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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 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. - PowerPoint PPT Presentation
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Measurement of Br of Ds → π0 l ν, Ds →Ks l ν, Ds →ρ l 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
Idea• In standard model ( leptonic decay of Ds ):
1. A c quark decays into a s quark via a virtual w boson which annihilates into a Ɩ and a ν, 2. In semi-leptonic decay of Ds ,
3. 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
4. This analysis probes all that by looking for the decay Ds →π0 /(ρ) l ν5. For Ds → Ks
l ν
Ds → Ks l ν is a
Cabbibo suppressed decay and it shares the same final state as ρ l ν
w
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*→Ds γ; Ds signal candidates are identified as a peak in recoil mass spectrum:
= MR (DtagKXfrag γ ) =
• All DtagKXfrag γ combinations with MR > 1.83 GeV and PR >2.8 GeV are retained for further analysis 3
Best Inclusive Ds sample: Mmiss(DtagKXfrag γ)Inclusive Ds reconstruction done as described in BN1244
Ds → π0 l ν Ds → ρ l ν Ds → Ks l ν
4
Mmiss distributions for correctly reconstructed inclusive Ds (with cate1 only) with Signal MC
Reconstruction of exclusive Ds→π0 l ν / Ks l ν / ρ l ν decay and data
sample used for analysis
Selection Criteria:
• For each DtagKXfrag γ 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
5
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).
Yield determination procedure
• 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 Xfrag l γ 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
6
Fully reconstruction in charm: e+ e- → cc ̅ → DtagKXfrag γ (π0 /Ks /ρ) l ν
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 l π0 (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.
7
•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 and Ds →Ks μ ν in Generic Monte Carlo: SIGNAL MODE: NUMBER 14 :anti-K0 μ+ ν μ
Black line with Eecl<= 0.4 cut and Red line without Eecl cut in Generic Monte Carlo 8
Ds →Ks μ ν : The peaking background is coming from mode 18:anti-K0 K+
MM2 Plots with Generic Monte Carlo(6 streams of MC) for a Dtag K Xfrag γ μ Ks system (BACKGROUND MODES)
Eecl<= 0.4
Ds →ρ μ ν: the dominant background mode: K+ K- μ+ ν μ (16); Other dominant background is f0 l ν; which is not in generic MC
Ds → π0
μ ν
• Conclusions with Eecl<=0.4 selection:
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 →ρ l 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.
Neutrino energy
• The neutrino energy for a Dtag K Xfrag γ l Ks (ρ ) system in the rest frame is defined as : •E 𝞶 l = (MDs
2 - MKs(ρ)l2)/ 2 MDs
10
The low E 𝞶 background events correspond to |MM2| == 0 region, we can obtain a significant background loss by choosing events with lower E 𝞶Conclusions 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 →ρ l ν channel, the high background with a shoulder near |MM2| = 0 is reduced.
2-dimensional scatter plots(y axis: MM2; x axis: Eecl_ks)
11
Ds → Ks e ν Signal MC Ds → Ks e ν Backgrounds (6 streams of generic MC)
Ds→ Ks μ ν Signal MCDs → Ks μ ν Backgrounds (6 streams of generic MC)
2-dimensional scatter plots(y axis: MM2; x axis: Enu_lepton_ks)
12
Ds → Ks e ν Signal MC Ds → Ks e ν Backgrounds (6 streams of generic MC)
Ds → Ks μ ν Signal MC Ds → Ks μ ν Backgrounds (6 streams of generic MC)
2-dimensional scatter plots(y axis Enu_lepton_ks; x axis: Eecl_ks)
13
Ds → Ks e νSignal MC
Ds → Ks e ν Backgrounds (6 streams of generic MC)
Ds → Ks μ νSignal MC
Ds → Ks μ ν Backgrounds (6 streams of generic MC)
14
Selection criterion
No. of signal events
No. of background events
ε_signal ε_background FOM(S/√S+44.6B)
1 Eecl < 6.9 *Enu -1.5
3422 (out 3778)
29(out of 169)
0.906 0.172 49.8
Ks μ ν
Ks e ν
Ks e ν : Very low background; No Cut
Selection criterion
No. of signal events
No. of background events
ε_signal ε_background FOM(S/√S+44.6B)
1 Eecl < 6.5 *Enu +1.7
4355(out of 4361)
13( out of 14)
0.998 0.928 61.9
MM2 for a Dtag K Xfrag γ e Ks system fitted with a Crystal ball and two Gaussian
