Studies of EPR-type flavor entangled states in Y(4s)->B0B0 We want to provide a Time Dependent Asymmetry (TDA) fully corrected for experimental effects (background, wrong tags, resolution) to test alternative models to QM. AQM(Dt)=cos(Dmd Dt) AB 17-Feb-06

Steps of this analysis selection of the events background subtraction correction for wrong tag events data deconvolution checks - 5.1 OF+SF=B0 lifetime - 5.2 second analysis with selection on Dz resolution 6) comparison with models MC heavily needed to do the subtractions/corrections of point 1 to 3 and to produce the deconvolution matrices! AB 17-Feb-06

Selection of D*ln events and tagging "B0 side": B0 D* l n D*  D0 + slow pion D0  Kp Kpp0 K3p The used particles are then discarded and the remaining particles are the ”Tag side". These remaining particles are sent to standard BELLE procedure to tag the B0 flavour. We select only the lepon tagged subset with highest purity parameter r>0.875. AB 17-Feb-06

Event selection summary AB 17-Feb-06

EVENT SELECTION : A few plots... Plepton in cms K,p momenta for D0K p Data distributions shown are obtained with all the “other” cuts applied MC pre-analysis cut MC AB 17-Feb-06

A few plots... Momenta for K3p shifted in opposite direction (vertex fit ?) ±0.1 GeV MC-data relative uncertainty AB 17-Feb-06

A few plots... M(D0) and M(D*)-M(D0) MC shifted by ~0.12 MeV Data width larger by 0.14 MeV adjust cuts to get equivalent configurations M(D*)-M(D0) AB 17-Feb-06

A few plots... impact parameters not perfect but cuts are large... ±0.01 cm AB 17-Feb-06

A few plots... chi2 from vertex fit ± 1bin = ± 5... AB 17-Feb-06

A few plots... s(Vz) from vertex fit Artificially rescaled by 1.125 Errors from vtx fit do not agree. N.B.: s(Vz) cut only used in control analysis with “high resolution” ± 2bin = ± 0.002 cm AB 17-Feb-06

A few plots... cos(qB,D*l) Fit using MC shapes: D*ln B0D**ln cut: |cos(qB,D*l)|<1.1 AB 17-Feb-06

Background subtraction Wrong tag evts correction - Continuum analyzed 8.3 1/fb of off resonance data => 0 evts Fake D* Wrong D* lepton combinations B± to D0** Wrong tags AB 17-Feb-06

Raw time dependent asymmetry 1 -1 After event selection syst stat Background subtracted 0 4 8 12 16 20 ps AB 17-Feb-06

Fake D* control sideband nominal sideband From sideband : background evts 126±6 and 54±4 OF and SF Control sideband 128±6 and 54±4 AB 17-Feb-06

Fake D* from sideband control sideband Effect on the asymmetry MC truth data with systematics change distributions by 1 sigma + move cuts False D* and/or false slow pion AB 17-Feb-06

Wrong D*-lepton combinations Reversed lepton technique: in the CMS take Plepton := - Plepton and redo the analysis 78 evts OF and 237 SF Effect on the asymmetry data with systematics change distributions by 1 sigma + move cuts main effect from large number of SF... AB 17-Feb-06

Wrong D*-lepton combinations Reversed lepton technique: method check with MC events reversed lepton MC truth prediction from MC: 20 evts OF and 200 SF consistent with data AB 17-Feb-06

Background subtraction B± Fit using MC shapes: D*ln B0D**ln B±D0**ln shapes ~identical ! - Need to correct only for B±, because B0 has mixing MC gives relative efficiency Assume MC BRs ratio... Systematics: ~8% from fit ~20% from BR(YB±  D0**)/BR(Y  B0  D**) AB 17-Feb-06

Background subtraction B± MC normalized 254 OF 1 SF Systematics: ~8% from fit ~20% from BR(YB±  D0**)/BR(Y  B0  D**) AB 17-Feb-06

Wrong tag correction Systematics: ±0.010 ±1 sigma in corrections High purity events: MC predicts 0.015±0.001(stat) Similar analysis (Phys. Rev. D 71 2005) gives 0.020±0.005 We consider 0.015±0.005. Expect (1-2w)-1 = 1.033±0.010 attenuation of the TDA Systematics: ±0.010 ±1 sigma in corrections ~3% attenuation double counting... AB 17-Feb-06

Construction of the raw TDA AB 17-Feb-06

Raw time dependent asymmetry 1 -1 After event selection syst stat Background subtracted 0 4 8 12 16 20 ps AB 17-Feb-06

