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Investigation of Strangeness Photo-
Productionnear the Threshold
Masashi Kaneta for the NKS2 collaboration
Department of Physics, Tohoku University
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2
Questions
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3
Q. 1You are:
(1) an under graduate student, (2) a master course student, (3) a doctor course student, or (4) not a student
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4
Q. 2
Have you ever taken a class of nuclear physics?
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Q. 3
Do you think thatQCD can calculate
everything of hadron?
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Quark StarNeutron StarStars
compression
phasetransition
QCD Phase Diagram
Baryon density
Baryon
Big bang
Tem
pera
ture
Quark-Gluon Plasma(QGP) phase
cool
ing
element synthesis
0
Meson
phase transition
Color superconductivity?
Our world
Neutron Star
Hadron Phase
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LHCCERN
7
Quark StarNeutron StarStars
compression
phasetransition
Accelerators and Facilities
Baryon density
Baryon
Big bang
Tem
pera
ture
Quark-Gluon Plasma(QGP) phase
cool
ing
element synthesis
0
Meson
phase transition
Color superconductivity?
Our world
Neutron Star
Hadron PhaseJLab
RCNPOsaka
U.
ELPHTohoku U.
RIBFRIKEN
FAIRGSI
J-PARC
Spring-8
SISGSI
AGSBNL
SPSCERN
RHICBNL
LHCCERN
SIS 200/300
GSI
AGS
J-PARC
Beam
Ion Hadron Photon
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LHCCERN
8
Quark StarNeutron StarStars
compression
phasetransition
My Phase Shift (Transition?)
Baryon density
Baryon
Big bang
Tem
pera
ture
Quark-Gluon Plasma(QGP) phase
cool
ing
element synthesis
0
Meson
phase transition
Color superconductivity?
Our world
Neutron Star
Hadron Phase
SPSCERN
1994-1999Graduate studentof Hiroshima Univ.
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9
Pictures of NA44 Era
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LHCCERN
10
Quark StarNeutron StarStars
compression
phasetransition
My Phase Shift (Transition?)
Baryon density
Baryon
Big bang
Tem
pera
ture
Quark-Gluon Plasma(QGP) phase
cool
ing
element synthesis
0
Meson
phase transition
Color superconductivity?
Our world
Neutron Star
Hadron Phase
SPSCERN
RHICBNL
ELPHTohoku U.
1999-2005PostDoc of LBNL and RIKEN-BNL Research Center
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11
2002, RNC Group,LBNL
2004, RBRCChirstmanPartyhosted byT.D. Lee
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LHCCERN
12
Quark StarNeutron StarStars
compression
phasetransition
My Phase Shift (Transition?)
Baryon density
Baryon
Big bang
Tem
pera
ture
Quark-Gluon Plasma(QGP) phase
cool
ing
element synthesis
0
Meson
phase transition
Color superconductivity?
Our world
Neutron Star
Hadron Phase
SPSCERN
RHICBNL
JLab
ELPHTohoku U.
2005-PresentAssistant Prof. of Tohoku Univ.
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Outlook of This Talk
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INTRODUCTION序
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• General aim– Understanding the mechanism of strangeness production
• Reaction– hadron-hadron– gamma-nucleaon
• Missing resonance search w/ energy scan
• Characteristics of our experiment– Neutral channel
• K + data is not enough to make a model to predict cross section of neutral channel
• K 0 data is the KEY of the study– Threshold region
• No resonance decay effect in the final products
Strangeness Photo-production
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16
g+N K+Y
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g+p K++L(Eg threshold: 911.1 MeV)
g+p K++S0
(Eg threshold: 1046.2 MeV)
g+p K0+S+
(Eg threshold: 1047.5 MeV)
g+n K0+L(Eg threshold: 915.3 MeV)
g+n K0+S0
(Eg threshold: 1050.5 MeV)
g+n K++S-
(Eg threshold: 1052.1 MeV)
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Data in the Market
+nK0+L
+nK++S-
+nK0+S0
LEPS experiment:differencial cross section in Eg=1.5-2.4 GeVwith polarized photon beamPRL97 (2006)082003
NKS experiment:differencial cross sectionin Eg=0.8-1.1 GeVPRC78(2008)014001
CLAS experiment:differencial cross section in Eg=1.1-3.6 GeVPLB688(2010)289
+pK0+S+
Phys.Rev.C73(2006)035202
Phys.Rev.C73(2006)035202
Phys.Lett.B464(1999)331SAPHIR
18
+pK++L
+pK++S0
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Experiments to investigateStrangeness Photo-Production
at LNS/ELPH, Tohoku Univ.
