recent (charm) electroweak results from cleo
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3/11/2005 CLEO / Doris Kim 1
Doris Y. KimUniversity of IllinoisUrbana-Champaign
Content
• I: The CESR-c and the CLEO-c Experiment.
• II: Leptonic D decays.
• III: Semileptonic D decays: Exclusive
• IV: Semileptonic D decays: Inclusive
• V: Inclusive BF of D Xland l
• VI: CPV from CLEO II.V
• VII: Summary & Future.
Recent (Charm) Electroweak Results from CLEO
Moriond EW sessionMarch 5-12, 2005
La Thuile, Italy
3/11/2005 CLEO / Doris Kim 2
I. The Cornell Electron Storage Ring (CESR)
Ebeam = 1.5 – 5.6 GeVAdded 12 superconducting wigglers to CESR for low
energy running.
3/11/2005 CLEO / Doris Kim 3
The CLEO-c Detector
• New inner drift chamber replaced old silicon vertex
• 1T B field (old 1.5 T)
• Track (93% of 4): = 0.6% @ 1 GeV
• PID: Rich (80% of 4, dE/dx, EM calorimeter, muon (> 1GeV)
• E: = 2.2% @ 1 GeV, 5% @ 100 MeV.
Run plan: ´, (3770) and Ds, J/ thresholds.
CLEO-c CLEO III det.
3/11/2005 CLEO / Doris Kim 4
Impact of CLEO-c Measurements
• Leptonic decays give fD and fDs
– validate Lattice QCD and improve fB
• Semileptonic decays give Vcs, Vcd and form factors
– test theoretical form factor models
– enhance LQCD calculations, which will improve B decay form factors.
– test CKM unitarity.
• Improved (already) BF measurements of many important normalization modes and more coming.
• Hadronic decays measure strong phases, needed for CPV.• Initial state is coherent: Ideal for charm mixing and CPV.
e+
W+
ElectroweakPhysics: Vcq
QCD: form factors
D
An example of semileptonic decay
3/11/2005 CLEO / Doris Kim 5
The Future of Precision Flavor Physics
Vub/Vub 15%lB
l
D
Vcd/Vcd 7%lD
Vcs/Vcs 16%l
B D
Vcb/Vcb 5%
Bd Bd
Vtd/Vtd 36%
Bs Bs
Vts/Vts 39% Vtb/Vtb 29%
Vus/Vus 1%
l Vud/Vud 0.1%
e
pn
t
b
W
The Goal: Measure all CKM matrix elements and associated phases in order to over-constrain the unitary triangles.
CLEO-c
Vcd/Vcd 1.7% Vcs/Vcs 1.6%l
D
lD
CLEO-c + Lattice QCD +B factories + ppbar
Bd Bd
Vtd/Vtd 5%
Bs Bs
Vts/Vts 5%
CLEO-c + Lattice QCD +B factories
Vub/Vub 5%lB
l
B D
Vcb/Vcb 3%
3/11/2005 CLEO / Doris Kim 6
(3770) Analysis Techniques
Fully reconstruct 1st D “the tag”, then analyze decay of 2nd D to extract exclusive or inclusive properties.
(3770) ~ DDbar threshold No extra fragmentation = simpler geometry / combination Clean neutrino reconstruction High tagging efficiency at 25% of all D’s produced.
e
De
DK-
-
e+
K+
0
0
0
0
(3770)
,
D
D
D
D K eK
3/11/2005 CLEO / Doris Kim 7
Examples of CLEO-c Tagged D samples
~60,000 tagged D0 decaysFrom Dec 03 to Mar 04, we
collected the first 60pb-1 @ 3770 MeV with 6 wigglers, corresponding to 360,000 DDbar pairs.
Preliminary MBC plots from semileptonic BF study
Basic selection / fit variables are …
beam
22beamBC
E E D E
M E p D
Signal: Gaussian + bifurcated GaussianBackground: ARGUS function
3/11/2005 CLEO / Doris Kim 8
II. Leptonic Decays: D++• A “D hadronic tag” is required.• An additional charged track as +
and no extra shower > 250 MeV as a signal.
