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Status of B s Mixing at CDF. Joseph Kroll (Penn) & Franco Bedeschi (INFN Pisa) Mixing Analysis Coordinators 15 October 2004 – CDF Collaboration Meeting. 2 nd St. Ocean City, NJ, 7 Feb 2004. Outline: Physics importance & current knowledge of m s Method of measurement
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Status of Bs Mixing at CDF Joseph Kroll (Penn) & Franco Bedeschi (INFN Pisa) Mixing Analysis Coordinators 15 October 2004 – CDF Collaboration Meeting Kroll/Bedeschi Collaboration Meeting 2nd St. Ocean City, NJ, 7 Feb 2004
Outline: • Physics importance & current knowledge of ms • Method of measurement • Organization of CDF B mixing analyses • Recent progress • Summary • Appendix: schedule Kroll/Bedeschi Collaboration Meeting Manasquan Inlet, NJ, 25 December 2003
Goal of Flavor Physics Measure parameters of the CKM Matrix Test consistency: do measurements of the same parameter with different decays & CP asymmetries give the same result? Is it unitary? B0 flavor oscillations (md) measure one side How do B0s oscillations (ms) fit in this picture? Why is ms considered one of the most important Run II measurements? Kroll/Bedeschi Collaboration Meeting
Neutral B Meson Flavor Oscillations Flavor oscillations occur through 2nd order weak interactions e.g. Same diagrams and formula for ms for Bs except replace “d” with “s” From measurement of md derive |V*tbVtd|2 All factors known well except “bag factor” £ “decay constant” md = 0.502 § 0.007 ps-1 (2%) (PDG 2004) from Lattice QCD calculations – see hep-ph/0406184 Kroll/Bedeschi Collaboration Meeting
B Meson Flavor Oscillations (cont) md well measured: |V*tbVtd| limited by theoretical uncertainties If we measure ms then we would know the ratio ms/md Many theoretical quantities cancel in this ratio, we are left with from Lattice QCD – see hep-ph/0406184 This is why ms is high priority in Run II Since Vts ¼ Vcb this gives us our side Kroll/Bedeschi Collaboration Meeting
Current Status of ms ms > 14.5 ps-1 95% CL Results from LEP, SLD, CDF I Amplitude method: H-G. Moser, A. Roussarie, NIM A384 p. 491 (1997) see http://www.slac.stanford.edu/xorg/hfag/osc/winter_2004/index.html Kroll/Bedeschi Collaboration Meeting
Experimental Steps for Measuring Bs Mixing 1. Extract B0s signal – decay mode must identify b-flavor at decay (TTT) Examples: 2. Measure decay time (t) in B rest frame (L = distance travelled) (L00) 3. Determine b-flavor at production “flavor tagging” (TOF) “unmixed” means production and decay flavor are the same “mixed” means flavor at production opposite flavor at decay Flavor tag quantified by dilution D = 1 – 2w, w = mistag probability Kroll/Bedeschi Collaboration Meeting
Measuring Bs Mixing (cont.) 4. Measure asymmetry Asymmetry is conceptual: actually perform likelihood fit to expected “unmixed” and “mixed” distributions Measure md to validate procedure these formulas assume perfect resolution for t Kroll/Bedeschi Collaboration Meeting
Comment on : Time Integrated Mixing is the time integrated mixing probability In principle, a measurement of determines m - the first Bd mixing measurements were measurements - d = 0.186 § 0.004 (PDG 2004) - this does not work for Bs: s = 0.5 (the limit as x!1) A measurement of is very interesting Kroll/Bedeschi Collaboration Meeting
B Flavor Tagging We quantify performance with efficiency and dilution D = fraction of signal with flavor tag D = 1-2w, w = probability that tag is incorrect (mistag) Statistical error A on asymmetry A (N is number of signal) statistical error scales with D2 Kroll/Bedeschi Collaboration Meeting
Produce bb pairs: find 2nd b, determine flavor, infer flavor of 1st b Two Types of Flavor Tags Opposite side + Applicable to both B0 and B0s −other b not always in the acceptance Same side Based on fragmentation tracks or B** + better acceptance for frag. tracks than opp. side b −Results for B+ and B0not applicable to B0s Reminder: for limit on ms must know D Kroll/Bedeschi Collaboration Meeting
