Searches for CP violation in decays from BABAR and Belle

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1 D Searches for CP violation in decays from BABAR and Belle Maurizio Martinelli on behalf of the BABAR Collaboration Università degli Studi di Bari and INFN FPCP 1 May 7 1, Torino ITALY

2 CP violation in D decays Standard Model: CP violation from KM phase in CKM quark mixing matrix: 1 λ λ Aλ 3 (ρ iη i ηλ λ 1 λ iηa λ 4 Aλ (1 iηλ Aλ 3 (1 ρ iη Aλ 1 Charmed Mesons: CP violation is CKM suppressed O(13 Experimental Sensitivity O(1 1% Signal = New Physics May 7, 1 Maurizio Martinelli Searches for CP violation in D decays from BABAR and Belle

3 New Physics Scenario CPV ~ 1% Strong Evidence for nonsm processes Direct CP violation at tree level («1% extra quarks in SM vectorlike representations supersymmetry without Rparity models two Higgs doublet models Direct CP violation at oneloop (1% QCD penguin and dipole operators FCNCs in supersymmetric flavor models. Singly Cabibbo Suppressed (CS decays are uniquely sensitive to Cabibbo Favoured and Double CS are not c uq q May 7, 1 Details: Y. Grossman, A. L. Kagan and Y. Nir, Phys. Rev. D75, 368 (7 I. I. Bigi, hepph/148 (1 Maurizio Martinelli Searches for CP violation in D decays from BABAR and Belle 3

4 Charm & Bfactories Why search for CP violation at Bfactories: Υ(4S: ccbar cross section = 1/4 total require p * (D >.5 GeV/c to reduce background Events/(1 MeV/c 4 3 MC BB 5 cc uds p(d* >.5 GeV/c D * D π provides D flavor 1 Drawback: Electroweak ForwardBackward asymmetry [D* D, D K sig] p(d* (GeV/c lab May 7, 1 Maurizio Martinelli Searches for CP violation in D decays from BABAR and Belle 4

5 Experimental Searches Direct CP violation Dalitz Plot analysis Time dependent T odd correlations May 7, 1 Maurizio Martinelli Searches for CP violation in D decays from BABAR and Belle 5

6 Direct CP violation In asymmetric detectors like BABAR and Belle, forwardbackward asymmetry could bias these measurements FB asymmetry = EWEM currents interference N c /N c = f(cos θ Two solutions: A CP = Γ D Γ D Γ D Γ D estimate FB asymmetry contribution normalize CP asymmetry to CF channels = yields A CP = R D R D R D R D, with R = Γ CS Γ CF May 7, 1 Maurizio Martinelli Searches for CP violation in D decays from BABAR and Belle 6

maximum likelihood fit to (m(d, m K π (nπ WS R D K π (nπ WS R D K π (nπ WS R D K π (nπ WS D K π π D K π π π Belle (81fb 1, with R WS = Γ(K

7 A CP = RD Doubly Cabibbo Suppressed D K π (nπ Phys. Rev. Lett. 95, 3181 (5 D* tagged Identification of Right Sign and Wrong Sign decay using K charge Both are DCS, using ratio DCS/CF yields D binned maximum likelihood fit to (m(d, m K π (nπ WS R D K π (nπ WS R D K π (nπ WS R D K π (nπ WS D K π π D K π π π Belle (81fb 1, with R WS = Γ(K π (nπ Γ(K π (nπ RS mass Q RS mass Q syst. <.1 WS WS ACP Kππ =.18±.44 mass Q mass Q ACP Kπππ =.6±.53 ND tot =1978±14 ND tot =171±75 May 7, 1 Maurizio Martinelli Searches for CP violation in D decays from BABAR and Belle 7

8 Cabibbo Suppressed Decays: D h h A CP = Γ(D h h Γ(D h h Γ(D h h Γ(D h h = Ahh CP,dir A hh CP,ind from mixing analysis Major issue: asymmetry in D tagging FB asymmetry soft pion(πs reconstruction asymmetry Need to separate contributions to ACP A hh CP,dir = A hh CP A FB A πs May 7, 1 Maurizio Martinelli Searches for CP violation in D decays from BABAR and Belle 8

