Post on 12-Jan-2016
1
Charm Results from FOCUS
Kihyeon Cho Kyungpook National University
Daegu, Korea
(On behalf of FOCUS Collaborations)
Flavor Physics CP Violation 2004 October 4 -9, 2004
KIHYEON CHOCENTER FOR HIGH ENERGY PHYSICS2
ContentsContents
Why Charm Physics? FOCUS Experiment Recent Charm Results from FOCUS
1. Pseudoscalar semileptonic decays2. Vector semileptonic decays3. Charm hadronic mixing4. Search for new particles – pentaquarks, double charm baryons
Conclusions
KIHYEON CHOCENTER FOR HIGH ENERGY PHYSICS3
Why charm physics?Why charm physics?
Window to new physics Standard model rates for rare decays, CP violation and mixing are very l
ow. With current experiments, observation of CP violation, rare decays or mi
xing new physics Provides information about QCD
Measurements of production characteristics, lifetimes, branching ratios and subresonant analyses provide insight into QCD.
Needed for b physics Many b particles decay to charm so branching ratios and lifetimes are ne
eded for accurate b results. Experimental techniques are developed in charm physics. (lifetime meas
urement, Dalitz plot analyses...) Heavy quark effective theory often needs charm to bootstrap to b physic
s.
KIHYEON CHOCENTER FOR HIGH ENERGY PHYSICS4
Photoproduction of Charm with an Upgraded Spectrometer
~100 Physicists, 18 institutes from 5 countries
Univ. of California-Davis, CBPF-Rio de Janeiro, CINVESTAV-Mexico City, Univ. Colorado-Boulder, FERMILAB, Laboratori Nazionali di Frascati,
Univ. of Illinois-Urbana-Champaign, Indiana Univ.-Bloomington, Korea Univ.-Seoul, Kyungpook National Univ.-Daegu, INFN and Univ.-Milano,
Univ. of North Carolina-Asheville, INFN and Univ.-Pavia, Univ. of Puerto Rico-Mayaguez,Univ. of South Carolina-Columbia, Univ. of Tennessee-Knoxville,
Vanderbilt Univ.-Nashville, Univ. of Wisconsin-Madison
FOCUS ExperimentFOCUS Experiment
KIHYEON CHOCENTER FOR HIGH ENERGY PHYSICS5
Vertexing is the KeyVertexing is the Key
Golden Modes:
D+ K- D0 K- D0 K- BeO
BeO
tarsiltarsil
| primary vtx | secondary vtx
Dec
ays
/ 200
m
BackgroundBackgroundSubtractedSubtracted
Golden ModeGolden ModeCharmCharm
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1.1. Pseudoscalar Pseudoscalar semileptonic decay semileptonic decay
Using D0D0 (D0(D0 Pole masses f-(0)/f+(0)
f+(0)/f+
K(0)
Non-parametric q2 dependent
KIHYEON CHOCENTER FOR HIGH ENERGY PHYSICS7
Why Pseudoscalar Why Pseudoscalar semileptonic decay?semileptonic decay?
The differential decay rate is
Measuring the q2 dependence and form factors in heavy quark transition is critical to our understanding of QCD.
Hadronic current contains information about strong contributions.
KIHYEON CHOCENTER FOR HIGH ENERGY PHYSICS8
What do we measure What do we measure in Din D00PlPl
(D0(D0
Pole masses
f-(0)/f+(0)
f+(0)/f+
K(0) provides the test of SU(3)
symmetry breaking
Non-parametric q2 dependent A model independent
measurement would allow to discriminate between different models.
f+(q2) parameter
Pole form
Modified pole from
KIHYEON CHOCENTER FOR HIGH ENERGY PHYSICS9
Fitting Technique on Fitting Technique on DD00
Fit D*-D0 mass difference plot to find the amount of combinatoric background.
