C C Charmonium: present and future ICPPA, October, 10, 2016, - PowerPoint PPT Presentation

Galina Pakhlova, LPI RAS, MEPHI, MIPT C C Charmonium: present and future ICPPA, October, 10, 2016, Moscow

Charmonium in standard quark model c c (n+1) (2S+1) L J X(4160) • n radial quantum number •  2 (3820) S total spin of quark- X(3940) antiquark _ open charm threshold • L relative orbital ang. DD mom. – L = 0, 1, 2 ... corresponds Below open charm threshold to S, P, D... all states are measured • J = S + L S=1 S=1 • P = ( – 1) L+1 parity S=0 S=0 • C = ( – 1) L+S charge conj. J PC 1974 -1980 Discovery of 10 standard charmonium states 1980-2002 … nothing 2002-2013 Discovery of 6 standard charmonium states

Charm factories LHC pp collider BESIII Symmetric e + e – collider E ~ 7 TeV: L~ 5fb – 1 per experiment e + e – →J/  ,  (2S),  (3770), etc E ~ 8 TeV: L~ 20fb – 1 per experiment scan 2.0 - 4.6 GeV L ~ 10 33 /cm 2 /s LHCb E ~ 7-8 TeV: L~ 3 fb – 1 Tevatron pp collider E ~ 1.8 TeV: L ~ 4fb – 1 per experiment Charmonium Charmonium Prompt production Prompt production B meson decays Beauty hadrons decays

B factories Belle : 8 GeV (e – )  3.5 GeV (e + ) designed luminosity: 10.0  10 33 cm – 2 s – 1 achieved 21.2  10 33 cm – 2 s – 1 (>2 times larger!) Belle completed data taking in 2010 to start Su р erKEKB/Belle II upgrade

Charmonium (+like) production at B factories B decays γγ fusion Any quantum numbers are possible, can be measured in angular analysis (Dalitz plot) J PC = 0 ± + , 2 ± + e + e − annihilation with ISR double charmonium production in association with J/ ψ only J PC = 0 ± + seen J PC = 1 – –

Observation of η c (2S) and h c PRL 89, 102001 (2002 )  η c (2S) B   c (2S)K  (K S K  )K с onfirmed by M=(2654  10) MeV CLEO,  <55MeV open charm threshold BaBar&Belle in   h c first  c (2S) observed by PRL 89, 142001 (2002) J PC CLEO e + e ‒  J/  c (2S) M=(2630  12) MeV η c (2S) and h c : mass, total width, decays modes,  -width are in good agreement with the potential model expectations PRL 95, 102003 (2005) ψ(2S) → π 0 h c → π 0 γη c Charmonium table below DD threshold is completed ! Future  c : new decay modes, absolute BR M=(3524.4 ± 0.6 ± 0.4) MeV measurements, improve mass, total width and Γ  h c : search in three body B decays: B → h c K π…

γγ → Z(3940) =  c2 (2P) PRL96,082003(2006 ) PRD81, 092003, 2010 5.3 σ open charm threshold Confirmed by BaBar 395fb -1 Helicity Decay mode, helicity distribution distribution, J PC favors J=2 Γ γγ width prove out: Z(3940) =  c2 (2P) = 2 3 P 2 Mass is ~50-100 МэВ / с 2 lighter than expected Future Improve parameters, search in multi-body B decays

PRL 111, 032001 (2013) X(3823) = ψ (1 3 D 2 ) B + →  c1  K + X(3823)→  c1  C = − X(3823) 4.2  1 − − 1 + − 2 − − 3 − − 711 fb -1 Ψ (3770) h c (2P)  2  3 → DD decay to DD is forbidden due to unnatural spin-parity  small Γ decay to  c1  should be prominent (E1) M (  c1  ), GeV Γ (  c1  ) ~ O(10KeV) is typical for Confirmed by BESIII, 6.2 σ charmonium PRL115,011803(2015) M = 3823.5  2.8 MeV  = 4  6 MeV, < 14 MeV @90%CL ψ 2 Future o Critical prove at Belle II γ o To measure X(3823) decays to J/  +  – and  c2  final states and to compare with theoretical predictions for ψ (1 3 D 2 )

X(3940) & X(4160) in e + e − → J/  D * D (*) J PC =0 – + X(3940) = 3 1 S 0 = η c (3S) X(4160) = 4 1 S 0 = η c (4S) Decays to open charm like standard charmonium X(3940)&X(4160): masses are ~100-150 (250-300)MeV lower than the masses predicted by the potential models X(4160) X(3940) open charm threshold Future o Angular analysis for solid identification o Search in B decays J PC

New charmoniumlike spectroscopy

Charmonium & Charmoniumlike states & X(4700) Y(4660) something Y(4630) Z(4430) + X(4500) Y(4360 ) c c Z(4250) + X(4274) Y(4260 ) X(4160) Z(4200) + X(4140) X(3915) X(3872) Z(4050 ) + Y(4080)  2 (3820) Z c (4020) + X(3940) Z c (3900) + _ X(3880) DD 2002-2016 Discovery of 18 (+4?) exotic charmonium states All of them above open charm S=1 S=1 S=0 S=0 threshold J PC Charmonium hybrids Multiquark states States with excited gluonic Tetraquark degrees of freedom Hadro-charmonium tightly bound four-quark state Specific charmonium state “coated” Molecular state by excited light-hadron matter two loosely bound charm mesons

