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Measurement of Br of D s → π 0 l ν, D s → K s l ν, D s → ρ l ν

Measurement of Br of D s → π 0 l ν, D s → K s l ν, D s → ρ l ν decays in Signal Monte Carlo and Generic Monte Carlo Sudeshna Ganguly Anze Zupanc Giovanni Bonvicini Based on my presentation to Belle General meeting, February 2014 04/30/2014. Idea.

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Measurement of Br of D s → π 0 l ν, D s → K s l ν, D s → ρ l ν

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  1. Measurement of Br of Ds→ π0 l ν, Ds→Ksl ν, Ds→ρl ν decays in Signal Monte Carlo and Generic Monte Carlo Sudeshna GangulyAnze Zupanc Giovanni Bonvicini Based on my presentation to Belle General meeting, February 2014 04/30/2014

  2. Idea • In standard model ( leptonic decay of Ds ): • A c quark decays into a s quark via a virtual w boson which annihilates into a Ɩ and a ν, • In semi-leptonic decay of Ds , • Ds can make hadrons without any s-quark by: 1) Fock’s development : Ds > = c0 | c ̅s > + c1 | c ̅s q ̅q > + c2 | c ̅s q ̅q q ̅q > +………….. 2) hadron mixing 3) higher order QCD processes • This analysis probes all that by looking for the decay Ds →π0 /(ρ) l ν Ds →Ksl ν is a Cabbibo suppressed decay and it shares the same final state as ρ l ν w

  3. Obtaining inclusive Ds sample Fully reconstruction in charm: e+ e-→ cc ̅ →DtagKXfragDs* • Dtag (See backup for details)→ D0, D+, ΛC+ (18 tag modes: involving kaons, pions, neutral pions, protons etc.) or excited D*0, D*+ • K = K+/- , Ks0 • Xfrag = nothing, π+/- , π0 , π+/-π+/- , π+/-π0 , π+/-π+/-π+/- , π+/-π+/-π0 • All possible reconstructed DtagKXfrag combinations are made so that there total charge is +(-) 1 and these candidates do not overlap with each other. Then we calculate MR(DtagKXfrag) closest to nominal Ds* mass. • Ds*→Dsγ; Ds signal candidates are identified as a peak in recoil mass spectrum: = MR(DtagKXfragγ ) = • All DtagKXfragγ combinations with MR > 1.83 GeV and PR >2.8 GeV are retained for further analysis

  4. Best Inclusive Ds sample: Mmiss(DtagKXfragγ)Inclusive Ds reconstruction done as described in BN1244 • Fully inclusive sample of Ds : by looking at Ds*→Dsγ • Selection criteria : cate1 : true signal: • Ds mother is Ds* • γmother is Ds* • particles forming Xfrag and primary Kaon do not originate from Ds decay • The number of inclusive sample is obtained from the Mmiss(Dtag K Xfrag γ ) distribution • MR (Ds ) = Mmiss(Dtag K Xfrag γ ) = Mmiss distributions for correctly reconstructed inclusive Ds (with cate1 only) with Signal MC Ds → π0 l ν Ds → Ksl ν Ds → ρl ν

  5. Reconstruction of exclusive Ds→π0 l ν / Ksl ν / ρl ν decay and data sample used for analysis Selection Criteria: • For each DtagKXfragγ candidate, exactly 1 charged track and one additional π0 / Ks/ ρ in the rest of the event. • Ks and ρ candidates do not overlap with inclusive Ds candidates. • 1.95 < MR (Ds ) < 1.99 GeV Selection of π0 (nominal mass 134.9 MeV) : 117.8 < mγγ < 150.2 MeV Selections used for good Ks (nominal mass 497.6 MeV)→ π+ π- :|mππ-MKS|< 20 MeV The dominant decay mode of ρ: ρ → π+ π- and all π+ π- combinations with invariant mass within +/-250 MeV around the rho's nominal mass (770MeV)are accepted Signal MC samples have been generated for each of the Ds decay modes : No. of events generated 4X10^7 To determine the reconstruction efficiencies and to study backgrounds six streams of generic MC samples are used(all 4 types: charged, mixed, charm, uds).

