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CHARM 2007, Cornell University, Aug. 5-8,CHARM 2007, Cornell University, Aug. 5-8, 2007 2007
11 Steven Blusk, Syracuse Steven Blusk, Syracuse UniversityUniversity
D Leptonic Decays D Leptonic Decays nearnear
Production ThresholdProduction Threshold
Steven BluskSteven BluskSyracuse UniversitySyracuse University
(on behalf of the CLEO Collaboration)(on behalf of the CLEO Collaboration)
CHARM 2007, Cornell University, Aug. 5-8,CHARM 2007, Cornell University, Aug. 5-8, 2007 2007
22 Steven Blusk, Syracuse Steven Blusk, Syracuse UniversityUniversity
Introduction: D Introduction: D ++
Partial width measurement probes the hadronic vertexPartial width measurement probes the hadronic vertex Soft-gluon effects Soft-gluon effects Non-perturbative QCD Non-perturbative QCD Decay constant, Decay constant, ffDD describes the hadronic vertex, and is proportional to the describes the hadronic vertex, and is proportional to the
wave-function overlapwave-function overlap (Prob (Prob cd(s) cd(s)W annihilation)W annihilation)
General solution (SM) for partial widthGeneral solution (SM) for partial width
_ 22+ 2 2 2
221
(P ) 1 | |8 F P P Q
Pq
mG m M Vf
M
Calculate, or measure if VQq known
(s)
or cs
CHARM 2007, Cornell University, Aug. 5-8,CHARM 2007, Cornell University, Aug. 5-8, 2007 2007
33 Steven Blusk, Syracuse Steven Blusk, Syracuse UniversityUniversity
Leptonic Decays in SMLeptonic Decays in SM
Measurement provides critical test of theory to Measurement provides critical test of theory to compute compute ffBB, f, fBsBs..
In a few years, we will have a precision measurement In a few years, we will have a precision measurement (~5(~5oo))of of ((33) by LHC) by LHCbb.. Expect Expect (()~5)~5oo
with 2 with 2 fbfb-1-1
Could provide signsCould provide signsof NP if of NP if measurement measurementdoesn’t coincide withdoesn’t coincide withmm(s,d)(s,d) band. band.
B B gives Vgives VububffB,B, but buthard to measurehard to measure
directly. directly.
Constraints from Vub, md, ms & B
CHARM 2007, Cornell University, Aug. 5-8,CHARM 2007, Cornell University, Aug. 5-8, 2007 2007
44 Steven Blusk, Syracuse Steven Blusk, Syracuse UniversityUniversity
New Physics in DNew Physics in D(s)(s) leptonic leptonic decaysdecays
Deviations from lepton universality possible if tan large Hewett [hep-ph/9505246] & Hou, PRD 48, 2342 (1993).
2 2 2 2( )
2 2 2
[1 tan ( / )( / )]
[1 ( / )]
s Dq q cHSM
Dq q c
r m m m m
R m m m
Interference between H± and W± suppresses Dsl, but NOT Dl Akeroyd, hep-ph/0308260
22 2 2+
2+ 2 2 2
1 /(P )
(P ) 1 /
P
P
m m M
m m M
HR=tan /m
Deviations of this ratio from SM value of 9.72 would signal New Physics
CHARM 2007, Cornell University, Aug. 5-8,CHARM 2007, Cornell University, Aug. 5-8, 2007 2007
55 Steven Blusk, Syracuse Steven Blusk, Syracuse UniversityUniversity
D and DD and Dss Landscape near Landscape near thresholdthreshold Produce DD at (3770).
No additional particles Coherent 1– state Ideal for absolute BF measurements Measurements from 281 pb-1
(Phys. Rev. Lett. 95, 251801 (2005))
Not reviewed in this talk
0.09 40.12
2.83.4
( ) (4.40 0.66 ) 10
(222.6 16.7 ) MeVD
B D
f
Ds Leptonic Decays Dedicated scan to find optimal energyfor Ds physics (see talk by B. Lang)
At Ecm = 4170 MeV (DsDs*)~0.9 nb Additional photon, ~100 MeV to contend with.
