Investigation of Strangeness Photo-Production near the Threshold

Investigation of Strangeness Photo-

Productionnear the Threshold

Masashi Kaneta for the NKS2 collaboration

Department of Physics, Tohoku University

2

Questions

3

Q. 1You are: (1) an under graduate student, (2) a master course student, (3) a doctor course student, or (4) not a student

4

Q. 2Have you ever taken a class of nuclear physics?

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Q. 3Do you think that

QCD 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

LHCCERN

7


compression

phasetransition

Accelerators and Facilities

Baryon density

Baryon

Big bang

Tem

pera

ture


cool

ing

element synthesis

0

Meson

phase transition


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

AGSJ-PARC

Beam Ion Hadron Photon

LHCCERN

8


compression

phasetransition

My Phase Shift (Transition?)

Baryon density

Baryon

Big bang

Tem

pera

ture


cool

ing

element synthesis

0

Meson

phase transition


Our world

Neutron Star

Hadron Phase

SPSCERN

1994-1999Graduate studentof Hiroshima Univ.

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Pictures of NA44 Era

LHCCERN

10


compression

phasetransition


Baryon density

Baryon

Big bang

Tem

pera

ture


cool

ing

element synthesis

0

Meson

phase transition


Our world

Neutron Star

Hadron Phase

SPSCERN

RHICBNL

ELPHTohoku U.

1999-2005PostDoc of LBNL and RIKEN-BNL Research Center

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2002, RNC Group,LBNL

2004, RBRCChirstmanPartyhosted byT.D. Lee

LHCCERN

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compression

phasetransition


Baryon density

Baryon

Big bang

Tem

pera

ture


cool

ing

element synthesis

0

Meson

phase transition


Our world

Neutron Star

Hadron Phase

SPSCERN

RHICBNL

JLab

ELPHTohoku U.

2005-PresentAssistant Prof. of Tohoku Univ.

13

Outlook of This Talk

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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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)

Data in the Marketg+nK0+L

g+nK++S-

g+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

g+pK0+S+

Phys.Rev.C73(2006)035202

Phys.Rev.C73(2006)035202

Phys.Lett.B464(1999)331SAPHIR

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g+pK++L

g+pK++S0

Experiments to investigateStrangeness Photo-Production

at LNS/ELPH, Tohoku Univ.

NKSNKS2

and

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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

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NKS22005

Construction of new spectrometer2006-2007

Data taking

2008-2009Upgrade inner detectors

2010Data taking

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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 )

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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BM4 tagger

BM5 tagger

to the GeV gexperimental hall

NKS2

Radiator (Carbon wire) to make Bremsstrahlung

B

Photo

n Bea

mOrb

it ele

ctron

(1.2

GeV

)

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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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 ++-

L -+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%

RECENT RESULTS最近の結果

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Particle Identification

1/b

char

ge×m

omen

tum

[GeV

/c]

Mass square [GeV2/c4]

+

-

p d

+

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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Invariant Mass Distributions

34Error bars : statistical only

Differential Cross SectionE

g = 0.90 – 1.00 GeV

Eg = 1.00 – 1.08 G

eVds

/dp La

b [mb

/(GeV

/c)]

pLab [GeV/c]

g + d K0 + X (mainly g + n K0 + L)

Error bars : statistical only

Eg = 0.90 – 1.00 G

eVE

g = 1.00 – 1.08 GeV

ds/d

p Lab [mb

/(GeV

/c)]

pLab [GeV/c]

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Differential Cross Sectiong + d L + X (mainly g + n K0 + L

and g + p K+ + L)

COMPARISON WITH MODELSモデルとの比較

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Models near the threshold

Effective Lagrangian Approachalso knows as Isobar model

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Rigge Plus Resonance Model

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*

D, D*

K,K*,K1

Y

YYY*

g

N

KContact term

Y 38

- 0.45 in Kaon-MAID, estimated from gpK0S+ data Free parameter in Saclay-Lyon A

53.1)()()( *

00** - ++ g

ggKKgKKgKKr

)( 1 gKKr

• However, the decay width of K1 resonance is not known

Characteristics of KL Channel - comparison with KS

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g

N

K

YN, N*, D, D* , ....

s channel

In the s-channel exchange, KL: N* KS: N* and D*

Characteristics of K0L Channel- comparison with K +L

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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

Models• Kaon-MAID

– T.Mart, C.Bennhold– PRC61 (2000) 012201(R)

• Saclay-Lyon A– T. Mizutani et al. – PRC58 (1998) 75

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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 ○ ○D(1900) S31 ○D(1910) P31 ○K*(892) ○ ○K1 (1270) ○ ○L(1405) ○L(1670) ○L(1810) ○S(1660) ○

Hadronic form factor ○contact term ○

42Error bars : statistical only

Comparison with Isobar Modelsds

/dp La

b [mb

/(GeV

/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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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 Modelsg + d K0 + X, Eg = 1.08 – 1.08 GeV

Error bars : statistical only

Invariant AmplitudeM = Mbackground (Regge) + S Ms(Isobar)

Phys.Rev.C73 045207 T. Corthals et al.

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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) D13D(1900) S31 D(1910) P31

K*(892) TrajectoryK(494) Trajectory

4

3

2

1

0

a(t)

0 1 2 3 4 5 6

t [GeV/c2]

Calculation of RPR Model Eg = 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

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Comparison with RPR Model

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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

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 models

Angular distributionbackward enhance in K 0

S + 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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VDCIH

Investigation of Strangeness Photo-Production near the Threshold

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