• Fit “missing-mass”2
Tag D
Signal D+
2 22
beam DMM E E p p
0D K
8 signal candidates
~60 pb–1
Yellow Book
1fb-1
Ph
ys. R
ev. D
, 70,
112
004
(200
4)
3/11/2005 CLEO / Doris Kim 9
fD from Absolute Br(D+ +)
150 180 210 240 270 300 330 360 390 420 450 480 510
Charged D Decay Constant (MeV)
• BES• Lattice 2004• CLEO-c• Isospin Mass Splittings• Potential Model• Rel. Quark Model• QCD Sum Rules• QCD Spectral Sum Rules• MILC• UKQCD
|fD|2
|VCKM|2
2222 2
21
8( ) / ( )F
cdD D DD
mGB D f m M V
M
Vcd (1.1%) from 3 generation unitarity
D+ (0.3%) well-measured
The first CLEO-c paper published.Phys. Rev. D, 70, 112004 (2004)• Based on 60 pb–1, 28651 tags and 8 signal events.• Background is ~ one event.
Mark III <290 MeV
BES I: 1 event (1998)
BES II: 3 events (2004) fD ~ 371 MeV
MeV 1741202
106.04.15.3 4
Df
DB
ICHEP 2004
3/11/2005 CLEO / Doris Kim 10
III. Exclusive Semileptonic BF.
Analysis Techniquese+
W+
Vcq
D
22
23 2
2 324F cqP
P p
G Vdp f q
dq
c qP, V
Decay rate for D P
Latest LQCD, PRL 94, 011601 (2005)
/ /
/
signal signal signal Xe
tag tag tag
N NB
N N
• Reconstruct one hadronic D tag.
• Reconstruct a semileptonic signal candidate from the remaining tracks/showers.
• Fit kinematic variable U( = Emiss – |Pmiss| ) for the
missing neutrino of the signal.
MC
Fit to MBC
Fit to U
3/11/2005 CLEO / Doris Kim 11
Signal Candidates of Neutral Semileptonic Modes.
Cabibbo favored modes Cabibbo suppressed modes
eKD0 eD0
0*
*0
KK
eKD0
0
D e
Preliminary U ( = Emiss – |Pmiss| ) plots
(~1400 events) (~110 events)
(~90 events) (~30 events) First Observation
The first 60pb-1
3/11/2005 CLEO / Doris Kim 12
Signal Candidates of Charged Semileptonic Modes.
Events
/ (
10
MeV
)Events
/ (
10
MeV
)
Events
/ (
10
MeV
)Events
/ (
10
MeV
)
eD 0
0D e
eKD 0
KK
eKD*0
*0 ,
(~60 events)
(~30 events)
(~500 events)
(~400 events)
Cabibbo suppressed modesCabibbo favored modes
Preliminary U ( = Emiss – |Pmiss| ) plots The first 60pb-1
3/11/2005 CLEO / Doris Kim 13
The Preliminary Exclusive BF.
Events
/ (
10
MeV
) 0
D e
(8 events)
Preliminary U( = Emiss – |Pmiss| )
World First Observation
The first 60pb-1
Preliminary
3/11/2005 CLEO / Doris Kim 14
Or We Can Do Without D Tagging!
• Require a signal: one e± and one
K or • Assume the other tracks/showeres are coming from the other D, ID them using dE/dx, RICH and EM calorimeter
information. Calculate Pmiss
• Fit on E, MBC
With D Tag, we have cleaner signal sample, but we loose statistics. What if we do not use D Tagging? Let’s try for D K/ e decays.
Signal MC
Background MC
3/11/2005 CLEO / Doris Kim 15
Semileptonic Events without D Tagging
D+D- Bkgd MCCont MCFakes
e e
e KS(+-) e
other e
Bkgd0 0D D
Data
D+D- Bkgd MCCont MCFakes
e S(+-) e
e K± e
other e
Bkgd0 0D D
Data
D+D- Bkgd MCCont MCFakes
e e
e KS(+-) e
other e
Bkgd0 0D D
Data
D+D- Bkgd MCCont MCFakes
KS(+-) e e
e K e
other e
Bkgd0 0D D
Data
eKD0 eD0
eKD 0 eD 0
Pre
limin
ary
3/11/2005 CLEO / Doris Kim 16
IV. Inclusive Semileptonic BF.
Analysis Techniques
• Reconstruct one hadronic D tag.