Apply the mass difference cut (< 0.154 GeV/c2) to suppress combinatoric and peaking background
KIHYEON CHOCENTER FOR HIGH ENERGY PHYSICS10
Results on Results on DD00
Fit to cos l and q2 to measure branching ratio, pole masses and the ratio f-(0)/f+(0).
28829
6574 92
30.015.091.1
M
007.0008.0074.0)(
)(0
0
KD
D
05.004.093.1
KM
6.14.17.1
)0(
)0(
K
K
f
fPreliminary
(GeV/c2),
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Extracting fExtracting f++(0)/f(0)/f++
KK(0)(0)
Compute a numerical integration on Dalitz
Get efficiency as a function of q2
Get yield from the fit
Using PDG
|Vcd/Vcs|2 =0.051
Consistent with the predictions from SU(3) symmetry breaking and lattice QCD
Preliminary
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Non-parametric qNon-parametric q22 dependentdependent
e
Ke
form factor f+(q²)
single-pole model
single-pole model
Based on 820 events
q² / GeV²
Kl
l
q² / GeV²
Using ~13,000 K events
3 brand new results from CLEO, Belle and FOCUS on form factor f+(q²) in DD00ll/ Kl/ Kl
f+(q²)
Excellent agreement with LQCD!
Preliminary
KIHYEON CHOCENTER FOR HIGH ENERGY PHYSICS13
Summary for pseudoscalar semSummary for pseudoscalar semileptonic decayileptonic decay
The and branching ratio is consistent with recent results from CLEO.
The pole masses are lower than the predicted value at the D* or Ds* masses.
We presented a non-parametric analysis of the q2 dependence for D0K which shows excellent agreement with the results obtained with the parametric analysis and lattice QCD.
007.0008.0074.0)(
)(0
0
KD
D
30.015.091.1
M05.004.093.1
KM
6.14.17.1
)0(
)0(
K
K
f
f04.004.085.0
)0(
)0(
Kf
f
Preliminary
, (GeV/c2)
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2. Vector Semileptonic decay2. Vector Semileptonic decay
D+ K*0 form factorBranching ratio D0 K*- form factorBranching ratio )(/)0( 00* KDKD
)(/)( 000* KDKD
KIHYEON CHOCENTER FOR HIGH ENERGY PHYSICS
(D(D++KK*0*0 / / DD++ K K00))
*0
00.594 0.043 0.033
D K
D K
Use upstream Ks (~10%) so that both the signal (K) and normalization (Ks ) leave 3 tracks in FOCUS microstrip
sK
*0 0D K l K l Theory
S-wave corrected
Old
qu
ark
mo
del
PLB 598 (2004) 33
KIHYEON CHOCENTER FOR HIGH ENERGY PHYSICS16
Form Factors of DForm Factors of D00KK*-*-
++ K*- Ks -
After background subtraction, we fit D*-D0 mass difference and cosl X cos v X q2 distribution at the same time.
Results
RV= 1.706 0.677 0.342
R2 = 0.912 0.370 0.104 World’s first measurement
Preliminary
KIHYEON CHOCENTER FOR HIGH ENERGY PHYSICS17
Summary of vector semilepotonSummary of vector semilepotonic decayic decay
Form Factor FOCUS D0K*-+ FOCUS D+K*0
Rv 1.706 0.677 0.342 1.504 0.057 0.039
R2 0.912 0.370 0.104 0.875 0.049 0.064
Reference Preliminary PLB 544 (2002) 89
013.0034.0337.0)(
)(00
*0
KD
KD
033.0043.0594.0)(
)(0
0*
KD
KDPLB 598 (2004) 33
Preliminary
KIHYEON CHOCENTER FOR HIGH ENERGY PHYSICS18
3. D3. D00-D-D00 hadronic mixing hadronic mixing and DCS decaysand DCS decays
D0 goes to K+- in two ways (mixing + CF decay and DCS decay) Interference
Assuming CP conservation, D0 K+- wrong sign to right sign decay ratio is written by
Three terms from DCS decays, interference & mixing Soft pion charge in D*+ D0+ defines right sign(RS) and wrong sign
(WS). Fit for RDCS, x’2 and y’
Mixing parameters
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Right Sign vs Wrong SignRight Sign vs Wrong Sign
KIHYEON CHOCENTER FOR HIGH ENERGY PHYSICS20
Summary for Mixing Summary for Mixing ResultsResults
All results shown here assume CP conservation.