Cabibbo Suppressed Decays: D h h map the πs asymmetry using D K π tagged and untagged data to retrieve the weighting factors to correct D yield a ± (cos θ = n D (± cos θ n D (± cos θ n D (± cos θ n D

9 Cabibbo Suppressed Decays: D h h map the πs asymmetry using D K π tagged and untagged data to retrieve the weighting factors to correct D yield a ± (cos θ = n D (± cos θ n D (± cos θ n D (± cos θ n D (± cos θ A CP [a (cos θ a (cos θ ]/ A FB [a (cos θ a (cos θ ]/ even: ACP uniform over cosθ odd: AFB asymmetric over cosθ measure ACP in cosθ bins in order to isolate production asymmetry measure ACP from χ fit over cosθ bins May 7, 1 Maurizio Martinelli Searches for CP violation in D decays from BABAR and Belle 9

Cabibbo Suppressed Decays: D h h a KK a KK FB CP..1.1...4.6.8..4.6..4.6.8 Sample K π untag K π tag K K π π Phys. Rev. Lett. 1, 6183 (8 D K K D π π (a (c a ππ a ππ FB CP..1.1...4.6.8 D..4 (b cos θ CMS D cos θ CMS (d.

10 Cabibbo Suppressed Decays: D h h a KK a KK FB CP Sample K π untag K π tag K K π π Phys. Rev. Lett. 1, 6183 (8 D K K D π π (a (c a ππ a ππ FB CP D..4 (b cos θ CMS D cos θ CMS (d D cos θ CMS D cos θ CMS Size 6.6x x1 6 13x1 3 64x1 3 Systematic errors BABAR (385fb 1 Category ACP KK ACP ππ dim PDF shapes πs corrections ACP corrections Quadrature sum twodimensional fit to D and m Results ACP KK = (.±.34stat±.13syst% ACP ππ = (.4±.5stat±.syst% ±.4% ±.5% ±.8% ±.8% ±.9% ±.% ±.13% ±.% May 7, 1 Maurizio Martinelli Searches for CP violation in D decays from BABAR and Belle 1

11 Cabibbo Suppressed Decays: D h h A FB A CP Phys. Lett. B67.19 ( a K K c K K cos * cos * A CP D K K D π π A FB b Sample Size Purity d cos * cos * Systematic errors Belle (54fb 1 Category ACP KK ACP ππ Signal Counting ±.4% ±.6% πs corrections ±.1% ±.1% ACP extraction ±.3% ±.4% Quadrature sum ±.11% ±.1% onedimensional fit to D mass spectrum Results K π untag K π tag K K π π 6.3x1 6 8% 1.3x1 6 99% 1x1 3 97% 51x1 3 91% ACP KK = (.43±.3stat±.11syst% ACP ππ = (.43±.5stat±.1syst% May 7, 1 Maurizio Martinelli Searches for CP violation in D decays from BABAR and Belle 11

12 Dalitz Plot Analysis Quantities that can be measured: Asymmetry on the Dalitz Plot Asymmetry in the angular moments Asymmetry in the amplitudes (model dependent Phase Space integrated asymmetry May 7, 1 Maurizio Martinelli Searches for CP violation in D decays from BABAR and Belle 1

13 Cabibbo Suppressed Decay D π π π Belle (53fb 1 Phase Space integrated asymmetry measurement Phys. Lett. B66.1 (8 Sample Yields π π π.4x1 6 peaking background from D random πs fit PDF from MC Systematics Source MC stat. Tracking Fit KS veto PID Binning AFB Total ACP = (.43±.41stat±1.3syst% May 7, 1 Maurizio Martinelli Searches for CP violation in D decays from BABAR and Belle 13

