1. N*ews from COSY
May | Hans Ströher (Forschungszentrum Jülich, Germany)

2. Selected recent results
N*ews from COSY – Outline
COSY-facility
Detection systems
Selected recent results 2 2

3. COSY N*ews from COSY – Storage Ring
Cooler and storage ring for (polarized) protons and deuterons
p = 0.3 – 3.7 GeV/c
Phase space
cooled internal &
extracted beams
COSY
e-Cooler
Injector
cyclotron 3

4. … the machine for spin physics
N*ews from COSY – Storage Ring
Cooler and storage ring for (polarized) protons and deuterons
p = 0.3 – 3.7 GeV/c
Phase space
cooled internal &
extracted beams
COSY
e-Cooler
… the machine for spin physics
with hadron beams
Injector
cyclotron 4

5. N*ews from COSY – Experiments
Hadron physics with hadronic probes
Experimental set-ups:
ANKE
WASA
EDM
TOF
NEW:
PAX
WASA
ANKE
EDM
PAX
TOF

6. N*ews from COSY – Experiments
Hadron physics with hadronic probes
Experimental set-ups:
ANKE
WASA
EDM
TOF
NEW:
PAX
WASA
ANKE
EDM
PAX
TOF
Future plan/project:
srEDM

7. N*ews from COSY – Experiments
ANKE:
forward magnetic spectrometer
solid, gas-jet, polarized targets
double polarization experiments
TOF:
large acceptance non-magnetic det.
liquid hydrogen, deuterium targets
(non-)strange meson, hyperon prod.
WASA:
~4p electromagnetic calorimeter
thin superconducting solenoid
hydrogen, deuterium pellet target
symmetries and symmetry violation

8. N*ews from COSY – Experiments
ANKE:
forward magnetic spectrometer
solid, gas-jet, polarized targets
double polarization experiments
TOF:
large acceptance non-magnetic det.
liquid hydrogen, deuterium targets
(non-)strange meson, hyperon prod.
WASA:
~4p electromagnetic calorimeter
thin superconducting solenoid
hydrogen, deuterium pellet target
symmetries and symmetry violation

9. N*ews from COSY – Experiments
ANKE:
forward magnetic spectrometer
solid, gas-jet, polarized targets
double polarization experiments
TOF:
large acceptance non-magnetic det.
liquid hydrogen, deuterium targets
(non-)strange meson, hyperon prod.
WASA:
~4p electromagnetic calorimeter
thin superconducting solenoid
hydrogen, deuterium pellet target
symmetries and symmetry violation

10. COSY N*ews from COSY – General N N  N N*  [N N] X (= g, p, h, …)
NN fusion: p N(+)  (N N*)+(+)  d p(+)
D-resonance
Mostly: no resonance structure, since
3(4)-body phase-space & strong FSI
 invariant mass distributions
COSY
HADES at GSI 10 10

11. COSY N*ews from COSY – General N N  N N*  [N N] X (= g, p, h, …)
Special cases, e.g. p p  p p p0p0
Roper
COSY
WASA at CELSIUS 11 11

12. COSY N*ews from COSY – General N N  N N*  N K Y (hyperons)
Isospin (-filter):
K L only N* resonances, e.g.
N*(1650, 1675, 1680,1700,
1710, 1720, 1840, 1875, 1900)
K S both N* and D* resonances, e.g.
D*(1600, 1620, 1700, 1750,
1900)
Polarization (target, beam):
K+, p, L asymmetries, L polarization
COSY 12 12

13. N*ews from COSY – Results (I)
p p  p K+ Y0
(Y0 = L, S0)
TOF 13 13

14. N*ews from COSY – pp  pK+ (L;S0)
Reaction: pp  p K+ (p p-)
3 beam energies: pp = 2.95 GeV/c (QL = 204, QS = 124 MeV);
3.06 GeV/c (239, 162 MeV);
3.20 GeV/c (284, 207 MeV)
Primary and secondary V-shape; charged multiplicity jump; ToF 14

15. N*ews from COSY – pp  pK+ (L;S0)
Reaction: pp  p K+ (p p-)
3 beam energies: pp = 2.95 GeV/c (QL = 204, QS = 124 MeV);
3.06 GeV/c (239, 162 MeV);
3.20 GeV/c (284, 207 MeV)
Primary and secondary V-shape; charged multiplicity jump; ToF
Result: (1) COSY-TOF collaboration, EPJ A 46, 27 – 44 (2010) 15