functions(Signal MC:4X10^7)Ds →Ks e ν Ds →Ks μ ν
15
χ2 = 0.663χ2 = 1.416
with Eecl < 6.9*Enu – 1.5 with no cut
MM2 for a Dtag K Xfrag γ μ Ks system fitted with a Crystal ball and two Gaussian functions(Signal MC:4X10^7)
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-K0 μ+ ν μ )
χ2 = 0.668 χ2 = 0.329
MM2 for a Dtag K Xfrag γ l Ks system 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
16
χ2 = 0.389χ2 = 0.359
with no cut with Eecl < 6.9*Enu – 1.5
Cross-checking of the Branching ratio of D s → Ks
l+ 𝞶e decay in MC(using the best selection criteria)
Branching fraction of D s → Ks e ν decays:
Expected Branching ratio of D s → Ks l+ 𝞶e
; B = 3.7 X 10-3
17
Estimated combined Belle Stat. error is 1.5X 10-4
Branching fraction of D s → Ks μ ν decays:
B ± δB (Statistical only) = (3.63±0.23)X10-3 B ± δB (Statistical only) = (3.72±0.20)X10-3
18
Selection criterion
No. of signal events
No. of background events
ε_signal ε_background FOM(S/√S+44.6B)
1 Eecl < 4.8 *Enu – 0.4
4058(out 4413)
762(out of 1031)
0.919 0.739 20.8
ρ μ ν
ρ e ν
ρ e ν : low background: No Cut
Selection criterion
No. of signal events
No. of background events
ε_signal ε_background FOM(S/√S+44.6B)
1 Eecl < 5.1*Enu +1.0
5308(out of 5351)
405( out of 422)
0.991 0.959 34.7
2-D scatter plots are in the backup slides
MM2 plot for Ds → ρ μ ν with 6 streams of Generic MC: only background modes
Efficiency = 74%Efficiency = 92%
19
MM 2 plot for Ds → ρ μ ν with Signal MC
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.
Backup slides
MM2 for a Dtag K Xfrag γ e ρ system fitted with a Crystal ball and two
Gaussian functions(Signal MC:4X10^7)
Ds →ρ e ν Ds →ρ μ ν
20with Eecl < 4.8*Enu – 0.4 with no cut
χ2 = 1.416χ2 = 2.267
MM2 fitted with a Crystal ball and a landau function (Generic MC-6 streams: background modes)
χ2 = 0.967
MM2 for a Dtag K Xfrag γ μ ρ system fitted with a Crystal ball and two Gaussian functions(Signal MC:4X10^7)
MM2 fitted with a Crystal ball and a landau function (Generic MC-6 streams: background modes)
χ2 = 0.757
21
Selection criterion
No. of signal events
No. of background events
ε_signal ε_background FOM(S/√S+44.6B)
1 Eecl < -4.6 *Enu + 4.2
2185(out 2473)
52(out of 87) 0.88 0.597 32.6
π0 μ ν
π0 e ν Selection criterion No. of
signal events
No. of background events
ε_signal ε_background FOM(S/√S+44.6B)
1 Eecl<-4.0*Enu+4.2 2368(out of 2447)
41( out of 62)
0.967 0.66 36.6
Ds →π0 μ ν
MM2 for a Dtag K Xfrag γ μ π0 system fitted with a background linear function and a signal function(Generic MC-6 streams)
22
Fit results are shown in the next slide
With Eecl<= -4.6*Enu+4.2
Ds →π0 μ ν
MM2 for a Dtag K Xfrag γ l π0 system fitted with Crystal ball and two Gaussian functions(Signal MC: 4X10^7)
χ2 = 2.690χ2 = 0.954
• Fit result : MM2 for a Dtag K Xfrag γ μ π0 system fitted 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
23
So N_s( Signal Yield) = -13.8+(-) 9.23
With Eecl<= -4.6*Enu+4.2
Ds →π0 e ν
MM2 for a Dtag K Xfrag γ e π0 system fitted with a background linear function and a signal function(Generic MC-6 streams)
24
Fit results are shown in the next slide
With Eecl<= -4.0*Enu+4.2
Ds →π0 e ν
MM2 for a Dtag K Xfrag γ e π0 system fitted with Crystal ball and two Gaussian functions(Signal MC: 4X10^7)
χ2 = 0.925 χ2 = 1.288
• Fit result : MM2 for a Dtag K Xfrag γ e π0 system fitted 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
25
So N_s( Signal Yield) = -7.67+(-) 10.59
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)
Inclusive Ds sample :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 MCThe upper limit on the branching ratio B(D s → π0 μ 𝞶e ) < 5.6X 10-4 (90% CL)
26
With Eecl<= -4.6*Enu+4.2
Inclusive Ds sample :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 MCThe upper limit on the branching ratio B(D s → π0 μ 𝞶e ) < 5.6X 10-4 (90% CL)
Upper limit on the Branching ratio (at 90% CL) for the D s → π0 e+ 𝞶e
decay (statistical only)
With Eecl<=-4.0*Enu+4.2
Estimated combined Belle limit is 3.9X 10-4 (90% CL)
• 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. ρ l 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.