14 Cabibbo Suppressed Decay D h h π 4 /c m ( (GeV 1 4 m ( 1 (GeV /c 3 May 7, 1 Phys. Rev. D78, 511(R (8 CL(no CPV = 3.8% CL(no CPV = 16.6% (a (b (ad π π π /c (GeV m (K Sample Size Purity K K π π π π 8x1 3 98% 11x13 98% BABAR (385fb 1 Search for asymmetries in the Dalitz plot Normalized Residuals 4 3 = (n D R n D 1 σ 1 nd R σ n D 1 R = efficiency corrected NDbar/ND (bd K K π 1 4 m (K (GeV /c ACP KKπ =(1.±1.67stat±.5syst% ACP πππ =(.31±.41stat±.17syst% average on cosθ to cancel FB asymmetry 3 4 χ /ν = ν Maurizio Martinelli Searches for CP violation in D decays from BABAR and Belle.1 a CP.1 (a i= CM cos D i CL = one sided gaussian Confidence Level for consistency with no CPV hypothesis a KK CP.. /ν.4 (b CM cos D 14

15 Cabibbo Suppressed Decay D h h π Phys. Rev. D78, 511(R (8 Study of the Angular Moments to search for asymmetries continued BABAR (385fb 1 X X 1 X X X 1 X m( (GeV/c m( (GeV/c m( (GeV/c m(k K (GeV/c m(k K (GeV/c m(k K (GeV/c X m( (GeV/c X m( (GeV/c X m( (GeV/c X m(k (GeV/c X m(k (GeV/c D π π π D K K π particle combination π π π π K K K π CL (No CPV 8.% 8.4% 63.1% 3.8% X m(k (GeV/c No CPV found in Dalitz amplitudes comparing amplitudes, phases and fractions May 7, 1 Maurizio Martinelli Searches for CP violation in D decays from BABAR and Belle 15

16 Time Dependent (TD for a definition of x, y, rm and f see Nicola s talk on D mixing D mixing affects D decay times (h=k,π τ hh =τ Kπ [1 r m (y cos ϕ f x sin ϕ f ] 1 τ hh =τ Kπ defining 1r 1 m (y cos ϕ f x sin ϕ f 1 τ hh = τ hh τ hh A τ = τ hh τ hh τ hh τ hh Y is a probe for CP violation in decay times (rm=1, f = May 7, 1 Y = τ Kπ τ hh A τ (SM: Y= Maurizio Martinelli Searches for CP violation in D decays from BABAR and Belle 16

17 Cabibbo Suppressed Decay D h h (TD Events per 61.5 fs Phys. Rev. Lett (7 (a KK Events per 61.5 fs (b K Belle (54fb 1 D* tagged events many systematics cancel in lifetime ratio Events per 61.5 fs t (fs t (fs (c (N KK N /N K 4 t (fs t(fs (d 4 t (fs t = m D L p / p t(fs ycp Sample Size Purity K π 111x1 3 98% K K 1x1 3 99% π π 49x1 3 9% AΓ KK =(.15±.35stat% (AΓ=Aτ AΓ ππ =(.8±.57stat% Systematics Source Acceptance Equal t M window Sig/SB bkg Bkg B(t Res Func Selection Binning Total.7.8 < AΓ = (.1±.3stat±.15syst% May 7, 1 Maurizio Martinelli Searches for CP violation in D decays from BABAR and Belle 17

18 Cabibbo Suppressed Decay D h h (TD Phys. Rev. D (8 BABAR (385fb 1 Events/.6 ps Norm. Residual Events/.6 ps Norm. Residual t (ps D * K K * D Source Sig Model Charm Bkg Comb Bkg Selection Detector Model Total Data Signal Charm Comb. Data Signal Charm Comb t (ps Events/.6 ps Norm. Residual Events/.6 ps Norm. Residual D * K K Data Signal Charm Comb t (ps * D Data Signal Charm Comb t (ps D* tagged events many systematics cancel in lifetime ratio Sample Size Purity Y = (.6±.36stat±.8syst% May 7, 1 Maurizio Martinelli Searches for CP violation in D decays from BABAR and Belle 18 K π K K π π 731x % 67x % 31x % Y KK =(.4±.44stat±.1syst% Y ππ =(.5±.64stat±.3syst% Systematics

