Rare Decays at Tevatron Rare Decays at Tevatron Marco Rescigno Marco Rescigno INFN/Roma INFN/Roma for the CDF and DØ for the CDF and DØ coll. coll. CKM06, Nagoya CKM06, Nagoya Dec 14 Dec 14 th th 2006 2006 Topics: 1)B Topics: 1)Bsearch at search at Tevatron Tevatron 2) b 2) bsl sl + l l - - at at Tevatron Tevatron
Rare Decays at Tevatron. Topics: 1)B mm search at Tevatron 2) b sl + l - at Tevatron. Marco Rescigno INFN/Roma for the CDF and DØ coll. CKM06, Nagoya Dec 14 th 2006. Chicago . p. p. 1.96 TeV. Booster. p. CDF. DØ. Tevatron. p. p sou rce. Main Injector - PowerPoint PPT Presentation
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Rare Decays at TevatronRare Decays at Tevatron
Marco RescignoMarco RescignoINFN/RomaINFN/Roma
for the CDF and DØ for the CDF and DØ coll.coll.
CKM06, Nagoya CKM06, Nagoya Dec 14Dec 14thth 2006 2006
Topics: 1)BTopics: 1)Bsearch at search at TevatronTevatron
Good momentum Good momentum resolution, tracking:resolution, tracking: CDF:CDF:(M(MBB)~25 MeV/c2 )~25 MeV/c2 reduce combinatorial and reduce combinatorial and
BBddhh’ hh’ B Bss search window search window contaminationcontamination
Good Vertexing Good Vertexing CDF: L00 CDF: L00 (r(rinnerinner~1.4cm)~1.4cm) DØ: L0 upgrade DØ: L0 upgrade
780 pb780 pb-1-1:: B Bss(B(Bd d ))limitlimit 920 pb920 pb-1-1:: Search for B Search for Bu,d,su,d,s hh
DØ:DØ: First 300 pbFirst 300 pb-1-1 di-muon triggered di-muon triggered
datadata with box opened with box opened limit limit 400 pb400 pb-1-1 data still blinded data still blinded Combined sensitivity for 700 pbCombined sensitivity for 700 pb -1-1
of recorded data (300 pbof recorded data (300 pb-1-1 + 400 + 400 pbpb-1-1 ) )
S/B is expected to beextremely small. Effectivebkg rejection is the keyto this analysis!!
Trigger @ high lumi?Trigger @ high lumi? Clever and Clever Clever and Clever
triggering as inst. triggering as inst. Luminosity increasesLuminosity increases
Keep high purity triggers Keep high purity triggers alive at high luminosityalive at high luminosity
Full use of available Full use of available bandwidth at lower inst. bandwidth at lower inst. Luminosity with Luminosity with dynamically adjusted dynamically adjusted prescalesprescales
Hardware upgrade on the Hardware upgrade on the level 1 track trigger level 1 track trigger processor processor reduce fake rate by reduce fake rate by
reconstructing track reconstructing track segments also in the stereo segments also in the stereo layerlayer
MotivationMotivation Standard Model prediction very suppressedStandard Model prediction very suppressed
Sizeable New Physics enhancement predicted in Sizeable New Physics enhancement predicted in many scenarios, e.g. high tanmany scenarios, e.g. high tan SUSY: SUSY:
StrategyStrategy Blind optimization using signal Monte Carlo Blind optimization using signal Monte Carlo
sample and sideband datasample and sideband data Normalize to known BNormalize to known B++J/J/KK++
Reconstruct Normalization mode in the Reconstruct Normalization mode in the same data, applying same criteria same data, applying same criteria reduce systematicsreduce systematics
Only ratio of efficiency mattersOnly ratio of efficiency matters Evaluate expected background and then Evaluate expected background and then
open the box and calculate BR or limitopen the box and calculate BR or limit
linear extrapolation linear extrapolation from sidebands into from sidebands into ±60 MeV/c±60 MeV/c22 signal signal window for CDF (± window for CDF (± 180 @ D0)180 @ D0)
BBhh’:hh’: expected signal expected signal convoluted with muon convoluted with muon fake rate (CDF)fake rate (CDF)
Cross check predictions using Cross check predictions using independent background independent background enriched samplesenriched samples Same Sign di-muonsSame Sign di-muons Opposite Sign di-muons with Opposite Sign di-muons with
Impact on New PhysicsImpact on New Physics Current Current
constraints from constraints from mmss and B and Bss are differently are differently effective in the effective in the new physics new physics parameter parameter phase space phase space
Improved limits Improved limits on Bon Bss can can further further constraint SUSY constraint SUSY at large tanat large tan Foster,Okumura,RoszkowsFoster,Okumura,Roszkows
ki Phys.Lett. B641 (2006) ki Phys.Lett. B641 (2006) 452 452
Area of ImprovementArea of Improvement Improved muon selection based Improved muon selection based
on additional information:on additional information: Energy deposition in the Energy deposition in the
calorimetercalorimeter dE/dx in the drift chamberdE/dx in the drift chamber
Significant reduction in fakes Significant reduction in fakes expected.expected.
