Quarkonia & XYZ at e+e– colliders “Charmonium production & decay”, 6-8 March 2013, LAL, Orsay Quarkonia & XYZ at e+e– colliders Roman Mizuk ITEP, Moscow

Spectroscopy  strong interactions at low energy Ultimate theory : Good accuracy for ground states High excitations more difficult Not intuitive Lattice QCD  Effective theories / phenomenological models Quark Model Collective degrees of freedom: constituent quarks Hadrons: qq and qqq _ g valence gluons qq di-quarks qqq tri-quarks, … gg glueballs qqg hybrids qqqq tetraquarks, … _ Exotics _ _ Theory & experiment  exotics among light mesons – no established states Heavy quarkonia – observation of anomalous XYZ states. Unexpected.

Charmonium table Potential models “Old” states (observed before 1980) Y(4660) Z(4430)+ Y(4360) X(4160) Y(4260) Z(4250)+ “Old” states (observed before 1980) X(3872) Y(3915) Z(4050)+ Y(4008) DD _ X(3940) 2(1D) New states (last decade) New states with unusual properties S=1 S=1 S=0 S=0 JPC L=0 L=1 L=2 States below DD threshold are narrow (annihilation or  other charmonia) _ States above DD threshold are broad ( DD, DD*, ...) _ 3

Charmonium Bottomonium Y(4660) Z(4430)+ (11020) Y(4360) 11.00 (10860) X(4160) Y(4260) Y(3915) Zb + X(3872) 10.75 Y(4008) DD _ X(3940) (4S) 2M(B) 2(1D) hb(3P) 10.50 b(3P) (2D) b(3S) (3S) hb(2P) b(2P) 10.25 (1D) S=1 S=1 S=0 S=0 (2S) b(2S) 10.00 hb(1P) b(1P) JPC L=0 L=1 L=2 9.75 9.50 (1S) b(1S) - 1 -- - -- JPC = 0 + 1+ (0,1,2)++ (0,1,2) L=0 L=1 L=2 4

Charmonium Bottomonium Y(4660) Z(4430)+ Above thresholds (11020) Y(4360) 11.00 (10860) X(4160) Y(4260) Zb + X(3872) Y(3915) 10.75 Thresholds Y(4008) DD _ X(3940) (4S) 2M(B) 2(1D) hb(3P) 10.50 b(3P) (2D) b(3S) (3S) hb(2P) b(2P) 10.25 (1D) S=1 S=1 S=0 S=0 (2S) b(2S) 10.00 hb(1P) b(1P) JPC L=0 L=1 L=2 9.75 Below threshold 9.50 (1S) b(1S) - 1 -- - -- JPC = 0 + 1+ (0,1,2)++ (0,1,2) L=0 L=1 L=2 5

Quarkonia below open flavor thresholds 6

pNRQCD: 4114 MeV Lattice: 608 MeV Spin-singlet states _  Spin-spin interaction in qq potential (11020) 11.00 (10860) 10.75  MHF  |(0)|2 (4S) 2M(B) hb(3P) 10.50 b(3P) (2D) b(1S) b(3S) (3S) Mass, GeV/c2 PDG 2012 hb(2P) b(2P) BaBar + CLEO : MHF(1S) = 69.3  2.8 MeV 10.25 (1D) pNRQCD: 4114 MeV Lattice: 608 MeV (2S) b(2S) Kniehl et al., PRL92,242001(2004) Meinel, PRD82,114502(2010) 10.00 some tension hb(1P) b(1P) MHF(1P) b(2S) 9.75 center of gravity ee[(nS)]  |(0)|2   0.5 ee [(2S)] ee [(1S)] MHF(2S)  MHF(1S) (1S) 9.50 b(1S) MHF(1S) - 1 -- - -- JPC = 0 + 1+ (0,1,2)++ (0,1,2) hb(1P, 2P) MHF(2S)  0 L=0 L=1 L=2 test of long-range spin-spin contribution 7

