B - SLAC

B 0 � ν ν (invisible) @Babar
�Semileptonic tags :
B0�D ( * )-l + ν (D* - �D0 π- )
�Require nothing in recoil:
- no charged tracks, – 8
- limited # of neutral clusters.
�ML fit to E extra
Ns =17 ± 9
Nb =19
+10
-8
�Upper limit (frequentist)
incl. systematics (additive;7.4events,
multiplicative; 10.9%)
B(B 0 → invisible) < 22 × 10 -5 (90%CL)
νν
ννγ
B pairs used:
(88.5±1.0)×10 6
Phys. Rev. Lett. 93, 091802 (2004)
37