Bled Workshops in Physics Vol. 5, No. 1 A Proceedings of the Mini-Workshop Quark Dynamics (p. 74) Bled, Slovenia, July 12-19, 2004 New ideas about production and detection of cc-tetraquarks * Mitja Rosinaa,b and Damijan Janca bJ. Stefan Institute, 1000 Ljubljana, Slovenia Q Faculty of Mathematics and Physics, University of Ljubljana, 1000 Ljubljana, Slovenia Abstract. We estimate the rate of double charm production in B-factories Belle and BaBar, in hadronic machines with fixed targets RHIC and SELEX, and in high energy colliders Tevatron and LHC. For detection we propose the branching ratio between pionic and gamma decay. 1 Introduction We have shown that the molecule-like configuration of the DD* dimeson (also called tetraquark) enables weak binding even in the case of the Bhaduri or Grenoble AL1 interaction (-0.7 or -2.6 MeV, respectively) [1,2]. The surprise that the cc-tetraquark is likely to be bound against the D + D * decay strongly motivates experimental exploration. To encourage future experimental analyses, we estimate the production rate on several present and future machines, and propose an experimental signature for detection. 2 Production Regarding the production of Tcc, we consider a three-step process: (i) production of two cc pairs, (ii) formation of a diquark c + c —> cc, (iii) dressing of the diquark cc —> ccq, q = u, d, s (90 %), or cc —> ccud (10 %). Here are some provocative guesses: [3] • SELEX [4] has seen 50 candidates for ccq the corresponding hypothetical 5 Tcc are to few to be recognized at present. • Belle reported prompt J/i|) production in e+e~ annihilation at y7? = 10.6 GeV and found that the most of the observed J/^ production is due to the double cc production a(e+e- —> J/^cc)/o-(e+e- —> J/^X) = 0.59 which correspond to 2000 events from their 46.2 fb-1 data sample promising for the Tcc production! Similar rate is also expected for BaBar. * Talk delivered by M. Rosina. Production and detection of ccud tetraquark 75 • High energy colliders (RHIC (p-p), RHIC (p-Au); Tevatron, LHCb, LHC--ALICE) might produce sufficient double charm by double two-gluon fusion [5-8,3] (g + g) + (g + g) —> (c + c) + (c + c). Our estimate for the Tcc cross section are 4, 750; 21, 27,58 nb, respectively. In most machines, the rate seems promising to start the hunt! 3 Detection The main problem with detection of the weakly bound Tcc tetraquark is how to distinguish the pion or photon emitted by the decay of the free D * meson from the one emitted by the D* meson bound inside the tetraquark. We can exploit the fact that the phase space for D * —> D + n decay is very small. Therefore we propose as a signature the branching ratio between radiative and pionic decay. In addition, the analysis using the Dalitz plot can help to distinguish whether the pion was emitted from a bound state, resonance state of D + D * or from free D * meson. 4.04 r 4.03- > 4.02- DDn decay, E is binding energy of Tc Right: The two graphs contributing in the case of resonance E > 0 D n D D D 3 is pion; 4 References 1. These Proceedings 2. D. Janc and M. Rosina, hep-ph/0405208, submitted to Few-Body Systems. 3. D. Janc and M. Rosina, hep-ph/0408258, submitted to Phys. Rev. D. 4. M. Mattson et al. (SELEX Collaboration), Phys. Rev. Lett. 89, 112001 (2002); J. S. Russ (on behalf of the SELEX Collaboration), hep-ex/0209075 5. A. Del Fabbro and D. Treleani, Phys. Rev. D61, 077502 (2000); Phys. Rev. D63, 057901 (2001); Nucl. Phys. B 92,130 (2001). 76 M. Rosina , D. Janc 6. M. Rosina, D. Janc, D. Treleani, and A Del Fabbro, Bled Workshops in Physics 3, No.3, 63 (2002). 7. D. Janc, M. Rosina, D. Treleani, and A. Del Fabbro, Few-Body Systems Suppl. 14 (2003) 25. 8. A. Del Fabbro and D. Treleani, Bled Workshops in Physics 4, No.1, 75 (2003).