Neural Net based final Neural Net based final discriminant with additional discriminant with additional background suppression powerbackground suppression power
Use the 2-dimensional dimuon Use the 2-dimensional dimuon mass-discriminant plane to mass-discriminant plane to evaluate signal/limitevaluate signal/limit
Stay tuned for an updated Stay tuned for an updated results at winter conferences…results at winter conferences…
Current muon fake rateCurrent muon fake rate Determined for Kaon and pions Determined for Kaon and pions
of each charge from high of each charge from high statistics D*statistics D*DD00KK--++ sample sample
bbslsl++ll-- decays at Tevatron decays at Tevatron
Re-establish signals in Tevatron data and Re-establish signals in Tevatron data and “discover” unseen “discover” unseen BBss decays decays BR(BBR(Bss )=1.6x10)=1.6x10-6-6 C. Geng and C. Liu, J. Phys. G 29, C. Geng and C. Liu, J. Phys. G 29,
1103 (2003)1103 (2003)
CDF new results with 0.92 fbCDF new results with 0.92 fb-1-1
D0 published a BR(BD0 published a BR(Bss limit with 0.4 fb limit with 0.4 fb-1 -1
StrategyStrategy Similar to the BSimilar to the B case case Normalize signal to analogous BNormalize signal to analogous BJ/J/h h
(J/(J/) decays) decays
Blind optimization Blind optimization Exclude J/Exclude J/ and and ’ region’ region Sideband data for optimization and Sideband data for optimization and
background estimatebackground estimate Monte Carlo and data for efficiency ratios Monte Carlo and data for efficiency ratios
Counting events in 2Counting events in 2 window window around B mass, excesses seen in around B mass, excesses seen in all modesall modes
Background from 3-9 Background from 3-9 sideband sideband extrapolated to signal window extrapolated to signal window Fit shown for illustration purposeFit shown for illustration purpose
SummarySummary CDF/DØ analyzed ~800 pbCDF/DØ analyzed ~800 pb-1 -1 of Run II data of Run II data
searching for Bsearching for B signal: signal: Current limits in the 10Current limits in the 10-8-8 territory territory No major obstacle in pushing down limits with No major obstacle in pushing down limits with
increasing exposureincreasing exposure Significantly improved analysis with >1 fbSignificantly improved analysis with >1 fb-1 -1
data sampledata sample Constraining more & more New Physics…Constraining more & more New Physics…
CDF/DØ entering the bCDF/DØ entering the bsll arena:sll arena: New solid BNew solid B++K signal from CDF K signal from CDF A 2.4 A 2.4 excess in the B excess in the Bss reported from CDF reported from CDF
U.L. limit close to SM prediction U.L. limit close to SM prediction
1.5 fb1.5 fb-1-1 on tape: more to come… on tape: more to come…
Mass spectra not corrected for efficiency/backgroundMass spectra not corrected for efficiency/background Resonance veto:Resonance veto:
2.9<m2.9<m<3.2 (J/<3.2 (J/)) 3.6<m3.6<m<3.75 (<3.75 (’)’) D (D+,Ds) any 2(3) track combination within 25 MeV of PDG D (D+,Ds) any 2(3) track combination within 25 MeV of PDG