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X,Y,Z at the LHC and e + e - colliders

QCD@LHC2013, 2-6 September 2013, DESY, Hamburg , Germany. X,Y,Z at the LHC and e + e - colliders. Patrick Robbe (LHCb Collaboration), LAL Orsay, 2 Sep 2013. Outline. Introduction A lot of experimental activities , concentrate on: Area where LHC experiments contribute :

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X,Y,Z at the LHC and e + e - colliders

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  1. QCD@LHC2013, 2-6 September 2013, DESY, Hamburg, Germany X,Y,Z at the LHC and e+e- colliders Patrick Robbe (LHCb Collaboration), LAL Orsay, 2 Sep 2013

  2. Outline • Introduction • A lot of experimentalactivities, concentrate on: • Area where LHC experimentscontribute: • Study of the X(3872) • Study of the X(4140) • Zc(3900)+ at BESIII

  3. Charmonium • Charmonium (cc) spectrum JPC: • J = S + L • P = (-1)L+1 (spatial parity) • C = (-1)L+S (charge parity) • Observed states match verywellpredicted states, mostrecentlydiscovered: hc(1P), cc0(2P) • All states below open charmthreshold (8) observed • 6 states abovethreshold • Everythingseemsunderstood and wellestablished…

  4. X, Y, Z exotics • After 2003, many new unexpected states discovered: • Theydecaywith a charmonium in the final state or to 2 charmed hadrons • But theycannotbeobviouslyassociatedwith a predictedcharmonium state. • Some of them have not been confirmed, or don’t have wellmeasuredproperties, but for sure some of them are not conventionalcharmonia(charged states) • Theycanbeproduced by differentmechanisms (Bdecay, ISR, hadron collisions, …) socanbestudied by differentexperiments: important to confirmthem and measureunambigouslytheirpropertiesand decay modes. • Interpretation not yetestablished: hybrid, tetraquarks, molecules, …

  5. X(3872) • First exoticobserved, studiednow in details: • Mass = 3871.68 ± 0.17 MeV [PDG], Width < 1.2 MeV • JPC = 1++[NEW LHCb] • Production: • In Bdecays, rate of B+ ➝ X(3872) K+similar to othercharmonium, B ➝ X(3872) K*smallercompared to conventionalcharmonium. • In pp/pp collisions • Decays: open charm (~50%), charmonium (J/yp+p-, …) • But interpretation not clear: • Looselybound D0D*0molecule[Tornqvist (2004), Voloshin (2004), Swanson (2004), Braaten (2004), Close & Page (2005)] • Mixture of cc1’ and D0D*0bound state [Meng, Gao, Chao (2005)] • Manyotherpossibilities • Need of experimental inputs Belle, 2003, PRL 91 262001. 140 fb-1 M(J/) –M(J/) [GeV]

  6. X(3872) quantum numbers • Observation of X(3872)➝J/yg[BaBar PRD74 (2006) 071101, BELLE PRL107 (2011) 091803] • C=+ • Spin-paritypossibilitiesreduced to 1++ and 2-+ by CDF [PRL 98, 132002 (2007)] and BELLE [hep-ex/0505038]measurements. • Important observable to confirmexotic nature of X(3872): • MX(3872) close to twounobservedconventionalcharmonium states [Eichten, Lane, Quigg, PRD69, 094019 (2004)]: • cc1(2P) [1++] • hc2(1D) [2-+]

  7. X(3872) quantum numbers • LHCb: Use B+ ➝ X(3872) K+decays, with X(3872) ➝ J/y p+p- , J/y➝m+m-[PRL 110, 222001 (2013)] • In 1fb-1 of data, 313±26 signal events (and 5642±76 B+➝y(2S) K+ control channel) • 5-dimension angularanalysis to benefitfrom all angularcorrelations and constraints in the B+decaychain.

  8. X(3872) quantum numbers • Likelihood ratio between 1++ and 2-+hypotheses • 2-+hypothesisrejectedat >8s. • This resultfavours the exoticexplanation of the X(3872): • Conventionalhc2(1D) • ruled out • Conventionalcc1(2P) • still possible • but expected mass higher by 100 MeV and small X(3872) ➝ J/y g ratio • verydisfavouredhypothesis • 1++expectedfromtetraquark and molecularmodels [PRL 110, 222001 (2013)]

  9. X(3872) mass • Interpretation as boundD0D*0molecule model requirescomparisonbetween X(3872) mass and M(D0)+M(D*0). If molecule, X(3872) mass shouldbebelowthreshold. • PreciseD0 mass determinationfrom LHCb [JHEP06, 065 (2013)] • FromD0 ➝ K-K+K-p+decays • Using PDG averages of DM and X(3872): • MX(3872)-(MD0+MD*0) = -0.09 ± 0.28 MeV. • RequireimprovedX mass measurementsto distinguishfromthreshold 849 ± 36 events