27
Reference : “Measurements of branching fractions of leptonic and hadronic Ds+ meson decays and extraction of the Ds+ meson decay constant” by Belle Collaboration arXiv:1307.6240v2[hep-ex] 1 Oct 2013
28
Backup slides
29
• The selection criteria π+/- , K+/- , π0 , Ks0 , Λ, p, γ used to reconstruct Dtag are
summarized in section 4.1, BN1244v3.
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.
30
Backup slides
Primary kaon reconstruction
• After the reconstruction of the Dtag hadrons, a strangeness balancing kaon is required.
• The strangeness balancing kaon can be K+/- , Ks
0 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
31
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].
Xfrag reconstruction
Fully reconstruction in charm: e+ e- → cc ̅ → DtagKXfragDs*
Backup slides
Selection Criteria For Inclusively Reconstructed Ds candidates:
e+ e- cc ̅ DtagKXfragDs*, Ds
* Ds γ e+ e- cc ̅ events containing Ds mesons proceed via :
A photon candidate consistent with the decay of Ds*→Ds γ which does not overlap with the
DtagKXfrag system, must satisfy :
1. E γ > 120 MeV2. E9/E25 > 0.753. 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.
32
Backup slides
Eecl plotsDs→ π0 e ν
6 streams of Generic MC Efficiency ε = 46%
Signal MC Efficiency ε = 74%
33
Ds→ π0 μ ν Efficiency ε = 77% 91.3%
Ds→ π0 e ν
Ds→ π0 μ ν Efficiency ε = 47%
Cut at Eecl = 0.4
Cut at Eecl =0.4Cut at Eecl = 0.4
Cut at Eecl = 0.4
Backup slides
Signal MC 6 streams of Generic MC
34
Ds→ Ks e ν Efficiency ε= 67%
Cut at Eecl = 0.4
Ds→ Ks μ ν Efficiency ε= 70% Efficiency ε= = 22%
Backup slidesEecl plots
Cut at Eecl = 0.4
Cut at Eecl = 0.4
Cut at Eecl = 0.4
Cut at Eecl = 0.4
Ds→ Ks e ν Efficiency ε= 22%
Ds→ Ks μ ν Efficiency ε= 18%
Ds →ρ e νEfficiency ε=67%
6 streams of Generic MC
Backup slides Eecl plots
Ds →ρ μ νEfficiency ε= 71%
Cut at Eecl = 0.4
Cut at Eecl = 0.4
Cut at Eecl = 0.4
Ds →ρ e νEfficiency ε=50%
Cut at Eecl = 0.4
Ds →ρ μ νEfficiency ε= 49%
Signal MC
35
Fractional Background Contribution in π0 l ν With Generic Monte Carlo (dsdm variable)
36
π0 e ν π0 μ ν
𝛕 + 𝞶 𝛕 (2)
𝟇 e+ ν e (4)
𝛈 e+ ν e (5)
anti-K0 e+ ν e (7)
K0 anti-K0 e+ ν e (10)
μ + 𝞶μ (1) 𝛕 + 𝞶 𝛕 (2)
𝟇 μ+ ν μ (11)
𝛈 μ+ ν μ (5)
anti-K0 μ+ ν μ (14)
K0 anti-K0 e+ ν e (17)
Backup slides
with Eecl<= 0.4
37
MM2 Plots for a Dtag K Xfrag γ e π0 system
Ds → π0 e ν (Signal Monte Carlo) Ds → π0
e ν (6 streams of Generic Monte Carlo)
MM2 for Ks l ν : Blue line with Eecl<= 0.4 cut and Red line without Eecl cut in signal Monte Carlo
with Eecl<= 0.4
Backup slides
MM2 Plots for a Dtag K Xfrag γ μ π0 system
38
Ds → π0 μ ν (6 streams of Generic Monte Carlo)Ds → π0
μ ν (Signal Monte Carlo)
MM 2 for π0 l ν : Blue line with Eecl<= 0.4 cut and Red line without Eecl cut in Generic Monte Carlo
with Eecl<= 0.4
Backup slides
MM2 for a Dtag K Xfrag γ l π0 system fitted with Crystal ball and two Gaussian functions(Signal MC: 4X10^7)
