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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