Sensitivity Study for B 0 π 0 π 0

Transcription

1 Sensitivity Study for B π π Fernando Abudinén June 7, SuperKEKB and Belle II 2 CP-Violation in the SM 3 Why CP-V. Sensitivity to B π π? 4 -Conversions and π e + e 5 Summary and Outlook

2 KEKB/SuperKEKB Collider Upgrade: KEKB SuperKEKB Belle Belle II 3km e+ e Colliding bunches 1 KEK = kō enerugī kasokuki kenkyū kikō high energy collider research organization At: Tsukuba, Ibaraki Prefecture, Japan

3 Belle/Belle II Experiment 2 KEKB/Belle SuperKEKB/Belle II operation e /e + beam E 8/3.5 GeV 7/4 GeV e /e + beam I 1.2/1.6 A 2.6/3.6 A Inst. Lumi. L cm 2 s cm 2 s 1 L dt 123 fb 1 ( B B pairs) 5 ab 1

4 Nano Beam Scheme Lorentz factor L = ± 2er e beam size σ x,y = ε x,y β x,y ( emittance SuperKEKB 1 + σ ) ( y I ± ξ ± σ x β y beam-beam parameters ) ( ) RL present KEKB R ξy Geometric factors 3

5 Time of Propagation counter with 2 mm quartz bars MCP-PMT readout K L /µ Detector (outside) RPC Plates and plastic scintillators with SiPM readout Superconducting Magnet homogeneous field of 1.5 T Electromagnetic Calorimeter 8 CsI Crystals, 16 X PMT/APD readout Pixel Vertex Detector 2 layer pixel detector (8MP) technology Silicon Vertex Detector 4 layer double sided strips 2 5 ns shaping time Central Drift Chamber proportional wire drift chamber 15 sense wires in 58 layers Aerogel RICH Proximity focusing RICH with silica aerogel

6 Our Contributions PXD development: Sensor design, prod. and testing Analysis of testbeam data Mechanical design, final assembly Cooling system (IBBelle) Software development: Belle II framework development PXD and SVD simulation w/o machine background 5 Tracking, Vertexing and Flavor Tagging Neural z-vertex trigger Machine commissioning: Design, prod. and operation of CLAWS detector Belle CP-Analysis: B π + π, π K +, K K + ρρ, ωk S Belle II sensitivity studies: B J/ψK S, π π

7 CP-Violation in the SM Why CP-Violation? Matter-Antimatter-Asymm. in the universe larger than in SM. Sakharov s 2 nd cond.: C-V, CP-V. Why in the B -system? largest CP-V. within the SM. 6 CP-V. in the SM Weak Interaction V CKM d V ud V us V ub d s = V cd V cs V cb s b V td V ts V tb b Wolfenstein-Parameters: λ= sin θ C.2, A, ρ, η λ2 λ Aλ 3 (ρ iη) V CKM = λ λ2 Aλ 2 + O(λ 4 ) Aλ 3 (1 ρ iη)] Aλ 2 1 L Yuk igw µ Jµ cc Jµ cc CP Jµ cc Jµ cc Unitarity: k V ikv jk = V udv ub + V cdv cb + V tdv tb = O(λ 3 ) O(λ 3 ) O(λ 3 )

8 CKM-Triangle η ρ = excluded area has CL >.95 ( 1 λ2 2 sin 2β LHCb sin 2β WA ε K ) ρ η = m d & m s m d α ( 1 λ2 2 ρ L dt = 5 ab 1?? ε K ) CKM f i t t e r La Thuile 215 sol. w/ cos 2β < (excl. at CL >.95) V ub.1 β α α η hep-ph/2171

9 Time-dep. CP-Analysis at B-Factories σ(e + e Hadrons) [nb] Υ(1S) Υ(2S) Υ(3S) Υ(4S) Υ(4S) above BB prod. threshold B-Factory 51 % are B + B 48 % are B B q B,B = 1, 1 continuum background e + e Center-of-Mass Energy [GeV] e Υ(4S) Boost B tag e + B CP l z z 13µm B B at rest in CMS t = z β c π π K β Belle =.425 β Belle II =.284 e + e 8 P Sig ( t, q) = e t /τ B 4τ B [1 + q (A CP cos( m t) + S CP sin( m t))]

