II Hadron spectroscopy Paradigm change Mikhail Bashkanov University
II Hadron spectroscopy Paradigm change Mikhail Bashkanov University of Edinburgh UK Nuclear Physics Summer School
Outline � Naïve quark model � N* puzzle � Molecular states � Exotics ◦ ◦ ◦ Tetraquarks Pentaquarks Hexaquarks Hybrids Glueballs 2
Types of particles/resonances Meson Baryon white color anticolor 3
Quarks 4
The early days Murray Gell Mann 1964 “A schematic model of baryons and mesons” • Baryons are 3 quark systems • Mesons are quark-antiquark systems 5
Excited states? Shell model 6
Nucleon excited states? P – parity L – angular momentum 7
Excited states - expectation u d u 8
Excited states - expectation u u d u 9
Excited states - expectation u u d u d u 10
Excited states - expectation d u u 11
Excited states - expectation d u u 12
Excited states - reality d u u 13
Hyperons u d s 14
Excited hyperons? d u s 15
Excited hyperons - reality 16
Lattice QCD 17
Lattice QCD Models Nature 18
Missing states- extra states 19
Ideas? � Di-quark u degrees of freedom ud u 20
Ideas? � u u ud u d d u u u d u 21
Previous pion-nucleon resonances were discovered from observations on the qualitative behavior of experimental observables. The resonance suggested in this paper, however, is not associated with conspicuous features in the observables measured so far and has been inferred from a more quantitative analysis. L. D. Roper, Phys. Rev. Lett. 12 (1964) 340 22
The Roper resonance Old days: First radial excitation Mass [Me. V] 23
The Roper resonance Now: Mass [Me. V] 24
Structure of the resonance. Transition form factor 25
Structure of the resonance. Transition form factor JLab 26
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Excited hyperons - reality 28
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Molecular states. Mesons 31
Molecular states. Baryons 32
T. Inoue, * E. Oset, and M. J. Vicente Vacas, Phys. Rev. C 65, 035204 (2002) 33
Dynamically generated resonances 34
Types of particles/resonances Meson Baryon white color anticolor 35
Possible particles Tetraquark Meson-Meson molecule Hexaquark Baryon-Baryon molecule Pentaquark Meson-Baryon molecule 36
Multiquark vs Molecule Tetraquark Meson-Meson molecule XYZ states in charm sector 37
Exotics: Hybrids 38
Exotics: Hybrid baryons Transition form factor measurements 39
Exotics: Hybrid baryons Hadron Spectrum Collaboration 40
Dibaryons, B=2 systems 41
Deuteron L=0 p n 0. 9 fm 4 fm n p L=2 42
Deuteron to Deltaron I(Jp) u = u 0(1+) u d d d I(Jp) = 0(3+) u u u d d d Threshold 2. 2 Me. V p n deuteron 80 Me. V d* Δ Δ 43
Dibaryon hadronic decays PLB 721 (2013) 229 PRL 106 (2011) 242302 WASA data pn d*(2380) PRL 112 (2014) 202301 PRC 90, (2014) 035204 d* d* d* PRC 88 (2013) 055208 PLB 743 (2015) 325 44
Dibaryon in elastic scattering p p n n + dibaryon background 45
Polarization is a key Effect of the resonance SAID New SAID solutions 46
Hexaquark vs molecule e- e- * d*(2380) d Transition form factor Charge distribution Internal structure 47
Dibaryon in Skyrm model David Foster, Nicholas S. Manton ar. Xiv: 1505. 06843 48
d*(2380) SU(3) multiplet Jp = 3 + * * 49
Baryon Summary Table (PDG 2014) 50
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Conclusion � Precise experiments change our knowledge about well known resonances � Transition form factors -> internal structure � New exotic states ◦ ◦ ◦ ◦ ◦ � Meson Molecules Tetraquarks Hybrids Meson-Baryon Molecules Pentaquarks Hybrid baryons Baryon-baryon molecules Hexaquarks … A lot of states still to be found and identified 52
NN SU(3) multiplet Jp = 1 + pn Deuteron +2. 2 Me. V -166 ke. V -400 ke. V 53
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