  6. Yield determination procedure Fully reconstruction in charm: e+ e-→ cc ̅ → DtagKXfrag γ (π0 /Ks /ρ) l ν • Each final stage candidate in the exclusive decay mode of Ds is reconstructed explicitly except for the neutrino candidate. • The signal yield from fit to the MM2 (Dtag K Xfraglγ π0 /Ks /ρ) = [Pmiss(DtagKXfrag l π0/Ks/ρ)]^2 distribution between -0.3 and +0.3 GeV. • The missing 4-momenta is given as Pmiss(DtagKXfrag l π0/Ks/ρ) = pe+ +pe−-pDtag-pK-pXfrag-pγ-pl-pπ0/Ks/ρ • First the Eecl variable ( energy of the ECL cluster) with a selection of Eecl<0.4 eliminated about 50% of the background. • Next the neutrino energy variable and a selection criteria of Eecl<0.4 & Enu>0.2 – the rectangular cut. • Calculate a figure of merit(FOM), defined by S/√(S+44.56B); S and B are the signal and background candidates ( for |MM2| < 0.05 ) respectively around the zero peaking region of MM2 distribution

  7. Eecl • Eecl is the asymmetric energy between the signal photon candidate and any other photon candidate defined as: • This extra energy is not associated to the Dtag K Xfrag γ lπ0 (Ks / ρ ) system in our analysis. • Eecl cluster with energy >50 MeV in barrel, >100 MeV in forward and >150 MeV in backward end cap are used to calculate Eecl. • With Eecl<=0.4 selection ; εS/√ εB only gives a marginal improvement for π0 l ν mode (a low background mode) • Looked at the sources of background (dsdm variables) for each of the decay modes, • Ds→Ks e ν in Generic Monte Carlo: SIGNAL MODE: NUMBER 7 :anti-K0 e+ ν e andDs→Ks μ ν in Generic Monte Carlo: SIGNAL MODE: NUMBER 14 :anti-K0μ+ νμ

  8. MM2 Plots with Generic Monte Carlo(6 streams of MC) for a Dtag K Xfrag γ μKssystem(BACKGROUND MODES) Ds→π0μ ν Ds→Ks μ ν : The peaking background is coming from mode 18:anti-K0 K+ Eecl<= 0.4 Ds →ρμ ν: the dominant background mode: K+ K- μ+νμ(16); Other dominant background is f0l ν; which is not in generic MC Black line with Eecl<= 0.4 cut and Red line without Eecl cut in Generic Monte Carlo

  9. Ds→Ks μ ν channel has a problem of peaking background at |MM2| = 0. • [Ds →Ks e ν mode: εS/√ εB = 0.77 • Ds →Ks μ ν mode: εS/√ εB = 0.76 : no improvement] • Ds→ρl ν channel has high background with a shoulder near |MM2| = 0. • [Ds→ρ e ν mode: εS/√ εB = 0.90 • Ds→ρ μ ν mode: εS/√ εB = 0.95 : no improvement] • Ds→ π0 l ν decay channel is a low background channel. • [Ds →π0 e ν mode : εS/√ εB = 1.09 ( a 9% improvement) • Ds→π0 μ ν mode : εS/√ εB = 1.24 ( a 24% improvement)] • So we try a new cut with neutrino energy. • Conclusions with Eecl<=0.4 selection:

  10. Neutrino energy • The neutrino energy for a Dtag K Xfrag γ lKs (ρ ) system in the rest frame is defined as : • E𝞶 l = (MDs 2 - MKs(ρ)l2)/ 2 MDs The low E 𝞶 background events correspond to |MM2| == 0 region, we can obtain a significant background loss by choosing events with lower E 𝞶 • Conclusions with “Eecl<=0.4 & Enu>=0.2” selection: • The problem of a peaking background at |MM2| = 0 in Ds→Ks μ ν decay can be removed applying this selection criteria. • For Ds→ρl ν channel, the high background with a shoulder near |MM2| = 0 is reduced.

