A.Mordá. INFN - Padova. 7 th July on behalf of the Belle2 Collaboration. CP Violation sensitivity at the Belle II Experiment

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1 A. Mordá CP Violation sensitivity at the Belle II Experiment 7 th July 7 / CP Violation sensitivity at the Belle II Experiment A.Mordá on behalf of the Belle Collaboration INFN - Padova 7 th July 7

2 Introduction CPV in tandard Model CP Violation (CPV) in the tandard Model (M) The B Unitarity Triangle (UT) Asymmetric Υ(4) Two angles depend on top-beauty coupling accessible through B oscillation processes α W A σ = ( ), β W A σ = ( ) [CKMFitter, ummer `6] t z/βγc Time dependent rate asymmetry of B meson decays into CP eigenstates a fcp ( t) Γ[B( t)] Γ[ B( t)] = C cos ( M t) sin ( M t) Γ[B( t)] + Γ[ B( t)] C : Direct CPV sin ( eff i ) : mixing induced CPV A. Mordá CP Violation sensitivity at the Belle II Experiment 7 th July 7 /

CP Violation sensitivity at the Belle II Experiment Introduction uperkekb & the Belle detector uperkekb & the Belle detector reduced luminosity projection CP V uperkekb large statistic

e II/uperKEKB higher Υ(4) boost background Pixel detector factor improvement in vertexing achievable Resolution J/ψ µµ Tag side 9 months/year days/month t Belle 43µm 89µm.9 ps Belle 5.

3 CP Violation sensitivity at the Belle II Experiment Introduction uperkekb & the Belle detector uperkekb & the Belle detector reduced luminosity projection CP V uperkekb large statistic samples BR Integrated luminosity (ab-) Goal of Be!e II/uperKEKB higher Υ(4) boost background Pixel detector factor improvement in vertexing achievable Resolution J/ψ µµ Tag side 9 months/year days/month t Belle 43µm 89µm.9 ps Belle 5.6µm 53µm.77 ps Peak luminosity (cm-s-) Two benchmark scenarios: yst : yst : KEKB uperkekb µm 3 µm no improvement factor improvement Calendar Year ( 34 L s R L + e e βγ < z > cm dt (ab ) energy (GeV) energy (GeV) A. Mordá ) E cient Flavor Tagger CP Violation sensitivity at the Belle II Experiment 7th July 7 3 /

4 A. Mordá CP Violation sensitivity at the Belle II Experiment 7 th July 7 4 / CP Violation sensitivity at the Belle II Experiment sin(β) measurement b c cs transitions sin (β) in tree dominated b c cs transitions One dominant weak phase J/ψ B B b d c W sin (β) Penguin pollution J/ψ b d u c W c c s s K K Current status from Belle [PRL 8 78] Value stat ( 3 ) syst ( 3 ) J/ψK c cs A C , A C (C) is statistically (systematically) dominated Irreducible systematics from vertexing & tag-side interference Belle expected 5 ab Expected errors ( 3 ) stat syst reducible yst yst J/ψK c cs A C ,- +4, A C Precision better than % is expected on β from b c cs

5 sin(β) measurement b q qs transitions sin (β) in penguin dominated b q qs : B K Loop process, same weak phase as b c cs B b d s W s t, c, u s K Current status from Belle: = K.9 Expected 5 ab Channel σ() σ(c) (K + K )K(π + π ) (K + K )K(π π ).3.96 (π + π π )K(π + π ).5.3 K modes.6.44 K + K L modes ensitivity studies without beam induced background Time resolution of benchmark modes Channel t resolution (ps) (K + K )K(π + π ).75 (K + K )K(π π ).77 (π + π π )K(π + π ).78 t rec t MC in (K + K )K (π+ π ) MC events Belle II Total fitting function Core component f =.5576 σ =.399 ps Tail component f =.3655 σ =.9 ps Outlier component f =.769 σ =.57 ps 4 4 t Resolution (ps) A. Mordá CP Violation sensitivity at the Belle II Experiment 7 th July 7 5 /

6 sin(β) measurement b q qs transitions sin (β) in penguin dominated b q qs : B η K Current status from Belle: = +.68 ±.7 ±.3 [JHEP 65] η K Crucial aspect is π, η reconstruction Non negligible fraction of mis-reconstructed signal (xf) ensitivity studies accounting for beam induced background Expected 5 ab Channel σ() σ(c) η (η γγ π + π )K(π + π ).6.4 η (η 3π π + π )K(π + π )..8 K modes.8. K L modes.8.5 K + K L modes.7. yst. (.7) yst () scenarios Time resolution of benchmark modes Channel True xf All η (η γγ π + π )K(π + π ). ps.87 ps.45 ps η (η 3π π + π )K(π + π ).7 ps.36 ps.5 ps Asymmetry Belle II - L = 5 ab J/ψ K η' K ( =.7) ( =.55) 5 5 t (ps) B η K is the rst b q qs mode systematic L () ab A. Mordá CP Violation sensitivity at the Belle II Experiment 7 th July 7 6 /

