Two-pion production in Delta-Two-pion production in Delta-DeltaDelta

region – approaching the ABC region – approaching the ABC puzzlepuzzle

by exclusive and kinematically by exclusive and kinematically completecomplete

measurements.measurements.

T.Skorodko, University Tuebingen

for CELSIUS-WASA

First step into the ABCFirst step into the ABC

Alexander Abashian, Alexander Abashian, Norman E. Booth and Norman E. Booth and Kenneth M. Crowe, Kenneth M. Crowe, Phys. Rev. Lett. Phys. Rev. Lett. 55, 258 (1960), 258 (1960)

5.113 He

X Hepd 3

labHe

P3

π

2 π Phase SpaceMeV 743pT

C

All of ABCAll of ABC

dXnp Xpd He3

Xdd He4

No ABC effect!

ABC effect

ΔΔΔΔ

π

N

Δπ

NΔ

π N

Δ

π

N

Δ

Large π π invariant mass

Small π π invariant mass

ππ

π π π

π π

ABC and ABC and ΔΔΔΔ models models

labdP

00

M HeM 3

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

He3

He3

(I=0,1)

(I=0)

pdpd33He He ππππ, T, Tpp=895 MeV=895 MeV

ΔΔΔΔ versus versus NN* decays* decays

HeM 3

He3

He3

He3

He3

*N

0

0

pdpd33He He ππππ, T, Tpp=895 MeV=895 MeV

ΔΔΔΔ versus Reality versus Reality

Bound Bound ΔΔΔΔ

3He

p

d

mol

ecul

e

ΔΔΔΔ interaction interaction

2

2

20

2

2

111

qqra

R

s

fmR 1.1

fmfmas 10

16

fmr 20

Migdal-Watson ansatz

ABC effect on ABC effect on 33He and dHe and d003 Hepd 00 dpn

GeV 037.1pTGeV 895.0pT

ΔΔ interaction data of O. Khakimova

Total x-section forTotal x-section for dpn

Celsius/WasaHeidelberg – Tel-Aviv

JINR

unbound (ΔΔ)int

bound (ΔΔ)int (24 MeV)

pp pp pp ppABC effect ? ABC effect ?

interaction

ConclusionConclusion

It is extremely important to make It is extremely important to make exclusive measurements:exclusive measurements:

ABC effect is one bump, not two!ABC effect is one bump, not two! ABC effect may be explained by ABC effect may be explained by ΔΔΔΔ

molecule or by molecule or by ΔΔΔΔ interactioninteraction.. Very strong attractive Very strong attractive ΔΔΔΔ interaction. interaction.

|a|ass||13fm13fm tottot indications of indications of ΔΔΔΔ bound state. bound state.