  10. X(3872) production • X(3872) production in hadron collisions reported by CDF [PRL93, 072001 (2004)], D0 [PRL93, 162002 (2004)], LHCb[EPJC72, 1972 (2012)] and CMS[JHEP 1304, 154 (2013)]. • X(3872) reconstructed in the J/yp+p-decay mode, in the central region (CMS, |y|<1.2) or in the forwardregion (LHCb, 2.5<y<4.5) [Artoisenet, Braaten, PRD81, 114018 (2010)] LHCb: sinclusiveB(X(3872)➝J/yp+p-) [2.5<y<4.5, pT>5 GeV] = 4.7±1.1±0.7 nb CMS: sinclusiveB(X(3872)➝J/yp+p-) [|y|<1.2, pT>10 GeV] = 1.06±0.11±0.15 nb CMS: Fraction of X(3872) fromB = (26.0±2.4±1.6)%

  11. X(3872) decay • CMS: p-p+spectrum in X(3872) ➝ J/yp+p-decays, consistent withr0[JHEP 1304, 154 (2013)] • LHCb: search for X(3872)➝ppdecays, in B+➝K+ppwith 1 fb-1 • 6951±176 • Upperlimit: [EPJC73, 2642 (2013)] 6951±176 BR(X(3872)➝pp) BR(X(3872)➝J/yp+p-) <2.0 × 10-3

  12. X(4140) • CDF observed a narrow (J/y f) structure in B+ ➝ J/y f K+decays(withf ➝ K+K-, J/y ➝ m+m-) [PRL102, 242002 (2009)] • Called X(4140): M=4143.2±3±0.6 MeV • 19±6 events for a total of 115±12 B+➝J/y f K+ • Necessarilyexoticsinceitisnarrow and above the DD threshold • [cscs] tetraquark ? • Hint of a second structure: X(4274) = 0.149±0.039±0.024

  13. X(4140) • In multibodydecayslike B+ ➝ J/y f K+, reflexionsfromintermediateresonances or thresholdeffectscan cause apparent structures: crucial to confirm all exotic states by a differentexperiment. • Analysis of the samedecay by LHCb and CMS, withlargerstatistics: LHCb 0.37 fb-1 382±22 events [PRD85, 091103 (2012)]

  14. X(4140) • LHCb: no observation of the X(4140) and X(4274) [PRD85, 091103 (2012)] • Fit withG=15 MeV, 2.4sdisagreementwith CDF result. • CMS: >5s observation of a near-threshold structure (>3s of the second one) [Preliminary] • MX(4140) = 4148.2±2.0±4.6 MeV • More data needed to conclude <0.07

  15. Zc(4430)+: charged exotics • Charged structure seen in B+ ➝ [y(2S) p-] K+ by BELLE [PRL100, 142001], but not confirmed (norexcluded) by BaBar . • Clear signature of exotic: • Decay to charmonium: contains a cc pair • Has electric charge: has 2 more light quarks, Nquarks >= 4 ! • [cdcu] tetraquark, D*D1molecule ? • Needs confirmation. BELLE

  16. Zc(3900)+: charged exotics • BESIII: reconstruct Y(4260) ➝ J/y p+p- running at √s(e+e-)=4.26 GeV. • Vectorexotic state alreadyseenat B factoriesthrough ISR production and CLEO: • LHCb: non-observation of Y(4260)➝m+m-decays in B+➝K+m+m-decays[LHCb-PAPER-2013-039] • BESIII:ReconstructJ/ywith muons or electrons, very clean sample, with cross-section in good agreement withBaBar and BELLE results[PRL110, 252001 (2013)]. BaBar [PRL95, 142001 (2005)] [PRL99, 182004 (2007)] 59528 J/ e+e- 88233 J/ +- BESIII

  17. Zc(3900)+: charged exotics BESIII [PRL110, 252001 (2013)] • S-wave Breit-Wigner with efficiency correction • Mass = (3899.0±3.6±4.9) MeV • Width = (46±10±20) MeV • Fraction = (21.5±3.3±7.5)%

  18. Zc(3900)+: confirmation CLEOc data at 4.17 GeV: [arxiv:1304.3036] Belle with ISR in Y(4260) decays: [PRL110, 252002 (2013)] • M = 3894.56.64.5 MeV •  = 632426 MeV • 159  49 events • >5.2 • M = 388551 MeV •  = 34124 MeV • 81  20 events • 6.1

  19. Conclusions • Experimentalanalysis of charmonium-likeexotics states is a very active field of particlephysics. • Growing contributions from LHC experiments, whichwillbecomeeven more important in the future. • New states continue to beobservedate+e-colliders, including the first chargedconfirmed state (growing importance of BESIII data: observation of Zc(4024)+ in precoil mass spectrum in 4.26 GeV collisions during the summer[arxiv:1308.2760])

  20. Zc(3900)+: charged exotics • Dalitz plot of J/y p+p-: one structure (plus the correspondingreflectionsobserved) BESIII [PRL110, 252001 (2013)]

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