CP Violation sensitivity at the Belle II Experiment sin(α) measurement The Gronau London method sin (α)

u d d u b ū B W t, c, u ū d π b W d Time dependent B π + π analysis measures α eff = α + δα peng π + π

isospin relation among A (i,j) A(B i+j h i h j ) (h = π, ρ / i, j = ±, ) A + / + A = A + Ā + / + Ā = Ā +

98] α eff = (Ā+, A + ), α = (Ā+, A + ) measure rates to construct the two triangles measure asymmetries

7 CP Violation sensitivity at the Belle II Experiment sin(α) measurement The Gronau London method sin (α) measurement: isospin analysis in B ππ, ρρ Two amplitudes of comparable size and dierent weak phase B π + u d d u b ū B W t, c, u ū d π b W d Time dependent B π + π analysis measures α eff = α + δα peng π + π Gronau-London method [PRL (99)] Im α eff Re A +- / A Estimate penguin contribution exploiting isospin relation among A (i,j) A(B i+j h i h j ) (h = π, ρ / i, j = ±, ) A + / + A = A + Ā + / + Ā = Ā + A + = Ā + Picture from [arxiv:75.98] α eff = (Ā+, A + ), α = (Ā+, A + ) measure rates to construct the two triangles measure asymmetries to x their relative position π + π leaves an 8-fold ambiguity in α xed by time dependent B π π analysis A. Mordá CP Violation sensitivity at the Belle II Experiment 7 th July 7 7 /

8 A. Mordá CP Violation sensitivity at the Belle II Experiment 7 th July 7 8 / CP Violation sensitivity at the Belle II Experiment sin(α) measurement B ππ sin (α) measurement: B π π sensitivity First attempt to measure π π B sig π γγ( γγ) π γγ( γγ) Conversion vertices in the innermost part of detector B sig π dal( e + e γ) π γγ( γγ) B sig π γ c γ( γ c ( e + e )γ) π γγ( γγ) y / cm 3 Pipe PXD PXD Reconstruction eciency is crucial tatistical uncertainty estimated through MC toys σ().9 Events / (. ) χ / ndf = =.6 ±.3 x / cm CP, i CP µ σ =.94 ±.9

9 sin(α) measurement B ππ sin (α) measurement: B ππ Isospin analysis input in B ππ Value ab 5 ab B + [ -6 ] π π 5.4 ±. ±.8 [] ±.3 ±.8 B [ -6 ] π π.3 ±.9 ±.8 [] ±.4 ±.4 B + [ -6 ] π π 5.86 ±.6 ±.38 [] ±.3 ±.9 C + π π.33 ±.6 ±.3 [3] ±. ±.3 + π π.64 ±.8 ±.3 [3] ±. ±. C π π.4 ±.36 ±. [] ±.3 ±. π π ±.9 ±.3 - CL Belle, Belle ( ) []: arxiv:75.83 []: PRD 87(3) 33 []: PRD 88(9) 93 Adding π π input = - CL π π α exp ππ 88 σ ( ) A. Mordá CP Violation sensitivity at the Belle II Experiment 7 th July 7 9 /

10 sin(α) measurement B ρρ sin (α) measurement: B ρρ Isospin analysis input in B ρρ Value ab 5 ab f + L,ρ ρ.988 ±. ±.3 [] ±. ±.3 f L,ρ ρ. ±. ±.5 [] ±.3 ±. B ρ + ρ [ -6 ] 8.3 ±.5 ±.5 [] ±.9 ±.4 B ρ ρ [ -6 ]. ±.3 ±.5 [] ±.4 ±. C ρ + ρ. ±. ±.6 [] ±. ±. ρ + ρ.3 ±.5 ±.5 [] ±. ±. Value ab 5 ab f + L,ρ ρ.95 ±. ±. [3] ±.4 ±.3 B ρ + ρ [ -6 ] 3.7 ±7. ± 5.3 [3] ±.3 ±.5 Value ab 5 ab C ρ ρ. ±.8 ±.3 [4] ±.8 ±. ρ ρ.3 ±.7 ±. [4] ±.7 ±. Belle, Belle (+ ρ ρ, π π ) B ρρ, α exp ρρ σ.7 []: PRD 93(3) 3, []: Add PRD 89 no. 993, [3]: PRL 9 8, [4]: PRD ( ) A. Mordá CP Violation sensitivity at the Belle II Experiment 7 th July 7 / - CL - CL ( ) B ρρ & B ππ α exp hh σ

