search for exotics by emulsion
DESCRIPTION
Search for exotics by emulsion. J.Kawada & U.Kose (Nagoya). Emulsion. 3-dimensional Sub-micron tracking detector. Possible to detect the short-lived particles. Direct observation of decay topology!!. First detection of …. X-particle in cosmic ray interaction(1971) - PowerPoint PPT PresentationTRANSCRIPT
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Search for exotics by emulsion
J.Kawada & U.Kose (Nagoya)
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Emulsion 3-dimensional Sub-micron tracking detector
π‐K productionRecorded in ballon experiment
~ 100 microns
Possible to detect the short-lived particles.Direct observation of decay topology!!
•X-particle in cosmic ray interaction(1971)•Tau-neutrino at Fermi Lab E872 exp.(2000)
First detection of …
.
.
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What will we search…?
In CHORUS experiment , a bout 150,000 νμ and νμ events have been located in emulsion and fully reconstructed. - 93,807 νμ analyzed event by event and 2,013 νμ induced charm events,-2,704 νμ analyzed 40 charm have been found
CHORUS experiment has a very large number of charm events, it may also produce anticharmed Pentaquarks and charmed hyper nuclei.
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CHORUS ExperimentShort Base-Line neutrino oscillation experiment
@ CERN (1994 ~ 1997)
5.06 1019 POTs (1994-1997)
<E> ~ 27 GeV
<L> ~ 0.6 km
Ratio< E > ( G
eV) νμ 93.9 % 26.9
νμ 5.3 % 21.7
νe 0.007 % 47.9
νe 0.002 % 35.3
ντnegligibl
e-
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770 kg emulsion target
and scintillating fibre tracker
Calorimeter
Air core spectrometer andemulsion tracker
Air core spectrometer andemulsion tracker Veto plane
Muon spectrometerMuon spectrometer
- -
h-h-
Nucl. Instr. Meth A 401 (1997) 7
CHORUSCHORUS detector detector
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CHORUS EmulsionCHORUS Emulsion
71cm
36cm
36plates
Charged particle
350μ m
90μ m
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CHORUS Analysis Method
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CCD and XYZ stage
CCD and XYZ stage Host CPUHost CPU
Network Network data data
storagestorage
Automatic microscopesAutomatic microscopesUltra Track Selector(UTS)Ultra Track Selector(UTS)
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Found track
track shifting
summing
track
Automatic Scanning
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CalorimeterAir-core magnet
beamMuon spectrometer
Emulsion target
Interaction vertex
Electronic detector
prediction
Scan-Back Method
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All track segments infiducial volume
After a low momentumtracks rejection(P > 100 MeV) and numberof segments 2
After rejection ofpassing-through tracks
Tracks confirmedby electronic detectors
NET SCAN
Decay!
νint
Vtx point
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CHORUS Results 1 - νμ→ντ Oscillation -
No ντ observation
143,742(CC) + 24,184(NC)Events were analyzed
No candidate
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CHORUS Results - charm associating only -
Phys. Lett. B. 613 (2005) 105
Phys. Lett. B. 604 (2004) 11
Phys. Lett. B. 604 (2004) 145
Phys. Lett. B. 575 (2003) 198
Phys. Lett. B. 555 (2003) 156
Phys. Lett. B. 549 (2002) 48
Phys. Lett. B. 539 (2002) 188
Phys. Lett. B. 527 (2002) 173
Phys. Lett. B. 435 (1998) 458
Charmed Hyper Nuclei
D*+ production
D0 production
Antineutrino charm production
Fragmentation properties
QE charm productionΛc productionBR CC associate charm productionD0 production Diffractive Ds
* production
Accepted to Nucl. Phys. BPhys. Lett. B 614 (2005) 155
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CHORUS Results 2 - Measurement of D0 production -
Phys. Lett. B. 613 (2005) 105
2 prong (V2) 841 (background: 37) 4 prong (V4) 230 (background:0.25)
Observed D0 events sample: 95450 νμ CC events
6 prong (V6) 3 (background:0.19)(D0)=0.4010.027
(D0)/(CC)=0.0269 ± 0.0018 ± 0.0013
= 0.207 ± 0.016 ± 0.004B(D0 V4)B(D0 V2)
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CHORUS Results 3 - Anti neutrino charm production -
Decay topology
Candidate events
Background
2-prongs
16 1.4±0.3
4-prongs
6 0.13±0.06
1-prongs
4 0.8±0.2
3-prongs
4 0.3±0.2
5-prongs
2 0.02±0.01
Total 32 2.7±0.4
(syst)% 1.0(stat) 1.5)(
)( 4.10.1
XN
XcN
Sample: 2,704 νμ CC interactions
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What will we do next…?
1. Charmed Pentaquark
2. Charmed Hyper Nuclei
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Charmed Pentaquark Search
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Θc Production from ν
uud
uudd
d
d
c
ν ( Lepton)+
proton Θ c
W -
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Theoretical OverviewΘ0c ( uuddc) Mass prediction
Θ0c Mass ModelTheoris
t
2710 MeV diquark-diquark-antiquark
Jaffe,Wilczek
2704 MeV skyrme model Wu , Ma3445 MeV lattice QCD Sasaki
2985 MeV diquark-triquarkKarliner,Lipki
n
If Θc mass is bellow DN threshold (2807MeV)Θc can decay “Weakly”
Weak
Weak
Strong
Strong
→ lifetime of Θc can be expected to be in the range of other charm hadrons.