CHARM 2007, Cornell University, Aug. 5-8,CHARM 2007, Cornell University, Aug. 5-8, 2007 2007
66 Steven Blusk, Syracuse Steven Blusk, Syracuse UniversityUniversity
Reconstructed DReconstructed Dss “Tags” at 4170 “Tags” at 4170 MeVMeV
Leptonic analyses requireLeptonic analyses requireone one fully reconstructedfully reconstructed D Dss decay (“tag”).decay (“tag”). 8 tag modes8 tag modes
Signal region: Signal region: |M|Mrecrec-M-MDsDs| < 2.5 | < 2.5
Sidebands:Sidebands: 5.0<|M5.0<|Mrecrec-M-MDsDs| < 7.5 | < 7.5
Total # of Tags Total # of Tags
= 31,302 ± 472 (stat)= 31,302 ± 472 (stat)K*K* from KsK
CHARM 2007, Cornell University, Aug. 5-8,CHARM 2007, Cornell University, Aug. 5-8, 2007 2007
77 Steven Blusk, Syracuse Steven Blusk, Syracuse UniversityUniversity
Measurements of Measurements of ffDsDs
Dtag
Ds*
Ds
or
e+ e-
Dtag
Ds
Ds
or
e+ e-
Dtag
Ds
Ds
e
e+ e-
“Missing Mass” Analyses (314 pb-1)Accepted to PRD arXiv:0704.0437v2
“Missing Energy” Analysis (195 pb-1)Preliminary
Only one additional track, K± rejection using PID No additional with E>300 MeV
Use (missing) mass recoiling against (Ds*+)
Ds() from Ds*Ds() from Ds
Only one additional track, consistentwith electron hypothesis
Signal discriminant: Remaining energy in calorimeter after tag and electron are removed.
CHARM 2007, Cornell University, Aug. 5-8,CHARM 2007, Cornell University, Aug. 5-8, 2007 2007
88 Steven Blusk, Syracuse Steven Blusk, Syracuse UniversityUniversity
Anatomy of Missing Mass Anatomy of Missing Mass Analyses Analyses
*( )
( )cand back
stag
N NB D
N
Dtag
Ds*
Ds
or
e+ e-
Ds() from Ds
Dtag
Ds
Ds
e+ e-
Ds() from Ds*
or
* * *( ) including from decay
muon detection efficiency
# of candidates
expected background
tag s s s
cand s
back
N N D D D
N D
N
CHARM 2007, Cornell University, Aug. 5-8,CHARM 2007, Cornell University, Aug. 5-8, 2007 2007
99 Steven Blusk, Syracuse Steven Blusk, Syracuse UniversityUniversity
Missing Mass Analyses – Missing Mass Analyses – NNtagtag
**
Take each DTake each Dss tag and photon tag and photon candidate and compute the candidate and compute the recoil mass against (Drecoil mass against (Dss
tagtag++). ).
regardless of whether Dregardless of whether Dss++ forms D forms Dss**, ,
recoil mass peaks at M(Drecoil mass peaks at M(Dss))22
NNtagtag**= 18645±426(stat) tags= 18645±426(stat) tags, ,
after 2.5after 2.5 selection on MM* selection on MM*22..
s s
2 2*2CM D γ CM D γMM = E -E -E - p -p -p
( )( )
cand backs
N NB D
*
tagN
All 8 Modes
Dtag
Ds*
Ds
or
e+ e-
Ds() from Ds
All 8 Modes
Dtag
Ds*
Ds
or
e+ e-
Ds() from Ds
*
All 8 modes combined
CHARM 2007, Cornell University, Aug. 5-8,CHARM 2007, Cornell University, Aug. 5-8, 2007 2007
1010 Steven Blusk, Syracuse Steven Blusk, Syracuse UniversityUniversity
Missing Mass Analyses – Signal Missing Mass Analyses – Signal SideSide
*( )
( )back
stag
NB D
N
candN
All 8 Modes
Dtag
Ds*
Ds
or
e+ e-
Ds() from Ds
All 8 Modes
Dtag
Ds*
Ds
or
e+ e-
Ds() from Ds
*
For each Ds* candidate, perform a
kinematic fit,imposing the following constraints:*
*
*
*
*
*
2 2
0
143.6 MeV
( )
2 2
s s
s s
ss
ss
s
D D
D CMD
DD
tag s
DDcmD
cm
p p
E E E
M M
M M D
M MEE
E
Two solutions for each Ds
* candidate belongs with Ds tag belongs with Ds(try both)
