Studies of EPR-type flavor entangled states in Y(4s)->B0B0 Summary: - We use Time Dependent Asymmetry (TDA) to test alternative models to QM. - We provide a fully corrected TDA distribution which can be directly compared to (a large class of) models. Models examined in the note: 1) QM 2) Pompili and Selleri "Local Realism" model (LR) 3) Home made Spontaneous & immediate Disentanglement (SD) 4) Possible contamination of QM events by a fraction l of SD i.e. Data = (1-l)QM + lSD AB 6-Feb-06

The models for AQM(Dt)=cos(Dmd Dt) Pompili and Selleri (Local Realism): Home made (Spontaneous Decorrelation at time~0): the non-QM models contain information on the decay time of the individual B mesons. AB 6-Feb-06

Time dependent asymmetry for the 3 models AB 6-Feb-06

Experimental study collect events with B mesons decaying with Opposite Flavor (OF) and Same Flavor (SF) Measure Dt (from Dz) Asymmetry function of Dt: AB 6-Feb-06

Using D*ln events "B0 side": B0 -> D* l n D* -> D0 + slow pion D0 -> Kp Kpp0 K3p "Tag side": remaining particles to standard BELLE procedure. Select only the subset with highest purity. see next presentation AB 6-Feb-06

Event selection summary AB 6-Feb-06

Background subtraction Wrg flavor correction see next presentation AB 6-Feb-06

Raw time dependent asymmetry 1 -1 After event selection syst stat Background subtracted 0 4 8 12 16 20 ps AB 6-Feb-06

Data deconvolution 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 Dmd, B0 lifetime (solution: mix OF and SF sets) AB 6-Feb-06

Corrected time dependent asymmetry QM for QM we use Dmd=0.502 1012 hbar/s AB 6-Feb-06

Systematic errors Sytematic errors in the time dependent asymmetry can originate from 1) errors in background subtraction (in the note) 2) intrinsic behaviour of deconvolution procedure (in appendix A) 3) imprecision of the Belle full MC Point 3): we can data-MC discrepancy in the following - resolution on Dz (appendix A) - wrong flavour correction (note) - observables on which we apply a cut (note and appendix B) AB 6-Feb-06

Systematics: selection, backgrd, wrong tag fit gives a B± fraction 3.11±0.22% cuts (appendix B)  M(D*)-M(D0)  cos(q(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 6-Feb-06

Other control: B0 lifetime Plot of Deconvolved(SF) + Deconvolved(OF) fit: 1.532±0.017 ps AB 6-Feb-06

Sensitivity to models Generated: QM (analysis errors not included) lambda from fit LR SD chi2/11 lambda generated AB 6-Feb-06

Results QM: chi2 = 5 for 11 bins LR: 112 " SD: 330 " lambda = 0.02±0.05 AB 6-Feb-06

Using pre-Y(4s) Dmd value 0.484 +- 0.012 chi2 ~9/11 bins AB 6-Feb-06

using Dm=0.484 +- 0.12 LR SD chi2=76/11bins chi2=277/11 bins AB 6-Feb-06