PRL91, 262001 (2003) X(3872) M X close to D 0 D *0 threshold J PC = 1 ++ M = 3871.68 ± 0.17 MeV Belle topcited: not clear below or above: finally 10 σ 1200+ Δm = – 0.11 ± 0.22 MeV established surprisingly narrow: Γ tot < 1.2 MeV at 90% CL M(J/  ππ ) Known BR relative Comments decays to J/  mode First observed by Belle in J/  1 isospin violation B→K J/  π + π – J/  0.8  0.3 Confirmed: isospin violation BaBar, LHCb, CMS, ATLAS, CDF J/  0.21  0.06 Belle&Babar good agreement  (2S)  0.50  0.15 Belle&Babar disagreement Hadronic collisions: produced mostly LHCb confirms promptly; only 0.263 ± 0.023 ± 0.016 BaBar from B-decays (CMS)  10 D 0 D* 0 dominant mode

X(3872) interpretations Conventional charmonium  c1 (2P) (J PC =1 ++ ) Problems: Γ (  c1 (2P)→J/  )/ Γ (  c1 (2P)  J/  ) ~ 30,  measured < 0.2 ~ 100MeV heavier then expected D 0 D *0 molecular state: (the most popular)  M X ~ M D0 + M D*0 is not accidental  J PC =1 ++ (D 0 D *0 in S-wave)  DD * decay  Tetraquark (cq)(cq): Small rate for decay into J/ ψγ is expected  + 3 states (cu)(cu), (cd)(cu), (cd)(cd) with a few MeV mass splitting Problems: Problems: too large X(3872) → ψ (2S) γ  no evidence of neither neutral doublet too small binding energy: D 0 and D *0 too far  nor charged partner yet in space to be produced in high energy pp collisions Possible solution: Mixture of P-wave charmonium level  c1 (2P) and S-wave DD *0 molecule

B 0 →X(3872)K + π – Observation of 7.0 σ X(3872) in B→X(3872)Kπ PRD91, 051101 (2015 ) K *0 (892) B + →X(3872)K 0 π – 3.8 σ Contrast to ψ (2S) case

Measurements of absolute Br of B →KX(3872) Υ(4S) → BB tag KX D π, … full reconstruction Looking for recoil mass to (B tag K) 424 fb −1 BaBar 2006: Br(B →KX(3872)) < 3.2·10 −4 at 90% C.L NEW: BaBar preliminary Low limit on Br(X(3872) → J/   +  – > 4.2%

X(3872): future o Detailed pattern of X(3872) to charmonium Search transitions (radiative and hadronic) with for Comments significantly improved accuracy X(3872) partners o Search for partners of X(3872) decays molecules with J PC = 0 ++ , 1 + – , 2 ++ …  c1  Forbidden by C-parity  c2  conservation o Measurements of absolute BR of C-odd partners: tetraquark, B →KX(3872 ) with improved accuracy molecule UL : < 1/4 from J/   +  – o Measurements of line shape of X(3872) J/   C-odd partners: tetraquark decaying to DD * at threshold and to J/  +  – UL : < 1/2 from J/   +  – to clarify nature of X(3872): virtual or bound state  c  Search for other X-like  c  0 molecular states  c  +  – UL : ~ J/   +  o Measurements of the total width of X(3872)  c 

Y(4630) Y(4660) Y(4360) Y(4260) Y(4008) Exotic vector states

ISR measurements at B factories Fixed quantum numbers of final state J PC = 1 – – o Study of charmonium(+like) final states from threshold in wide energy region o Huge accumulated luminosity at B factories o Limited statistics o o strong electromagnetic suppression o typical events topology: fast photon with small p t

e + e − →π + π − ψ (2S) e + e − →π + π − J/ ψ Unlike conventional charmonium No room for Y states among 1 – – charmonium o 3 3 S 1 =  (4040); 2 3 D 1 =  (4160) ; 4 3 S 1 =  (4415); masses of predicted 3 3 D 1 (4520); 5 3 S 1 (4760); 4 3 D 1 (4810) are higher (lower) o Absence of open charm production o Anomalous large partial width Y(4660)  (Y  J/   ) > 1 MeV Y(4630) o Only one decay channel per one Y state: Y(4360 ) π + π − π + π − light charmonium +  Y(4260 ) Y(4080) PRD89,072015(2014) e + e − →K + K − J/ ψ via ISR All available statistics Y(4260) π + π − π + π − does not allow fits to the cross sections

11th anniversary of Y family discovery e + e − →π + π − J/ ψ cross section is inconsistent with a single pick of Y(4260) Two peaks are favored over one peak by 7 σ Y(4008) is not needed to describe BESIII data BESIII confirms lineshape of Y(4360) in e + e − →π + π − ψ (2S) cross section The π + π − h c shape is clearly different from π + π − J/ ψ

e + e − → J/ ψ  PRD87,051101R(2013)  (4040)  (4160) o Peaks of ψ(4040) and ψ(4160) o No sign of any Y state 6.0  6.5  o  (  (4040,4160)  J/  )  1 MeV 980 fb -1 o Anomalous transitions: common feature of all 1 – – states above threshold ? BESIII is in agreement with Belle:  (4160)  J/  structure η η New BESIII scan