NKSNKS2
and
19
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NKS2000-2004:
Using TAGX spectrometerReconstruct K0
S from +- decayThe first measurement of K0 cross sectionfrom +g nK0+L reaction [Phys.Rev.C78(2008)014001]
Neutral Kaon Spectrometer
20
Experiments to investigateStrangeness Photo-Production
at LNS/ELPH, Tohoku Univ.
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NKS2
2005Construction of new spectrometer
2006-2007Data taking
2008-2009Upgrade inner detectors
2010Data taking
21
Experiments to investigateStrangeness Photo-Production
at LNS/ELPH, Tohoku Univ.
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The NKS2 Collaboration• Department of Physics, Tohoku University
B. Beckford, T. Fujii, Y. Fujii, T.Fujibayashi, K. Futatsukawa,O. Hashimoto, A. Iguchi, H. Kanda, Kaneko, M. Kaneta,T. Kawasaki, C. Kimura, S. Kiyokawa, T. Koike, K. Maeda,N. Maruyama, Matsubara, Y. Miyagi, K. Miwa, S.N. Nakamura, A. Okuyama, H. Tamura, K. Tsukada, N. Terada, F. Yamamoto
• Research Center of Electron-Photon Science, Tohoku University K. Hirose, T. Ishikawa, T. Tamae, H. Yamazaki
• Department of Nuclear Science, Lanzhou University, Lanzhou, ChinaY.C. Han, T.S. Wang
• Nuclear Institute, Czech RepublicP. Bydzovsky, M. Sotona
博士課程前期 (修士で卒業 )博士課程後期 (Dr.Sc.を所得 )
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EXPERIMENT実験
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2424
青葉山キャンパス
電子光理学研究センター
Research Center of Electron-Photon Science(ELPH), Tohoku Univ.
Linac (Max 200 MeV)
Stretcher Booster Ring (Max 1.2 GeV)
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25
BM4 tagger
BM5 tagger
to the GeV gexperimental hall
NKS2
Radiator (Carbon wire) to make Bremsstrahlung
B
Phot
on B
eam
Orb
it el
ectro
n (1
.2 G
eV)
Scattered electron (0.1-0.4 GeV)
Tag F
Tag B
Sweep magnet
Photon Beam line – top view
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g beam
vacuum of STB-ring
CollimatorRejection of beam halo
Sweep MagnetRejection of e+e-
Dipole Magnet
Target SystemMaking of liq. D2 target
Vacuum Region Suppress of pair creation
Liquid D2 Target
Lead glass counterMeasurement of tagging efficiency
Photon Beam line – side view
BPM
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27
NKS2 Detector Setup• Dipole Magnet
– B=0.42 [T] at the center
• Inner Hodoscope– Trigger– Start timing of TOF
• Outer Hodoscope– Trigger– Stop timing of TOF
• Straw Drift Chamber– Tracking (2D)
• Cylindrical Drift Chamber– Tracking (3D)
• Electron Veto Counter
g beam
1.0 m
A vertical cross section along beam
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NKS
NKS2
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g+d K0+L+(p)
K0S p++p- L p-+p
Reaction
Decay Mode
TriggerPhoton: Tagger hit2 charged particle: nHit on IH2 and nHit on OH2Background rejection: Veto of e from upstream
Trigger rate: ~1 kHz at 2 MHz tagger rateDAQ efficiency ~70%
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RECENT RESULTS最近の結果
30
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31
Particle Identification
1/b
charg
e×
mom
en
tum
[G
eV
/c]
Mass square [GeV2/c4]
p+
p-
p d
p+
p
d
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Background Rejection
- decay volume cut
Target cell
No cut
Decay vertex resolution1.1mm for
horizontal4.2mm for
vertical
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33
Invariant Mass Distributions
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34Error bars : statistical only
Differential Cross Section
Eg =
0.90 – 1.00 GeV
Eg =
1.00 – 1.08 GeV
ds/d
p Lab [
mb/
(GeV
/c)]
pLab [GeV/c]
g + d K0 + X (mainly g + n K0 + L)
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Error bars : statistical only
Eg =
0.90 – 1.00 GeV
Eg =
1.00 – 1.08 GeV
ds/d
p Lab [
mb/
(GeV
/c)]
pLab [GeV/c]
35
Differential Cross Section g + d L + X (mainly g + n K0 + L
and g + p K+ + L)
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COMPARISON WITH MODELSモデルとの比較
36
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Models near the threshold
Effective Lagrangian Approachalso knows as Isobar model
37
Rigge Plus Resonance Model
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Theoretical Study: Effective Lagrangian Approach
• Hadron coupling– Isospin symmetry
• Electromagnetic (photo) coupling– Helicity amplitude
• Charged and neutral nucleon resonances
– Decay width• Charged and neutral Kaon resonances
g
g
g
N
N
N
K
K
K
s channel
t channel
u channel
YNN*
, DD*
K,K*,K1
Y
YYY*
g
N
K
Contact term
Y 38
- 0.45 in Kaon-MAID, estimated
from gpK0S+ data
Free parameter in Saclay-Lyon A
53.1)(
)()(
*
00**
KKg
KKgKKr
)( 1 KKr
• However, the decay width of K1
resonance is not known
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Characteristics of KL Channel - comparison with KS
39
g
N
K
YN, N*, D, D* , ....