  11. 2-dimensional scatter plots(y axis: MM2; x axis: Eecl_ks) Ds → Ks e ν Backgrounds (6 streams of generic MC) Ds → Ks e ν Signal MC Ds → Ks μ ν Backgrounds (6 streams of generic MC) Ds→ Ksμ ν Signal MC

  12. 2-dimensional scatter plots(y axis: MM2; x axis: Enu_lepton_ks) Ds → Ks e ν Backgrounds (6 streams of generic MC) Ds → Ks e ν Signal MC Ds → Ks μ ν Backgrounds (6 streams of generic MC) Ds → Ks μ ν Signal MC

  13. 2-dimensional scatter plots(y axis Enu_lepton_ks; x axis: Eecl_ks) Ds → Ks e ν Signal MC Ds → Ks e ν Backgrounds (6 streams of generic MC) Ds → Ks μ ν Backgrounds (6 streams of generic MC) Ds → Ks μ ν Signal MC

  14. Ks μ ν Ks e ν Ks e ν : Very low background; No Cut

  15. MM2 for a Dtag K Xfrag γ μKssystemfitted with a Crystal ball and two Gaussian functions(Signal MC:4X10^7) MM2 for a Dtag K Xfrag γ eKssystemfitted with a Crystal ball and two Gaussian functions(Signal MC:4X10^7) Ds →Ks e ν Ds →Ks μ ν χ2 = 1.416 χ2 = 0.663 MM2 fitted with the signal function combined with a background linear polynomial function (Generic MC-6 streams: signal mode : number 7 : anti-K0 e+ ν e ) MM2 fitted with the signal function combined with a background linear polynomial function (Generic MC-6 streams: signal: number14 anti-K0μ+ ν μ ) χ2 = 0.329 χ2 = 0.668 with no cut with Eecl < 6.9*Enu – 1.5

  16. MM2 for a Dtag K Xfrag γ lKssystem fitted with a Crystal ball added to a linear polynomial function for the muon mode and with a Gaussian added to a linear function for the electron mode(Generic MC-6 streams: background modes) Ds→Ks e ν Ds→Ks μ ν χ2 = 0.359 χ2 = 0.389 with no cut with Eecl < 6.9*Enu – 1.5

  17. Cross-checking of the Branching ratio of D s →Ksl+ 𝞶e decay in MC(using the best selection criteria) Branching fraction of D s →Kse ν decays: Branching fraction of D s →Ksμ ν decays: B ± δB (Statistical only) = (3.72±0.20)X10-3 B ± δB (Statistical only) = (3.63±0.23)X10-3 Estimated combined Belle Stat. error is 1.5X 10-4 Expected Branching ratio of D s →Ksl+ 𝞶e; B = 3.7 X 10-3

  18. ρμ ν ρ e ν ρe ν : low background: No Cut 2-D scatter plots are in the backup slides

  19. Backup slides MM2 plot for Ds → ρμ ν with 6 streams of Generic MC: only background modes MM2 plot for Ds → ρμ ν with Signal MC Efficiency = 92% Efficiency = 74% MM2 for ρ l ν : Blue line with Eecl < 4.8*Enu – 0.4 cut and Red line without Enu cut, only Without this cut.

  20. MM2 for a Dtag K Xfrag γ μρsystemfitted with a Crystal ball and two Gaussian functions(Signal MC:4X10^7) MM2 for a Dtag K Xfrag γ eρsystemfitted with a Crystal ball and two Gaussian functions(Signal MC:4X10^7) Ds →ρe ν Ds →ρμ ν χ2 = 1.416 χ2 = 2.267 MM2 fitted with a Crystal ball and a landau function(Generic MC-6 streams: background modes) MM2 fitted with a Crystal ball and a landau function(Generic MC-6 streams: background modes) χ2 = 0.967 χ2 = 0.757 with no cut with Eecl < 4.8*Enu – 0.4

  21. π0μ ν π0e ν

  22. MM2 for a Dtag K Xfrag γ μπ0systemfitted with a background linear function and a signal function(Generic MC-6 streams) MM2 for a Dtag K Xfrag γ lπ0systemfitted with Crystal ball and two Gaussian functions(Signal MC: 4X10^7) With Eecl<= -4.6*Enu+4.2 Ds→π0 μ ν Ds→π0 μ ν χ2 = 0.954 χ2 = 2.690 Fit results are shown in the next slide

