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Belle “Engineering Run” on the Υ (3S). S. L. Olsen. The Cosmic Mystery-Pie. o% antimatter. WIMPs (Weakly-Interacting-Massive-Particles) are good dark matter candidates. DAMA NaI 3 s Region. c. c. N’. b. CDMS 04. CDMS 05. Upper Limits from Direct Measurements.

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Presentation Transcript
the cosmic mystery pie
The Cosmic Mystery-Pie

o% antimatter

WIMPs (Weakly-Interacting-Massive-Particles) are good dark matter candidates

slide3

DAMA NaI 3s Region

c

c

N’

b

CDMS 04

CDMS 05

Upper Limits from Direct Measurements

90% CL upper limits assuming standard halo A2 scaling

Predictions: Ellis & Olive, Baltz & Gondolo, Mandic & all

c

N

c

b

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
Possibility of Dark Matter Search in B-factory

PRD 72, 103508 (2005)

Br( Υ(1S)cc ) ~ 0.0041 (mc<4.73GeV/c2)

Υ(3S)gISR

Υ(3S)  p+p-Υ(1S), Υ(1S) invisible

However …

Two-photon backgrounds are quite high …

Hard to reach Br ~ O(0.001)

idea to improve s n ratio
Idea to improve S/N ratio

s(e+e- Υ(3S)gISR ) ~ 0.02 nb

s(e+e- Υ(3S)) ~ 3.3 nb

S/N ratio x150

Energy scan in CLEO

expected sensitivity on y 3s run
Expected Sensitivity on Y(3S) run

Y(3S) run

w/o TRG modification

Y(3S) run

x 4 trigger efficiency

Y(4S) run

460 /fb

90 %C.L

Theory prediction

*) Syst. error is not considered

We took engineering data on the Υ(3S) to check:

 sensitivity with different trigger logic

 KEKB performance at lower Ecm

 sensitivity for other physics topics

trigger conditions were too tight for Υ(3S)p+p-nothing

looser triggers were needed for the required sensitivity

belle took data for 4 5 days end of feb 2006
Belle took data for 4.5 days(end of Feb, 2006)

CLEO

~3.3nb----

Energy scan ~ 4hours

We set E(4S)-223.6 MeV

~ 3 /fb on Υ(3S) resonance

~0.25 /fb on; 30MeV below 3S

trigger logic was optimized for dm channel
Trigger logic was optimized for DM channel

Control sample data

Υ(3S)  Υ(1S)p+p-

Υ(1S)  m+m-

Eff. depends on opening angle

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

opening angle (degree)

p+

p-

y

x

trigger rate
Trigger Rate

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

Trigger Rate (Hz)

slide10

Last BGM slide by Ito-san

w/o

Event Builder

Upgrade

w/

Event Builder

Upgrade

Belle Dead Time (%)

Trigger Rate (Hz)

DAQ

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
Summary
  • Υ(1S)invisible is sensitive for light dark-matter
    • Υ(3S)  p+p-Υ(1S)invisible
    • direct searches have no sensitivity ~GeV mass region
  • We tookΥ(3S) engineering runs for 4.5 days
    • ~3 /fb (~10M evts) on Υ(3S); ~0.25 /fb off-resonance)
    • world’s largest Υ(3S) data sample
  • Offline analysis of Υ(1S) invisible is in progress
  • Only a few other analyses are currently planned
    • interested parties encouraged to apply
  • Also have ~20 /fb data sample @ theΥ(5S)
    • also the world’s largest Υ(5S) sample (by far!)