CHARM 2007, Cornell University, Aug. 5-8,CHARM 2007, Cornell University, Aug. 5-8, 2007 2007
1111 Steven Blusk, Syracuse Steven Blusk, Syracuse UniversityUniversity
Missing Mass Analyses – Signal Missing Mass Analyses – Signal SideSide
All 8 Modes
Dtag
Ds*
Ds
or
e+ e-
Ds() from Ds
All 8 Modes
Dtag
Ds*
Ds
or
e+ e-
Ds() from Ds
*
s
s
22CM D γ
2
CM D γ
MM = E -E -E -E
- p -p -p -p
For each Ds* candidate, perform a
kinematic fit,imposing the following constraints:
Choose solution with lowest 2 (but no cut), and compute:
Signal Ds Signal Ds→
Two possibilities for each Ds
*
candidate belongs with Ds tag belongs with Ds(try both)
Signal MC
*
*
*
*
*
*
2 2
0
143.6 MeV
( )
2 2
s s
s s
ss
ss
s
D D
D CMD
DD
tag s
DDcmD
cm
p p
E E E
M M
M M D
M MEE
E
*( )
( )cand back
stag
N NB D
N
CHARM 2007, Cornell University, Aug. 5-8,CHARM 2007, Cornell University, Aug. 5-8, 2007 2007
1212 Steven Blusk, Syracuse Steven Blusk, Syracuse UniversityUniversity
MMMM22 from CLEO-c Data from CLEO-c Data
Electron Sample
92 events
31 events
Return to 3 separate cases:i. Etrk
CC<300 MeV “D-like”: (~99%)
-0.05<MM2<0.05 GeV2
“D-like”: (~60%) 0.05<MM2<0.20 GeV2
ii. EtrkCC>300 MeV
“D-like”: (~40%) -0.05<MM2<0.20 GeV2
iii.Electron-like
EtrkCC > 0.3 GeV in CC
EtrkCC < 0.3 GeV in CC
25 events
*( )
( )back
stag
NB D
N
candN
CHARM 2007, Cornell University, Aug. 5-8,CHARM 2007, Cornell University, Aug. 5-8, 2007 2007
1313 Steven Blusk, Syracuse Steven Blusk, Syracuse UniversityUniversity
Backgrounds Backgrounds Combinatoric background under Combinatoric background under
peaks:peaks: Use DUse Dss cand. mass sidebands cand. mass sidebands
DDssbackgrounds from real Dbackgrounds from real DSS decaysdecays
Signalregion
High SBregion
Low SBregion
SampleSample SignalSignal Comb. Comb. Back.Back.
(i) EtrkCC<300 MeV, “D-
like”9292 3.53.5±1.4±1.4
(ii) EtrkCC<300 MeV, “D-
like”3131 2.52.5±1.1±1.1
(iii) EtrkCC>300 MeV, “D-
like”2525 3.03.0±1.3±1.3
TotalTotal 148148 9.0 9.0 ±1.3±1.3Background BFBF
(%)(%)Etrk
CC<300 MeV,
“D-like”
EtrkCC<300 MeV,
“D-like”
DsX 00+1.8+1.8-0-0 00
DsX 1.01.0 0.030.03±0.04±0.04 0.080.08±0.03±0.03
Ds
1.51.5 0.550.55±0.22±0.22 0.640.64±0.24±0.24
Ds
1.01.0 0.370.37±0.15±0.15 00
TotalTotal 1.01.0+1.8+1.8-0.3-0.3 0.70.7±0.2±0.2
Negligible real Ds decay background to DsSince B(Ds ) <1.1x10-3 @ 90% CL
*( )
( )cand
stag
NB D
N
backN
CHARM 2007, Cornell University, Aug. 5-8,CHARM 2007, Cornell University, Aug. 5-8, 2007 2007
1414 Steven Blusk, Syracuse Steven Blusk, Syracuse UniversityUniversity
Branching fractionsBranching fractions
[ ( ; )( ) ]ag st sN N BB D D
Ntag =18645±426±1081 = efficiency for reconstructing = 80.1% = efficiency for ECC<300 MeV + |MM2|<50 MeV = 91.4% = efficiency for ECC<300 MeV(60%) + |MM2|<50 MeV(13%) = 13.2%N = 92 – (3.5±1.4) = 88.5±9.7
B(DS+→+(0.597±0.067±0.039)%
B(DS+→+
B(DS+→+
Type (i)Type (i) Type (ii)Type (ii)
NNcandcand 3131 2525
NNbackback 3.53.5+1.7+1.7-1.1-1.1 5.15.1±±1.61.6
(EtrkCC) 60%60% 40%40%
(MMMM22)req.)req. 32%32% 45%45%
B(DS+→+(8.0±1.3±0.4)%
( ; ) 1.059 ( ) ( / )s sB D B D SM PDG
CHARM 2007, Cornell University, Aug. 5-8,CHARM 2007, Cornell University, Aug. 5-8, 2007 2007
1515 Steven Blusk, Syracuse Steven Blusk, Syracuse UniversityUniversity
Combined Combined ffDsDsCombine (i) and (ii).
