1. Project D: Hidden Charm Exotics at BES III Klaus J. Peters, Institut für Kernphysik, Goethe Universität Frankfurt The QuestBESIII Findings Research GroupWorkpackages Central Goal: Search and Validation of QCD Exotics Part 2: ccbar-like states with open strangeness Investigate Y(4360)  η c K + K - Investigate Y(4360)  D 0 D s + K - + c.c. Project Goals Search for additional charmonium-like states Focus on search for the lightest molecules/tetraquarks Investigate DD, D s + D s - and DD s +/- thresholds References: M. Ablikim et al., Observation of a charged charmonium-like structure Z c (4020) and search for the Z c (3900) in e + e - to π + π - h c, Phys. Rev. Lett. 111 (2013) 242001 M. Ablikim et al., Observation of a charged charmonium-like structure in e + e - to D * D *+/- π -/+ at √s =4.26 GeV, Phys. Rev. Lett. 112 (2014) 132001 M. Ablikim et al., Observation of a charged charmonium-like structure in e + e - to π + π - J/ψ at √s =4.26 GeV, Phys. Rev. Lett. 110 (2013) 252001 B. Aubert et al., Observation of a broad structure in the π + π - J/ψ mass spectrum around 4.26-GeV/c 2, Phys. Rev. Lett. 95 (2005) 142001 K. J. Peters, A Primer on partial wave analysis, Int.J.Mod.Phys. A 21 (2006) 5618 Experience and Previous Work Part 1: ccbar-like states Investigate Y(4260)  η c π + π - Investigate Y(4260)  D s - D s + π 0 Tasks: Raw data is available MC studies to optimize selection Data filtering  reconstruction and select channels Amplitude Analysis Consequences of QCD at low energies Binding actually contributes strongly to mass and degrees of freedom Non-perturbative theory yields strong residual forces (nuclear force) Therefore may yield a variety of unconventional states Unfortunately States can mix Discovery of the Z c +/- (3900) in the J/ψ π +/- inv. mass spectrum in the decay Y(4260)  J/ψ π + π - Observation of the Z c +/- (4025) in the h c π +/- inv. mass spectrum in the decay Y(4260/4360)  h c π + π - as a peaking structure Hidden flavor open charm meson pair thresholds compared to known states Open charm meson pair thresholds with net open strangeness Exotic QCD systems Heavy and light flavor spectroscopy Amplitude analysis at Crystal Barrel and BaBar Development of partial wave analysis technologies Experiment Project A, Study of light mesons in two-photon interaction Project B, Search for glueballs in charmonia decays Project C, Further investigation of X(3872) and contribution to the hardware upgrade of BES III Project D, Hidden charm exotics at BES III Project E, Central tasks: Admistration & scientific exchange Charmonium Sector Reduces level density and longer lifetimes  less mixing Better understanding of conventional states Light Quark Sector Some candidates for molecules/tetraquarks like sigma, kappa, a 0 /f 0 (980), but not conclusive too Next Steps Search for complementary final states Search for isoscalar partners Search for strangeonium counterparts Tags (to be extended as necessary) η c  K +/- K S π -/+ D s +/-  K + K - π +/- D 0  K -/+ 2π +/-, K S π + π -, K - π +, K - π 0 π + ; D 0 accordingly Common Tasks: Development of PWA software Data taking Quality assurance and data filtering techniques 4.5 4.0 GeV/c 2 4.5 4.0 GeV/c 2 Outlook: Cumulative η c signal in BES III data from multiple decay channels to search for, Z c +/- (3900)  η c π +/-