16. N*ews from COSY – pp  pK+ (L;S0)
Reaction: pp  p K+ (p p-)
3 beam energies: pp = 2.95 GeV/c (QL = 204, QS = 124 MeV);
3.06 GeV/c (239, 162 MeV);
3.20 GeV/c (284, 207 MeV)
Primary and secondary V-shape; charged multiplicity jump; ToF
Result: (2) L case (239 MeV):
complete coverage
cms frame:
cos(q)= 0 symmetric
Jackson-frames
helicity-frames 16

17. N*ews from COSY – pp  pK+ (L;S0)
Reaction: pp  p K+ (p p-)
3 beam energies: pp = 2.95 GeV/c (QL = 204, QS = 124 MeV);
3.06 GeV/c (239, 162 MeV);
3.20 GeV/c (284, 207 MeV)
Primary and secondary V-shape; charged multiplicity jump; ToF
Result: (3) helicity-frames:
strong evidence for:
N*(1650)S11
N*(1710)P11 and/or
N*(1720)P13
unlikely:
N*(1675)D15
N*(1680)F15
N*(1700)D13 pL
K+p 17

18. N*ews from COSY – pp  pK+ (L;S0)
Reaction: pp  p K+ (p p-)
3 beam energies: pp = 2.95 GeV/c (QL = 204 MeV);
3.20 GeV/c (284 MeV)
3.30 GeV/c (316 MeV)
Primary and secondary V-shape; charged multiplicity jump; ToF
Result: (3) COSY-TOF collaboration, PL B 688, 142 (2010)
Dalitz-plot analysis
Importance of
N*(1650)
compared to
N*(1710)
N*(1720)
2.85 GeV/c … TOF (2006) 18

19. N*ews from COSY – pp  pK+ (L;S0)
Reaction: pp  p K+ (p p-)
3 beam energies: pp = 2.95 GeV/c (QL = 204, QS = 124 MeV);
3.06 GeV/c (239, 162 MeV);
3.20 GeV/c (284, 207 MeV)
Primary and secondary V-shape; charged multiplicity jump; ToF
Result: (4) S0 case (162 MeV):
complete coverage
small statistics
cms frame
Jackson-frames
helicity-frames
differences to L 19

20. N*ews from COSY – pp  pK+ (L;S0)
Next: additional high-statistics data  PWA
(i) upgraded detector (STT) (ii) polarized proton beam (2.95 GeV/c)
pb = 2.95 GeV/c
P = ( ) % 20

21. N*ews from COSY – pp  pK+ (L;S0)
Next: additional high-statistics data  PWA
(i) upgraded detector (STT) (ii) polarized proton beam (2.95 GeV/c)
PAC39 (May 2011) allocated 9 weeks to finalize physics program;
after that TOF will be decomissioned in 2012.
pb = 2.95 GeV/c
P = ( ) % 21

22. N*ews from COSY – Results (II)
p p  n K+ S+
ANKE,
COSY-11
HIRES 22 22

23. N*ews from COSY – pp  n K+ S+
Reaction: pp  K+ n X (COSY-11)
pp  K+ X ; (K+p) X ; (K+p+) X (ANKE)
pp  K+ X (HIRES)
Result: (1) COSY-11 collaboration, PL B 643, 251 (2006)
ANKE collaboration, PR C81, (2010)
HIRES collaboration, PL B 692, 10 (2011)
Disappointing expt´l situation, but:
very high X-section
clearly excluded
 no D* ++ (1620) contribution needed
s [µb] 23

24. N*ews from COSY – Results (III)
p p  p p w
(Resonances?)
TOF 24 24

25. N*ews from COSY – pp  pp w
Reaction: pp  p p p+p- X
3 beam energies: pp = 2.95 GeV/c (Qw = 92 MeV);
3.06 GeV/c (128 MeV)
3.20 GeV/c (173 MeV)
4 charged particles; ToF; missing p0
Result: (1) COSY-TOF collaboration, EPJ A 44, 7 (2010)
w via missing mass
„… no obvious indication of w production via
N* resonances
found …“ 25

26. N*ews from COSY – Results (IV)
p p  {pp}s g
(D(1232))
ANKE 26 26

27. N*ews from COSY – pp  {pp}s g
Reaction: pp  pp X (X = g, p0)
6 beam energies: Tp = 353 … 800 MeV
2 protons, DEpp < 3MeV  1S0 (Diproton); qlab < 20°
Result: (1) ANKE collaboration, J.Phys. G 37, (2010)
missing mass analysis
p0 dominating;
clear g-contribution 27

28. N*ews from COSY – pp  {pp}s g
Reaction: pp  pp X (X = g, p0)
6 beam energies: Tp = 353 … 800 MeV
2 protons, DEpp < 3MeV  1S0 (Diproton); qlab < 20°
Result: (2)
energy dependence shows resonant
behavior;
comparison with
pn  d g
D-resonance
shifted, smaller width
(note: no M1 possible)
WASA/Promise result (Uppsala) – covers much larger angular range 28