  23. With Eecl<= -4.6*Enu+4.2 • Fit result : MM2 for a Dtag K Xfrag γ μ π0systemfitted with a background linear function and a signal Gaussian function(Generic MC-6 streams) • EDM=3.65521e-05 STRATEGY= 1 ERROR MATRIX ACCURATE • EXT PARAMETER PARABOLIC MINOS ERRORS • NO. NAME VALUE ERROR NEGATIVE POSITIVE • 1 a0 1.21310e-02 9.10972e-01 at limit 2.76888e-01 • 2 a1 -1.31653e+00 1.88251e+00 -1.75494e+00 2.04943e+00 • 3 fO -3.71207e-02 2.47444e-02 -2.39079e-02 2.55819e-02 • 4 yld 3.73024e+02 1.93141e+01 -1.90057e+01 1.96242e+01 • ERR DEF= 0.5 • MINOS: status = 0 So N_s( Signal Yield) = -13.8+(-) 9.23

  24. MM2 for a Dtag K Xfrag γ eπ0systemfitted with a background linear function and a signal function(Generic MC-6 streams) MM2 for a Dtag K Xfrag γ eπ0systemfitted with Crystal ball and two Gaussian functions(Signal MC: 4X10^7) With Eecl<= -4.0*Enu+4.2 Ds→π0 e ν Ds→π0 e ν χ2 = 1.288 χ2 = 0.925 Fit results are shown in the next slide

  25. With Eecl<= -4.0*Enu+4.2 • Fit result : MM2 for a Dtag K Xfrag γ e π0systemfitted with a background linear function and a signal Gaussian function(Generic MC-6 streams) • NO. NAME VALUE ERROR STEP SIZE VALUE • 1 a1 2.38530e+00 4.58179e-01 3.36359e-05 2.40852e-01 • 2 a2 1.45757e+00 2.68091e+00 8.93050e-04 1.46278e-01 • 3 fO -2.61217e-02 3.60411e-02 3.04862e-04 -6.17071e-01 • 4 yld 2.93997e+02 1.71463e+01 5.43898e-07 -1.56737e+00 • ERR DEF= 0.5 So N_s( Signal Yield) = -7.67+(-) 10.59

  26. With Eecl<= -4.6*Enu+4.2 With Eecl<=-4.0*Enu+4.2 Upper limit on the Branching ratio (at 90% CL) for the D s → π0 μ+ 𝞶e decay (statistical only) Upper limit on the Branching ratio (at 90% CL) for the D s → π0 e+ 𝞶e decay (statistical only) Inclusive Dssample : N( inclusive)= number of inclusively reconstructed Ds mesons in the first step = 95000 known tags from BN1244 N( inclusive)= number of inclusively reconstructed Ds mesons in the first step = 601665 in 6 streams of Generic MC Efficiency ε from signal MC (4X10^7 events) = 3200/28989= 0.110 N(exclusive) = number of exclusively reconstructed D s →π0 μ ν decays = (-13.8+-9.23) events in 6 streams of Generic MC The upper limit on the branching ratio B(D s →π0 μ 𝞶e ) < 5.6X 10-4 (90% CL) Inclusive Dssample : N( inclusive)= number of inclusively reconstructed Ds mesons in the first step = 95000 known tags from BN1244 N( inclusive)= number of inclusively reconstructed Ds mesons in the first step = 601665 in 6 streams of Generic MC Efficiency ε from signal MC (4X10^7 events) = 3650/28989= 0.126 N(exclusive) = number of exclusively reconstructed D s →π0 μ ν decays = (-7.67+-10.59) events in 6 streams of Generic MC The upper limit on the branching ratio B(D s →π0 μ 𝞶e ) < 5.6X 10-4 (90% CL) Estimated combined Belle limit is 3.9X 10-4 (90% CL)

  27. Work done so far: • Established and optimized selection method for each channel • Estimated expected error for Ks l ν (factor of 7 better than world average) • Estimated expected upper limit on the Branching ratio (at 90% CL) for π0 l ν is 2.27X 10-4 (about a factor 4 better than Cleo-c) • Started BN1344 • “Opened the box”, the final data sample collected near ϒ(4S) and ϒ(5S) resonances with Belle detector at the KEKB asymmetric energy e+e- collider, with total luminosity of the sample being 913 fb^-1 . • Future plans: 1. ρl ν limit not estimated, it will depend on fitting the f0 component plus interference terms (not included in Generic MC). 2. Present the absolute branching fraction measurements for each of the decay modes.