Ds →π0 e ν Ds →π0 μ ν
χ2 = 1.496χ2 = 1.385
39
With Eecl<=0.4
Backup slides
MM2 for a Dtag K Xfrag γ e π0 system fitted with a background linear function and a signal Gaussian function(Generic MC-6 streams)
Ds →π0 e ν Ds →π0 μ ν
MM2 for a Dtag K Xfrag γ μ π0 system fitted with a background linear function and a signal Gaussian function(Generic MC-6 streams)
40
Fit results are shown in the next slide
With Eecl<=0.4
Backup slides
41
Fit result 1: MM2 for a Dtag K Xfrag γ e π0 system fitted 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 2 a1 1.42101e+00 3.79198e+00 5.88228e-03 1.42584e-01 3 fO -2.60707e-02 2.46990e-02 6.90975e-04 -6.16975e-01 4 yld 1.27976e+02 1.13121e+01 1.63403e-06 -1.56853e+00 5 ERR DEF= 0.5So N_s ( Signal Yield) = -3.3+(-) 3.2
Fit result 2: MM2 for a Dtag K Xfrag γ μ π0 system fitted 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.2 a1 7.51464e-01 4.69634e+00 1.13668e-03 7.52173e-02 3 fO 2.33465e-02 4.54002e-02 1.87376e-04 -5.26539e-01 4yld 8.29988e+01 9.11033e+00 3.74073e-07 -1.56897e+00 ERR DEF= 0.5So N_s( Signal Yield) = 1.9+(-) 3.8
Backup slides
with Eecl<= 0.4
Upper limit on the Branching ratio (at 90% CL) for the D s → π0
e+ 𝞶e
decay (statistical only)
Upper limit on the Branching ratio (at 90% CL) for the D s → π0 μ+ 𝞶e
decay (statistical only)
Inclusive Ds sample :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 MCThe upper limit on the branching ratio B(D s → π0 e+ 𝞶e ) < 4.9X 10-4 (90% CL)
Inclusive Ds sample :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)
Estimated combined Belle limit is 3X 10-4 (90% CL)
42
With Eecl<=0.4
Fractional Background Contribution in Ks l ν With Generic Monte Carlo (dsdm variable)
43
Kseν Ksμν
𝟇 e+ ν e (4)
K0 anti-K0 e+ ν e (10)
K* anti-K0 (23)
anti-K0 K+ (18)
𝟇 π+ (20)
K0 anti-K0 e+ ν e (17)
𝟇 μ+ ν μ (11)
Backup slides
with Eecl<= 0.4
44
MM2 Plots for a Dtag K Xfrag γ e Ks system
Ds →Ks e ν (Signal Monte Carlo)
MM2 for Ks e ν : Black line with Eecl<= 0.4 cut and Red line without Eecl cut in Signal Monte Carlo
Ds →Ks e ν with Generic Monte Carlo: 6 streams of MC(SIGNAL MODE: NUMBER 7 :anti-K0 e+ ν e
Eecl<= 0.4
Backup slides
45
MM2 Plots for a Dtag K Xfrag γ μ Ks system
Ds →Ks μ ν (Signal Monte Carlo)
MM2 for Ks μ ν : Black line with Eecl<= 0.4 cut and Red line without Eecl cut in Signal Monte Carlo
Ds →Ks μ ν with Generic Monte Carlo: 6 streams of MC(SIGNAL MODE: NUMBER 14 :anti-K0 μ+ ν e
Eecl<= 0.4
Backup slides
Ds →Ks e ν: the dominant background modes are : e𝟇 + ν e (4),K0 anti-K0 e+ ν e (10)
MM 2 for Ks l ν : Black line with Eecl<= 0.4 cut and Red line without Eecl cut in Generic Monte Carlo
46
Ds →Ks μν : the dominant background modes are : 𝟇 μ+ νμ (11), K0 anti-K0 e+ 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 Plots with Generic Monte Carlo(6 streams of MC) for a Dtag K Xfrag γ l Ks system (BACKGROUND MODES)