Data deconvolution (see appendix A) Data correction is done by a program based on a Singular Value Decomposition (SVD) of the deconvolution matrices. The matrices are constructed from a MC set of events which are supposed to reproduce detector effects. Problems: MC is not perfect (main problem: reproduction of Dz resolution (we add an extra smearing of 46 ± 40 mm) 2) Unfolding contains regularization/filtering to get rid of elements which are statistically non significant, with the MC shapes used as a priori => can discard Data information 3) We have MC events generated only with QM hypothesis, given DM, B0 lifetime (solution: mix OF and SF sets) AB 17-Feb-06

Corrected time dependent asymmetry QM for QM we use fitted value Dmd = 0.503 1012 h/s AB 17-Feb-06

Discussion on systematic errors Sytematic errors on the TDA can originate from 1) errors in background subtraction (in the note) 2) intrinsic behaviour of deconvolution procedure (appendix A) 3) imprecision of the Belle full MC (note and appendix B) 2) will be discussed next presentation AB 17-Feb-06

Systematics: selection, bckgrd, wrong tag fit errors in B± fraction and BRs ratio cuts (appendix B)  M(D*)-M(D0)  cos(qB,D*l) ±1s variation in SF/OF distrib w = 1.5±0.5% ±1 %  ±1s variation in SF/OF distrib M(D*)-M(D0) different sidebands AB 17-Feb-06

Method used to get systematic errors in evt selection for each observable X 1) we first estimate D-MC relative precision on X then, in a way which should reduce the effect of statistical fluctuations 2) we evaluate syst. error from the integrated asymmetry distribution as a function of X AB 17-Feb-06

Exemple: slow pion vertex chi2 ±5 Asymmetry vs chi2 Dt>3ps linear fit AB 17-Feb-06

Exemple: slow pion chi2 comparison DATA & MC Dt>3ps data Dt>3ps MC AB 17-Feb-06

Error estimates (~low Dt) total ±0.001 AB 17-Feb-06

Error estimates (Dt>3 ps) our choice of syst errors: total ±0.005 0-1 ps ± 0.001 1-6 ps ± 0.005 6-20 ps ± 0.010 AB 17-Feb-06

Analysis Checks AB 17-Feb-06

Alternative analysis with s(Vz)<0.01 cm Select events with better resolution in Dz => deconvolution procedure has less to do ... rescale by 1.125 AB 17-Feb-06

Alternative analysis with s(Vz)<0.01 cm Dt>3ps Dt>3ps 0-1 ps ± 0.003 1-6 ps ± 0.019 6-20 ps ± 0.04 syst errors: AB 17-Feb-06

Analysis with s(Vz)<0.01 cm N of events reduced by ~18% s(Vz)<0.01 Errors shown are ~ unfolding  d[s(Vz)] AB 17-Feb-06

Other control: B0 lifetime Plot of Deconvoluted(SF) + Deconvoluted(OF) fit: 1.532±0.017 ps AB 17-Feb-06

Results 1 c2=5/11bins for QM we use pre-BABAR&Belle Dmd = 0.495±0.013 1012 h/s AB 17-Feb-06

Results 2 LR SD c2=74/11bins c2=229/11bins Using pre-BABAR&Belle Dmd = 0.495±0.013 1012 h/s AB 17-Feb-06

Results 3 Let free Dmd QM: Dmd = 0.503±0.010(stat) c2 = 5/11bins LR : Dmd = 0.434±0.009(stat) c2 = 25/11bins SD : Dmd = 0.400±0.010(stat) c2 = 111/11bins to be compared with pre-BABAR&Belle Dmd = 0.495±0.013 1012 h/s AB 17-Feb-06

Results 4 Possible contamination of QM events by a fraction l of SD i.e. Data = (1-l)QM + lSD gives l=0.028±0.063 => compatibe with zero AB 17-Feb-06

Deconvolution Goal: get resolution corrected data. Constraint: we need to be fair with a “large” class of theoretical models. Studied with a toy MC with parametrized resolution in Dz Set of 400 runs, each run consists of: Generation of ~35000 "MC" events based on QM Generation of ~7000 "Data" events based on QM or LR or SD Production of the 2 unfolding matrices for SF, OF events from "MC" Deconvolution of the "Data" independently for the SF and OF subsets 1) Main problem: need to populate event region where QM does not produce events, ex: SF~0 when Dt~0. Trick: add some OF ! 2) Some residual systematic effects observed. Add correction and get systematic errors. AB 17-Feb-06

Deviations wrt generated model stat QM LR SD syst from deconvolution AB 17-Feb-06

Sensitivity to models Generated: QM (analysis errors not included) lambda from fit LR SD chi2/11 lambda generated AB 17-Feb-06

Results QM: chi2 = 5 for 11 bins LR: 112 " SD: 330 " lambda = 0.02±0.05 AB 17-Feb-06