11 Conclusions Conclusions The Belle program large dataset improved detector and physics software (Flavor tagging, vertex reconstruction) unique possibilities for modes with nal state with neutral particles sin (β) will remain the most precise measurement on the UT parameters (precision level of penguin pollution) sin (α) measurement will benet of reduced errors and new inputs ( π π, B ρπ mode) for isospin analysis other time dependent CP-violation analysis Belle (photon polarization in B K ( π K)γ) Current world average Belle 5ab η excluded area has CL >.95 sin 3 3 ρ ε K CKM f i t t e r ICHEP 6 sol. w/ cos < (excl. at CL >.95) CPV only inputs More details in the Belle II Physics Book η sin 3 3 ρ sol. w/ cos < (excl. at CL >.95) A. Mordá CP Violation sensitivity at the Belle II Experiment 7 th July 7 / excluded area has CL >.95 CKM f i t t e r - BELLEII 5 ab M

12 Conclusions - BELLEII 5 ab WA 7 Conclusions The Belle program large dataset improved detector and physics software (Flavor tagging, vertex reconstruction) unique possibilities for modes with nal state with neutral particles sin (β) will remain the most precise measurement on the UT parameters (precision level of penguin pollution) sin (α) measurement will benet of reduced errors and new inputs ( π π, B ρπ mode) for isospin analysis other time dependent CP-violation analysis Belle (photon polarization in B K ( π K)γ) Current world average Belle 5ab η excluded area has CL >.95 sin 3 3 m d & m s m d ρ V ub ε K CKM f i t t e r ICHEP 6 sol. w/ cos < (excl. at CL >.95) All inputs More details in the Belle II Physics Book η excluded area has CL >.95 sin 3 3 & m s m d ρ V ub sol. w/ cos < (excl. at CL >.95) A. Mordá CP Violation sensitivity at the Belle II Experiment 7 th July 7 / CKM f i t t e r

13 A. Mordá CP Violation sensitivity at the Belle II Experiment 7 th July 7 / Backup

14 A. Mordá CP Violation sensitivity at the Belle II Experiment 7 th July 7 3 / Belle Vertexing DEPFET Technology Benchmark modes J/ψ µµ in B J/ψK z 6µm B tag in B J/ψK x B B D + z Events / (.6 cm ) B tag vtx residuals Mean 7. µm td Dev 5. µm Events / (. ps ) t residuals Mean.5 ps td Dev.7 ps TagVz - GenTagVz / cm t Gen. ps - t /

15 A. Mordá CP Violation sensitivity at the Belle II Experiment 7 th July 7 4 / sin(β) in b c cs transitions J/ψK (5 ab ) No Vertex Leptonic improvement improvement categories stat syst. reducible... syst. irreducible (5 ab ) A J/ψK stat syst. reducible syst. irreducible J/ψπ (5 ab ) No Vertex Leptonic improvement improvement categories stat syst. reducible syst. irreducible A (5 ab ) J/ψπ stat syst. reducible syst. irreducible No Vertex Leptonic improvement improvement categories c cs (5 ab ) stat syst. reducible syst. irreducible A c cs (5 ab ) stat syst. reducible syst. irreducible

16 A. Mordá CP Violation sensitivity at the Belle II Experiment 7 th July 7 5 / Penguin pollution in sin(β) from B J/ψK Let us denote the O(λ s u/λ s c) terms in by J/ψK J/ψK sin + J/ψK sin( + δ J/ψK ) δ J/ψK O(λ s u/λ s c). mall parameters J/ψK or δ J/ψK referred to as the `penguin pollution' in the extraction of from J/ψK. trategy J/ψK [%] δ J/ψK [ ] ( ) QCDF/pQCD [,] (. ). Need strategies to either compute, bound or control OPE [3].9 (.68 ) J/ψK. Broken U-spin [4,5] ±. ±.6 ( ) Broken U-spin [6] [ 5,.5] [.,.4] J/ψK = λ Re P f sin 3 cos + O( λ 4 ) T f U(3) at O(ε) [7].8 ( +.9 Broken U(3) [8] (.4.) ) ( ) []: PRD 7 366, []: JHEP 3 9, [3]: PRL 5 68, [4]: PRL 95 84, [5]: arxiv:.39, [6]: PRD79 43, [7]: PRD , [8]: JHEP 53 45

17 Penguin pollution in sin(β) from B J/ψK U-spin-breaking corrections are parametrized by the parameter ε m s /Λ QCD.. Flavor breaking corrections cannot be controlled with a single partner mode, and hence such U-spin analyses require additional assumptions ( + λ ) sin = J/ψK λ J/ψπ ( K + λ π ) cos tan 3 where penguin pollution eects are cancelled to O(ε) and leading corrections arise from isospin-breaking terms. Here K,π are splittings of the charged and neutral CP-averaged rates, K Γ Bd J/ψK Γ B + J/ψK + Γ Bd J/ψK + Γ B + J/ψK + Γ Bd J/ψπ Γ + + B J/ψπ π Γ Bd J/ψπ + Γ + + B J/ψπ Expected uncertainty of. on from B J/ψK, when estimating penguin pollution and ignoring for now the O(ɛ ) eects from U(3) breaking. A. Mordá CP Violation sensitivity at the Belle II Experiment 7 th July 7 6 /

