“sin2f1” measurement with bs penguin decays at Belle Koji Hara (Nagoya University) for the Belle Collaboration

Measurement of time-dependent CP violation (tCPV) in B0h’K0 Introduction Measurement of time-dependent CP violation (tCPV) in B0h’K0 tCPV result for B0KSp0 2018/12/8

Introduction J/ B0 B0 K0 K0 tCPV measurements in B0 decays / b→ccs tree b→sqq penguin _ d b c s w d b _ _ w J/ s η’,φ… B0 t g B0 s _ K0 s K0 Check if d S=sin21 , A ~ 0 / “sin21” ≡-ξfS= sin21, A ~ 0 Extra CPV phase “sin2φ1“≠sin2φ1 Hint of New Physics SM Anchor

SM Contamination It is essential to estimate possible deviation from sin2f1within the SM to claim new physics. bu Tree contamination Final state rescattering T’ P 2 P’ T 4 color-allowed   +1 KsKsKs 1 Ks P’ T P T’  Ks Ks  f0Ks Ks ~+1 K+KKs CP mode color-suppresed _ sdd penguin _ sss penguin 2018/12/8

Theoretical Estimation h’K0, fK0, KSKSKS are the “Golden modes” with the smallest expected difference from sin2f1 in SM Expected differences are mostly positive. For example, [Chua, talk at FPCP06, hep-ph/0605301] 2018/12/8

2018/12/8

New tCPV result for B0h’KS+h’KL 2018/12/8

Event Selection Dominant Background is e+e-  qq continuum  Distinguished from signal by the Likelihood Ratio made with event shape variables. Bkg signal Likelihood Ratio Event Shape (Jet-like) (Spherical) 2018/12/8

B0h’KS Signal Event-by-event signal fractions extracted from 3D Mbc-DE-LR fit. LR0.5 LR<0.5 LR fs h’ rg Ks(p+p-) 794  36  h(2g)pp Ks(p+p-) 363  21  h(3p)pp Ks(p+p-) 100  11 rg Ks(p0p0) 103  15 h(2g)pp Ks(p0p0) 62  9 Total 1421  46 2018/12/8

B0h’KL Signal Signals are extracted from PB*-LR 2D fit Background subtracted h’h(2g)pp KL 392  37 h(3p)pp KL 62  13 Total 454  39 LR PB*(GeV/c) 2018/12/8

B0h’K0 Result Consistent with sin2f1 Background subtracted “sin2f1”= + 0.64  0.10  0.04 A = - 0.01  0.07  0.05 Consistent with sin2f1 5.6s First observation of tCPV in bsqq penguin good tag 2018/12/8

CP Fit Results for B0h’KS, KL h’KS Background subtracted “sin2f1” good tag h’KL Background subtracted good tag A 2018/12/8 errors are statistical only

New tCPV result for B0KSp0 2018/12/8

tCPV in KSp0 bs penguin dominant mode S  sin2f1 (Possible deviation within SM ~O(0.1) ) A Member of Kp Family A is important to check the sum rule A(K+p-)+A(K0p+)=A(K+p0)+A(K0p0) No primary tracks from B vertex Vertex reconstruction with KS trajectory [Gronau, Phys. Lett. B627, 82 (2005)] 2018/12/8

B0KSp0 Signal LR<0.7 LR0.7 Signal yield: 515  32 2018/12/8

Vertex Reconstruction with KS Ks track p+ p- Extrapolate KS track to the Interaction Point Vertex reconstruction efficiency ~33% Events without the vertex can still be used for A measurement. IP profile BCP vertex The validity is confirmed with the J/yKS as control sample. B0 Lifetime 1.503+/-0.036 ps sin2f1=+0.68+/-0.06 J/yKS with the KS Vertexing Raw asymmetry good tag 2018/12/8

B0KSp0 tCPV Result “sin2f1”= + 0.33  0.35  0.08 A = - 0.05  0.14  0.05 Consistent with sin2f1 from bc the sum rule expectation A = -0.150.06 using Belle 532M A, Br and PDG2006 t+/t0 good tag 2018/12/8

Summary tCPV in bsqq modes are sensitive to the new physics “Golden modes” are fK0, h’K0, KSKSKS New Results from Belle with 532 M BB Other tCPV results will be reported in the Plenary Talk by M. Hazumi. B0h’K0 “sin2f1”= + 0.64  0.10  0.04 A = - 0.01  0.07  0.05 5.6s tCPV observation B0KSp0 “sin2f1”= + 0.33  0.35  0.08 A = - 0.05  0.14  0.05 2018/12/8

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B0h’KS DE distribution 2018/12/8

B0h’KS,h’KL Results “sin2f1”= + 0.67  0.11 A = - 0.03  0.07 2018/12/8 errors are statistical only

“sin2f1” A 2018/12/8

Systematic Errors h’K0 KSp0 dS dA dS dA Vertexing 0.013 0.021 0.011 0.020 Flavor tagging 0.004 0.007 0.008 0.005 Resolution 0.035 0.024 0.066 0.010 Physics 0.001 0.007 0.007 0.001 Possible Fit bias 0.007 0.005 0.009 0.004 BG fraction 0.020 0.022 0.009 0.001 BG dt shape 0.004 0.002 0.046 0.019 Tag-side interference 0.001 0.024 0.001 0.043 ---------------------------------------------- Total 0.043 0.047 0.082 0.053 2018/12/8