Same Side Flavor Tags Based on correlation between charge of fragmentation particle and flavor of b in B meson Decay of P-wave mesons B** also contributes to B0, B+ (not B0s) Expected correlations different for B+, B0, B0s TOF Kroll/Bedeschi Collaboration Meeting
Illustration of Bs Oscillations Example of Asymmetry with lots of statistics ms = 20 ps-1 Illustrated are - tagging reduces statistics dilution reduces amplitude - decay length resolution damps amplitude further - momentum uncertainty damps amplitude more as decay time t increases Large ms: Bs! Ds l no good need fully reconstructed decays e.g., Bs! Ds Kroll/Bedeschi Collaboration Meeting
CDF Bs Mixing History & Organization • Expected Bs mixing to come early in Run II • turned out not to be the case • Bs task force created by Tony Liss late Fall 2003 • Task force report issued June 2004 (CDFNOTE 7042) • MACs appointed to help organize & coordinate • Franco Bedeschi (INFN-Pisa) & Joseph Kroll (Penn) • MACs began in June 2004 • Have held three workshops • 9 June 2004 • 12 July 2004 (close out on 14 July) • 1 October 2004 • Current focus is Winter Conferences 2005 • Also planning for longer term: Summer 2005 & beyond Kroll/Bedeschi Collaboration Meeting
Flavor tagging continued PID around B mesons (D. Usynin/Penn) SSKT MC studies (P. Catastini/Pisa) Status of PID (R. Snider/FNAL) Fitting for md Terms for likelihood(I. Kravchencko/MIT) md with J/ K (N. Leonardo/MIT) md with semileptonics (G.Giurgiu/CMU) Preparing for results on ms t in SST biased samples (discussion) Summary and Schedule (J. Kroll/Penn) see B meeting on 14 October Introduction (F. Bedeschi/Pisa) Proposal for blind analysis (G. Punzi/Pisa) Status of data sets (Ch. Paus/MIT) Signals Semileptonic (G. Gomez-Ceballos/MIT) Hadronic (A. Belloni/MIT) Ds+! K0S K+ (M. Casarsa/Padova) Status of lifetimes Semileptonic (S. Farrington/Liverpool) Hadronic (F. Azfar/Oxford) Flavor tagging Summary of OSTs (I. Kravchenko/MIT) Plan for SSKT (F. Bedeschi/Pisa) Monte Carlo Tuning (E. Ben-Haim/Paris6) Workshop Agenda from 1 October 2004 Big effort involving > 20 CDF institutions also involved: ANL, Brandeis, Cantabria, Chicago, Geneva, JHU, Karlsruhe, LBNL/Berkeley, Pittsburgh, Purdue, Rome, Tsukuba, Yale Kroll/Bedeschi Collaboration Meeting
Significant Progress Since June 2004 • Blessed Mixing w SST & OST in l + D (CDFNOTE 7127) • Blessed update mixing w SST in hadronics (CDFNOTE 7145) • Blessed several flavor tags • improved soft muon tag (CDFNOTE 7043) • improved/extended jet charge tag (CDFNOTE 7131) • new soft electron tag (CDFNOTE 7121) • Blessed improved evaluation of sensitivity (CDFNOTE 7170) • Updated semileptonic/hadronic signals (PR plots) • All of above presented at ICHEP 2004 (50% B Summer 04 results) • improved lifetime resolution w event-by-event PV & L00 • Studies of SSKT underway – using TOF & dE/dx, MC tuning • Working towards competitive limit on ms for Winter 2005 • summary of activities with people & schedule appended at end of talk Kroll/Bedeschi Collaboration Meeting
Examples of Progress on B0s Signals “Golden mode” Ds mode Kroll/Bedeschi Collaboration Meeting
Examples of B0 & B+ Calibration Signals 6 & 8 track modes! Kroll/Bedeschi Collaboration Meeting
Progress on Lifetimes Know how to measure lifetimes when there is no SVT trigger bias CDF: (B+)=1.662 § 0.033 § 0.008 ps (PDG 2004 (B+) = 1.671 § 0.018 ps) Do we get correct lifetime from SVT biased signals? Expect 488 m (14) Outstanding mystery in lepton + SVT sample Recent progress in understanding what is NOT the problem Need result from B! D (2 SVT) Kroll/Bedeschi Collaboration Meeting
jet from b (b) has negative (positive) charge on average Results on Opposite Side Flavor Tags Lepton tags lower higher D mistags from SLT(): D2 = (0.70 § 0.04 § 0.05)% SLT(e): D2=(0.37 § 0.03 § 0.06)% Jet charge tag Run II: D2 = (0.72 § 0.03)% higher , lower D includes lifetime info too Kaon tag Run II: no useful tag yet (have seen D, too low) Largest D2 @ B factories TOF Kroll/Bedeschi Collaboration Meeting
