Plans for B s Mixing

12 May 2005 Kroll/Bedeschi 1

Plans forBs Mixing

B Meeting12 May 2005

Franco Bedeschi (INFN-Pisa)Joseph Kroll (Penn)


Agenda of Discussion on 28 April 2005


Goals of this Discussion

Find out who is doing what

Questions for CDF Bs mixing analysis

- What are the near term goals for Summer 2005? - What is the time scale and content of 1st publication? - How do we go from a limit to a measurement?

We hoped the presentations and discussion todaywould help us understand the answers to these questions

Decide on date of next workshop


Calendar for Near Term Summer 2005

= on week

Lepton Photon, Uppsala (4 on weeks)

HEPP-EPS, Lisbon (5 on weeks)

CDF Week, Sitges


Planned Improvements & Extensions

• Same-side kaon tag & fit with SST and OST

• use muon versus two-track trigger data sample

• Semileptonic decays in two-track trigger

• improved proper decay time resolution

• add more decay modes (e.g., Ds)

• improve opposite-side tags (e.g., neural net jet charge)

• add data after August 2004

• updated projections


Same-side Kaon Tag

• Same-side kaon tag & fit with SST and OST– already had presentation (4/19) on unbinned fit with SST + OSTs

• addition of SST increases fit time substantially

– until Bs mixing observed, SSKT requires D from MC

• cannot measure D from B0 & B+

• how will we evaluate systematics on predicted D from MC?

• Check of B0 & B+ in data complicated by B**

– Summary of discussion on 28 April• 2 groups working in parallel

• requires detailed comparison between data and MC

• evaluation of systematics requires many MC samples – will take time

• mid-summer very ambitious – one group stated goal of end of summer

• 2nd group reported plans and progress on 10 May 2005


vs. two-track trigger data sample

• vs. two-track trigger data sample– no prescale – recovers some TTT (with tag!) rejected by prescale– 120 pb-1 collected before August 2004– CDF 7510: comparable sensitivity to 360 pb-1 TTT sample– continued implementation since December 2004– As L increases, this may be our trigger path to observing mixing

• should give high priority to analyzing this trigger path asap• look at post Fall 2004 shutdown data• should implement electron vs. TTT trigger path

• Summary of discussion– SLT() more strict than trigger – same D– add trigger path to existing hadronic analysis– part of next public update of hadronic analysis– work on e vs. TTT planned – no timescale– should be included in high-PT trigger table


Semileptonic Decays in TTT

• Semileptonic decays in two-track trigger– identify e () down to 1 (1.5) GeV

– softer lepton pT requirement than lepton + SVT trigger

– significant addition of statistics (more than factor 2)• see presentation on 4/26

– has significantly larger fraction of fake backgrounds (WS fraction)• useful for studying fake leptons and semileptonic lifetime problem

– Using in a mixing analysis requires complete re-evaluation of• signal optimization

• K factors

• SVT efficiency functions

• physics backgrounds (e.g., B! Ds D)

• fake contributions (larger WS fraction)

• all associated systematics


Semileptonic Decays in TTT

• Summary of discussion and recent progress– two groups working in parallel

– presentations at subgroup since 4/28• 3 May 05

– showed signal statistics with likelihood based e and \mu identification

– 1st presentation of physics backgrounds (B ! DsDX)

• 10 May 05– reoptimization of signals

– significantly reduces WS and physics backgrounds while maintaining S

• Excellent progress

– both groups presented plans – no timescale provided• mid-summer very ambitious


Improving Proper Decay Time Resolution

• improved proper decay time resolution– add event-by-event primary vertex to hadronic analysis

• this should be included in next public iteration

• Summary of discussion– near term

• update CDF7500 (e.g., 5.3.3 to 5.3.4, ebePV, hourglass beamline)

• PV: implement time-dependent beamline parameters from DB

• SV: study pull of d0 for 3rd track, e.g., K in J/ K

– longer term: can we understand/improve scale factors?• lifetime resolution ultimate limitation on ms reach

• need more effort here – e.g., silicon alignment


Adding More Decay Modes

• Summary of discussion– D modes

– add D*3, D03 to B0 mixing analysis

– add Ds3 to B0s mixing analysis

– so far only BCHARM – add LOWPT path too (and +TTT?)

– should be available for next public iteration


Opposite-side Flavor Tags

• improve opposite-side tags– neural net jet charge (CDF 7482) already blessed

– other improvements underway• neural net SLT (see presentation 4/19)

• improved muon likelihood (see presentation 4/26)

• also seen recent reports on kaon tag (see presentationon 4/12)

– Future improvements• Combination of OST

– Summary of discussion• include blessed NN JQT in next public iteration

• situation with NN proprietary software needs to be addressed


Data after August 2004

• add data after August 2004– When will we start including post Fall 2004 shutdown data?

– particularly important for + TTT path analysis

– Summary of discussion and recent news• This data will not be available for Summer analysis

• need to address problem of data processing with SPs– limitation is people for processing, updating calibrations etc.


• updated projections– continually prompted for projections: when will we measure ms?

– need update for Summer 2005

– (actually need update for next week: Oddone presentation)

– important for evaluation of move from limit to measurement

• Progress since workshop– produced update for Oddone

– see http://www.cdf.fnal.gov/internal/spokes/RunIIb_Physics_Triggers/agenda_2005_05_10.html

Updated Projections


Updated Projection for EPP2010 5/16/2005

Discussion later todayCDF Weekly Meeting

prepared for P. Oddone


Near Term Goals for Summer 2005

• Limited time for major summer conferences– 3 on-weeks until Lepton Photon

• need to be ready to prebless in one month!

– 4 on-weeks until HEPP-EPS

• Do not want to decide in advance what is possible– however, we should focus on realistic goals

• including ebePV in hadronics

• update scale factors for lifetime resolution

• adding modes like Ds (and similar modes for B0 analysis)

• include + TTT trigger in hadronic analysis

• go to NN JQT


1st Publication and Measuring ms

• First publication– Enormous overhead => wait until next iteration of analysis

– use OSTs and possibly SSKT

– include event by event PV

– use current hadronic and semileptonic samples

– may include new trigger paths or semileptonics in TTT path

– timescale? (driven partially by career issues)

• Observation of ms

– We need to think about path to measuring mixing

– limited in resources: physicists to do analysis

– trigger challenge at higher luminosity


Next Steps

• Next B Mixing workshop is Thursday, 16 June 2005– already having trouble booking a room

– any analysis for LP05 will have already been preblessed

– any analysis for HEPP-EPS will have to prebless following week

– remember: by-laws say unblinding at preblessing

• Need to make a list of tasks with schedule– especially need to identify personnel for near term summer goals

Documents

Plans for B s Mixing