  28. Reference : “Measurements of branching fractions of leptonic and hadronic Ds+ meson decays and extraction of the Ds+ meson decay constant” byBelle Collaboration arXiv:1307.6240v2[hep-ex] 1 Oct 2013

  29. Backup slides

  30. Backup slides Tagging method Dtag (BN1244): The tagging charmed hadron can be D0, D+, ΛC+ , or excited D*0, D*+. The ground state Dtag hadrons, D0, D+, ΛC+ are reconstructed in total 18 hadronic decay modes. Large backgrounds avoided by using modes with up to one π0, only. D*0, D*+ decays are identified by reconstructing D*+→ D0 π + , D+π0 and D*0→ D0 π0 , D0ϒ. Accept Dtag candidate with invariant mass between 1.82 GeV and 1.91 GeV(1.80 and 1.93 GeV if one of decay products is π0 ) and p* > 2.3(or 2.5)GeV. • The selection criteria π+/- , K+/- , π0 , Ks0 , Λ, p, γ used to reconstruct Dtag are summarized in section 4.1, BN1244v3.

  31. Fully reconstruction in charm: e+ e-→ cc ̅ → DtagKXfragDs* Primary kaon reconstruction Xfrag reconstruction The tracks and π0candidates left in the event, not overlapping with the Dtag K system can be used to reconstruct the Xfrag candidates in the following modes: • nothing • π+/- • π0 • π+/-π0 The modes which contain only one π0 and only up to 3 charged pions are allowed to form Xfrag system to discard a large combinatory background. The selection criteria for all charged pions and neutral pion making up the Xfrag system is the same as given in BN1244[XXX]. • After the reconstruction of the Dtag hadrons, a strangeness balancing kaon is required. • The strangeness balancing kaon can be K+/- , Ks0 candidates which do not overlap with the Dtag candidate. • The selection criteria for the strangeness balancing kaon : • K+/- : p>0.1 GeV • L K/ π = atc_pid(3,1,5,3,2) > 0.6 • L e = eid < 0.9 (electron veto) • L K/ p = atc_pid(3,1,5,3,4) > 0.1 (proton veto) • Ks0 : loose goodKs selection • |mππ-MKS|< 20 MeV • Vertex fit is performed Backup slides

  32. Backup slides Selection Criteria For Inclusively Reconstructed Ds candidates: e+ e- cc ̅ events containing Ds mesons proceed via : e+ e- cc ̅ DtagKXfragDs*, Ds* Dsγ A photon candidate consistent with the decay of Ds*→Dsγ which does not overlap with the DtagKXfrag system, must satisfy : 1. Eγ > 120 MeV 2. E9/E25 > 0.75 3. The cosine of the angle between the direction of tagged charm hadron and the direction of the photon candidate is negative, as the signal photon should be in the signal hemisphere of the event. 4. All DtagKXfrag combinations with Pmiss(DtagKXfrag γ ) > 2.8 GeV Mmiss(DtagKXfrag γ ) > 1.83 GeV can be used.

  33. Backup slides Eecl plots Signal MC Efficiency ε = 74% 6 streams of Generic MC Efficiency ε = 46% Ds→ π0 e ν Ds→ π0 eν Cut at Eecl = 0.4 Cut at Eecl =0.4 Ds→ π0 μ ν Efficiency ε = 77% 91.3% Ds→ π0 μ ν Efficiency ε = 47% Cut at Eecl = 0.4 Cut at Eecl = 0.4

  34. Backup slides Eecl plots Signal MC 6 streams of Generic MC Ds→Ks e ν Efficiency ε= 67% Ds→Ks e ν Efficiency ε= 22% Cut at Eecl = 0.4 Cut at Eecl = 0.4 Cut at Eecl = 0.4 Ds→Ksμ ν Efficiency ε= 70% Efficiency ε= = 22% Ds→Ksμ ν Efficiency ε= 18% Cut at Eecl = 0.4 Cut at Eecl = 0.4

  35. Backup slides Eecl plots Signal MC Ds→ρ e ν 6 streams of Generic MC Ds→ρ e ν Efficiency ε=50% Efficiency ε=67% Cut at Eecl = 0.4 Cut at Eecl = 0.4 Ds→ρ μ ν Efficiency ε= 49% Ds→ρ μ ν Efficiency ε= 71% Cut at Eecl = 0.4 Cut at Eecl = 0.4