Backup slides
with Eecl<= 0.4
Fractional Background Contribution in ρ l ν With Generic Monte Carlo (dsdm variable)
[f0 is not in the generic Monte Carlo]
47
ρ e ν ρ μ ν
𝟇 e+ ν e (4)
𝛈’ e+ ν e (6)
K+ K- e+ ν e (9)
𝟇 μ+ ν μ (11)𝛈’ e+ ν e (13)
K+ K- μ+ ν μ (16)
Backup slides
with Eecl<= 0.4
48
MM2 Plots for a Dtag K Xfrag γ e ρ system
Eecl<= 0.4 cut Ds →ρ e ν (Signal MC) Ds →ρ e ν (6 streams of generic MC)
MM2 for ρ l ν : Blue line with Eecl<= 0.4 cut and Red line without Eecl cut in Signal Monte Carlo
Backup slides
MM2 Plots for a Dtag K Xfrag γ μ ρ system
49
Ds → ρ μ ν (Signal Monte Carlo)Ds → ρ μ ν (6 streams of Generic Monte Carlo)
MM 2 for π0 l ν : Blue line with Eecl<= 0.4 cut and Red line without Eecl cut in Generic Monte Carlo
with Eecl<= 0.4
•The fitted plots are in the back up slides. A dominant source of background in Ds → ρ l ν decay comes from Ds → f0 l ν .
Backup slides
Eecl plots for a Dtag K Xfrag γ l f0 system ( same mass cut as ρ selection; f0 is in data but not in Generic Monte Carlo)
Ds → f0 e ν Ds → f0 μ ν
Signal MC
50
Backup slides
MM2 for a Dtag K Xfrag γ l f0 system ( same mass cut as ρ selection; f0 is in data but not in Generic Monte Carlo)
Signal MC
Ds → f0 e ν Ds → f0 μ ν
51
Backup slides
MM2 for a Dtag K Xfrag γ l Ks system fitted with Crystal ball and two Gaussian functions(Signal MC:4X10^7)
Ds →Ks e ν Ds →Ks μ ν
52
With Eecl<=0.4
χ2 = 0.566χ2 = 0.897
Backup slides
MM2 for a Dtag K Xfrag γ l Ks system fitted with Crystal ball and two Gaussian functions(Generic MC-6 streams: signal mode : number 7 : anti-K0 e+ ν e and
number14 anti-K0 μ+ ν μ )
Ds → Ks e ν Ds →Ks μ ν
53
With Eecl<=0.4
These are not the final plots, later we have tried the neutrino energy cut on MM2 for Ds →Ks l ν with 1 streams of Generic MC
χ2 = 0.325 χ2 = 0.873
Backup slides
MM2 for a Dtag K Xfrag γ l Ks system (Generic MC-6 streams: background modes)
(With Eecl<=0.4)
Ds →Ks e ν Ds →Ks μ ν
Fitted with a Gaussian and a linear function
Fitted with crystal ball and a linear function
χ2 = 0.066χ2 = 0.786
54
These are not the final plots, later we have tried the neutrino energy cut on MM2 for Ds →Ks l ν with 1 stream of Generic MC
Backup slides
MM2 for a Dtag K Xfrag γ l ρ system fitted with Crystal ball and two Gaussian functions(Signal MC: 4X10^7)
Ds →ρ e ν Ds →ρ μ ν
χ2 = 1.314 χ2 = 1.519
55
With Eecl<=0.4
Backup slides
MM2 for a Dtag K Xfrag γ l ρ system fitted with Crystal ball and Landau functions(Generic MC-6 streams)
Ds →ρ e ν Ds →ρ μ ν
χ2 = 0.629 χ2 = 0.787
56
With Eecl<=0.4
Backup slides
MM2 for a Dtag K Xfrag γ e ρ system fitted with Crystal ball function for peaking modes(6 and 9)(Generic MC-6 streams)
MM2 for a Dtag K Xfrag γ e ρ system fitted with Crystal ball function for non- peaking modes(4 and 8)(Generic MC-6 streams)
χ2 = 0.501χ2 = 0.253
57
With Eecl<=0.4
Backup slides
