Recent CDF Results on B s Flavor Oscillations

1. Recent CDF Results on Bs Flavor Oscillations The CDF Bs Mixing Group CDF Executive Board Meeting 13 April 2006 J. Kroll (Penn), F. Bedeschi(INFN – Pisa), M. Herndon (Wisconsin), Ch. Paus (MIT), K. Pitts (Illinois)

2. The CDF Bs Mixing Group 80 people, 27 Institutions Big effort with many separate important contributions

3. Made Possible By the CDF Detector • Trigger • high bandwidth & tremendous flexibility • XFT and SVT • Exquisite charged particle tracking • excellent pattern recognition & mass resolution (COT, solenoid) • precise production & decay point reconstruction (L00, SVX) • Particle identification • Time of Flight (TOF) and dE/dx in COT • Extremely dedicated collaborators for operations • a lot of sleepless nights for analysis but many more for operations • many of the analyzers spent sleepless nights working on critical detector components too

4. Sequence of CDF Run II Results on Bs Mixing • Fall 2001: 1st heavy flavor signal from TTT data • Summer 2002: 1st lifetime measurements • Winter 2003: 1st fully reconstructed Bs! Ds • Summer 2003: 1st blessed opposite side flavor tag (muon) • Summer 2004: 1st B0md result A lot of ideas and development in Run I

5. Sequence of CDF Run II Results on Bs Mixing • 1st result March 2005 – presented at Moriond QCD • hadronic modes from two-track trigger • semileptonic modes from lepton + SVT trigger • opposite-side flavor tags: muons, electrons, jet-charge • combined sensitivity ms > 8.4 ps-1 • 1st update: October 2005 – presented at PANIC 2005 • substantial increase in semileptonic signal from TTT • several analysis improvements, e.g., • neural net based jet-charge opposite side flavor tag • improved opposite side flavor tag calibration • improved boost resolution on semileptonic decays • combined sensitivity  ms > 13.0 ps-1 These results based on 360 pb-1 (0d data)

6. Current CDF Bs Oscillations Analysis • This winter our focus shifted to three main areas • adding same-side kaon tagging (SSKT) • blessed on 23 February 2006 • adding 0h and 0i data (an additional 640pb-1) (done – see later) • using partially reconstructed hadronic decays (still in progress) • 1st step – add SSKT to 360pb-1 hadronic analysis • Schedule had us unblinding on 13 March 2006 • DØ announcement at Moriond EWK on 12 March 2006 • CDF unblinded hadronic scan on 13 March 2006 as foreseen • found ~3 excess @  ms = 17.3 ps-1 • 0d hadronic-only result already much more significant than DØ • preblessed at B meeting on 16 March 2006 • decided to add 0h & 0i data asap for both hadronics & semileptonics

7. reminder: oscillation probability DØ Result Presented at Moriond EWK on 3/12/06 Amplitude peaks @  ms = 19ps-1 2.5 discrepant with A=0 (1%) 10% compatible with A=1 17 <  ms < 21 ps-1 @ 90% CL Probability that random fluctuation produces this signal p-value = (5.0 § 0.3)%

8. CDF Hadronic Data (355pb-1) We were on schedule to unblind 1st part of hadronic data on 3/13/06 caution: arbitrary offset 90% This result was comparable in sensitivity to DØ result We had a lot more data, so we decided to add it, and fast

9. Rapid Progress from 3/13 to 3/31 • This was a well-tuned analysis & extensively reviewed • Winter 2005 had two independent semileptonic analyses • included independent fits and data sets, which were fed to each other • direct comparison of amplitude scans • also independent lifetime measurement in Bs! Ds • Emphasis on adding new data was validation • signal invariant mass distributions • signal lifetime distributions • particle identification (TOF and dE/dx) • proper time resolution • Had to understand how to move from limit to measurement • required evaluation of probability of background fluctuation • determination of ms including systematic uncertainties • Unblinded amplitude scans after B meeting on 3/30/06 • presented at Joint Physics Meeting on 3/31/2006

10. Result: Amplitude Scans in 1 fb-1 Hadronic Decays Semileptonic Decays Single experiment sensitivity > combination of previous results

11. Result: -ln(likelihood) & ms, |Vtd/Vts| A = 1.01 § 0.29 (3.5) p value: 0.5% Limited by theoretical (lattice) uncertainties

12. Impact on CKM Unitarity Triangle EPS05 EPS05 + CDF Figures courtesy of Z. Ligeti (LBNL)

13. Since Blessing on 6 April 2006 • Special Wine & Cheese on Monday 10 April 2006 • 3 rehersals: Friday & Sunday afternoon, Monday morning • 1 West was standing room only • spectacular performance by speaker Ivan Furic • FNAL press release on Tuesday 11 April 2006 • 1st Conference presentation at FPCP 2006, Vancouver, BC • CDF contingent flew Monday night • Rehersal in hotel room Tuesday morning • Excellent presentation by Guillelmo Gomez Ceballos • Received with great enthusiasm by Flavor community • Several requests for seminars from National Labs • ANL, BNL, DESY, LBNL, SLAC …

14. Public Documentation • PRL in preparation • 1st draft: Ch. Paus, JK • Godparents: Ristori (Chair), Glenzinski, Wuerthwein • Heinrich, Punzi are statistics committee consultants • plan for accelerated review process • Public Document (CDFNOTE 8204) • K. Pitts editor, many contributors • circulating in collaboration now – please read and send comments • would hope to make public by next week • could serve as PRD draft • Web page • link on main CDF public page to main plots & talks • http://www-cdf.fnal.gov/physics/new/bottom/060406.blessed-Bsmix/

15. What’s Next? • Analysis improvements (all already well underway) • add satellite peaks (Ds*, Ds) in hadronic modes • neural networks for hadronic signal selection • use all semileptonic trigger paths (lepton + SVT, SUSY dilepton) • neural networks for opposite side tags • improve SSKT by combining kinematics and particle id • use particle id in signal selection (Ds! K*K) • Technical improvements • reprocess all data offline version 6 at least 1st 360 pb-1 • improvements to fitter implementation • e.g., replace ascii input file with ntuple • Related physics results (e.g., lifetimes) Goal: 5 observation for ICHEP 2006