= 91.4% = 45.2%N = 148 – (10.7+2.9
-
2.3)
[ ( ; )( ) ]ag st sN N BB D D (still applies)
Beff(DS+→+
(0.638±0.059±0.033)%
fDs= 274 ± 13 ± 7 MeV
B(DS+→e+x10-4 @90%CL
Signalregion
Results
CHARM 2007, Cornell University, Aug. 5-8,CHARM 2007, Cornell University, Aug. 5-8, 2007 2007
1616 Steven Blusk, Syracuse Steven Blusk, Syracuse UniversityUniversity
Missing Energy AnalysisMissing Energy Analysis DDSS
++→→++++→→ee++
Xe+
Use 195 pb-1 at Ecm=4170 MeV
Reconstruct Ds tag, use recoil from Ds to get N(DsDs*)
Require one extra electron candidate + no other tracks.
No need to find from DS*
Main backgrounds from DS+→Xe+
Discriminant is ECCextra: extra energy in CC
left over after showers associated to reconstructed particles are removed.
Signal region: ECCextra < 400 MeV
Background obtained by scaling MC
B(DS+→+(6.29±0.78±0.52)%
fDs= 278 ± 17 ± 12 MeV
(Preliminary)(Preliminary)
400400 600
600
MeVMeV MeVMC
data dataMeVMC
NN N
N
CHARM 2007, Cornell University, Aug. 5-8,CHARM 2007, Cornell University, Aug. 5-8, 2007 2007
1717 Steven Blusk, Syracuse Steven Blusk, Syracuse UniversityUniversity
Combined resultsCombined results
Weighted Average: Weighted Average: ffDsDs=275±10±5 MeV, =275±10±5 MeV, the the (systematic errors are mostly uncorrelated between (systematic errors are mostly uncorrelated between the measurements)the measurements)
Previously CLEO-c measuredPreviously CLEO-c measured
M. Artuso et al., Phys .Rev. Lett. 95 (2005) 251801M. Artuso et al., Phys .Rev. Lett. 95 (2005) 251801
Thus Thus ffDsDs//ffDD++=1.24±0.10±0.03=1.24±0.10±0.03 (D(DSS
++→→++(D(DSS++→→++
11.5±2.0, SM=9.72, 11.5±2.0, SM=9.72, consistent with lepton universalityconsistent with lepton universality
++2.3-3.4D
f =(222.6±16.7 ) MeVD+→
pbat
K0+
†
CHARM 2007, Cornell University, Aug. 5-8,CHARM 2007, Cornell University, Aug. 5-8, 2007 2007
1818 Steven Blusk, Syracuse Steven Blusk, Syracuse UniversityUniversity
Comparisons with theoretical Comparisons with theoretical expectationsexpectations
CLEO-c data CLEO-c data consistent with consistent with most models, most models, more precision more precision neededneeded
Using Lattice Using Lattice ratio find ratio find |V|Vcdcd/V/Vcscs||=0.2166±0.020 =0.2166±0.020 (exp) (exp) ±0.0017(theory±0.0017(theory))
CHARM 2007, Cornell University, Aug. 5-8,CHARM 2007, Cornell University, Aug. 5-8, 2007 2007
1919 Steven Blusk, Syracuse Steven Blusk, Syracuse UniversityUniversity
Comparison to previous Comparison to previous measurementsmeasurements
CLEO-c is most precise result to date for CLEO-c is most precise result to date for both both ffDsDs & & ffDD++
275±10±5
-2
-2
CHARM 2007, Cornell University, Aug. 5-8,CHARM 2007, Cornell University, Aug. 5-8, 2007 2007
2020 Steven Blusk, Syracuse Steven Blusk, Syracuse UniversityUniversity
Decay constants from CLEO-c are most precise to dateDecay constants from CLEO-c are most precise to date
Expect to reach a precision of ~4.0-4.5% onExpect to reach a precision of ~4.0-4.5% onthese decay constants with full CLEO-c (through Apr these decay constants with full CLEO-c (through Apr 2008).2008).
SummarySummary
++2.3-3.4D
=(222.6±16.7 ) MeVfsD =(275±10±5) MeVf
CHARM 2007, Cornell University, Aug. 5-8,CHARM 2007, Cornell University, Aug. 5-8, 2007 2007
2121 Steven Blusk, Syracuse Steven Blusk, Syracuse UniversityUniversity
BackupsBackups
CHARM 2007, Cornell University, Aug. 5-8,CHARM 2007, Cornell University, Aug. 5-8, 2007 2007
2222 Steven Blusk, Syracuse Steven Blusk, Syracuse UniversityUniversity
Missing Mass Distributions - MCMissing Mass Distributions - MCCheck of resolution, procedure using DsKsK- Remove extra track/shower/K± veto
MC resolution consistent w/ data Find BF=(2.90±0.19±0.18)%,
Result from double tags: (3.12±0.16±0.10)%
This background is wiped out by the PID requirement on the stiff .