  36. Backup slides Fractional Background Contribution in π0l ν With Generic Monte Carlo (dsdm variable) with Eecl<= 0.4 𝛕 + 𝞶𝛕 (2) 𝛕 + 𝞶𝛕 (2) μ + 𝞶μ (1) 𝟇 e+ ν e (4) 𝟇 μ+ ν μ (11) 𝛈 e+ν e(5) 𝛈 μ+νμ(5) anti-K0 e+ν e (7) anti-K0μ+ν μ (14) K0 anti-K0e+ν e(17) K0 anti-K0e+ν e(10) π0μ ν π0e ν

  37. Backup slides MM2 Plots for a Dtag K Xfrag γ eπ0system with Eecl<= 0.4 Ds→ π0e ν (Signal Monte Carlo) Ds→ π0e ν (6 streams of Generic Monte Carlo) MM2 for Ksl ν : Blue line with Eecl<= 0.4 cut and Red line without Eecl cut in signal Monte Carlo

  38. Backup slides MM2 Plots for a Dtag K Xfrag γ μπ0system with Eecl<= 0.4 Ds→ π0μ ν (Signal Monte Carlo) Ds→ π0μ ν (6 streams of Generic Monte Carlo) MM2 for π0l ν : Blue line with Eecl<= 0.4 cut and Red line without Eecl cut in Generic Monte Carlo

  39. Backup slides MM2 for a Dtag K Xfrag γ lπ0systemfitted with Crystal ball and two Gaussian functions(Signal MC: 4X10^7) With Eecl<=0.4 Ds→π0 e ν Ds→π0 μ ν χ2 = 1.496 χ2 = 1.385

  40. Backup slides MM2 for a Dtag K Xfrag γ eπ0systemfitted with a background linear function and a signal Gaussian function(Generic MC-6 streams) MM2 for a Dtag K Xfrag γ μπ0systemfitted with a background linear function and a signal Gaussian function(Generic MC-6 streams) With Eecl<=0.4 Ds→π0 e ν Ds→π0 μ ν Fit results are shown in the next slide

  41. with Eecl<= 0.4 Fit result 1: MM2 for a Dtag K Xfrag γ eπ0systemfitted with a background linear function and a signal Gaussian function(Generic MC-6 streams) • EXT PARAMETER INTERNAL INTERNAL • NO. NAME VALUE ERROR STEP SIZE VALUE • 1 a0 1.00000e+00 1.54326e-01 2 .02909e-03 1.57093e+00 • WARNING - - ABOVE PARAMETER IS AT LIMIT. • a1 7.51464e-01 4.69634e+00 1.13668e-03 7.52173e-02 • fO 2.33465e-02 4.54002e-02 1.87376e-04 -5.26539e-01 • yld 8.29988e+01 9.11033e+00 3.74073e-07 -1.56897e+00 ERR DEF= 0.5 • So N_s( Signal Yield) = 1.9+(-) 3.8 Fit result 2: MM2 for a Dtag K Xfrag γ μ π0systemfitted with a background linear function and a signal Gaussian function(Generic MC-6 streams) • EXT PARAMETER INTERNAL INTERNAL • NO. NAME VALUE ERROR STEP SIZE VALUE • 1 a0 2.02130e-01 5.81907e-01 2.15528e-02 -6.38187e-01 • a1 1.42101e+00 3.79198e+00 5.88228e-03 1.42584e-01 • fO -2.60707e-02 2.46990e-02 6.90975e-04 -6.16975e-01 • yld 1.27976e+02 1.13121e+01 1.63403e-06 -1.56853e+00 • ERR DEF= 0.5 • So N_s ( Signal Yield) = -3.3+(-) 3.2 Backup slides

