order to track and summarize the experimental results in this area, which are sensitive to physics beyond the Standard Model.
Decay mode Category
90% CL Limit Exp. Ref.
Γ156 = e− γ lγ < 12.0 · 10−8 Belle [85] < 3.3 · 10−8 BaBar [86]
Γ157 = µ− γ < 4.5 · 10−8 Belle [85] < 4.4 · 10−8 BaBar [86]
Γ158 = e− π0 lP0 < 2.2 · 10−8 Belle [87] < 13.0 · 10−8 BaBar [88]
Γ159 = µ− π0 < 2.7 · 10−8 Belle [87] < 11.0 · 10−8 BaBar [88]
Γ162 = e− η < 4.4 · 10−8 Belle [87] < 16.0 · 10−8 BaBar [88]
Γ163 = µ− η < 2.3 · 10−8 Belle [87] < 15.0 · 10−8 BaBar [88]
Γ172 = e− η′(958) < 3.6 · 10−8 Belle [87] < 24.0 · 10−8 BaBar [88]
Γ173 = µ− η′(958) < 3.8 · 10−8 Belle [87] < 14.0 · 10−8 BaBar [88]
Γ160 = e− KS0 < 2.6 · 10−8 Belle [89] < 3.3 · 10−8 BaBar [90]
Γ161 = µ− KS0 < 2.3 · 10−8 Belle [89] < 4.0 · 10−8 BaBar [90]
Γ174 = e− f0(980) l S0 < 3.2 · 10−8 Belle [91]
Γ175 = µ− f0(980) < 3.4 · 10−8 Belle [91]
Γ164 = e− ρ0 l V0 < 1.8 · 10−8 Belle [92] < 4.6 · 10−8 BaBar [93]
Γ165 = µ− ρ0 < 1.2 · 10−8 Belle [92] < 2.6 · 10−8 BaBar [93]
Γ168 = e− K*(892)0 < 3.2 · 10−8 Belle [92] < 5.9 · 10−8 BaBar [93]
Γ169 = µ− K*(892)0 < 7.2 · 10−8 Belle [92] < 17.0 · 10−8 BaBar [93]
Γ170 =
e−
K *(892)0 < 3.4 · 10−8 Belle [92] < 4.6 · 10−8 BaBar [93]
Γ171 =
µ−
K *(892)0 < 7.0 · 10−8 Belle [92] < 7.3 · 10−8 BaBar [93]
Γ176 = e− φ < 3.1 · 10−8 Belle [92] < 3.1 · 10−8 BaBar [93]
Γ177 = µ− φ < 8.4 · 10−8 Belle [92] < 19.0 · 10−8 BaBar [93]
Γ166 = e− ω < 4.8 · 10−8 Belle [92] < 11.0 · 10−8 BaBar [94]
Γ167 = µ− ω < 4.7 · 10−8 Belle [92] < 10.0 · 10−8 BaBar [94]
Γ178 = e− e+ e− lll < 2.7 · 10−8 Belle [95] < 2.9 · 10−8 BaBar [96]
Γ181 = µ− e+ e− < 1.8 · 10−8 Belle [95] < 2.2 · 10−8 BaBar [96]
Γ179 = e− µ+ µ− < 2.7 · 10−8 Belle [95] < 3.2 · 10−8 BaBar [96]
Γ183 = µ− µ+ µ− < 2.1 · 10−8 Belle [95] < 3.3 · 10−8 BaBar [96] < 4.6 · 10−8 LHCb [97]
Γ182 = e− µ+ e− < 1.5 · 10−8 Belle [95] < 1.8 · 10−8 BaBar [96]
Γ180 = µ− e+ µ− < 1.7 · 10−8 Belle [95] < 2.6 · 10−8 BaBar [96]
Γ184 = e− π+ π− lhh < 2.3 · 10−8 Belle [98] < 12.0 · 10−8 BaBar [99]
Γ186 = µ− π+ π− < 2.1 · 10−8 Belle [98] < 29.0 · 10−8 BaBar [99]
Γ188 = e− π+ K− < 3.7 · 10−8 Belle [98] < 32.0 · 10−8 BaBar [99]
Γ194 = µ− π+ K− < 8.6 · 10−8 Belle [98] < 26.0 · 10−8 BaBar [99]
Γ189 = e− K+ π− < 3.1 · 10−8 Belle [98] < 17.0 · 10−8 BaBar [99]
Γ195 = µ− K+ π− < 4.5 · 10−8 Belle [98] < 32.0 · 10−8 BaBar [99]
Γ192 = e− K+ K− < 3.4 · 10−8 Belle [98] < 14.0 · 10−8 BaBar [99]
Γ198 = µ− K+ K− < 4.4 · 10−8 Belle [98] < 25.0 · 10−8 BaBar [99]
Γ191 = e− KS0 KS0 < 7.1 · 10−8 Belle [89]
Γ197 = µ− KS0 KS0 < 8.0 · 10−8 Belle [89]
Γ185 = e+ π− π− (L) < 2.0 · 10−8 Belle [98] (L) < 27.0 · 10−8 BaBar [99]
Γ187 = µ+ π− π− (L) < 3.9 · 10−8 Belle [98] (L) < 7.0 · 10−8 BaBar [99]
Γ190 = e+ π− K− (L) < 3.2 · 10−8 Belle [98] (L) < 18.0· 10−8 BaBar [99]
Γ196 = µ+ π− K− (L) < 4.8 · 10−8 Belle [98] (L) < 22.0 · 10−8 BaBar [99]
Γ193 = e+ K− K− (L) < 3.3 · 10−8 Belle [98] (L) < 15.0 · 10−8 BaBar [99]
Γ199 = µ+ K− K− (L) < 4.7 · 10−8 Belle [98] (L) < 48.0 · 10−8 BaBar [99]
Γ211 = π− Λ BNV < 3.0 · 10−8 Belle [100] < 5.8 · 10−8 BaBar [101]
Γ212 =
π−
Λ < 2.8 · 10−8 Belle [100] < 5.9 · 10−8 BaBar [101]
Γ213 = K− Λ < 4.2 · 10−8 Belle [100] < 15.· 10−8 BaBar [101]
Γ214 =
K−
Λ < 3.1 · 10−8 Belle [100] < 7.2 · 10−8 BaBar [101]
Γ215 = p µ− µ− < 44.0 · 10−8 LHCb [102]
Γ216 =
p µ+ µ− < 33.0 · 10−8 LHCb [102]