Observation of hb(1P) and hb(2P) (11020) PRL108,032001(2012) Mmiss(+-) 11.00 residuals (10860) +- hb(2P) 10.75 (4S) hb(1P) 2M(B) 10.50 b(3P) (2D) b(3S) (3S) Mass, GeV/c2 hb(2P) b(2P) 10.25 (1D) 19%  (2S) b(2S) 10.00 hb(1P) b(1P) MHF(1P) = +0.8  1.1 MeV MHF(2P) = +0.5  1.2 MeV 13% Belle :  consistent with zero, as expected 9.75 41% Godfrey & Rosner, PRD66 014012 (2002) (1S) N[hb(1P)] = (50.4  7.8 +4.5) 103 9.50 b(1S) –1.9 - 1 -- - N[hb(2P)] = (84.4  6.8 +23) 103 JPC = 0 + -- –10 1+ (0,1,2)++ (0,1,2) hb(nP)  b(mS)   study b(1S)  search for b(2S) L=0 L=1 L=2 8

Method M(b) M(hb) (5S)  hb (nP) +- reconstruct  b(mS)  Decay chain (5S)  hb (nP) +- reconstruct  b(mS)  Use missing mass to identify signals MC simulation M(b) true +- true  M(hb)

Method M(b) M(hb) (5S)  hb (nP) +- reconstruct  b(mS)  Decay chain (5S)  hb (nP) +- reconstruct  b(mS)  Use missing mass to identify signals MC simulation true +- fake  M(b) true +- true  fake +- true  M(hb)

Method M(b) M(hb) (5S)  hb (nP) +- reconstruct  b(mS)  Decay chain (5S)  hb (nP) +- reconstruct  b(mS)  Use missing mass to identify signals MC simulation true +- fake  Mmiss(+- )  Mmiss(+-) – Mmiss(+-) + M(hb) M(b)  no correlation true +- true  fake +- true  M(hb)

Method Approach: M(b) M(hb) (5S)  hb (nP) +- reconstruct Decay chain (5S)  hb (nP) +- reconstruct  b(mS)  Use missing mass to identify signals MC simulation Mmiss(+- )  Mmiss(+-) – Mmiss(+-) + M(hb) M(b)  no correlation Approach: fit Mmiss(+-) spectra in Mmiss(+-) bins M(hb)

Method M(b) b M(hb) (5S)  hb (nP) +- reconstruct  b(mS)  Decay chain (5S)  hb (nP) +- reconstruct  b(mS)  Use missing mass to identify signals MC simulation M(b) b hb yield vs. Mmiss(+-) M(hb)

Observation of hb(1P,2P) b(1S)  (5S)hb(nP) +–  b(1S)  PRL 109, 232002 (2012) MHF(1S) Belle : 57.9  2.3 MeV (11020) hb(1P) yield 3 11.00 PDG’12 : 69.3  2.8 MeV (10860) b(1S) 10.75 +- BaBar (3S) (4S) 2M(B) BaBar (2S) 10.50 b(3S) (3S) hb(2P) b(2P) hb(2P) yield b(1S) CLEO (3S) 10.25 b(2S) (2S) 10.00 hb(1P) b(1P) pNRQCD LQCD  9.75 Kniehl et al, PRL92,242001(2004) Mmiss (+-) (n) Meinel, PRD82,114502(2010) (1S) 9.50 b(1S) MHF(1S) First measurement  = 10.8 +4.0 +4.5 MeV (as expected) –3.7 –2.0 JPC = 0 + - 1 -- 1 + - (0,1,2)++ Belle result eliminates tension with theory

Observation of hb(1P,2P) b(1S)  PRL101, 071801 (2008) (5S)hb(nP) +–  b(1S)  BaBar (3S)b(1S) MHF(1S) ISR b(1S) Belle : 57.9  2.3 MeV hb(1P) yield PDG’12 : 69.3  2.8 MeV b(1S) b(1P) PRL103, 161801 (2009) BaBar (2S)b(1S) hb(2P) yield b(1S) ISR b(1S) pNRQCD LQCD Kniehl et al, PRL92,242001(2004) PRD81, 031104 (2010) Mmiss (+-) (n) Meinel, PRD82,114502(2010) First measurement  = 10.8 +4.0 +4.5 MeV (as expected) –3.7 –2.0 Belle result eliminates tension with theory CLEO (3S)

