Takeshi K. Komatsubara
last update 2002-Apr-18

Results on  from the E787-1gamma analysis

1. Results on  : 1996-97 data, PR D65(2002)052009
• =  (after prescaled by 2450),  triggers
• B( ) <  at 90%C.L.

S.E.S( ) = 
from this final plot.
• reconstruct the highest-energy photon in BV with loose fiducial cuts on the energy and direction.
• impose extra-photon veto cuts and the charged-track dE/dx cut to remove the  background.
• impose loose fitpi cut to remove the muon background.
• count the number of events whose charged track is in the momentum/range/energy box cuts ... zero events.
2. Results on  , from the 1gamma analysis (preliminary)
• B( , phsp) <  at 90%C.L.

S.E.S( , phsp) = 
• B( , wpigg) <  at 90%C.L.

S.E.S( , wpigg) = 
• These results are obtained from this plot.

These are worse than  in 1991 by factor of two, while the  is only 2%.
• remove extra-photon veto cuts and the charged-track dE/dx cut, which could be sensitive to the second photon from  .
• If we remove extra-photon veto cuts but impose the charged-track dE/dx cut, the plot gets cleaner.
• This is an inclusive search:

reconstruct pion and the higher energy photon, without doing Kinematic Fitting.
• count the number of events in the box cuts ... still zero events (This is an ``opened-eye'' analysis!).
• The acceptance for  gets about 1/3 to 1/4 of the acceptance for  :
• The acceptance of the charged track box cuts is about 1/2. These cuts may be optimized for  .
• Due to the loss of the second photon by the online photon veto cuts (in particular by HEXCUT), the acceptance of photon(s) is about 1/2.

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