Two-pion program at WASA

Mikhail BashkanovInvestigations of the Basic double-pionic fusion in the region of the ABC effect

Wasa-at-COSY1Content2Fusion3npnpgDouble-pionic fusion4npnpppggggDouble-pionic fusion5npnpppThe ABC-effect6npnpppHistory of the ABC effectLow mass enhancement in M

Alexander Abashian, Norman E. Booth Kenneth M. Crowe, Phys. Rev. Lett. 5, 258 (1960)

M.Bashkanov et. al, Phys. Lett. B637 (2006) 223-228

P. Adlarson et. al, Phys. Rev. C86 (2012) 032201P. Adlarson et. al, Phys. Rev. Lett. 106 (2011) 2423028

ABC resonance70 MeVTotal cross section pn d00 P. Adlarson et. al Phys. Rev. Lett. 106:242302, 2011NN*(1440)9

t-channel ABC effectM for different energies10

Angular distribution in the peak

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

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

1+ excluded by ().3+ assigned 1112Status of Theoretical Descriptionpn R DD dp0p0

dpnI(Jp) = 0(3+)Isospin relations13I=0I=114Total cross section pN d P. Adlarson et. al Phys. Lett. B721 (2013) 229

15M in pN d

16M in pN d

17M in pN d

Open channel18pn pp-0

19ABC expectedPreliminaryConventional processConventional process +ABCElastic channel20213+ Resonance in pnnpL=2npL=4Kinematics

22Proton spectatorprotonneutrondpnp + psp23Total pn cross-section

SAIDDevlin et al, PRD8, 136 (73) LisowskI et al, PRL49, 255(82)24

Expectationspnnp

SAIDSAID with resonance

25Expectationpnnp

SAID

26Realitypnnp

SAID

27pn Vector Analysing power

SAIDVery PreliminaryConclusion28Thank youMultiplet1010=35282710**Y()=2I()=0Kim Maltman, Nucl. Phys. A501 (1989) 843Mirror dibaryon31DDI(Jp) = 0(3+)d*uuudddI(Jp) = 3(0+)DDuuuuuuMirror Multiplet1010=35282710***+***+**+**++++--33M in pN d

34M in pN d

35M in pN d