10 Pixel Vertex Detector Ac or tiv ep ec t i x e l Det active area gaten clearn 76 8 px 25 px m gaten m clearn+1 ( 12.5 mm pixel center) SwitcherB (32 channels gate/clear) DCD-B (analog readout) DHP (digital processing) power 75 μm active area thickness 2 mm / 42 μm rigid frame differential data transmission ( 1.6 Gb/s) ground 9 Background Closest to IP Occupancy ( r 2 ) mounting hole flexible interconnect (polyimide/copper) Inst. Lumi.: LBelle II 4 LBelle conductive layers (Al/Al/Cu) hβibelle II < hβibelle smaller z Pixel Detector needed! Technology most suited Depleted Field Effect Transistor

11 1 Active Pi xel Detector The Impact Parameter Particle track parametrization: t(d, φ, Ω = q p t, z, tan(λ)) d (z ): distance from point of closest approach to origin. Improvement by factor 2

12 Time-dependent CP-Analysis B B B B A CP For B ππ: tree and penguin diags. contribute! f f B B S CP f CP i: A CP = S CP = sin(2α) i+f: A CP S CP = 1 A CP sin(2α eff ) b d * V ub + W V ud + W u d u d Isospin I =, 2 11 α eff = α α I α CKM-Triangle β R b d V tb t g * V td d u u d I =

13 12 Active Pi xel Detector Extraction of α angle from B ππ Extr. α through isospin analysis: PhysRevLett A A + = A(B π + π ) 1 2 A + + A = A Ā + + Ā = Ā 1 A α 1 A +- 2 = A - A + A Pure Tree: A + = Ā Isospin analysis requires also S π + π and S π π. S π π needs z 13µm of B π π where π Challenge!

14 13 Active Pi xel Detector Extraction of α angle from B ππ p-value 1 - CL w/out S π π 8 fold ambiguity on α CKM f i t t e r WINTER 12 B ππ (BABAR) B ππ (Belle) B ππ (WA) α (deg) CKM fit 1 - CL Extrapolated to L Belle II = 5ab α ( ) arxiv:hep-ex/7329 with S π π 2 fold ambiguity on α Converted e + e and π e + e req. for z Possible with L Belle II = 5 L Belle and Belle II PXD? α ( )

15 Expected Asymmetry Events / (.22 ps ) both - q = +1 - q = t / ps A π π CP =.43 (PDG) S π π CP = 1 A CP sin 2 (α α ) hep-ex/7339

16 Vertex of -Conversions in B π π y / cm 3 e + e Pipe 2 PXD 1 PXD x / cm Υ(4S) B 1 B 2 B 1 generic B 2 π π π (B = 98.82%) π e + e (B = 1.17%) N Belle II = L Belle II B(Υ(4S) B B ) 2 B(B π π ) 5ab 1 1.1nb k events. Accept.: θ [17, 15] ECL: θ [12.4, 155.1]

17 Events with -Conversions % a) If there is an event with -conversions How Many? % b) How many Events have at least one -conversion? Vertex in Events % Beam Pipe 2. % 1st. PXD Layer.6 % 2nd. PXD Layer.5 % Total inside PXD 3.1 % %.8%.1% Number of -Conversions c)... and at least one -conversion or one π e + e decay? π e + e 2. % Total π 5.5 % 16 Requirement: All converted in accept. and not converted in ECL

18 B Vertex Reconstruction Algorithm: Kinematic Vertex Fit Access: RAVE (Reconstruction in a Abstract, Versatile Environment) TNS Vertex Reconstruction with spatial constraint centered at the Beam Spot. τ π.9 as =.1 nm π Vertex ˆ= B Vertex. Q on e ± Tracks: At least one PXD hit. Check with MC truth. x e x e BS B e + z BS B e + z 17 e + e π e + e

