Hadronic Transitions in Bottomonia at Belle Simon Eidelman Budker - PowerPoint PPT Presentation

MESON 18, Krak´ ow June 2018 Hadronic Transitions in Bottomonia at Belle Simon Eidelman Budker Institute of Nuclear Physics SB RAS and Novosibirsk State University, Novosibirsk, Russia, and Lebedev Physical Institute RAS, Moscow, Russia (on behalf of the Belle Collaboration) Outline 1. Transitions in bottomonia at Belle 2. Prospects for BelleII 3. Conclusions S.Eidelman, BINP&Lebedev p.1/30

MESON 18, Krak´ ow June 2018 General • Spectroscopy of heavy quarkonia provides crucial information for understanding strong interactions since QCD calculations become possible: heavy-quark spin symmetry (HQSS), multipole expansion etc. • Measurements of hadronic transitions ( π + π − , η, ω, . . . ) btw. bottomonia yield important input for QCD • η transitions are believed to be suppressed compared to π + π − because of the spin flip • π + π − transitions and their peculiarities were studied by both BaBar and Belle, the contribution of Belle being particularly strong due to high statistics and versatile analyses like use of missing mass distributions • Large integrated luminosity collected by Belle above the Υ(4 S ) opened unique possibilities resulting in exciting observations of h b (1 P ) , h b (2 P ) , η b (2 S ) , Z b (10610) and Z b (10650) S.Eidelman, BINP&Lebedev p.2/30

MESON 18, Krak´ ow June 2018 Observation of h b (1 P ) and h b (2 P ) at Belle Events / 5 MeV/c 2 ϒ(2 S)→ ϒ(1 S) ϒ(2 S) 40000 30000 ϒ(1 S) h (2 P) b ϒ(3 S)→ ϒ(1 S) h (1 P) 20000 b ϒ(3 S) ϒ(1 D) 10000 0 9.4 9.6 9.8 10 10.2 10.4 2 M miss (GeV/c ) Belle used efficiently high-statistics data samples of the Υ(10860) to study the M miss ( ππ ) spectrum in e + e − → h b ( nP ) π + π − which shows a variety of states with different J P Also important for discovery of the Z b (10610) and Z b (10650) I. Adachi et al., Phys. Rev. Lett. 108, 032001 (2012) S.Eidelman, BINP&Lebedev p.3/30

MESON 18, Krak´ ow June 2018 Study of η and π + π − Transitions in Υ(4 S ) Decays to Lower ( b ¯ b ) – I From 538M Υ(4 S ) Belle studied Υ(4 S ) → π + π − Υ(1 S, 2 S ), Υ(4 S ) → η Υ(1 S ) and searched for inclusive Υ(1 3 D 1 , 2 ) → η Υ(1 S ), η → π + π − π 0 , Υ(1 S, 2 S ) → µ + µ − ) A 2 Υ → π π Υ + - . (2S) (1S) ) (GeV/c D 10.2 B Υ → π π Υ + - . (3S) (1S) C Υ → π π Υ + - . (4S) (1S) 10 D Υ → π π Υ + - . (4S) (2S) µ µ 9.8 M( C 9.6 9.4 A B 9.2 0.3 0.4 0.5 0.6 0.7 0.8 0.9 1 1.1 1.2 ∆ 2 M (GeV/c ) ∆ M = M ( ππµµ ) − M ( µµ ), E. Guido et al., Phys. Rev.D 96, 052005 (2017) S.Eidelman, BINP&Lebedev p.4/30

MESON 18, Krak´ ow June 2018 Study of η and π + π − Transitions in Υ(4 S ) Decays to Lower ( b ¯ b ) – II 250 ) ) 2 2 50 Events / (5 MeV/c Events / (4 MeV/c D. C. Υ → π π Υ + - (4S) (2S) 200 Υ → π π Υ + - (4S) (1S) 40 Υ → µ µ + - Υ → µ µ (2S) + - (1S) 150 30 100 20 50 10 0 0 1.07 1.08 1.09 1.1 1.11 1.12 1.13 1.14 1.15 1.16 0.5 0.51 0.52 0.53 0.54 0.55 0.56 0.57 0.58 0.59 0.6 ∆ ∆ 2 2 M (GeV/c ) M (GeV/c ) B , 10 − 5 B PDG , 10 − 5 Decay Events Υ(4 S ) → π + π − Υ(1 S ) 1095 ± 74 8 . 2 ± 0 . 5 ± 0 . 4 8 . 1 ± 0 . 6 Υ(4 S ) → π + π − Υ(2 S ) 821 ± 107 7 . 9 ± 1 . 0 ± 0 . 4 8 . 6 ± 1 . 3 E. Guido et al., Phys. Rev.D 96, 052005 (2017) S.Eidelman, BINP&Lebedev p.5/30

