CLEO-c Sensitivity to Radiative Decay of Scalar Mesons. Jim Napolitano Rensselaer Polytechnic Institute

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1 CLEO-c Sensitivity to Radiative Decay of Scalar Mesons Jim Napolitano Rensselaer Polytechnic Institute JN SURA 1-12 Feb 25

2 Discussion Points Scalar mesons f (137), f (15), and f (171) What we know about J/ψ γf What can CLEO-c add about J/ψ γf Unravelling glue and qq with f γv Specific example: f (171) γρ in CLEO-c JN SURA Feb 25

3 The f (137), f (15), and f (171) Well established light scalar mesons All are seen in some experiments, but none of them are seen in all experiments. Current best guess: These are mixtures of isoscalar quarkonia and the lightest glueball The mixing remains an unknown matrix, both experimentally and theoretically JN SURA Feb 25

4 What we know about J/ψ γf For f (171): Clear peak in J/ψ γf γk+ K,etc... Branching ratio 1 3 Spin well established in partial wave analysis The f (137) is a broad S-wave peak in the PWA. The f (15) is not (obviously) observed. JN SURA Feb 25

5 Orientation: Inclusive J/ψ γx Bloom & Peck (Crystal Ball) Ann.Rev.Nuc.Part.Sci. 33(1983)143 Minimum Ionizing Photon Energy (MeV) η(144) η No other prominent peaks in the inclusive spectrum. JN SURA Feb 25

6 EVENTS /.25GeV/c a) K + K Exclusive final state shows lots of peaks. Recent results from BES EVENTS /.25GeV/c b) K S K S π + π M(!! ) (GeV/c 2 ) JN SURA Feb 25

7 Partial Wave Analysis SLAC Mark-III (Dunwoodie, et al.) a a 2, 2 a 2,1 2 a 2,2 2, 2 K + K (a) (a) (b) (c) 2 (b) K S K S 1 (d) (e) (f) 1 1 (c) π + π (g) (h) (i) Mass (GeV) A Mass (GeV) 7236A6 JN SURA Feb 25

8 What can CLEO-c add? Up to 1 9 J/ψ ( 2 BES) High resolution photon detection Excellent particle identification Obviously, CLEO-c will look for narrow structures ala f J (223) with high sensitivity. What other specific measurements can CLEO-c make that bear on the issue of gluonic excitations? JN SURA Feb 25

9 Unravelling glue and qq with f γv Basic idea: Glue component doesn t couple to photons, and flavor component sensitive to V={ρ,ω,φ}. Radiative decays: A New flavor filter. By Close, Donnachie, and Kalashnikova. Phys.Rev.D67:7431,23 Radiative scalar decays in the light front quark model. By DeWitt, Choi, and Ji. Phys.Rev.D68:5426,23 Decay width calculations are basically consistent, especially in the ratios to different vector mesons. JN SURA Feb 25

10 Calculations from Close, et al: Radiative Decay Widths (kev) f γρ(77) f γφ(12) Total width State (MeV) L M H L M H f (137) f (15) f (171) For example, for the three different mixing scenarios, we have B[ f (171)!"] = (42 to 75)/( ) = (.3 to 5) 1 3 B[ f (171)!"] = (8 to 78)/( ) = (6.4 to.6) 1 3 B[ f (171)!"]/B[ f (171)!#] = 42/8 to 75/78 = 1/19 to 9 JN SURA Feb 25

11 Specific example: f (171) γρ in CLEO-c The Challenge: Need to extract a signal with BR 1 6 Monte Carlo study: Signal: Generate J/ψ γf (171) γγρ γγπ+ π and attempt to extract events with high efficiency Background: Generate generic J/ψ events using best available information and apply same cuts as those used to extract the signal Work done by Istvan Danko (RPI) JN SURA Feb 25

12 Signal Monte Carlo: Reconstruction efficiency f (171) γπ + π ""! 2 mass 1 2 Generated Reconstructed Efficiency=65.2% ρ π + π "" mass JN SURA Feb 25

13 Signal Monte Carlo: Truth matching π + π correct All correct π + π correct, γ s wrong f (171) γπ + π ρ π + π ""! 2 mass JN SURA Feb "" mass

14 Generic Monte Carlo: Generated events total momentum total energy JN SURA 1-12 Feb All events Exactly two tracks w/opposite charge Exactly two, high energy, unmatched showers in CsI Result of imposing vertical line cut on other histogram

15 6 6 Understanding the remaining2backgrounds J/ψ ρπ ππ+π γγπ+π (BR=1.27%) +π Also J/ψ {ρη,γη,...} γγπ E(!2) in lab !!"2 momentum 2.4 η 12 π η ω? η E(!1) vs. M(!1!2) JN SURA M(!!"2) Feb 25

16 Removing the remaining backgrounds (work in progress) E(! 1 ) E("") Signal MC Generic MC M(!!" 2 ) after cut Results so far: 64 events remain (1 4 rejection) with signal detection efficiency 39.4%. Not bad, but more to go. JN SURA Feb 25

17 Where we are going from here... Continue to study generic backgrounds and reduce them as far as possible. Work on a partial wave analysis technique for verifying the J/ψ γf (171) γγρ signal Study J/ψ γf (171) γγφ (in progress) Study J/ψ γf (171) γγω JN SURA Feb 25

18 Summary The situation of glueball components in the scalar meson sector remains murky CLEO-c will contribute high statistics and precision techniques towards the problem One key problem we will attack is finding the mass mixing matrix elements Simulations are underway so that we are ready for the problem when the data arrives JN SURA Feb 25