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Innovative Research: Expected Properties of the hc' State and Decay Modes

Study by Sookyung Choi and Stephen L. Olsen on the expected mass and decay modes of the hc state, exploring narrow decay channels with low background for signals. Utilizing event selection criteria and particle identification techniques to identify the hc' state properties. Experimental data analysis reveals promising results for the hc' state.

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Innovative Research: Expected Properties of the hc' State and Decay Modes

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  1. ‘ Evidence for the hc Sookyung Choi Gyeongsang University & Stephen L. Olsen University of Hawaii

  2. ‘ Expected mass of the hc 3Dc3 3Dc1 3Dc2 cc level diagram: y’ ?? D’=??? 1h1? ‘ hc cc0,1,2 D=117 MeV J/y hc potential model: close to they’ expect M(hc’)  3.62~3.64 GeV

  3. Expected widths/decay modes • Similar to hc • narrow (but not like the J/y) • 10< G< 20~30 MeV • ~same decay channels • Search in a channel with strong hc signal but absent in y’ decays

  4. Search in hc’KSK±pchannel • Br(hcK0K-p+) is respectable (2%) • all charged particles (s(DE) 13 MeV) • low combinatoric background • noy’ background (Br(y’K0K-p+)<10-4 • Br(y’K0Kp)<Br(J/yK0Kp)/30

  5. Event selection Use expts 7 thru 13; b20010523_0725 library • Skim Hadron B: • R2<0.35 • 2chrgd K’s; 1chrgd p; 1KS • Mbc>5.2 GeV; |DE|<0.2 GeV • |cosqthrust| < 0.9 between B and rest of evnt • all candidate tracks constrained to IP

  6. Charged kaon selection • K/p-id: atcpid(3,1,5)>0.6 • p/K-id: atcpid(3,1,5)<0.95 • m veto: m_likelihood < 0.9 • e veto: eid_prob(3,-1,5)<0.9 • CDC hits: Nax8 ; Nster3 • vertex : dr<0.3 ; |dz|<2.2

  7. Charged pion selection • K/p-id: atcpid(3,1,5)<0.4 • p/p-id: atcpid(3,1,5)<0.9 • e veto: eid_prob(3,-1,5)<0.95 • CDC hits: Nax8 ; Nster3 • vertex : dr<0.3 ; |dz|<2.2

  8. KSp+p- selection • flight-length > 0.3 • |Df| <0.2 • |Mpp – MKs|< 12 MeV • if both trks have SVD hits: • Zdist<1.2 • otherwise: • Zdist<10 ; dr>0.015 ; |Df|<0.1

  9. continuum-bkgd suppression • Fisher • 5 SFW moments • cosqthrust • S|pt|particles with qthrust>60o • cosqB  B candidate production angle L = PDF( fisher ) x PDF(cosqB)

  10. Fisher SFW cosqthrust S|pt| use: R 2,4 & R 2,3,4 major maj minor

  11. Likelihood Ratio Fisher cosqB cut LR = Lsig/(Lsig+ Lqq)

  12. K* and charm veto • 0 -+ 1–-- 0-+ suppressed by an angular • hc  K* K momentum barrier • backgrounds commonly have K*’s •  veto events with K*: • |MKp – M K* |>50 MeV • also veto events with charm: • |MKp – M D |>10 MeV • |MKKs – M Ds |>10 MeV

  13. Look at K KsK+p- combinations Select events in the DE Mbc signal box

  14. M(KSK+p-) for signal-box evts (B+ K+ KS K+p- + B0KS KSK+p- combined) 1.5-entries/evnt 2-entries/evnt 100 evts 38 evts ? 28 evts “hc’ ” properties • M = 3653 ± 9 MeV • G= 30 +44 MeV • S = 3.8s -?? NB: N(y’KSKp)<N(J/yKSKp)/30 1evt

  15. Do slice fits: 3.55 GeV 6±4 evts 3.60 GeV 13± 4 evts 26±6 evts 3.65 GeV (S=5.2s) 16± 5 evts 3.70 GeV 4 ± 4 evts 3.75 GeV

  16. Slice fit results BW with M =3653 & G = 30 MeV; not a fit! Poor agreement maybe due to the coarseness (50MeV) of the slice-fit bins

  17. Summary 3625<MKSKp<3675 MeV • We observe a 5.2s signal for BK KSK+p- near 3650 MeV. • This cannot be the y’ • Most likely this is BKhc’ with: • Mhc’ = 3653 ± 9 MeV • Ghc’ = 30 +44 MeV • This disagrees with the Crystal-Ball result Mhc’=3594±5 MeV but agrees with potential models. -?? Mbc

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