B pTrel Fully Exploit Tag Power by “Binning” e.g., pTrel for soft leptons Larger pTrel increases b! suppresses b! c!, fakes pTrel Dilution dependence determined from data Requires enormous statistics of lepton + SVT sample Kroll/Bedeschi Collaboration Meeting
Fully Exploit Tag Power by “Binning” e.g., Qjet for jet-charge Dilution increases with Q_{jet} Need unbinned likelihood fit to exploit dilution binning Kroll/Bedeschi Collaboration Meeting
Progress on Same Side (Kaon) Tagging • SST (re)established in Run II in B0 mixing • B0: D2 = (1.04 § 0.15 § 0.17)% • B+: D2 = (4.69 § 0.49 § 0.36)% • SSKT predicted to be most powerful flavor tag for Bs • Problem: cannot measure D without seeing oscillations • Limit requires knowledge of D (to predict sensitivity) • do not know if Monte Carlo prediction of D is reliable • Have ambitious program to compare data and MC for SST • established short term goals • comparison of fragmentation particles in Monte Carlo to data • establish B** signals • measure kaons around B+, B0, Bs in data & MC – should see difference • Best performance of dE/dx and TOF is critical Kroll/Bedeschi Collaboration Meeting
Fit for md & D in lepton + D with OSTs 1st time in Run I or II (only SST in Run I) • md = 0.593 § 0.53 ps D2 = 0.8% (OST only) D2 = 1.8% (OST & SST) soft muon tag D = (28§2)% These are binned asymmetry fits Do not exploit full power of OSTs (binning in Qjet, pTrel not used) SECVTX Jet Charge D = (19§ 1)% Kroll/Bedeschi Collaboration Meeting
ICHEP 2004: Our Projected Sensitivity See CDFNOTE 7170 v2.0 Uses full unbinned likelihood to estimate sensitivity for l Ds (more like 74 fs) Baseline: D2 = 1.6% (OST only) = 67 fs (achieved) (OST is SLT(e) = 0.4% + SLT() = 0.7% + JQT = 0.7%) Stretch: D2 = 2.6% (add SST) = 47 fs (L00, event by evt. PV) Kroll/Bedeschi Collaboration Meeting
ICHEP 2004 Projected Sensitivity (cont) Hadronic Semileptonic Kroll/Bedeschi Collaboration Meeting
ICHEP 2004 Projected Sensitivity (cont) Message: even with only OST could have sensitivity comparable to best experiment. Good motivation to work hard Combined semileptonic and hadronic Kroll/Bedeschi Collaboration Meeting
Highest Priority Items • Unbinned likelihood fit for md exploiting full power • of flavor tags, event by event t, S/B in different modes, etc. to accomplish 1. we must 2. Resolve lifetime problem in semileptonic modes (l Ds) 3. Measure lifetime in SVT-biased hadronic modes (Ds, etc.) With blessed OST’s, 1, 2, & 3 may be enough to say something 4. Study SSKT – determine defensible D from data and MC in parallel with 1, 2, 3 Kroll/Bedeschi Collaboration Meeting
Summary • Large group of people (> 20 institutes) dedicated to crucial components of Bs mixing measurement • Significant progress was made this summer – we continue to work towards a 1st result in Winter 2005 • A lists of tasks with responsible people & deadlines is available – see Appendix to this talk. It will continue to evolve. There is still room to get involved This is a long term analysis It is a collaborative effort “No physicist left behind” Kroll/Bedeschi Collaboration Meeting
Appendix: Schedule • Notes: • There is a web page in preparation – see B web page • The names on the following schedule indicate the people • who are responsible for the particular tasks now & in the • future. Many other collaborators contributed to these tasks • in a significant way in the past. Kroll/Bedeschi Collaboration Meeting
Schedule • We have put together a list of tasks • Each task has • list of people doing the work • these people are considered “responsible” for delivering • the venue where they report the results of their work • specify the subgroup or B group • the various near term tasks including time estimates • long term tasks have more vague time estimates • Weekly status reports • we want status reports at subgroups on key tasks every week • does not have to be full presentation, can be one slide on previous week’s activities Kroll/Bedeschi Collaboration Meeting