MESON 18, Krak´ ow June 2018 Study of η and π + π − Transitions in Υ(4 S ) Decays to Lower ( b ¯ b ) – III 5 ) ) 2 2 20 Υ → η Υ Events / (10 MeV/c Events / (5 MeV/c 3 (1 D ) (1S) 4.5 1,2 η → π π π 18 - 0 + 4 Υ → η Υ Υ → µ µ + - 16 (4S) (1S) (1S) η → π π π - 3.5 + 0 14 Υ → µ µ + - (1S) 3 12 2.5 10 2 8 1.5 6 1 4 0.5 2 0 0 0.5 0.52 0.54 0.56 0.58 0.6 0.62 0.64 0.12 0.13 0.14 0.15 0.16 0.17 0.18 ∆ ∆ 2 2 M (GeV/c ) M (GeV/c ) η η B , 10 − 4 B PDG , 10 − 5 Decay Events Υ(4 S ) → η Υ(1 S ) 49 ± 7 1 . 70 ± 0 . 23 ± 0 . 08 1 . 96 ± 0 . 28 Υ(1 3 D 1 , 2 ) → η Υ(1 S ) 2 . 1 ± 3 . 0 < 0 . 23 – E. Guido et al., Phys. Rev.D 96, 052005 (2017) S.Eidelman, BINP&Lebedev p.6/30

MESON 18, Krak´ ow June 2018 Study of η and π + π − Transitions in Υ(4 S ) Decays to Lower ( b ¯ b ) – IV 180 1.2 ) Efficiency ) Efficiency 2 2 200 1.2 Events / (30 MeV/c Events / (20 MeV/c D. 160 C. 180 Υ → π π Υ + - Υ → π π Υ + - (4S) (2S) 1 (4S) (1S) 140 1 Υ → µ µ + - 160 Υ → µ µ + - (1S) (2S) 120 0.8 140 0.8 100 120 80 0.6 100 0.6 60 80 0.4 0.4 40 60 20 40 0.2 0.2 0 20 − 20 0 0.3 0.4 0.5 0.6 0.7 0.8 0.9 1 1.1 1.2 0.3 0.35 0.4 0.45 0.5 0.55 π π π π - 2 - 2 + + M( ) (GeV/c ) M( ) (GeV/c ) Striking difference of M ( ππ ) spectra E. Guido et al., Phys. Rev.D 96, 052005 (2017) S.Eidelman, BINP&Lebedev p.7/30

MESON 18, Krak´ ow June 2018 Study of η and π + π − Transitions in Υ(4 S ) Decays to Lower ( b ¯ b ) – V 180 ) 2 Events / (30 MeV/c 160 data non-resonant 140 Υ non-resonant + (1S)f (980) 120 0 100 80 60 40 20 0 − 20 0.3 0.4 0.5 0.6 0.7 0.8 0.9 1 1.1 1.2 π π - 2 + M( ) (GeV/c ) The model with the f 0 (980) is preferred with 2.8 σ E. Guido et al., Phys. Rev.D 96, 052005 (2017) S.Eidelman, BINP&Lebedev p.8/30

MESON 18, Krak´ ow June 2018 Observation of Υ(4 S ) → η ′ Υ(1 S ) – I From 538M Υ(4 S ) Belle searched for Υ(4 S ) → η ′ Υ(1 S ), η ′ → ηπ + π − ( ρ 0 γ ) , η → γγ, Υ(1 S ) → µ + µ − 0.4 ] 2 [GeV/c 0.35 σ σ -3 +3 0.3 ' η M 0.25 ∆ 0.2 0.15 0.1 0.05 0 0.32 0.34 0.36 0.38 0.4 0.42 0.44 0.46 0.48 0.5 η η 2 M( ') - M( ) [GeV/c ] ∆ M η ′ = M (Υ(4 S )) − M (Υ(1 S )) − M ( η ′ ) identifies the signal, 2 π 1 γ : N sig = 22 ± 7(4 . 2 σ ), 2 π 2 γ : N sig = 5 . 0 ± 2 . 3(4 . 1 σ ), Systematic uncertainties: 7.6%(2 π 1 γ ) and 3.5%(2 π 2 γ ) E. Guido et al., arXiv:1803.10303 S.Eidelman, BINP&Lebedev p.9/30