MM2 for a Dtag K Xfrag γ μ ρ system fitted with inverted Crystal ball function for peaking modes(14,15,18,20,21)(Generic MC-6 streams)
MM2 for a Dtag K Xfrag γ μ ρ system fitted with inverted Crystal ball function for non-peaking modes(11,13,16,17,27,29)(Generic MC-6 streams)
χ2 = 0.351 χ2 = 0.384
58
With Eecl<=0.4
Backup slides
Electron Neutrino energy for Ds →Ks e ν decay
Muon Neutrino energy for Ds →Ks μ ν decay
59
(1 stream of Generic MC)
(Signal MC)
Backup slides
Electron Neutrino energy for Ds → ρ e ν decay
Muon Neutrino energy for Ds → ρ μ ν decay
60
(1 stream of Generic MC)
(Signal MC)
Backup slides
MM2 plot for Ds →Ks e ν with eecl cut and
neutrino energy cut (Signal MC:4X10^7)
MM2 plot for Ds →Ks e ν with eecl cut and
neutrino energy cut (Generic MC- 1 stream only background modes)
61
Efficiency = 96%
MM2 for Ks l ν : Black line with Enu_l_ks>=0.2 and With Eecl<=0.4 cut and Red line without enulks cut, only With Eecl<=0.4 in signal Monte Carlo
MM2 distribution with the effect of “Eecl<=0.4 Enulks>=0.2”
Efficiency = 100%
Backup slides
MM2 plot for Ds →Ks μ ν with Eecl cut and
neutrino energy cut (1 stream of Generic MC: only background modes)
MM2 plot for Ds →Ks μ ν with Eecl cut and
neutrino energy cut (Signal MC:4X10^7))
MM2 for Ks l ν : Black line with Enu_l_ks>=0.2 and With Eecl<=0.4cut and Red line without enulks cut, only with Eecl<=0.4 in 1 stream of Generic Monte Carlo
Efficiency = 46%
62
Efficiency = 97%Eecl<=0.4 Enu>=0.2
MM2 plot for Ds → ρ e ν with Eecl cut and neutrino energy cut (Signal MC: 4X10^7)
MM2 for ρ l ν : Black line with Eecl<= 0.4 cut and Enu_l_rho>=0.2 and Red line without Enulrho cut, only with Eecl<= 0.4 in 1 stream of Generic Monte Carlo
63
Efficiency = 81%Efficiency = 99%
MM2 plot for Ds →ρ e ν with Eecl cut and neutrino energy cut (1 stream of Generic MC)
Backup slides
Eecl<=0.4 Enu>=0.2
MM2 plot for Ds →ρ μ ν with Eecl cut and neutrino energy cut (1 stream of Generic MC)
MM2 for ρ l ν : Black line with Eecl<= 0.4 cut and Enu_l_rho>=0.2 and Red line without enulrho cut in Generic Monte Carlo
64
Efficiency = 85%Efficiency = 87%
MM2 plot for Ds → ρ μ ν with Eecl cut and neutrino energy cut (Signal MC: 4X10^7)
Backup slides
Eecl<=0.4 Enu>=0.2
MM2 for a Dtag K Xfrag γ l ρ system fitted with signal function(Generic MC-1 streams) [all background modes]
with Eecl<= 0.4 and Enu_l rho>=0.2 selection
MM2 for D s → ρ e ν MM2 for D s → ρ μ ν
65
Backup slides
Best selection criteriaAfter producing the two dimensional scatter plots between MM2 Vs. Eecl, MM2 Vs. Enu and Enu Vs. Eecl, with signal MC and 6 streams of generic MC, we searched for the best selection criteria based on the maximum value of Figure Of Merit (FOM), defined by S/√(S+44.6*B), where S and B are the number of signal and background candidates ( for |MM2|<0.05), respectively around the zero peaking region of MM2
distribution, out of 10,000 combinations of Eecl and Enu.