Data set definition 5.3.X all data up to August 2004 shutdown except COT compromised Good run list Furic & Nahn reports at BPAK by 4 November 2004 Skim of SVT two track data set Belforte, Casarsa, Delli, Fella, Lucchesi reports at BPAK 2 sections of the data up to 13 February 2004 after COT recovery Skim (continued) Status of data up to 13 Feb 2004 Bs! Ds, Ds! K*K or KSK complete finish other 7 modes by 4 Nov 2004 B-! D0-, D0! K+-, K+-+-, K+K-, +- B0! D-+, D-! K-++ B0s! Ds-+, Ds!, post COT recovery data processing in parallel with above complete by end of November 2004 Some modes not included e.g., B! D* & D can be added – no time estimate Data Sets Kroll/Bedeschi Collaboration Meeting
B Sntuple Paus reports at BPAK based on 5.3.1 includes all modes will include all data to Aug 2004 J/ K by 18 Oct 2004 lepton + D by 26 Oct 2004 B hadronic by 8 Nov 2004 Direct access to data (datlists) Furic & Paus reports at BPAK available 1 Dec 2004 Comments must do better for Summer 05 & beyond need to start organizing this now volunteer (BPAK) needed for Winter 2004 success of datlists is critical B sntuple no update of TOF possible event by event PV, L00 not included in present production 1 Oct 2004: Ch. Paus reports 30 pb-1 data bad due to CMX – use anyway? Data Sets (continued) Kroll/Bedeschi Collaboration Meeting
Signal Optimization • Hadronic modes • Casarsa, Lucchesi, Squillacioti, Shapiro • reports at B Hadronic • complete by 4 Nov 2004 • Semileptonic modes • Gibson • reports at Semileptonics • update on 26 Oct 2004 • schedule for finalizing not established Concern: inadequate personnel and coming too late Kroll/Bedeschi Collaboration Meeting
Semileptonic Clark, Farrington, Tanaka, Ukegawa, Uozumi reports at Semileptonics near term (by 4 Nov 2004) Tanaka x-check of l + D+ d0 cut on D* (D+, D0 too?) generate more c-cbar MC result in 8 GeV (no SVT) long term (no estimate) have to see results of near term to decide how to proceed Hadronic “MC free” approach Azfar, Boudreau, Huffman, Rademacher, Rahaman reports at B hadronic fitting test and refinement Azfar, Rademacher B+! D0+ in progress stripping & ntuple production (data & MC) Azfar, Rahaman B+! D0+ done B0, Bs, &b modes in progress complete by 4 Nov 2004 Lifetimes Kroll/Bedeschi Collaboration Meeting
Hadronic “MC free” continued Systematics alignment (Boudreau, Rahaman) SVT eff. (Azfar, Rademacher) background parameterization (Huffman, Rademacher) all in progress already for B+ mode – done by 4 Nov 2004 others follow later Hadronic – SVT eff. method Da Ronco, Donega, Giagu, Giolo, Lucchesi update SVT curves by 4 Nov 2004 preliminary result (lifetime okay or not okay) by 22 Nov 2004 Lifetimes (continued) Kroll/Bedeschi Collaboration Meeting
Opposite Side Flavor Tags • Validation of blessed Summer 2004 SLT(), SLT(e), JQT • Giurgiu, Kravchenko • reports at Semileptonics • means putting taggers in repository & verifying we get the same results • complete by 19 Oct 2004 • Creation of simple combination of above tags • Giurgiu, Kravchenko • reports at Semileptonics • determine tag overlaps and combined D2 (including binning) on J/K • report on 19 Oct 2004 • evaluation of more sophisticated combinations (max D, diff. classes) • time scale not established Kroll/Bedeschi Collaboration Meeting
Same Side (Kaon) Tag • Further development of SS(K)T • Bedeschi, Catastini, Punzi, Scuri, Squillacioti • reports to Semileptonics • compare SS(K)T algorithms in data & MC using J/ K samples • use combined dE/dx & TOF particle ID • report by 4 Nov 2004 • Study particle species produced around B+, B0, B0s • Heijboer, Jones, Kroll, Usynin • reports to Semileptonics • Measure particle species in data • initial report using private TOF calibration in July 2004 • further progress requires updated TOF calibration and B Sntuples • MC production in parallel – estimate Dec 2004 Kroll/Bedeschi Collaboration Meeting