  42. With Eecl<=0.4 Upper limit on the Branching ratio (at 90% CL) for the D s → π0e+ 𝞶e decay (statistical only) Upper limit on the Branching ratio (at 90% CL) for the D s → π0 μ+ 𝞶e decay (statistical only) Inclusive Dssample : N( inclusive)= number of inclusively reconstructed Ds mesons in the first step = 355163 in 6 streams of Generic MC Efficiency ε from signal MC (4X10^7 events) = 3001/34129 = 0.088 N(exclusive) = number of exclusively reconstructed D s →π0 e + ν decays = (1.9+-3.8) in 6 streams of Generic MC The upper limit on the branching ratio B(D s →π0 μ 𝞶e ) < 3.6X 10-4 (90% CL) Inclusive Dssample : N( inclusive)= number of inclusively reconstructed Ds mesons in the first step = 355163 in 6 streams of Generic MC Efficiency ε from signal MC (4X10^7 events) = 2683/34129= 0.079 N(exclusive) = number of exclusively reconstructed D s →π0 μ ν decays = (-3.3+-3.2) events in 6 streams of Generic MC The upper limit on the branching ratio B(D s → π0 e+ 𝞶e ) < 4.9X 10-4 (90% CL) Estimated combined Belle limit is 3X 10-4 (90% CL)

  43. Backup slides Fractional Background Contribution in Ks l ν With Generic Monte Carlo (dsdm variable) with Eecl<= 0.4 K0 anti-K0e+ν e(17) 𝟇 e+ ν e (4) anti-K0 K+ (18) K0 anti-K0e+ ν e (10) 𝟇 μ+ ν μ (11) 𝟇 π+ (20) K* anti-K0 (23) Kseν Ksμν

  44. Backup slides MM2 Plots for a Dtag K Xfrag γ eKssystem Eecl<= 0.4 Ds→Ks e ν (Signal Monte Carlo) Ds→Ks e ν with Generic Monte Carlo: 6 streams of MC(SIGNAL MODE: NUMBER 7 :anti-K0 e+ ν e MM2 for Kse ν : Black line with Eecl<= 0.4 cut and Red line without Eecl cut in Signal Monte Carlo

  45. Backup slides MM2 Plots for a Dtag K Xfrag γ μKssystem Eecl<= 0.4 Ds→Ks μ ν (Signal Monte Carlo) Ds→Ks μ ν with Generic Monte Carlo: 6 streams of MC(SIGNAL MODE: NUMBER 14 :anti-K0μ+ ν e MM2 for Ksμ ν : Black line with Eecl<= 0.4 cut and Red line without Eecl cut in Signal Monte Carlo

  46. MM2 Plots with Generic Monte Carlo(6 streams of MC) for a Dtag K Xfrag γ lKssystem(BACKGROUND MODES) Backup slides Ds→Ks e ν: the dominant background modes are : 𝟇 e+ ν e (4), K0 anti-K0e+ ν e (10) Ds→Ks μν : the dominant background modes are :𝟇 μ+ νμ (11), K0 anti-K0e+ ν e (17),anti-K0 K+ (18), 𝟇 π+ (20),K* + anti-K0 (23); The peaking background is coming from mode 18:anti-K0 K+ MM2 for Ksl ν : Black line with Eecl<= 0.4 cut and Red line without Eecl cut in Generic Monte Carlo with Eecl<= 0.4

  47. Backup slides Fractional Background Contribution in ρ l ν With Generic Monte Carlo (dsdm variable)[f0 is not in the generic Monte Carlo] K+ K- e+ν e(9) K+ K- μ+νμ(16) 𝟇 μ+ ν μ (11) 𝟇 e+ν e(4) 𝛈’ e+ν e(13) 𝛈’ e+ν e(6) ρ e ν ρ μ ν with Eecl<= 0.4

  48. Backup slides MM2 Plots for a Dtag K Xfrag γ eρsystem Eecl<= 0.4 cut Ds→ρe ν (Signal MC) Ds →ρe ν (6 streams of generic MC) MM2 for ρl ν : Blue line with Eecl<= 0.4 cut and Red line without Eecl cut in Signal Monte Carlo

  49. Backup slides MM2 Plots for a Dtag K Xfrag γ μρsystem with Eecl<= 0.4 Ds→ρ μ ν (Signal Monte Carlo) Ds→ ρμ ν (6 streams of Generic Monte Carlo) MM2 for π0l ν : Blue line with Eecl<= 0.4 cut and Red line without Eecl cut in Generic Monte Carlo • The fitted plots are in the back up slides. A dominant source of background in Ds→ ρl ν decay comes from Ds→ f0l ν .

  50. Backup slides Eecl plots for a Dtag K Xfrag γ lf0system ( same mass cut as ρ selection; f0 is in data but not in Generic Monte Carlo) Signal MC Ds→ f0e ν Ds→ f0μ ν

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