Nucleon resonances via H,D( ) reactions GeV Experiments at GeV Hall at LNS 2001-02: GeV Hall, 2003: STB tagger II, SCISSORS II, STB special.

Nucleon resonances via H,D() reactions

GeV Experiments at GeV Hall at LNS 2001-02: GeV Hall,

2003: STB tagger II, SCISSORS II, STB special e-beam

2004-05: Experiments with 0.6 < E < 1.15 GeV 2006: FOREST construction

1. C,Cu() S11(1535) in nuclei; Phys. Lett. B639 (2006) 4292. H() proton cross section; p→p; Phys. Rev. C (2006) in press

3. D() neutron cross section; S11, D15, pentaquark; submitted soon4. H,D(0) Nucleon resonances

5. C,Si,Cu() E < 0.8 GeV, threshold region

Heavy baryon (with c/b/t quarks) 3 quarks in short distance one gluon exchange field

r < 0.3 fm

r ~ 1 fm

Light baryon (with u/d/s quarks) 3 dynamical (dressed) quarks effective chiral field (Goldstone boson exchange)

diquark-quark clusterization?

Perturbed region

Non-perturbed region

Baryon density

Bar

yon

inte

rnal

ene

rgy

Why light baryon?

Existence of pentaquark state constituent quark model chiral quark soliton model

SpontaneousChiral

symmetry breaking10MeV

current-quarks (~5 MeV) Constituent-quarks (~350 MeV)

Particles Quasiparticles

2*350MeV

0

0

Quark- Model

Nucleon

•Three massive quarks

•2-particle-interactions:

•confinement potential

•gluon-exchange

•meson-exchage

•(non) relativistisc

• chiral symmetry is not respected

•Succesfull spectroscopy (?)

Chiral Soliton

Nucleon

Mean Goldstone-fields (Pion, Kaon)

Large Nc-Expansion of QCD ????

Quantum numbers Quantum #

Quantum #

Quantum #Coherent :1p-1h,2p-2h,.... Quark-anti-quark pairs „stored“ in chiral mean-field

Coupling of spins, isospins etc. of 3 quarks

mean field non-linear system soliton rotation of soliton

Natural way for light baryon exotics. Also usual „3-quark“ baryons should contain a lot of antiquarks

S11 S11

D15?P11 , P13

S11 S11

D15?P11 , P13

H,D(g,h) reactions so far reported

Nucleon Energy Spectrum

Electron Beam from 300MeV LINAC

1.2 GeV　 STB Ringelectron Synchrotron

Tagged Photon Beam

GeV-Experimental Hall

17 m

GeV experiments at LNS

Pseudosphere 55 cm

Backward Block(29)

BackwardBlock(29)

ForwardBlock(74)

ForwardBlock(74)

Solid Target Chamber

Incident γ

Plastic Counters

Invariant Mass Analysis

M2 = 2E

E(1 - cos

) Energy :E = Ei

Position :R = Ri Ei /Ei

SCISSORS II :206 pure CsI Crystals(1.57 str = 12.5% of 4 )16.2 X0 for Forward 148 crystals 13.5 X0 for Backward 58 crystals

+ N → + X

Hydrogen/DeuteriumSolid Targett = 8 cm (NT ～ 4×1023/cm2 )

Identification of meson = (39.43±0.26)%

　 　 → → Decay ChannDecay Chann

elel

Experimental setup

M Gate :440—620 MeV

Empirical Fitting Function:Empirical Fitting Function:

F(M)= L(M) + B(M)

L(x)=l0 exp[ l1(l2 - x) + exp( -l1(l2 - x))]B(x)=exp(b0 +b1 x + b2 x2)

Invariant Mass

Double Differential Yield d 2N/dp dcos (at +N CMS)

p→ p

p→N

channel open Momentum Cut　 P*(3b max) p→ p　抽出

d/d d/dp

(p→p)

(p→N)

H(,)H reaction

For E < 1.15 GeV(LNS) ～ (CLAS, ELSA) no third S11 (Saghai and Li) (E) ～ (MAID) S11(1535) largest S11(1650) destructive P11(1720) very small + direct (Born, , ex.)

E > 1 GeV p→N not negligible (N) ～ (p) at 1.1 GeV

MAID

p→p process

Direct 3 Body

S11

P33

New observation: p→*→→N ～ 50%

N(938)

N(1535)

L=0

(1720)

L=0

(1670)

L=0

(1750)

L=0

(1232)(1116)

(1192)3/2+ 1/2+

1/2+

1/2- 1/2-

1/2-

3/2-

1/2+

　 p→N, p→0p

phase space

Jido, Oka, Hosaka Prog. Theor. Phys.106,873 (2001)

N(938)-S11(1535): parity partner

chiral transformation scheme

NN* N*

N

gN*N*/gNN =+ or -?