66
Modes Best Selection criteria
Ks μ ν Eecl < 6.9 *Enu -1.5
Ks e ν No cuts
ρ μ ν Eecl < 4.8 *Enu -0.4
ρ e ν No cuts
π0 μ ν Eecl < -4.6*Enu+4.2
π0 e ν Eecl<-4.0*Enu+4.2
MM2 plot for Ds → Ks μ ν with
6 streams of Generic MC: only background modes
Efficiency = 17%
Efficiency = 91%
67
MM 2 plot for Ds → Ks μ ν with
Signal MC
MM2 for Ks l ν : Blue line with Eecl < 6.9*Enu – 1.5 cut and Red line without Enu cut, only Without this cut.
Backup slides
Best cut plots
2-dimensional scatter plots(y axis: MM2; x axis Eecl)
68
Ds → ρ e νSignal MC
Ds → ρ e ν Backgrounds (6 streams of generic MC)
ρ l ν
Ds → ρ μνSignal MC
Ds → ρ μ ν Backgrounds (6 streams of generic MC)
Backup slides
2-dimensional scatter plots(y axis: MM2; x axis Enu)
69
Ds → ρ e νSignal MC
Ds → ρ e ν Backgrounds (6 streams of generic MC)
Ds → ρ μνSignal MC
Ds → ρ μν Backgrounds (6 streams of generic MC)
Backup slides
2-dimensional scatter plots(y axis Enu_electron_rho; x axis: Eecl_rho)
70
Ds → ρ e νSignal MC
Ds → ρ e ν Backgrounds (6 streams of generic MC)
Ds → ρ μ νSignal MC
Ds → ρ μ ν Backgrounds (6 streams of generic MC)
Backup slides
Fractional Background Contribution in π0 l ν With Generic Monte Carlo (dsdm variable)
with best selection
71
Ds →π0 μ ν Ds →π0 e ν
Cross-checking of the Branching ratio of D s → Ks e+ 𝞶e
decay in MC
Inclusive Ds sample :N( inclusive)= number of inclusively reconstructed Ds mesons in the first step = 601665 in Generic MC 6 streams
Inclusive Ds sample :N( inclusive)= number of inclusively reconstructed Ds mesons = 30816 in Signal MC
N(exclusive) = number of exclusively reconstructed D s → Ks
e ν decays = 374 in generic MC (6 streams)
N(exclusive) = number of exclusively reconstructed D s → Ks
e ν decays = 5147 in Signal MC
𝝴 is the efficiency of reconstructing D s → Ks e ν decays given
inclusively reconstructed D s in signal MC
B ± δB (Statistical only) = (3.72±0.20)X10-3
Expected Branching ratio of D s → Ks
e+ 𝞶e ;
B = 3.7 X 10-3
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Estimated combined Belle Stat. error is 1.5X 10-4
Cross-checking of the Branching ratio of D s → Ks μ+ 𝞶e decay
in MC
Inclusive Ds sample :N( inclusive)= number of inclusively reconstructed Ds mesons in the first step = 601665 in Generic MC 6 streams
Inclusive Ds sample :N( inclusive)= number of inclusively reconstructed Ds mesons = 30816 in Signal MC
N(exclusive) = number of exclusively reconstructed D s → Ks
μ ν decays = 265 in generic MC (6 streams)
N(exclusive) = number of exclusively reconstructed D s → Ks
μ ν decays = 3744 in Signal MC
𝝴 is the efficiency of reconstructing D s → Ks e ν decays
given inclusively reconstructed D s in signal MC
Expected Branching ratio of D s → Ks
e+ 𝞶e ;
B = 3.7 X 10-3
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= 3.63X10-3
Estimated combined Belle Stat. error is 1.5X 10-4
(remember there are 95000 tags in data, so the estimated combined statistical error is going to be 1.5-3.8X10^-4)
B ± δB (Statistical only) = (3.63±0.23)X10-3