Two-pion program at WASA

Mikhail BashkanovNew Results on the ABC-Resonance Structure

Wasa-at-COSY1Content2Two-pion production3N*DDDN*sDD(1600)Tp < 1.5 GeVExpectations in total cross section

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ABC resonance70 MeVTotal cross section pn d00 P. Adlarson et. al Phys. Rev. Lett. 106:242302, 2011NN*(1440)6

Angular distribution in the peak

J=1J=3Quantum numbers of the structureAntisymmetrization: Jp=1+or 3+ : if L=0

pn d* d 00 pn d 00I=0,1I=0I=0,2I=01+3+

1+ excluded by ().3+ assigned 78

t-channel ABC effectM for different energies9Status of Theoretical Descriptionpn R DD dp0p0

dpnI(Jp) = 0(3+)Isospin relations10I=0I=111Total cross section pN d P. Adlarson et. al Phys. Lett. B721 (2013) 229

12M in pN d

13M in pN d

14M in pN d

Isospin violation

15+-00Non-fusion channel1617

pn pp-0ABC expectedPreliminaryConventional processConventional process +ABCPrediction for the open channels18

M. Albaladejo, E. Oset nucl-th:1304.7698Elastic channel19Kinematics

20Proton spectatorprotonneutrondpnp + psp213+ Resonance in npnpL=2npL=4pnnp22Total pn cross-section

SAIDDevlin et al, PRD8, 136 (73) LisowskI et al, PRL49, 255(82)23

Expectationspnnp

SAIDSAID with resonance

24Expectationpnnp

SAID

25Realitypnnp

SAID

26pn Vector Analysing Power

SAIDVery PreliminaryConclusion27Thank you

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SAID

Beam polarization0Polarization 2Polarization 1

35pn Vector Analysing Power

SAIDVery Preliminary

Isospin DecompositionSkorodko at al., Phys. Lett. B679 (2009) 30

N*(1440)[(1600)]

Beam polarization0Polarization 2Polarization 1

38Total cross section pp d+0 Shimizu et al.F. Kren et al.

39Total cross section pn d00

40Total cross section pn d+-

41Total cross section pn d+- 42M in pN d

43M in pN d

44M in pN d

Isospin violation

45+-00