Two-pion program at WASA

Mikhail BashkanovA discovery of the Di-baryon state with Wasa-at-COSY

Wasa-at-COSY

1Types of particles/resonancescoloranticolorwhiteMesonBaryonMikhail Bashkanov "Dibaryons"2

Possible particlesPentaquarkMeson-Baryon moleculeHexaquarkBaryon-Baryon moleculeMikhail Bashkanov "Dibaryons"3TetraquarkMeson-Meson moleculeDeuteron to Deltaron4Thresholdpn2.2 MeVdeuteron80 MeVd*I(Jp) = 0(1+)I(Jp) = 0(3+)uuuddduuudddd*(2380)The Discovery5

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

7Angular distribution in the peak

J=1J=3P. Adlarson et. al Phys. Rev. Lett. 106:242302, 20118The extracted properties of the new particlepn dibaryon DD dp0p0

dpnI(Jp) = 0(3+)Mikhail Bashkanov "Dibaryons"9Isospin relations10I=0I=111Total cross section pN d P. Adlarson et. al Phys. Lett. B721 (2013) 229

Only with deuteron?1213From fusion to free case pn d* DD dpp

dpnpn d* DD NNpp

pnNNFldt & Wilkin, PLB 701 (2011) 619Albaladejo & Oset, Phys.Rev. C88 (2013) 014006

14pn pn00d*Conventional process

Conventional process +d*d* P. Adlarson et al., Phys.Lett. B743 (2015) 325-332Dibaryon non-fusion decays15

PLB 743 (2015) 325d* d* PRC 88 (2013) 055208HADESarXiv:1503.04013Dibaryon hadronic decays16

pn d*(2380)

PRL 112 (2014) 202301PRC 90, (2014) 035204PLB 721 (2013) 229PRL 106 (2011) 242302PRC 88 (2013) 055208PLB 743 (2015) 325WASA datad* d* d* 17The decay modes of the dibaryonChannelPublicationsd p0p0 M. Bashkanov et. al Phys.Rev.Lett. 102 (2009) 052301P. Adlarson et. al Phys. Rev. Lett. 106:242302, 2011P. Adlarson et. al Phys.Lett. B721 (2013) 229-236d p+p- P. Adlarson et. al Phys.Lett. B721 (2013) 229-236ppp0p-P. Adlarson et. al Phys. Rev. C 88, 055208npp0p0P. Adlarson et. al Phys.Lett. B743 (2015) 325npA. Pricking, M. Bashkanov, H. Clement. arXiv:1310.5532P. Adlarson et al. Phys. Rev. Lett.112, 202301, (2014)P. Adlarson et al. Phys. Rev. C90, 035204, (2014)pn e+e-M. Bashkanov, H. Clement, Eur.Phys.J. A50 (2014) 1073He pp M. Bashkanov et. al Phys.Lett. B637 (2006) 223-228P. Adlarson et. al Phys. Rev. C 91 (2015) 1, 0152014He pp P. Adlarson et. al Phys.Rev. C86 (2012) 032201+ activities from other groups Mikhail Bashkanov "Dibaryons"M. Bashkanov, Stanley J. Brodsky, H. Clement Phys.Lett. B727 (2013) 438-442

Only with two pions?1819pn d* DD dpp

dpnpn d* DD NNpp

pnNNpn d* pn

pnnp20

Expectationspnnp

SAIDSAID with resonanceA. Pricking, M. Bashkanov, H. Clement: arXiv:1310.5532

21pnnp

SAIDA. Pricking, M. Bashkanov, H. Clement: arXiv:1310.5532

22pnnp

SAIDNew SAIDsolutionsP. Adlarson et al. Phys. Rev. Lett.112, 202301, (2014) Dimensionless partial wave amplitudes23

ReImSP07SP14Dimensionless partial wave amplitudesResonance in the pn systemP. Adlarson et al. Phys. Rev. Lett.112, 202301, (2014)

24Argand plotP. Adlarson et al. Phys. Rev. Lett.112, 202301, (2014)P. Adlarson et al. Phys. Rev. C90, 035204, (2014)

25Argand plotsP. Adlarson et al. Phys. Rev. Lett.112, 202301, (2014)P. Adlarson et al. Phys. Rev. C90, 035204, (2014)

Molecule vs Hexaquark26Deuteron27npnpL=20.9 fm4 fmL=0d*(2380) internal structure and the ABC effect

28L=20.9 fm0.9 fmL=01.2 fmM. Bashkanov et al, arXiv:1502.07500Deltaron vs Hexaquark29L=20.9 fm0.9 fmL=01.2 fm0.7 fmF. Huang et al, arXiv:1408.0458The family of dibaryons30Mirror dibaryon31DDI(Jp) = 0(3+)d*uuudddI(Jp) = 3(0+)DDuuuuuuFreeman J. Dyson, Nguyen-Hue Xuong Phys. Rev. Lett. 13(1964) 815Avraham Gal, Humberto Garcilazo Nucl. Phys. A928, (2014), 73**+***+***+**++++--d*How many ways can you combine 6q?IsospinStrangenessZ=+4 dibaryon isospin coefficientsppppI34

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Preliminary36pppppppppppp

37Double-RoperPreliminaryCharge Z=+4 dibaryon upper limit

38PreliminaryNN vs 39Thresholdpnpn2.2 MeV66 keVdeuteron?80 MeVd*Z=+4**+***+***+**++++--d*How many ways can you combine 6q?IsospinStrangenessd*(2380) SU(3) multiplet**41Jp = 3+Strange DibaryonIsospinStrangeness**+***+*d*d*(2380) in photoproduction?43

dpnR. Gilman and F. Gross nucl-th/0111015 (2001)T. Kamae, T. Fujita Phys. Rev. Lett. 38, Feb 1977, 471H. Ikeda et al., Phys. Rev. Lett. 42, May 1979, 1321d*I(Jp) = 0(3+)The benchmark measurement44dpn

Newly installedEdinburgh polarimeterM.H. Sikora, D.P. Watts et al, Phys.Rev.Lett. 112 (2014) 022501Mikhail Bashkanov "Dibaryons"Measure polarization of both proton and neutron !d*ConclusionThe very first dibaryon d*(2380) is establishedMassWidthQuantum numbersMain decay branchesStructure: Hexaquark vs Molecule?No convincing signs for the mirror dibaryon (charge Z=+4) so farSize and shape of the conventional background?Mirror multiplet (28-plet) is likely to be unbound45Thank youZ=+4 dibaryonNNppppWASA, HADES48

49Dyson-Xuong, PRL 13 (1964) 815Mulders-Aerts-de Swart, PRD 21 (1980) 2653Oka-Yazaki, PLB 90 (1980) 41.Mulders-Thomas, JPG 9 (1983) 1159.A. Gal, H. Garcilazo Nucl.Phys. A928 (2014) 73-88 d*(2380) begins50Celsius WASA

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M.Bashkanov et. al, Phys. Lett. B637 (2006) 223-228(I=0)pd3He, Tp=0.89 GeVThe ABC-effect ==-FSI effect?

WASA 4 Detector pdn53First hints on d*(2380) at CELSIUS

Phys.Rev.Lett.102, 052301 (2009) CELSIUS/WASACELSIUS to COSYThe Discovery55