FOCUS results agree better with BaBar in location and shape than CLEO.
KIHYEON CHOCENTER FOR HIGH ENERGY PHYSICS21
4. New particle searches4. New particle searches
S=-1 pentaquark (1540)+ with uuddsS=-2 pentaquark (1860)– – with uddssCharm pentaquark c(3100)0 with uuddc
Double charm baryons cc with ccu and ccd
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Evidence for Evidence for ++(uudds)(uudds)
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Evidence for Evidence for + + (cont’d) (cont’d)
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(1540)(1540)++ p Ks search p Ks search
No evidence for (1540)+ pKs but reconstructs 8 million K*(892)+ Ks+ and 240,000 (1385)+ 0+
KIHYEON CHOCENTER FOR HIGH ENERGY PHYSICS25
(1860)(1860)– –– – search search(1860)- - -- (S=-2 pentaquark)
NA49 shows evidence for (1860)- - and (1860)0 decaying -..
No evidence for (1860)- - -- but reconstructs 60,000 (1530)0 - +, approximately 1,000 times more than observing experiment.
KIHYEON CHOCENTER FOR HIGH ENERGY PHYSICS26
Charm Pentaquark searchCharm Pentaquark search
No evidence for a charm pentaquark decaying to D*-p or D-p with a factor of 10 more D*+ decays than the observing experiment.
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CCCC search search
No evidence
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Summary for Search Summary for Search ResultsResults
No evidence for (1540)+ pKs but reconstructs 8 million K*(892)+ Ks+ and 240,000 (1385)+ 0
No evidence for (1860)- - -- but reconstructs 60,000 (1530)0 - +, approximately 1,000 times more than observing experiment
No evidence for a charm pentaquark decaying to D*-p or D-p with a factor of 10 more D*+ decays than the observing experiment.
No evidence for double charm baryons with 10 times more C decays than the observing experiment.
KIHYEON CHOCENTER FOR HIGH ENERGY PHYSICS29
ConclusionsConclusions
Charm mode …Charm physics gives a rich source of new results.FOCUS is playing a major role in understanding the
charm decays.The recent charm results from FOCUS include
Charm pseudoscalar semileptonic decays Charm vector semileptonic decays Charm hadronic mixing Search for pentaquarks and double charm.
FOCUS is continuing studies of charm physics.
KIHYEON CHOCENTER FOR HIGH ENERGY PHYSICS30
BackupsBackups
KIHYEON CHOCENTER FOR HIGH ENERGY PHYSICS31
FOCUS SpectrometerFOCUS Spectrometer
At FermilabBeO charm
Segmented target
Silicon vertexing
MWPC tracking
~175 GeV
Cenenkov ID
EM/hadronic Calorimeter
Muon detectors
KIHYEON CHOCENTER FOR HIGH ENERGY PHYSICS32
Fo
cus 04
MK
3
E691
Cleo
91
Cleo
93
E687 tag
E687 in
c
Cleo
041.4
1.6
1.8
2.0
2.2
2.4
2.6
po
le m
ass
Kl
1.910.04
qq22 dependent (cont’d) dependent (cont’d)Clearly the data does not favor the simple Ds* pole
We presented a non-parameteric analysis of the q2 dependence for D0K which shows excellent agreement with the results obtained with the parameteric analysis and lattice QCD.
KIHYEON CHOCENTER FOR HIGH ENERGY PHYSICS33
DD++ K K*0 *0 channelchannel
Only external diagram involved.
Factorization is possible between hadronic and leptonic current.