• Signal e+ : ID’d by dE/dx, RICH and E/p calorimeter
• Right/Wrong sign defined by K charge for D0, signal side charge for D+ background subtraction by wrong sign events.
PDG(2004) B(D0 X e+ ) = 6.87 ± 0.28 %
PDG(2004) B(D+ X e+ ) = 17.2 ± 1.9 %
Preliminary P(e+) spectra
CLEO-c (in D rest frame)
Cut-off
3/11/2005 CLEO / Doris Kim 17
Expected Uncertainty from the First 60 pb-1
%3.0~sysstat:PDG
%2.0~stat:c-CLEO : 0
BR
BRXeD
%9.1~sysstat:PDG
%3.0~stat:c-CLEO :
BR
BRXeD
tag m
ode
tag m
ode
PreliminaryNo BR yet
3/11/2005 CLEO / Doris Kim 18
V: Inclusive BF of D Xll
Electron and Neutrino Spectra are Different!
s
e+
se+
W+*
W+*
Low Q2
Low Q2
High , Low eE E
High , LoweE E
Conservation of angular
momentum get boost from W+ in the lab frame.
Analysis Techniques
• Reconstruct one hadronic D tag.
• Signal side: ID’d by dE/dx, RICH and E/p calorimeter, than add all.
• Get Pmiss and Mmiss^2.
• KL suppression is important.
3/11/2005 CLEO / Doris Kim 19
Emiss(GeV)
D0 D±
Red = signal
Blue = background
Black = Red + Blue
MCMC
MC Example of Emiss Spectra
Emiss(GeV)
D± l
3/11/2005 CLEO / Doris Kim 20
MC Data
Mis
sin
g E
ner
gy
(GeV
)
2 2 2( )miss missE P GeV
The Inclusive D XllCandidates
60 pb-1
2 2 2( )miss missE P GeV
KL Background
KL BackgroundSignal
Signal
3/11/2005 CLEO / Doris Kim 21
VI. CPV search in D0 Ks + - from CLEO II.V
• PRL 92, 142001 (2004)
• D0 / D0bar tagged by D* D0 +
(slow).
• Standard Model prediction at 10–6 for this channel from K mixing. sensitive to new physics
• Dalitz technique studies decay amplitude, not decay rate. sensitivity increase.
0 010 0 0130 043 0 0370 009 0 021 . .
. .. .CPA
M(Ks -)
M(Ks +)
M(+ -)
D0 + D0bar D0 - D0bar
3/11/2005 CLEO / Doris Kim 22
(1) New results on BF D+ and fD
(2) Exclusive BF of semileptonic decays coming (pretty) soon.• With just 60 pb-1, stastistical power of many decay modes already
at the world best.• The world first events of and
• We have two analysis options available: With and wo DTag
3 Inclusive BF of D Xeand D Xllcoming.
(4) Currently we are running at (3770) with 12 “8-pole” wigglers.
More data is coming on (3770), Ds threshold, etc.
VII: Summary and Future
MeV 1741202
106.04.15.3 4
Df
DB
0D e D e
fDs
3/11/2005 CLEO / Doris Kim 23
Question slides
3/11/2005 CLEO / Doris Kim 24
CLEO-c Impacts on the Unitarity Triangle
Now: Theory Uncertainties Dominate
Future: With CLEO-c, improved LQCD and 500 fb-1 each from the B factories
3/11/2005 CLEO / Doris Kim 25
Electron Spectrum of Inclusive Events
Very Preliminary
CLEO-c (in D rest frame)
time
3/11/2005 CLEO / Doris Kim 26
Charged D Meson Tags – Distributions of Mbc
SD K D K
0D K
0SD K
SD K D K K
~30,000 tagged D±
decays
Preliminary MBC plots from semileptonic BF study
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