s channel
In the s-channel exchange, KL: N* KS: N* and D*
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Characteristics of K0L Channel- comparison with K +L
40
g
N
K
t channel
K, K*, K1, . . .
Y
g
N
K
u channel
YYY*
.
.
g
N
K
YNN*
DD*
.
.
s channel
No contribution of charge term in coupling constants
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Models
• Kaon-MAID– T.Mart, C.Bennhold– PRC61 (2000) 012201(R)
• Saclay-Lyon A– T. Mizutani et al. – PRC58 (1998) 75
41
Kaon-MAID
Saclay-Lyon A
Inputdata
+g pK++L ○ ○
+g pK++S0 ○
+g pK0+S+ ○
Resonancesincluded in the model
N(1650) S11 ○
N(1710) P11 ○
N(1720) P13 ○ ○
(1900) S31 ○
(1910) P31 ○
K*(892) ○ ○
K1 (1270) ○ ○
(1405) ○(1670) ○(1810) ○(1660) ○
Hadronic form factor ○
contact term ○
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42Error bars : statistical only
Comparison with Isobar Modelsds
/dp La
b [m
b/(G
eV/c
)]
pLab [GeV/c]
g + d K0 + X, Eg = 0.90 – 1.00 GeV
Kaon-MAID All K0 L K0 S0
K0 S+
Saclay-Lyon A rkk = -1.0 rkk = -1.5 rkk = -2.0
Kaon-MAID All
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43
ds/d
p Lab [
mb/
(GeV
/c)]
pLab [GeV/c]
Kaon-MAID All K0 L K0 S0
K0 S+
Saclay-Lyon A rkk = -1.0 rkk = -1.5 rkk = -2.0
Kaon-MAID All
Comparison with Isobar Models g + d K0 + X, Eg = 1.08 – 1.08 GeV
Error bars : statistical only
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Invariant Amplitude
M = Mbackground (Regge) + S Ms(Isobar)
Phys.Rev.C73 045207 T. Corthals et al.
44
Regge Plus Resonance (RPR) Model
g
N
K
YN, N*, D, D* , ....
s channel
N(1650) S11 , N(1710) P11 N(1720)P13, N(1720) P13 N(1900) D13
(1900) S31 (1910) P31
K*(892) TrajectoryK(494) Trajectory
4
3
2
1
0
a(t
)
0 1 2 3 4 5 6
t [GeV/c2]
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Calculation of RPR Model E g = 0.9-1.0 GeV, cosqK0
Lab = 0.9-1.0
Nucleon Resonances in the KL process N(1650) S11, N(1710) P11, N(1720) P13, N (1900) P11, N(1900) D13
N(1900) D13 : Missing Resonance
No data to helicity amplitude of N(1900) D13
→ From -2.0 To 2.0 (Cyan Line 0.0)
P.Vancraeyveld et al.: private communication
Our results are two times larger than the calculations of RPR at least
45
Comparison with RPR Model
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46
K0L: Backward Distributions (fitting results)K+L: Forward Distributions (SAPHIR, CLAS)
SAPHIR: K. H. Glander et al., Eur. Phys. J., A19:251–273, 2004.CLAS: R. Bradford et al., Phys. Rev., C73:035202, 2006.
Kaon Angle distribution in CM
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SUMMARYまとめ
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Investigating strangeness photo-productionvia g + n K 0
S + L channelusing the NKS2 spectrometer at ELPH, Tohoku Univ.
Differential cross sections of K 0S and L in g+d
K 0S
Larger angle coverage than previous experiment L
The first measurement K 0
S + L total cross section estimatedsimilar shape to K +
+ L as a function of Eg
Suggestion from comparison of data with modelsAngular distribution
backward enhance in K 0S + L
(K + + L: slightly forward peak)
Detector upgrade was done and we took new data
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Upgrade Project
To increase acceptance Inner detectors are replaced
byVertex Drift Chamber (VDC)New Inner Hodoscope (IH)
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VDC
IH