19 T odd correlations W. Bensalem, A. Datta and D. London, Phys. Rev. D66, 944 ( W. Bensalem and D. London, Phys. Rev. D64, 1163 (1 W. Bensalem, A. Datta and D. London, Phys. Lett. B538, 39 ( Asymmetry in Todd observable T violation CPV (assuming CPT invariance measured on D Todd observable (v = spin or momentum A T = Γ(v 1 (v v 3 > Γ(v 1 (v v 3 < Γ(v 1 (v v 3 > Γ(v 1 (v v 3 < Final State Interactions could fake the measure producing AT Remove FSI effects A T = 1 AT ĀT measured on D T violating observable May 7, 1 Maurizio Martinelli Searches for CP violation in D decays from BABAR and Belle 19

20 D K K π π I. I. Bigi, hepph/171 (1 Todd correlation observable (CT can be built using final state particle momenta: D rest frame C T = p K (p π p π p K C T p p p K p p A T = Γ(D,C T > Γ(D,C T < Γ(D,C T > Γ(D,C T < Ā T = Γ(D, C T > Γ(D, C T < Γ(D, C T > Γ(D, C T < May 7, 1 Maurizio Martinelli Searches for CP violation in D decays from BABAR and Belle

21 Cabibbo Suppressed Decay D K K π π Events/ (.8 MeV/c^ Pull Systematics: May 7, 1 hepex/ (accepted by PRD D* tagged events D fit to (m(d, m 47 signal events data Signal D peaking m peaking Combinatoric D s BABAR preliminary m(k K (GeV/c Events/ (.15 MeV/c^ Pull fit projections signal region data Signal D peaking m peaking Combinatoric D s BABAR preliminary m (GeV/c A T =( 68.5 ± 7.3 stat ± 5.8 syst 1 3 Ā T =( 7.5 ± 7.3 stat ± 3.9 syst 1 3 A T =(1. ± 5.1 stat ± 4.4 syst 1 3 Maurizio Martinelli Searches for CP violation in D decays from BABAR and Belle Events/ (.8 MeV/c Pull Events/ (.8 MeV/c Pull data Signal Background m(k K (GeV/c m(k K (GeV/c D (C > D (C < T BABAR (47fb m(k K (GeV/c D (C T > D (C T < BABAR Preliminary m(k K (GeV/c Effect signal PDF m peak PDF bin size PID p*(d cosθ * fit bias mistag det asym Total σ(x T 1

Conclusions D and charm decays provide a powerful probe for non SM processes involving CPV Experimental sensitivity comparable to higher SM predictions Many experimental techniques developed by BABAR

22 Conclusions D and charm decays provide a powerful probe for non SM processes involving CPV Experimental sensitivity comparable to higher SM predictions Many experimental techniques developed by BABAR and BELLE No evidence of CPV found yet Is the best yet to come? Belle(5 D K Belle(5 D K Belle(7 D Belle(7 D K K BaBar(8 D BaBar(8 D K K BaBar(8 D BaBar(8 D K K Belle(8 D Belle(8 D K K Belle(8 D BaBar(8 D BaBar(8 D K K BaBar(1 D K K ( 1 A CP May 7, 1 Maurizio Martinelli Searches for CP violation in D decays from BABAR and Belle

arxiv: v1 [hep-ex] 14 Sep 2015

arxiv: v1 [hep-ex] 14 Sep 2015 WSU HEP XXYY September 5, 5 arxiv:59.3v [hep-ex] Sep 5 Search for CP violation in D K + K, π + π and D π π Tara Nanut Department for Experimental Particle Physics Jozef Stefan Institute, Jamova 39, Ljubljana,