MESON 18, Krak´ ow June 2018 Observation of Υ(4 S ) → η ′ Υ(1 S ) – II ) ) 18 6 2 2 Events / (10 MeV/c Events / (20 MeV/c 16 5 2 π 1 γ 2 π 2 γ 14 12 4 10 3 8 6 2 4 1 2 0 0 0 0.05 0.1 0.15 0.2 0.25 0.3 0.35 0.4 0 0.05 0.1 0.15 0.2 0.25 0.3 0.35 0.4 2 2 ∆ M [GeV/c ] ∆ M [GeV/c ] η ’ η ’ B (Υ(4 S ) → η ′ Υ(1 S )) = (3 . 43 ± 0 . 88 ± 21) · 10 − 5 , R η ′ /h = B (Υ(4 S ) → η ′ Υ(1 S )) / B (Υ(4 S ) → h Υ(1 S )), R η ′ /η = 0 . 20 ± 0 . 06 , R η ′ /π + π − = 0 . 42 ± 0 . 11 E. Guido et al., arXiv:1803.10303 S.Eidelman, BINP&Lebedev p.10/30

MESON 18, Krak´ ow June 2018 Observation of the Υ(4 S ) → ηh b (1 P ) Transition – I From 771.6M Υ(4 S ) decays Belle studied Υ(4 S ) → ηh b (1 P ) � ( P e + e − − P η ) 2 , η → γγ . using the η missing mass, M miss = 2 Events / 5 Mev/c 30000 2 Events / 0.1 MeV/c 80000 25000 60000 20000 40000 15000 20000 0 10000 9.2 9.4 9.6 9.8 10 η 2 M ( ) [GeV/c ] miss 5000 0 -5000 9.3 9.4 9.5 9.6 9.7 9.8 9.9 10 η 2 M ( ) [GeV/c ] miss N h b (1 P ) = 112469 ± 5537 (11 σ significance) U. Tamponi et al., Phys. Rev. Lett. 115, 142001 (2015) S.Eidelman, BINP&Lebedev p.11/30

MESON 18, Krak´ ow June 2018 Observation of the Υ(4 S ) → ηh b (1 P ) Transition – II Then h b (1 P ) → γη b (1 S ) is searched via ∆ M miss = M miss ( η ) − M miss ( η ) 16000 2 (1P) yield / 10 MeV/c 14000 12000 10000 8000 6000 b 4000 h 2000 0 -2000 -4000 -0.8 -0.7 -0.6 -0.5 -0.4 -0.3 -0.2 ∆ γ γ 2 M ( ) [GeV/c ] miss N η b (1 S ) = 33116 ± 4741 (9 σ significance) U. Tamponi et al., Phys. Rev. Lett. 115, 142001 (2015) S.Eidelman, BINP&Lebedev p.12/30

MESON 18, Krak´ ow June 2018 Observation of the Υ(4 S ) → ηh b (1 P ) Transition – III Observable Value (2 . 18 ± 0 . 11 ± 0 . 18) · 10 − 3 B (Υ(4 S ) → ηh b (1 P )) B ( h b (1 P ) → γη b (1 S )) (56 ± 8 ± 4)% M h b (1 P ) (9899 . 3 ± 0 . 4 ± 1 . 0) MeV M η b (1 S ) (9400 . 7 ± 1 . 7 ± 1 . 6) MeV (8 +6 Γ η b (1 S ) − 5 ± 5) MeV ∆ M HF (1 P ) = M sa χ bJ (1 P ) − M h b (1 P ) (+0 . 6 ± 0 . 4 ± 1 . 0) MeV ∆ M HF (1 S ) = M Υ(1 S ) − M η b (1 S ) (59 . 6 ± 1 . 7 ± 1 . 6) MeV U. Tamponi et al., Phys. Rev. Lett. 115, 142001 (2015) S.Eidelman, BINP&Lebedev p.13/30

MESON 18, Krak´ ow June 2018 e + e − → η ( b ¯ b ) Near Υ(5 S ) – I b ) near √ s = 10.966 GeV, From 121.4 fb − 1 Belle studied e + e − → η ( b ¯ η → γγ only reconstructed, M miss ( η ) studied A possible way to observe Υ J (1 D ) via triangular B ( ∗ ) loops U. Tamponi et al., arXiv:1803.03225, EPJC S.Eidelman, BINP&Lebedev p.14/30

MESON 18, Krak´ ow June 2018 e + e − → η ( b ¯ b ) Near Υ(5 S ) – II 2 Υ Residual / 5 MeV/c (1D) 3000 Υ (2S) h (1P) 2000 h (2P) b b Υ (1S) 1000 0 − 1000 − 2000 9.2 9.4 9.6 9.8 10 10.2 γ γ 2 M ( ) [GeV/c ] miss N, 10 3 N, 10 3 Process Σ Process Σ η Υ(1 S ) 1 . 5 σ 1 . 7 ± 1 . 0 η Υ(2 S ) 3 . 3 σ 5 . 6 ± 1 . 6 η h b (1 P ) 2 . 7 σ 3 . 9 ± 1 . 5 η Υ(1 D ) 5 . 3 σ 9 . 3 ± 1 . 8 U. Tamponi et al., arXiv:1803.03225, EPJC S.Eidelman, BINP&Lebedev p.15/30