1. Moving to a 1 st Result on  m s : A Discussion Joseph Kroll (Penn) Franco Bedeschi (INFN/Pisa) 6 th CDF B Mixing Workshop 14 January 2005

2. Kroll/Bedeschi2 Calendar We are hereLa Thuile begins Other dates: Moriond EWK (3/5-3/12), Moriond QCD (3/12-3/19) CKM (3/15-3/18), APS/DPF (3/16-3/19) Coll. Mtg. Last Thur. 6 B meetings left before La Thuile

3. 14 January 2005Kroll/Bedeschi3 Towards a 1 st Result on  m s Two analysis paths –Fully reconstructed B decays (D  & J/  K) –Semileptonic B decays (lepton + D) –some potential common areas, e.g., flavor tag dilution calibrations Before attempting  m s must bless (in each path) –signals –lifetime measurement (B 0, B + & B 0 s ) –dilutions binned OSTs may also use SST in B 0, B +, esp. if helps constrain OST performance –Measurement of  m d using unbinned likelihood fit Have closed the loop on a simplified version of the above list

4. 14 January 2005Kroll/Bedeschi4 What Comes After These Steps? Amplitude scan for  m s fully tested with toy MC Re-evaluation of sensitivity –fully reconstructed modes alone –semileptonic modes alone –combined sensitivity –does predicted sensitivity warrant looking at data? (it will) Complete evaluation of systematics Agree in advance on cross-checks after looking (if any) Run fit on data with randomized tags – check for problems Run fit on data with tags (open the box) Who takes responsibility for (drives) this part of the analysis? Documentation

5. 14 January 2005Kroll/Bedeschi5 Systematics We must evaluate systematics before we look at result Examples –Dilutions statistical error error due to uncertainties in parameters of binning functions –Backgrounds size dilutions lifetime distributions –Lifetime resolution –Fit biases –etc.

6. 14 January 2005Kroll/Bedeschi6 Issues and Concerns (in no particular order) Lifetime resolution –how do we determine the resolution and the associated systematic? –crucial for determining sensitivity for a limit –needs to be documented & blessed (schedule) Using L00 and event-by-event primary vertex (ebepv) –Have very little experience with using L00 and evepv –getting correct lifetime ≠ understanding resolution for \Delta m_s –need to validate simulation of L00 and evepv Fit speed –can we vary enough parameters to study systematics? e.g., the parameters describing dilutions?

7. 14 January 2005Kroll/Bedeschi7 Issues and Concerns (continued) Access to data –must use datlists – will they work reliably? Semileptonic lifetime discrepancy –probably will not resolve this discrepancy by Winter conferences –most of our sensitivity to  m s expected from semileptonics - can we show a mixing result anyway? –discrepancy is small (6%) – small systematic in determination of dilutions using lepton + D –need to investigate affect of possible causes of lifetime discrepancy as a systematic effect on  m s –blessing result from 8 GeV trigger (no SVT trigger bias) important part of this story

8. 14 January 2005Kroll/Bedeschi8 Final Remark: Authorship We are getting close to a 1 st result on  m s A lot of progress – there is cause to be optimistic At this stage, we should agree on a policy for authorship of the CDFNOTES that are part of this 1 st result on  m s Proposal: –all notes use an inclusive list of authors that are part of the “CDF B Mixing group” –each note has a list of contact people – these are the people who did the majority of the work who will answer the questions on that note –Franco and Joe will assemble a 1 st pass at list (Bs mailing list) & send out mail to B group requesting that everyone who wants to be on this author list send in their name immediately

9. 14 January 2005Kroll/Bedeschi9 Authorship Continued Notes with common authorship include –B lifetimes from semileptonic decays –B lifetimes from hadronic decays –Results on B 0 mixing using semileptonic decays –Results on B 0 mixing using hadronic decays –1 st results on B s mixing –and other notes This has many advantages –Collaboration sees that this is an effort of a very large group –people working on specific results get recognition –no one should feel left out