“look elsewhere effect” First evidence for b(2S) PRL 109, 232002 (2012) (5S)hb(2P) +–  b(2S)  MHF(2S) = 24.3 +4.0 MeV –4.5 First measurement b(2S) 4.2 with systematics & “look elsewhere effect” pNRQCD LQCD Belle In agreement with theory Mmiss (+-) (2) (2S) = 4  8 MeV, < 24MeV @ 90% C.L. expect 4MeV Branching fractions Expectations BF[hb(1P)  b(1S) ] = 49.25.7+5.6 % BF[hb(2P)  b(1S) ] = 22.33.8+3.1 % BF[hb(2P)  b(2S) ] = 47.510.5+6.8 % 41% 13% 19% –3.3 Godfrey Rosner PRD66,014012(2002) –3.3 –7.7 c.f. BESIII BF[hc(1P)  c(1S) ] = 54.38.5 % 39%

Charmonium table Potential models “Old” states (observed before 1980) Y(4660) Z(4430)+ Y(4360) X(4160) Y(4260) Z(4250)+ “Old” states (observed before 1980) X(3872) Y(3915) Z(4050)+ Y(4008) DD _ X(3940) New states (last decade) New states w/ unusual properties JPC States below DD threshold are narrow (annihilation or  other charmonia) _ States above DD threshold are broad ( DD, DD*, ...) _ 17

Charmonium table Potential models “Old” states (observed before 1980) Y(4660) Z(4430)+ Y(4360) X(4160) Y(4260) Z(4250)+ “Old” states (observed before 1980) X(3872) Y(3915) DD* _ Z(4050)+ Y(4008) DD _ X(3940) New states (last decade) c2 2 New states w/ unusual properties JPC D-wave states all observed States below DD threshold are narrow (annihilation or  other charmonia) _ States above DD threshold are broad ( DD, DD*, ...) _ Expect two more narrow states (unnatural spin-parity + below DD* threshold) _ 18

Evidence for 2(1D) preliminary Study B+  c1  K+ |  J/  M(c1 ) X(4160) Y(4260) X(3872) Y(3915) DD* _ 4.2 w/ syst. Y(4008) DD _ X(3940) c2 2 M = 3823.5  2.8 MeV  = 4  6 MeV, <14 MeV @90% C.L. JPC D-wave states Radiative decay seen  O(100keV) 19

Evidence for 2(1D) preliminary Study B+  c1  K+ JPC = 2– – L=2 S=1 |  J/  Y(4360) M(c1 ) X(4160) Y(4260) X(3872) Y(3915) DD* _ 4.2 w/ syst. Y(4008) DD _ X(3940) 2(1D) M = 3823.5  2.8 MeV  = 4  6 MeV, <14 MeV @90% C.L. JPC C (c1) = – Radiative decay seen  O(100keV) JPC = 2– – L=2 S=1 ~2/3 BF(B+  2K+)  BF(2  c1) = = (9.7 +2.8 +1.1) 10-6 -1.0 -2.5 factorization suppression c.f. BF(B+  (2S) K+) = 6.4 10-4 20

Charmonium Bottomonium Y(4660) (11020) Y(4360) 11.00 (10860) X(4160) Y(4260) X(3872) Y(3915) 10.75 Y(4008) DD _ X(3940) (4S) 2M(B) 2(1D) hb(3P) 10.50 b(3P) (2D) b(3S) (3S) hb(2P) b(2P) 10.25 (1D) S=1 S=1 S=0 S=0 (2S) b(2S) 10.00 hb(1P) b(1P) JPC L=0 L=1 L=2 9.75 Recent finding: b(2S), hb(1P,2P), b(3P) 2(1D) 9.50 (1S) b(1S) Properties of all states below open flavor thresholds are consistent with expectations - 1 -- - -- JPC = 0 + 1+ (0,1,2)++ (0,1,2) L=0 L=1 L=2 21

Quarkonia at open flavor thresholds 22

X(3872) 10th anniversary! 739 618 381 CP B→Xsγ Belle citation count Phys.Rev.Lett.91, 262001 (2003) 10th anniversary!

production at high energy X(3872) PDG’12 MX(3872) – (MD0 + MD*0) = -0.16 ± 0.32 MeV Z(4430)+ Relative BF J/  J/  J/  D0D*0 _ 1 0.8  0.3 0.21  0.06 10 isospin violation Z(4250)+ X(4160) X(3872) Y(3915) Z(4050)+ DD _ JPC = 1++ X(3940) 2(3820) Most likely interpretation: DD* molecule with admixture of c1(2P) isospin violation production at high energy Fractions of admixtures? Bound or virtual? Dynamical model? Experimental issues: M (D0 mass uncertainty dominates) (2S)  (Belle/BaBar controversy) line-shape in DD* (statistics limited) absolute BF (inelastic channels?) _ 24