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Experimental Evidence at Experimental Evidence at H1H1
hep-ex/0403017hep-ex/0403017
•Only one evidence by H1 Collaboration: m=3099 MeV can be Only one evidence by H1 Collaboration: m=3099 MeV can be
considered as pD* stateconsidered as pD* state
•ΘΘcc (3099) can be considered as an excited state (chiral partner) (3099) can be considered as an excited state (chiral partner)
of the predicted ground pentaquark state of the predicted ground pentaquark state ΘΘcc(2710)(2710)
M. Nowak et al, hep-ph/0403184M. Nowak et al, hep-ph/0403184
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Possible decay Mode of Θ0c
Strong Decay
Θ0c → D*- P → D* 0 n → D- P → D 0 n
Weak Decay
Θ0c → θ +( Lepton) - ν → θ + π - → P π -Ks0 → P K+ π - π - ( golden topolog
y) : :
Above threshold
Below threshold
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Background of Θ c
Main background in emulsion are D0 , K0 and Λ0 decay. And neutron , K0 and Λ0 interaction without any visible nuclear breakup at the interaction point.
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How to Detect and Identify ?
Proton Identification to eliminate D0 B.G.
D0 → K - π+ (2-prongs) → K0π+π - (2-prongs) → K - π+π+π - (4-
prongs) : :
Any way , no proton in daughters.
cτ=123μm
Proton ID is the key to distinguish Θ0c and D0!!
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Proton ID by dE/dX and P.H.
..…..
1.2GeV/cπ
1.2Gev/c P
Test experiment@KEK
T.Toshito et al. N.I.M A516(2004)436-439
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dE/dX VS Momentum(GeV/c)
PKπμ
separatable region
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How to Detect and Identify ?
Topological analysis to eliminate Λ0 B.G.
Λ0 decay mode
Λ0 → P π - 2-prongs ( 63.9 %) → n π0 all neutral ( 35.8 %)
cτ=7.89cm
2-prongs only ( also Ks0 ).
4-prongs decay is only for D0,Θ0c.
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summary of Identification
4-prongsdecay mode
proton daughter
Θ0c Yes Yes
D0 Yes No
Λ0 No Yes
Ks0 No No
If 4-prongs decay have proton daughter, it could be Θ0c !!
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So far…
Decay topology
Candidate events
Background
2-prongs
16 1.4±0.3
4-prongs
6 0.13±0.06
1-prongs
4 0.8±0.2
3-prongs
4 0.3±0.2
5-prongs
2 0.02±0.01
Total 32 2.7±0.4
We have already found6 , 4-prongs decay ,in 2,704 νμ int.
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estimation of lifetime
P[GeV/c] = 1.5 × λ ー 1
λ = < θdecay >
θdecay
momentum → gamma factor → estimated “cτ”
D0
measured in emulsion
<θdecay>
D0 Momentum[GeV/c]
MC simulation
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Estimated cτ for 4-prongs decay
cτ ( D0 ) 123μmEstimated cτ[μm]
About cτ, these 6 eventsare very D0 like.
data MC
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How to Detect and Identify ?
Long flight length decay search
So far
6.4mm
10mm
1.5mm 3mm
1.5mm3mm
Θ0c may have long lifetime
This range is never searched before!!
Θ0c search
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Near Future plan…
Long Flight Length decay search (Now just started)
Proton ID Research & Development
A little bit far Future plan…?
New experiments to search Pentaquark
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Charmed Hyper Nuclei Search
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Roughly drawing of charmed hyper-nuclei production
νμP
n P
P PP
PP
n
n
nn
nn
nP
n
Charm hadron interactswith nuclei and Λ+ c is absorbed
μ -
hadron
νμ created μ - andhadrons and charm hadron
Decay
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How does it look?
s=1 hyper fragment decayobserved in CHORUS emulsion
Decay pointF.L. is a few microns
M.Miyanishi et al. CERN-PH-EP/2005-017
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How to identify a “charmed”
1. Energy release is bigger than “stranged”.
→ Stranged Hyper-Nuclei can’t exceed 200 MeV.
2. Charmed Hyper-Nuclei can have s=1 particle as a daughter.
→ K/π/P separation by dE/dX
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So far…Searched in 22,200 νμ interactions.
No candidate
Upper limit of production rate by 27GeV νμ
M.Miyanishi et al. CERN-PH-EP/2005-017
further search will be done…
4109.1)(
)(
XA
XSFA
2103.1)(
)(
XA
XSFA
c
(90%CL)
ε (CC) /ε (HF) = 0.87 ± 0.10
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Summary
Emulsion can give the “first direct observation” of pentaquark , and charmed hyper nuclei.
We have already had several thousands of νμ
interactions , and analysis is going on.
For charmed hyper nuclei , 22,200 νμ interactions have been analyzed and no candidate have been found. Further search will be done…
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Backup
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Summary of Identification
proton 4-prongs2-prong
with neutral
Θ0c
D0 no
Λ0 no no
Ks0 no no no
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How to Detect and Identify ?
Also 2-prongs…Kinematical analysis to eliminate Λ0 B.G.
2-prongs decay is also possible. If proton ID is done.
no neutral escapeΛ0 , Ks0 case~100%
θy
θx
parent
daughter
daughter
neutral escapeD0,Θ0c case
θy
θx
parent
daughter
daughterneutraldaughter
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Flight Length of D0
F.L.(micron)
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