D0 Results on FCNC charm and rare B decays

1

• D0 Results on FCNC charm and rare B decays
• Alice Bean for the D0 Collaboration
• University of Kansas
• D0 Experiment
• c ? u??-
• Bs ? ??-
• Bs ? ???-
• Bs ? ? ?(2S)

2
D0 Experiment
Located at Fermilab (near Chicago) in the
Tevatron - proton/antiproton collider at 1.96
TeV center of mass energy Data reported from Run
II sample with Luminosity of over 1 fb-1
Silicon Microstrip Tracker Scintillating Fiber
Tracking inside of 2 Tesla solenoid ? lt
3 Muon triggers for B physics ? lt 2 Good
electron/muon ID
3
Experimental Tools

• ?Muon identification ? lt 2 with pTgt2 GeV
• ? Hits in both the Silicon and Fiber tracker
• Good ?2 for B (D) vertex
• Collinearity or pointing angle (?D)
• Decay length significance of B (D) vertex (SD)
• Isolation variable (ID)
• Impact parameter of track (i.e. S?)

D ???? analysis
4
FCNC c ? u??-

• - FCNC decays forbidden at tree level in SM
• - Some scenarios SUSY R parity violation /
  little Higgs models only see FCNC in up quark
  sector
• We look for Ds??????-?, D??????-? and
  continuum production of ??- above and below the
  ?

5
D(s)? ??? selection

• Cuts separately optimized for D and Ds
• where
• Isolation

6
D??? ????-
26 9 D 6511 DS

• Expected value is 1.77?10?6 from the product b.f.

7
Continuum D????-

• ? ? mass window excluded
• ? 1.8 0.4 DS events

8
Comparisons

• D0 results
• Predictions
• Other results
• Best limits so far and improved version of
  analysis in paper submission stages (not public
  yet)

9
Bs ????
Standard Model Expectations B(Bs???) 10-9 In
MSSM, BF is enhanced by 3 orders of
magnitude Results are published in PRL 94, 071802
(2005) Luminosity of 300pb-1 results with
sensitivity study for 700pb-1 Normalize to
B?J/?(????)K
10
Analysis variables

• Blind Analysis with cut optimization based on MC
  signal with background from data sidebands
• Final event selection based on
• pointing angle, isolation, and decay length
  significance

11
B ?J/?K
Small correction to account for Bd decays

• Normalize to B?J/?(????)K

12
Results for Bs????

• After selection cuts, Bs????
• The analysis has not been unblinded for 700pb-1
• B(Bs????) lt 3.7?10-7 (95 CL) 300pb-1
• Combined sensitivity 2.3 ?10-7 700pb-1
• Results for 2fb-1 expected for Moriond

13
Bs?????

• In Standard Model, B(Bs????)10-6
• Analysis is similar to Bs ????
• Look for ??KK?

14
Bs????? Selection

• Cuts
• Di-muon trigger
• Two muons pTgt2.5 GeV/c, ?lt2.0
• Muons form common sec. vertex ?2lt10, pT(???)gt5
  GeV/c
• Kaons have pTgt0.7GeV/c, 1.008 lt m? lt1.032
  GeV/c2
• Opening angle lt0.1 rad
• Decay Length Significance gt10.3
• Isolation gt0.72
• Main Errors
• B(Bs?J/??) - 35 B(J/????) -
  1.7
• ?J/?? / ???? - 7.5 of Bs?J/??
  - 13.7
• MC weighting - 1.1 pre-Geant weight -
  3.5
• CP odd-even lifetime differences - 8.0

15
Results for Bs?????

• Based on 450pb-1 of data - PRD 74, 031107 (2006)
• Normalization Bs ? J/? ?
• B(Bs ?
  J/? ?)
• 
  (9.3 ? 3.3) ? 10-4

16
Bs ??(2S) ?

• Studies provide info on the interplay of strong
  and weak interactions.
• Do Bs decays agree with 60 of the rate from
  B0/B decays to ?(2S) as compared to ??
• Results presented here based of 300pb-1 of data
• Bs ? ?(2S) ?
• ? ??? ?KK?

17
B??(2S) K

• ?Use as control channel

B? ? ???
B??(2S) K
18
Bs ??(2S) ? Results
??
?(2S)?
19
Coming soon

• Bs ??(2S) ?
• Working on a publication with 1.3fb-1 for c?u??
• Bs??? updated result with 2fb-1

20
Conclusions

• Have observed
• Limit lt
  0.46 _at_ 90
• Bs ??(2S)?
• From 300pb-1 B(Bs????) lt 3.7?10-7 _at_ 95 CL
• Bs?????