Anomaly in hb(nP) production (11020) PRL108,032001(2012) Mmiss(+-) 11.00 residuals (10860) +- hb(2P) 10.75 (4S) hb(1P) 2M(B) 10.50 b(3P) (2D) b(3S) (3S) Mass, GeV/c2 hb(2P) b(2P) 10.25 (1D) (2S) b(2S) 10.00 hb(1P) b(1P) spin-flip [(5S)  hb(mP) +–] 9.75  1 [(5S) (nS) +–] (1S) 9.50 b(1S) expect suppression (QCD/mb)2 - 1 -- - JPC = 0 + -- 1+ (0,1,2)++ (0,1,2) L=0 L=1 L=2 Mechanism of (5S) decays ? 25

Resonant structure of (5S)  (bb) +– _ Resonant structure of (5S)  (bb) +– Belle PRL108,122001(2012) (5S)  hb(1P)+- (5S)  hb(2P)+- zero non-res. contribution Two peaks in all modes phsp Minimal quark content _  bbud  phsp flavor-exotic states M[ hb(1P) π ] M[ hb(2P) π ] Dalitz plot analysis (5S) (1S)+- (5S) (2S)+- (5S) (3S)+- note different scales

(5S) (nS) +- Dalitz plots M2(π+π-) M2(π+π-) M2(π+π-) Angular analysis favors JP=1+ S-wave S-wave (5S)  Zb, Zb  (nS) – no spin orientation change Spins of (5S) and (nS) can be ignored S(s1,s2) = A(Zb1) + A(Zb2) + A(f0(980)) + A(f2(1275)) + ANR BW Flatte BW C1 + C2∙m2(ππ)

Fit results 180o (2S) hb(1P)  = 0o  Zb  Zb ’ Average over 5 channels M1 = 10607.2  2.0 MeV 1 = 18.4  2.4 MeV MZb – (MB+MB*) = + 2.6  2.1 MeV M2 = 10652.2  1.5 MeV 2 = 11.5  2.2 MeV MZb’ – 2MB* = + 1.8  1.7 MeV M(hb), GeV/c2 hb(1P) yield / 10MeV 180o (2S) hb(1P)  = 0o Phase btw Zb and Zb amplitudes is 0o for (nS) 180o for hb(mP) ’ destr. interf. Resonant behavior of Zb amplitudes (intensity & phase). 28

flip of phase in hb amplitude Structure of Zb JP = 1+ , IG = 1+ Bondar et al, PRD84,054010(2011) _  B B*  =   Proximity to thresholds favors molecule over tetraquark Zb  + S-wave _  B*B*  =   – Zb’  not suppressed (nP) hb(mP) flip of phase in hb amplitude Assumption of molecular wave-function allows to explain all properties of Zb hb(nP) is not suppressed due to mB*–mB splitting A (hb)  1 MZb – M + i/2 –  0 MZb’ – M + i/2 If mb    mB*  mB and mZb’  mZb

Search for Zb  BB* and B*B* _ _ Search for Zb  BB* and B*B* _ arXiv:1209.6450 e+e-  (5S)  B(*)B(*) _ M(B) Mmiss(B) BB* Full reconstruction of one B _ BB _ B*B* BF[ (5S)  B(*)B(*) ] _ PRD81,112003(2010) Belle 121.4 fb-1 significance Belle 23.6 fb-1 _ BB BB* + BB* B*B* <0.60 % at 90% C.L. (4.25  0.44  0.69) % (2.12  0.29  0.36) % (0  1.2) % (7.3  2.3) % (1.0  1.4) % _ _ _ _ 9.3 5.7 _ BFs are consistent with previous measurement

Observation of ZbBB* and Zb’B*B* _ _ Observation of ZbBB* and Zb’B*B* arXiv:1209.6450 _ Zb’  BB* is suppressed w.r.t. B*B* despite larger PHSP _ M (BB*) Zb Molecule  admixture of BB* in Zb’ is small _ 8 Zb’ ? phsp Challenging for tetraquark _ M (B*B*) Zb’ 6.8 phsp Z b properties are consistent with molecular structure

