Production of singletP-wavecc¯andbb¯

Abstract

No spin-singlet bb quarkonium state has yet been observed. In this paper we discuss the production of the singlet P-wave bb and cc 1 P 1 states h b and h c . We consider two possibilities. In the first the 1 P 1 states are produced via the electromagnetic cascadesA more promising process consists of single pion transition to the 1 P 1 state followed by the radiative transition to the 1′ 's produced we expect these processes to produce several hundred events.PACS Categories: 14.40.Gx, 13.20.Gd, 13.40.Hq, 12.39.KiThe study of bound states of heavy quarks has provided important tests of quantum chromodynamics (QCD) [1]. The heavy quarkonium cc and bb resonances have a rich spectroscopy with numerous narrow S, P , and D-wave levels below the production threshold of open charm and beauty mesons. The spin-triplet S-wave states, ψ(nS) and Υ(nS) with J P C = 1 −− , are readily produced by virtual photons in e + e − or hadronic interactions, and then undergo electric dipole (E1) transition to the spin-triplet P -wave levels. Previous studies have discussed the production of the spin-triplet D-wave bb states [2,3] and there has been some discussion of how one might produce the 1 1 P 1 cc state [4,5,6,7,8,9]. Up to now, the only observed heavy quarkonium spin-singlet state has been the η c (1 1 S 0 ), but the Belle Collaboration [10] has just announced the discovery of the η ′ c (2 1 S 0 ) in B decays at a mass of (3654 ± 6 ± 8) MeV/c 2 . There have also been a few measurements suggesting the 1 1 P 1 (cc) state inpp annihilation experiments [11,12,13] but these results have yet to be confirmed. No bb spin-singlet states have yet been seen.The mass predictions for the singlet states are an important test of QCD motivated potential models [14,15,16,17,18,19,20,21,22,23] and the applicability of perturbative quantum chromodynamics to the heavy quarkonia cc and bb systems 1 Enrico Fermi Institute preprint EFI 02-79, hep-ph/0205255. Submitted to Physical Review D.

Properties of heavy quarkonia andBcmesons in the relativistic quark model

“…For numerical calculations of hadronic decay rates of χ b states we use α s = 0.18 obtained from the experimental ratio of Γ(Υ → ggγ)/Γ(Υ → ggg) [5]. The calculated partial decay rates and branching fractions for 1P and 2P states of the bottomonium are compared with available experimental data in Table XI.…”

“…Such missing or unconfirmed states are present both in charmonium (2 1 S 0 , 1 1 P 1 , 1 1 D 2 , 1 3 D 2,3 ) and bottomonium (spin-singlet 1 S 0 and 1 P 1 states, D states). The different possibilities for their experimental observation are proposed and widely discussed in the literature [1][2][3][4][5][6]. Radiative transitions from the spin-triplet levels with J P C = 1 −− to these states as well as their subsequent radiative decays play an important role in these proposals.…”

Investigation of meson properties with the Belle detector

“…It [11]. Belle did that first with 121.4 fb −1 and observed the η b (1S ) [12], then the analysis of the full data sample of 133.4 fb −1 gave first evidence for the η b (2S ) [13].…”

Studyof h[sub c]([sup 1]P[sub 1]) at BESIII

“…The absolute branching ratios of ψ(2S) → π 0 h c and h c → γη c are very important to understand QCD theory and charmonium spectrum, but none of them have been measured in previous experiments. Recent theoretical predictions are B(h c → γη c ) = 38% [5] and B(ψ(2S) → π 0 h c ) = (0.4 − 1.3) × 10 −3 , B(h c → γη c ) = 88%(PQCD) or 48%(NRQCD) [6]. According to the equivalent potential theory [2], the lowest order 1P hyperfine splitting is expected to be ∆ M h f ≡ M(1 3 P) − M(1 1 P 1 ) = 0, where M(1 3 P J ) = (M(χ c0 ) + 3(M(χ c1 )) + 5M(χ c2 ))/9 = 3525.30 ± 0.04 MeV [7] is the mass of the spin-weighted centroid of the triplet 3 P J (χ c0,1,2 ) and M(1 1 P 1 ) is the mass of the singlet state h c ( 1 P 1 ).…”