19 B z-vertex Resolution B π π e + e Events / (.6 cm ) Entries 112 Mean -4.9 µm Std Dev µm Events / (.6 cm ) Entries 556 Mean.2 µm Std Dev 88.5 µm B_Z - Gen. B_Z / cm No PXD Hit required B_Z - Gen. B_Z / cm At least one track (e + or e ) has one PXD Hit

20 B z-vertex Resolution B π π e + e Events / (.6 cm ) Entries 9294 Mean 2.8 µm Std Dev 71.6 µm Events / (.6 cm ) Entries 916 Mean 3.3 µm Std Dev 69.3 µm B_Z - Gen. B_Z / cm No PXD Hit required B_Z - Gen. B_Z / cm At least one track (e + or e ) has one PXD Hit

21 t Resolution Events / (.1 ps ) t = t B CP t B tag B CP π π Entries 1316 Mean.6 ps Std Dev 3.42 ps t - Gen. t / ps No PXD Hit required Events / (.1 ps ) e + e Entries 5861 Mean -.17 ps Std Dev 2.22 ps t - Gen. t / ps At least one track (e + or e ) has one PXD Hit

22 t Resolution t = t B CP t B tag B CP π π e + e Events / (.1 ps ) 4 Entries 9613 Mean -.2 ps 35 Std Dev 1.85 ps Events / (.1 ps ) 4 Entries Mean -.14 ps Std Dev 1.76 ps t - Gen. t / ps t - Gen. t / ps 21 No PXD Hit required At least one track (e + or e ) has one PXD Hit

23 22 Active Pi xel Detector Summary and Outlook Beam Spot constrained kinematic vertex fit reaches higher resolution with PXD Information. Higher t resolution. Next: Continuum suppression and MC Campaign. New Physics needed to explain observed matter-antimatter asymmetry New Sources of CP-Violation needed. Search at next generation B-Factory SuperKEKB with 5 ab 1 complementary to LHC. Machine commissioning started! Begin of data taking planned for 218! Strong contribution from our institute!

24 NP in Semileptonic Decays R(X) R( ) R(D ) b Vqb H R(D ( ) ) = B(B! D( ) ) B(B! D ( )` `) q 23 R(D) R(D ) χ χ

25 NP in Lepton Flavor Violation μ 24 9% CL bound μ μ μn τ τ e 3e μ 3μ en Year BABAR / Belle MEGA Super-B (5 ab 1 ) MEG SINDRUM-II MEG II Spectacular perspectives: Mu2e / COMET PRISM / PRIME

26 B Reconstruction 1 Select single ECL clusters: s Inputs: E9E25, LAT, NHits, R, E, σ E, t, σ t, 2 Rec. and sel. c e + e Inputs: m, p, E, p highest, θ e +,e 3 Rec. and sel.: π ss s s π sc s c π dal e+ e s Inputs: m, p, E, p lowest, θ e +,e, θ,e + e Selection with FBDTS Rec. and sel.: B ss π ss π ss B sc π sc π ss B dal π dal π ss Inputs: m bc, E, σ m, θ π 1,π 2

27 π Kinematics Number of Events/.3 GeV/c p/ GeV/c 1 5 π Boost θ, e + e θ e+,e Number of Events/ Number of Events/ θ, / Degrees θ e +, e / Degrees

28 π e + e Kinematics 1 Number of Events/.3 GeV/c p/ GeV/c π Boost e + e θ, e + e θ e + e Number of Events/ Number of Events/ θ, e + e / Degrees θ e +, e / Degrees

29 π e + e CMS Kinematics Number of Events/.3 GeV/c p/ GeV/c 1 3 π Boost e + e θ, e + e θ e + e Number of Events/ 1 Number of Events/ θ, e + e / Degrees θ e +, e / Degrees

30 t t t Active Pi xel Detector e +, e e +, e Track Reconstruction / cm σ d.25.2 Fit / GeV/c p MC p / GeV/c t MC p / GeV/c t / cm σ z p / GeV/c MC t MC / p Fit p p / GeV/c MC t