S11(1535) only is not enough

(p→N) = (2 ～ 3)×(p→0N)

p→0N process

Doring, Oset, Stottman Phys. Rev. C73,045209 (2006)

Chiral unitary approach for meson-baryon scattering D33(1700), S11(1535), D13(1520)

Jido et al.

Doring et al.

D() reaction

?

Original motivation:<u|e|u>=2/3, <d|e|d>=-1/3 →difference in magnetic transitions between proton and neutron

proton target: only S11(1535), S11(1650) neutron target: D15(1675) should be enhanced

Present interest: antidecuplet state N* (S=0) originally assigned to P11(1710) reanalisys N scattering PR C69(04)035208 W=1680, ～ 10 MeVGRAAL preliminary n coin. Data W=1675 MeV sharp state

The anti-decuplet

1539 < 25 MeV

1862

～ 1646

～ 1754

Reevaluation by Diakonov and Petrov, 04

Modified analysis pN scattering Arndt et al. PRC69(04)035208

n measurement in D(n)p Kunznetsov et al. preprint (05)

Jp:1/2+ or 1/2- ?Width: very small < 10 MeV?Other members: S=0 sector? strongly observed in n >> p sharp resonance

CB-ELSA(IX International WorkshopOn Meson Photoproduction,Crakow,Poland,9.-13,June 2006)

N→N exclusive measurementTotal Cross Section

GRAAL (hep-ex0601002)

n→n exclusive measurementDifferential Cross Section cos~-0.7

proceedings, preliminary Results

n measurement: quasi-free kinematics (advantage) incomplete arrangement of neutron detectors →low statistics, not high E resolution, spectrum deformed

inclusive measurement d→pn: whole kinematics, complex analysis (disadvantage) high statistics, high E resolution, spectrum not deformed W, , Jp, transition strength,….. may be obtained precisely.

Comparison with proton data

・ broader momentum distribution ～ 20 MeV increased due to the deuteron target

・ however, good separation between

d→ pn, d→pn

momentum distributions in d→pn

angular distributions in c.m. frame of photon incident on nucleon at rest (‘c.m.’)

Total cross section vs E

d→pn ’p’→p

(d)-(’p’)

Narrow resonance! rough estimate peak at E=1020 MeV apparent width E ～ 80 MeV

Effects of nucleon motion in the deuteron

FWHM =75 MeV

solid line : F(pN)open circles: CD-Bonn

Hulthen Wave Function

F(pN) =pN2/((pN

2+2)(pN2+2)) 2

=45.7 MeV=260 MeV

cos

Angular DistributionE=1 GeV n

cos

1 = 0.5

=10MeV (18MeV in E

=60 MeV(E~100MeV)

Analysis: isobar model +impulse approx.

)~()~()( nnd

dpp

d

dpnd

d

d

; neglect p-n interference and f.s.i

)~( ppd

d

)~( nnd

d

; on shell cross section result of MAID for p→p

; result of the isobar model similar to the MAID calculation

Direct term (Born and and exchange): from MAIDResonances: Mass N A1/2 A3/2

D13(1520) 1520 120 0.06 -59 -139 S11(1535) 1541 191 50 varied S11(1650) 1638 114 7.9 varied D15(1675) 1665 150 17 varied F15(1680) 1681 130 0.06 29 -33 D13(1700) 1700 100 26 0.0 -3.0 P11(1710) 1721 100 36 varied P13(1720) 1720 150 3.0 varied + narrow P11 or S11

Angular distributions compared with calculationsP11 at 1670 MeV, = 7.5 MeV S11 at 1660 MeV, = 8.5 MeV,

Total cross section

P11 at 1670 MeV, = 7.5 MeV

S11 at 1660 MeV, = 8.5 MeV

A1/2 = 12.5 for P11

= -12.5 for S11

Anti-decuplet N* is established! 1/2+ or 1/2-

S11(1535)S11(1650)

Narrow P11

D15(1675)P11(1710)P13(1720)

Narrow S11

neutron cross section

Further measurement with FOREST

n coincidence with good geometry

Parity + or – need more statistics

Branching ratio 0 channel: Miyahara channel

Anti-decuplet in nuclei 7Li()

S11(1535) resonance molecular nature? Magnetic moment