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Table 14: Experimental upper limits on lepton flavour violating τ decays. The modes are grouped according to the particle content of their final states. Modes with baryon number violation are labelled with “BNV”.

Decay mode	Category	90% CL Limit		Exp.	Ref.
Γ156 =  e− γ	ℓγ	<	12.0 · 10−8	Belle	[86]
		<	3.3 · 10−8	BaBar	[87]
Γ157 =  µ− γ		<	4.5 · 10−8	Belle	[86]
		<	4.4 · 10−8	BaBar	[87]
Γ158 =  e− π0	ℓ P0	<	2.2 · 10−8	Belle	[88]
		<	13.0 · 10−8	BaBar	[89]
Γ159 =  µ− π0		<	2.7 · 10−8	Belle	[88]
		<	11.0 · 10−8	BaBar	[89]
Γ162 =  e− η		<	4.4 · 10−8	Belle	[88]
		<	16.0 · 10−8	BaBar	[89]
Γ163 =  µ− η		<	2.3 · 10−8	Belle	[88]
		<	15.0 · 10−8	BaBar	[89]
Γ172 =  e− η′(958)		<	3.6 · 10−8	Belle	[88]
		<	24.0 · 10−8	BaBar	[89]
Γ173 =  µ− η′(958)		<	3.8 · 10−8	Belle	[88]
		<	14.0 · 10−8	BaBar	[89]
Γ160 =  e− KS0		<	2.6 · 10−8	Belle	[90]
		<	3.3 · 10−8	BaBar	[91]
Γ161 =  µ− KS0		<	2.3 · 10−8	Belle	[90]
		<	4.0 · 10−8	BaBar	[91]
Γ174 =  e− f0(980)	ℓ S0	<	3.2 · 10−8	Belle	[92]
Γ175 =  µ− f0(980)		<	3.4 · 10−8	Belle	[92]
Γ164 =  e− ρ0	ℓ V0	<	1.8 · 10−8	Belle	[93]
		<	4.6 · 10−8	BaBar	[94]
Γ165 =  µ− ρ0		<	1.2 · 10−8	Belle	[93]
		<	2.6 · 10−8	BaBar	[94]
Γ168 =  e− K*(892)0		<	3.2 · 10−8	Belle	[93]
		<	5.9 · 10−8	BaBar	[94]
Γ169 =  µ− K*(892)0		<	7.2 · 10−8	Belle	[93]
		<	17.0 · 10−8	BaBar	[94]
Γ170 =   e−  K *(892)0		<	3.4 · 10−8	Belle	[93]
		<	4.6 · 10−8	BaBar	[94]
Γ171 =   µ−  K *(892)0		<	7.0 · 10−8	Belle	[93]
		<	7.3 · 10−8	BaBar	[94]
Γ176 =  e− φ		<	3.1 · 10−8	Belle	[93]
		<	3.1 · 10−8	BaBar	[94]
Γ177 =  µ− φ		<	8.4 · 10−8	Belle	[93]
		<	19.0 · 10−8	BaBar	[94]
Γ166 =  e− ω		<	4.8 · 10−8	Belle	[93]
		<	11.0 · 10−8	BaBar	[95]
Γ167 =  µ− ω		<	4.7 · 10−8	Belle	[93]
		<	10.0 · 10−8	BaBar	[95]
Γ178 =  e− e+ e−	ℓℓℓ	<	2.7 · 10−8	Belle	[96]
		<	2.9 · 10−8	BaBar	[97]
Γ181 =  µ− e+ e−		<	1.8 · 10−8	Belle	[96]
		<	2.2 · 10−8	BaBar	[97]
Γ179 =  e− µ+ µ−		<	2.7 · 10−8	Belle	[96]
		<	3.2 · 10−8	BaBar	[97]
Γ183 =  µ− µ+ µ−		<	2.1 · 10−8	Belle	[96]
		<	3.3 · 10−8	BaBar	[97]
		<	4.6 · 10−8	LHCb	[98]
		<	37.6 · 10−8	Atlas	[99]
Γ182 =  e− µ+ e−		<	1.5 · 10−8	Belle	[96]
		<	1.8 · 10−8	BaBar	[97]
Γ180 =  µ− e+ µ−		<	1.7 · 10−8	Belle	[96]
		<	2.6 · 10−8	BaBar	[97]
Γ184 =  e− π+ π−	ℓ hh	<	2.3 · 10−8	Belle	[100]
		<	12.0 · 10−8	BaBar	[101]
Γ186 =  µ− π+  π−		<	2.1 · 10−8	Belle	[100]
		<	29.0 · 10−8	BaBar	[101]
Γ188 =  e− π+ K−		<	3.7 · 10−8	Belle	[100]
		<	32.0 · 10−8	BaBar	[101]
Γ194 =  µ− π+  K−		<	8.6 · 10−8	Belle	[100]
		<	26.0 · 10−8	BaBar	[101]
Γ189 =  e− K+ π−		<	3.1 · 10−8	Belle	[100]
		<	17.0 · 10−8	BaBar	[101]
Γ195 =  µ− K+  π−		<	4.5 · 10−8	Belle	[100]
		<	32.0 · 10−8	BaBar	[101]
Γ192 =  e− K+ K−		<	3.4 · 10−8	Belle	[100]
		<	14.0 · 10−8	BaBar	[101]
Γ198 =  µ− K+  K−		<	4.4 · 10−8	Belle	[100]
		<	25.0 · 10−8	BaBar	[101]
Γ191 =  e− KS0 KS0		<	7.1 · 10−8	Belle	[90]
Γ197 =  µ− KS0  KS0		<	8.0 · 10−8	Belle	[90]
Γ185 =  e+ π− π−		<	2.0 · 10−8	Belle	[100]
		<	27.0 · 10−8	BaBar	[101]
Γ187 =  µ+ π− π−		<	3.9 · 10−8	Belle	[100]
		<	7.0 · 10−8	BaBar	[101]
Γ190 =  e+ π− K−		<	3.2 · 10−8	Belle	[100]
		<	18.0· 10−8	BaBar	[101]
Γ196 =  µ+ π− K−		<	4.8 · 10−8	Belle	[100]
		<	22.0 · 10−8	BaBar	[101]
Γ193 =  e+ K− K−		<	3.3 · 10−8	Belle	[100]
		<	15.0 · 10−8	BaBar	[101]
Γ199 =  µ+ K− K−		<	4.7 · 10−8	Belle	[100]
		<	48.0 · 10−8	BaBar	[101]
Γ211 =   π− Λ	BNV	<	3.0 · 10−8	Belle	[102]
		<	5.8 · 10−8	BaBar	[103]
Γ212 =    π−  Λ		<	2.8 · 10−8	Belle	[102]
		<	5.9 · 10−8	BaBar	[103]
Γ213 =   K− Λ		<	4.2 · 10−8	Belle	[102]
		<	15.· 10−8	BaBar	[103]
Γ214 =    K−  Λ		<	3.1 · 10−8	Belle	[102]
		<	7.2 · 10−8	BaBar	[103]
Γ215 =   p µ− µ−		<	44.0 · 10−8	LHCb	[104]
Γ216 =     p  µ+ µ−		<	33.0 · 10−8	LHCb	[104]

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