Same Side Kaon Tag (continued) • Comparison MC & data, tuning fragmentation • Ben-Haim, Maksimovic, Pursley • reports to Monte Carlo & Semileptonics • update on 4 Nov 2004 • B** • Ben-Haim, Maksimovic, Pursley • reports to J/ & B hadronics • signal in B+! J/ K+ (update 4 Nov 2004) • signal in SVT hadronic samples (December?) Kroll/Bedeschi Collaboration Meeting
MIT/Cantabria/Karlsruhe Belloni, Gomez-Ceballos, Kravchenko, Leonardo, Paus, Piedra reports to Semileptonics likelihood fit B!J/ K with SST exists – see last workshop need to add OSTs developing fits for l + D & D, D3p Fully tested with preliminary result on md by 1 Dec 2004 Argonne/CMU Giurgiu, Paulini, Tanaka reports to Semileptonics full likelihood for ms exists; used for ICHEP 04 projections developing for md w l + D incorporating blessed OSTs 1st version fit working and tested on toy MC – see last workshop working on including tagging & vertexing in data ntuple – report at 4 Nov 2004 run on MC to determine add. K factors: 30 Nov 2004 1st result on md by 7 Dec 2004 Likelihood Fitting for md Kroll/Bedeschi Collaboration Meeting
Result on ms • Difficult to work this far ahead – we can work backwards from La Thuile & draw some conclusions: • 24 Feb 2005 last day to bless results for La Thuile • 17 Feb 2005 unblind results on ms • 03 Feb 2005 prebless results on ms • 20 Jan 2005 bless results on md for ms (Collaboration mtg.) • 06 Jan 2005 prebless results on md for ms • Better have full likelihood machinery for md determination using hadronic and semileptonic samples and OSTs before the Winter holiday – this includes a substantial amount of documentation prepared. Kroll/Bedeschi Collaboration Meeting
In Preparation for ms • Decision on blinding procedure • Punzi • reports to B meeting • written proposal submitted to B group before 4 Nov 2004 • present at workshop on 4 Nov 2004, sign off at following B meeting • Quantities for input to likelihood fit (flat file content) • Kravchenko & Tanaka • reports to semileptonics • written proposal submitted to B group before 4 Nov 2004 • present at workshop on 4 Nov 2004 Kroll/Bedeschi Collaboration Meeting
Common Tools • dE/dx in COT • COT dE/dx group (Giagu) • reports to BPAK group • validation of entire data set up to Aug 2004 shutdown in progress • ready for 5.3.4 release on 29 Oct 2004 • TOF • TOF group (Snider) • reports to BPAK group • in process of revising/validating calibration schemes • hope to be ready for 5.3.4 release on 29 Oct 2004 Kroll/Bedeschi Collaboration Meeting
Combined dE/dx & TOF PID Ciocci, Morello, Punzi, Squillacioti, Tonelli reports to BPAK available now in private version: resolution functions for each particle type separately for dE/dx & TOF include in public code infrastructure by 18 Oct 2004 – validate include in 5.3.4 release on 29 Oct 2004 include combination of TOF and dE/dx for 29 Oct 2004 release demonstrate utility with examples by 4 Nov 2004 Event by Event Vertexing incl. L00 Cerri, Lucchesi, Shapiro reports to BPAK code available & will be in 5.3.4 rel. documentation by 4 Nov 2004 Common Tools (continued) Kroll/Bedeschi Collaboration Meeting
Monte Carlo Production • Oversight of Monte Carlo Generation/Production • D’Auria • reports to Monte Carlo • outstanding issues • existing MC samples produced by various groups privately not registered • only aware of one collaborative effort to generate MC for semileptonics • see talk by Usynin at semileptonics subgroup on 28 Sep 2004 Kroll/Bedeschi Collaboration Meeting
Some Concluding Remarks • We have made progress assigning tasks and making a schedule • The schedule needs to be studied further to see if we are on target to have a result for Winter 2005 • Particular concern is Dec 2004 – how do we go from 1st results on md to documented blessed results by early Jan 2005? • Two more workshops planned in 2004 • November 3 & 4 • off week – we thought it would help to spread the pain over 2 days • December 16 Kroll/Bedeschi Collaboration Meeting
Calendar Gasp! now we are here! on week proposed B mixing workshop Collaboration meeting last Thursday meeting holiday Better get back to work La Thuile begins here Kroll/Bedeschi Collaboration Meeting