Engineering Runs on Y(3S)

The Cosmic Mystery-Pie o% antimatter WIMPs (Weakly-Interacting-Massive-Particles) are good dark matter candidates

DAMA NaI 3  Region CDMS 04 CDMS 05 90% CL upper limits assuming standard halo A 2 scaling Upper Limits from Direct Measurements Predictions: Ellis & Olive, Baltz & Gondolo, Mandic & all Direct measurements have no sensitivity for ~GeV mass region LHC will reach ~TeV mass region Who will search ~GeV mass region ?

Possibility of Dark Matter Search in B-factory PRD 72, (2005) Br( Y(1S)   ) ~ (m  <4.73GeV/c 2 ) Y(3S)  ISR Y(3S)   +  - Y(1S), Y(1S)  invisible However … Two-photon backgrounds are quite high … Hard to reach Br ~ O(0.001)

Idea to improve S/N ratio  (e + e -  Y(3S)  ISR ) ~ 0.02 nb  (e + e -  Y(3S)) ~ 3 nb S/N ratio x150 Energy scan in CLEO

Y(3S) run w/o TRG modification Expected Sensitivity on Y(3S) run Current trigger condition is too tight for this channel Loose trigger condition gives large the sensitivity *) Syst. error is not considered Y(4S) run 460 /fb Theory prediction 90 %C.L

Y(3S) run w/o TRG modification Expected Sensitivity on Y(3S) run Current trigger condition is too tight for this channel Loose trigger condition gives large the sensitivity *) Syst. error is not considered Y(4S) run 460 /fb Theory prediction 90 %C.L Y(3S) run x 4 trigger efficiency We took engineering data taking on Y(3S) to check the sensitivity with different trigger logic to check the capability of DAQ with such trigger to check the sensitivity for other physics topics

We took data for 4.5 days (end of Feb, 2006) Energy scan ~ 4hours We set E(4S) MeV ~ 3 /fb on 3S resonance ~0.25 /fb on 30MeV below 3S CLEO 3 times hadrons ~0.47 on Y(4S) ~0.33 off-resonance

Trigger logic was optimized for DM channel Control sample data  (3S)   (1S)   (1S)   Eff. depends on opening angle opening angle (degree) 4 times efficiency gain is expected - loose opening angle cut 135  45 degree - loose pt cut pt>350 MeV for both tracks  for one (or both) track   x y

Trigger Rate Trigger Rate (Hz) Trigger rate was rather higher than usual condition (~460Hz)

w/o Event Builder Upgrade w/ Event Builder Upgrade Last BGM slide by Ito-san DAQ Belle Dead Time (%) Trigger Rate (Hz) Dead time was consistent with expectation We confirm great advantage of event builder upgrade (2005 summer) However, there were frequent DAQ errors  remaining subject …

Summary Invisible decay of Y(1S) is sensitive for light Dark –Y(3S)  p+p-Y(1S) invisible –Direct search has no sensitivity ~GeV mass region We took Y(3S) engineering runs for 4.5 days –(~3 /fb on-reso., ~0.25 /fb off-reso.) Trigger was optimized for DM channel loose opening angle, pt-cut  quite high trigger rate  DAQ capability was checked  Frequent fatal errors are next subject… Offline analysis are on going