Evidence for a neutral Zb (2S) e+e-  (5S)  (nS)00 (1S) BF[(5S)(1S)00] = (2.250.110.20) 10-3 BF[(5S)(2S)00] = (3.790.240.49) 10-3 in agreement with isospin relations M miss (0 0) Dalitz plot analysis of (1S,2S)00  w/ Zbs w/o Zb Zb(10610)0 5.3 (4.9 w/ syst.) Zb(10650)0  2 (2S) 00 : (1S) 00 : Zb signals not significant Yields agree with isospin expectations  Confirmation that Zb is an isotriplet M [(2S)0 ]

Origin of structure at threshold 1. Threshold effect   Chen Liu PRD84,094003(2011) Zb Zb’ B(*) B(*) (5S) (2S) B(*) _ S-wave M [(2S)π] Danilkin Orlovsky Simonov PRD85,034012(2012) 2. Coupled-channel resonance multiple re-scatterings  pole Zb  B(*)   B(*)  B(*)  Zb’ + + ... (5S) B(*) _ B(*) _ B(*) _ (2S) (2S) (2S)   3. Deuteron-like molecule B(*) Ohkoda et al arxiv:1111.2921 ,,, exchange (5S)  B(*) _ (2S) Request to theory: predictions (formulas) to fit data !

Quarkonia above open flavor thresholds 34

“Conventional” states (3770) (4040) (4160) (4415) _ _ DD, DD*, ... Y(4660) DD, DD*, ... Y(4360) X(4160) Y(4260) X(3872) Y(3915) Y(4008) X(3940) Y(4008) Y(4260) Y(4360) Y(4660) Y(3915) “Anomalous” states J/ +- (2S) +- J/  from ISR JPC = 1– – decays to DD, DD*, ... not seen _ 2(1D) e+e-  J/ ISR (4040) (4160) arxiv:1210.7550 c.f. ((2S)  J/)  102keV ((3770) J/)  50keV typical (Y   ) > 1MeV  huge for charmonium (  J/ )  1 MeV _ All states above DD threshold have anomalous properties? 35

Anomalies in (5S)  (nS) +– transitions (11020) Belle PRL100,112001(2008) 11.00 (10860) [(5S)  (1S,2S,3S) +–] >> [(4S,3S,2S) (1S) +–] Zb + 10.75 260 – (4S) 2M(B) 10.50 2 + (3S) Mass, GeV/c2 hb(2P) 10.25 430  Rescattering of on-shell B(*)B(*) ? _ 1 (2S) b(2S) 10.00 hb(1P) 290 6 9.75 partial (keV) Simonov JETP Lett 87,147(2008) 9.50 (1S) b(1S) Meng Chao PRD77,074003(2008) - 1 -- - JPC = 0 + 1+  More transitions ? 36

Observation of (5S) (1D)+- 121 fb-1 PRL108,032001(2012) Mmiss(+-) residuals Seen inclusively (2.4): hb(2P) N (1D)  1/7 N (2S)  [(5S)  (1D) +-]  60 keV is anomalously large hb(1P) (1D) PRELIMINARY Mmiss(+-) Observed using exclusive reconstruction : (5S)  (1D) +-  (1S)  |  bJ(1P)  (1D) (2S) 9  +- | BF[(5S)  (1D) +-  (1S) +- ] = (2.0  0.4  0.3)×10−4 reflection c.f. CLEO: BF[(3S)  (1D)   (1S)  ] = (2.5  0.5  0.5)×10−5 more details: P.Krokovny @ LaThuile 2012 37

Observation of (5S)  (1S,2S)  121 fb-1 PRELIMINARY Mmiss(+-0) Exclusive reconstruction (2S) BF[ (5S)  (1S)  ] = (0.73  0.16  0.08)×10−3 BF[ (5S)  (2S)  ] = ( 3.8  0.4  0.5 )×10−3 [ (5S)  (1S,2S)  ]  40 – 200 keV anomalously large (1S) E1M2 [(5S)  (nS)  ] [(5S)  (nS) +-] 0.16  0.04  0.02 for (1S) 0.48  0.05  0.09 for (2S) R5n = = E1E1 no strong suppression c.f. Belle R21 = (1.99  0.14 +0.12) 10–3 –0.08  hadron loops? BaBar R41 = 2.41  0.40  0.12 Simonov, Veselov arXiv:0806.2919 Meng, Chao PRD78, 074001(2008) Voloshin MPLA26,773(2011) 38

