First Observation ofτ→3πηντandτ→f

Effective-field theory analysis of the τ − → η(′)π−ντ decays

“…Those upper limits lie very close to the SM estimates based on isospin breaking [9][10][11][12][13][14][15][16][17][18][19][20]. The corresponding BaBar limit for the τ − → η π − ν τ decays is < 7.2 · 10 −6 , 95% CL [26], while Belle obtained < 4.6 · 10 −6 , 90% CL [24] (CLEO set the earlier upper bound 7.4 × 10 −5 , 90%CL [27]). Future experiments at the intensity frontier like Belle II [28], which will accumulate 4.5 × 10 10 tau lepton pairs in the full dataset, are expected to provide the first measurements of the τ − → η ( ) π − ν τ SCC decays [29].…”

Experimental summary on hadronic decays: A TAU98 review

“…The KKπ final state seems to arise through the axial-vector current a − 1 → K * K [19,23]. Five and six pion final states are quite complex, but receive important contributions from f 1 π and π − 2π 0 ω [13,15,16].…”

“…There have also been new results on other high multiplicity final states. CLEO finalized their TAU96 analysis [12] on τ → f 1 π − ν τ with a publication [13], reporting B(3π ± ην τ ) = (3.4 +0. 6 −0.5 ± [14] of the f 1 (1285) → ηππ branching fraction as (52.8±3.8±2.5)% allows reduction of the CLEO systematic error, resulting…”

Hadron production viae+e−collisions with initial state radiation

“…For the Bð À ! 0 À 0 Þ they give an upper limit of <3:2 Â 10 À5 at 90% C.L., which is a factor of 2.5 more restrictive than the upper limit based on the only existing measurement by CLEO: <8 Â 10 À5 (Bergfeld et al, 1997).…”