29. p n  d p0p0 (ABC-Effect) WASA N*ews from COSY – Results (V)
May 18, Session II-C (15:20)
T. Tolba; „Double pion production in pp-interactions at Tp = 1.4 GeV“ 29 29

30. N*ews from COSY – pp  pp p0p0
high energies
near threshold
pp→pN*(1440)
pp→∆ ∆(1232)
p π
p π π
∆ (1232) π
p π 30

31. N*ews from COSY – pn  d p0p0
Reaction: pd  d p0p0 pspectator ; d and p0p0 detected
3 beam energies: Tp = 1.0, 1.2, 1.4 GeV; Fermi momentum
Effective energy ranges: 2.22 – 2.36; 2.33 – 2.44; 2.42 – 2.56 GeV
Result: (1) WASA-Collaboration, submitted PRL (2011) 31

32. N*ews from COSY – pn  d p0p0
Reaction: pd  d p0p0 pspectator ; d and p0p0 detected
3 beam energies: Tp = 1.0, 1.2, 1.4 GeV; Fermi momentum
Effective energy ranges: 2.22 – 2.36; 2.33 – 2.44; 2.42 – 2.56 GeV
Result: (2)
Maximum (2.38 GeV) Off-peak (2.50 GeV) 32

33. N*ews from COSY – pn  d p0p0
Reaction: pd  d p0p0 pspectator ; d and p0p0 detected
3 beam energies: Tp = 1.0, 1.2, 1.4 GeV; Fermi momentum
Effective energy ranges: 2.22 – 2.36; 2.33 – 2.44; 2.42 – 2.56 GeV
Result: (2) 33

34. N*ews from COSY – pn  d p0p0
Reaction: pd  d p0p0 pspectator ; d and p0p0 detected
3 beam energies: Tp = 1.0, 1.2, 1.4 GeV; Fermi momentum
Effective energy ranges: 2.22 – 2.36; 2.33 – 2.44; 2.42 – 2.56 GeV
Result: (3)
What is this?
independently normalized
Mass ~ M(DD) - 80 MeV
Width ~ ¼ of G(DD) 34

35. N*ews from COSY – pn  d p0p0
Reaction: pd  d p0p0 pspectator ; d and p0p0 detected
3 beam energies: Tp = 1.0, 1.2, 1.4 GeV; Fermi momentum
Effective energy ranges: 2.22 – 2.36; 2.33 – 2.44; 2.42 – 2.56 GeV
Result: (3)
Roper-contribution (R  Dp  Npp) 35

36. N*ews from COSY – pn  d p0p0
Reaction: pd  d p0p0 pspectator ; d and p0p0 detected
3 beam energies: Tp = 1.0, 1.2, 1.4 GeV; Fermi momentum
Effective energy ranges: 2.22 – 2.36; 2.33 – 2.44; 2.42 – 2.56 GeV
Result: (3)
t-channel DD-contribution (from pp  d p+p0 via isospin) 36

37. N*ews from COSY – pn  d p0p0
Reaction: pd  d p0p0 pspectator ; d and p0p0 detected
3 beam energies: Tp = 1.0, 1.2, 1.4 GeV; Fermi momentum
Effective energy ranges: 2.22 – 2.36; 2.33 – 2.44; 2.42 – 2.56 GeV
Result: (3)
s-channel resonance at M = 2.37 GeV and G = 68 MeV 37

38. N*ews from COSY – pn  d p0p0
Reaction: pd  d p0p0 pspectator ; d and p0p0 detected
3 beam energies: Tp = 1.0, 1.2, 1.4 GeV; Fermi momentum
Effective energy ranges: 2.22 – 2.36; 2.33 – 2.44; 2.42 – 2.56 GeV
Result: (4)
Next: (i) pn  pn p0p0, (ii) pol. d-beam (i.e. np  d p0p0), (iii) pn elastic
pn  R(3+)  DD  dp0p0
J=3
J=1 38

39. N*ews from COSY – Summary
Part of the ongoing COSY program devoted to N* physics
(NN- and NY-interaction (ANKE, TOF), symmetries (WASA), …)
Hyperon production at TOF  extension to pol. beams  PWA
ABC-resonance at WASA  nature (s-channel resonance?) 39

40. N*ews from COSY – Summary
Part of the ongoing COSY program devoted to N* physics
(NN- and NY-interaction (ANKE, TOF), symmetries (WASA), …)
Hyperon production at TOF  extension to pol. beams  PWA
ABC-resonance at WASA  nature (s-channel resonance?) 40

41. N*ews from COSY – Information
pp  pp m 41 41