18 A. Mordá CP Violation sensitivity at the Belle II Experiment 7 th July 7 7 / sin(β) in b c cs transitions - systematics from Belle J/ψK ψ()k χ c K J/ψK L All Vertexing f ±.8 ±.3 ±.5 ±. ±.7 A f ±. ±.6 ±. ±.5 ±.7 t f ±.7 ±.7 ±.5 ±.7 ±.7 resolution A f ±.4 ±.3 ±.4 ±.3 ±. Tag-side f ±. ±. ±. ±. ± interference A f ±.8 Flavor f ±.3 ±.3 ±.4 ±.3 ±.4 tagging A f ±.3 ±.3 ±.3 ±.3 ±.3 Possible f ±.4 ±.4 ±.4 ±.4 ±.4 t bias A f ±.5 ±.5 ±.5 ±.5 ±.5 ignal f ±.4 ±.6 <. ±.6 ±.4 fraction A f ±. ±.6 <. ±.6 ±. Background f <. ±. ±.3 ±. ±. t PDFs A f <. <. ±.4 <. <. Physics f ±. ±. ±. ±. ±. parameters A f <. <. ±. <. <. Total f ±.3 ±.36 ±.4 ±. ± A f ±. ystematic errors in f and A f C f in each f CP mode and for the sum of all modes [PRL 8 78]

19 A. Mordá CP Violation sensitivity at the Belle II Experiment 7 th July 7 8 / b q qs modes eciencies B η K Channel trategy ε ε xf η (η γγ π ± )K (±) C 3. % 3.8 % A 6.7 %.6% η (η 3π π ± )K (±) B 8. % 6.% C 9.5 % 8.6% election eciency ε and fraction of signal cross feed candidates ε xf for the η (η γγ π ± )K (±) and η (η 3π π ± )K (±) channels when selecting only one (A), two (B), or all (C) the candidates in the event. The selected strategy is labeled with. B ωk ω(π + π π )K (π± ) L (ab ) yield σ() σ(a) Extrapolated sensitivity for the ωk mode. The t resolution is taken from the η K study, while we assume a reconstruction eciency of % B K Channel ε reco Yield σ( K ) σ(a K ) ab lumi.: (K + K )K (π+ π ) 35% (K + K )K (π π ) 5% (π + π π )K (π+ π ) 8% K modes combination K + K L modes combination ab lumi.: (K + K )K (π+ π ) 35% (K + K )K (π π ) 5% (π + π π )K (π+ π ) 8% K modes combination.6.44 K + K L modes combination ensitivity estimates for and A parameters. The eciency K K ε reco used in this estimate has not been taken from the simulation, but is rather an estimate taking into account the expected improvements. ystematic uncertainties, negligible for these integrated luminosities, are not included

20 A. Mordá CP Violation sensitivity at the Belle II Experiment 7 th July 7 9 / sin(β) expected sensitivities Channel L Event yield σ() σ()7 σ(a) σ(a) 7 J/ψK 5 ab K 5 ab η K 5 ab ωk 5 ab Kπ γ 5 ab Kπ 5 ab Expected yields and uncertainties on the and A parameters for the channels sensitive to sin( ) discussed in this chapter for an integrated luminosity of 5 (5) ab for J/ψK (penguin dominated modes). In the 5th and the last column are shown the present WA errors on each of the observables (HFAG summer 6).

21 A. Mordá CP Violation sensitivity at the Belle II Experiment 7 th July 7 / Flavor tagging ε & w Fast BDT Combiner r- bin ε i (%) ε i (%) w i (%) w i (%) ε e,i (%) ε e,i (%) Total ε e = i ε i w i = 35.8% ε e =.7%

22 A. Mordá CP Violation sensitivity at the Belle II Experiment 7 th July 7 / Flavor tagging ε & w Number of Events/ (q r) FBDT B B rmc = wmc r FBDT

23 A. Mordá CP Violation sensitivity at the Belle II Experiment 7 th July 7 / B ππ, B ρρ ( ) exp χ (x data x theo ) T Σ (x data x theo ) = log (π) n det Σ - CL π π CL π π ( ) ( )

CP Violation sensitivity at the Belle II Experiment

CP Violation sensitivity at the Belle II Experiment for the Belle II collaboration Max-Planck-Institut für Physik, München 29th Rencontres de Blois May 30th 2017 The Unitarity Triangle All flavor variables