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H0(q2), H+(q2), H-(q2) are helicity-basis form factors computable by LQCD
right-handed +
left-handed +
Two amplitudes get summed over W polarization using D-matrices
22 2
(0)( )
1i
iA
AA q
q M
22 2
(0)( )
1 V
VV q
q M
Helicity FF are combinations of one vector and two axial form factors.
v 1(0) (0)r V A
2 2 1(0) (0)r A A
Two observables parameterize the decay
Four body decays requires five variables: 3 angles, Mk , q .
DD++ K K*0 *0 decaysdecays
KIHYEON CHOCENTER FOR HIGH ENERGY PHYSICS35
2
20
2
2
2
5
)(sincos2
)()cos1(sin
)()cos1(sin
coscos
0*
0*
0*
qHB
qHBe
qHBe
ddddqdm
d
KV
Ki
V
Ki
V
Vk
0*KD
Yield 31,254
DataMC
Focus “K*” signal
matches model
-15% F-B asymmetry!
Interference in DInterference in D++ K K*0 *0
Huge Asymmetry in cosv below K* pole led to a discovery of s-wave interference.
KIHYEON CHOCENTER FOR HIGH ENERGY PHYSICS36
KK** interference term (Ae interference term (Ae ii))
2
20
2
2
2
5
)()(cossin2
)(sin)cos1(
)(sin)cos1(
coscos
0*
0*
0*
qHAeB
qHBe
qHBe
ddddqdm
d
iKV
Ki
V
Ki
V
Vk
S-wave interference term
Signal events weightedby avg(cosV):
No added term
PLB535(2002) 43
KIHYEON CHOCENTER FOR HIGH ENERGY PHYSICS37
S-Wave effects apparent only with high statistics
Lattice Gauge!
Experiment Models PLB544(2002) 89
Form Factors Form Factors DD++KK*0*0ll
A=0.3300.0220.015GeV-1
=0.68 0.07 0.05 rad
RV= 1.5040.0570.039
R2= 0.8750.0490.064
KIHYEON CHOCENTER FOR HIGH ENERGY PHYSICS38
DD00KK*-*-++ channel channel
KIHYEON CHOCENTER FOR HIGH ENERGY PHYSICS39
KK** interference term (Ae interference term (Ae ii))
A term which is non-symmetric vs. cosv appears due to the S-wave
Use a model that includes S-wave
= 0.68 rad fixed from
A=0.3470.2220.053 GeV-1
*0 KD
0** KD
KIHYEON CHOCENTER FOR HIGH ENERGY PHYSICS40
Branching Ratio Branching Ratio
D*-D mass difference plot for normalization mode
Accounting for S-wave component in 00 KD
Normalization mode
Excellent agreement with semielectronic decay
)(
)(00
*0
KD
KD
013.0034.0337.0)(
)(00
*0
KD
KD
KIHYEON CHOCENTER FOR HIGH ENERGY PHYSICS41
Summary of vector semilepotonSummary of vector semilepotonic decayic decay
FOCUS D0 FOCUS D+
Rv 1.706 0.677 0.342 1.504 0.057 0.039
R2 0.912 0.370 0.104 0.875 0.049 0.064
A(GeV-1) 0.347 0.222 0.053 0.330 0.022 0.015
(rad) 0.68 (fixed) 0.68 0.07 0.05
Reference Preliminary PLB 544 (2002) 89013.0034.0337.0
)(
)(00
*0
KD
KD
033.0043.0594.0)(
)(0
0*
KD
KD
PLB 598 (2004) 33
Preliminary
KIHYEON CHOCENTER FOR HIGH ENERGY PHYSICS42
Fit Shape (Signal)Fit Shape (Signal)
KIHYEON CHOCENTER FOR HIGH ENERGY PHYSICS43
Double charm baryon Double charm baryon production comparedproduction compared
If the C+K-+ (CK-++) signal is real, SELEX produces at
least 42 (111) times more cc baryons relative to C than FOCUS.