– Bottomonium Charmonium c +- &  transitions +- transitions Y(4660) “(5S)” +- Y(4360)  +- _ Y(4260) BB (4160) (4040) (3S) Y(4008)  _ hb(2P) DD (1D) (2S) (2S) hb(1P) J/ J/ (1S) _ similar [ “(5S)”  (bb) +- ]  1 MeV [ /Y   hadrons ]  1 MeV _ _ One-to-many (bb) vs. Many-to-one (cc).  Hadron loops? c – π  Hadrocharmonium? Voloshin 39

Z(4050) Z(4250) Also hadrocharmonium? _ DD JPC Y(4660) Y(4360) Y(4260) Y(4008) Y(3915) X(3872) X(3940) X(4160) 2(1D) DD _ JPC Also hadrocharmonium? Charged charmonium like states – multiquark candidates produced in B  Z K decays Z(4050) Belle: Z(4430)  (2S) + and  c1 + Within the reach of LHCb Z(4250) BaBar: no significant signals 40

Only (constituent) quarks so far (no valence gluons, di-quarks,..) ! Summary Many new results from B-factories, hadronic machines : Quarkonia below threshold: 2(1D), b(2S) , hb(1P) , hb(2P), b(3P) Isotriplet molecular states seen in 6 decay modes: (1S)+, (2S)+, (3S)+, hb(1P)+, hb(2P)+, BB*(B*B*) Ground states & ~low excitations – Potential models etc are OK Open flavor thresholds – new types of hadrons: meson molecules Above open flavor thresholds – anomalous transitions Zb – very rich phenomenological objects  understanding of highly excited states need “unquenched” Quark Model Only (constituent) quarks so far (no valence gluons, di-quarks,..) ! 41

Back-up 42

Claim of exclusively reconstructed b(2S) 5 authors from CLEO: Dobbs, Metreveli, Seth, Tomaradze, Xiao PRL109,082001(2012) e+e-  (2S)  b(2S) , b(2S)  26 exclusive channels MHF(2S) b(2S) is here according to Belle Dobbs et al. 48.72.7 MeV Belle 5σ 24.3 +4.0 MeV 24.3 +4.0 MeV –4.5 –4.5 Origin of Belle signal and Dobbs et al. signal can not be the same Dobbs et al. have no sensitivity to low values of MHF(2S)

Claim of exclusively reconstructed b(2S) 5 authors from CLEO: Dobbs, Metreveli, Seth, Tomaradze, Xiao PRL109,082001(2012) exp Dobbs et al. assumed exponential background FSR FSR is known to contribute power law tail e.g. (2S)  K+K- n(+-) FSR 4.6 Background model is incomplete  significance of 4.6 is overestimated Properties of the Dobbs et al. signal ... factor 30 LQCD pNRQCD Belle 0.6 0.9 0.8 0.7 Dobbs et al. N[(2S)b(2S)]  0.2 N[(2S) b1(1P) ] c.f. [’c(2S)] = 0.007 [’c1] BESIII PRL109,042003(2012) ... does not look physical It is unlikely that the signal of Dobbs et al. is due to b(2S).

Branching fractions of (4040,4160)J/ preliminary Fit: (4040) and (4160) only (4040) 6.0 w/ syst. 6.5 w/ syst. < 3 ~ (4160) BF, % 1st solution: (4040) 0.56  0.10  0.17 (4160) 0.48  0.10  0.17 2nd solution: (4040) 1.30  0.15  0.26 (4160) 1.66  0.16  0.29 [(4040,4160)] = (80,103) MeV  [ (4040,4160)  J/ ]  1 MeV First time  states exhibit anomalous coupling to (J/ hadrons). Common feature of all  states above threshold ? 45

Calibration tolerable Energy of  Shift in  energy Mdata–MMC lab.system Shift in  energy Mdata–MMC 2P2S Use signals : 0  |E1–E2| E1+E2 <0.05 M /M 1P1S E E M /M = 2P1S D*0  D0  M /(MD* –MD) Shift in  energy Fudge-factor 0  D* Agreement! tolerable Typical syst. uncertainty : M ~ 0.7–1.5 MeV,  ~ 1.5 MeV.