Single eta production in heavy quarkonia: Breakdown of multipole expansion

Simonov, Yu. A.; Veselov, A.I.

doi:10.1016/j.physletb.2009.02.025

Cited by 14 publications

(22 citation statements)

References 29 publications

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“…An alternative explanation for the large decay width of the Υ(4S) → Υ(1S)η transition has been reported in Ref. [16]. Based on the Field Correlator Method (FCM) [15], the authors of [16] assume that the η transition between two heavy quarkonia proceeds via intermediate states of BB, BB * , etc.…”

Section: Resultsmentioning

confidence: 99%

“…The anomalous hadronic decay widths can be due to several mechanisms: Contribution of hadron loops [11][12][13]; four-quark components in the quarkonium wave functions [14]; internal loop radiation [15,16]; or, as we have pointed out in Ref. [17] and we will see herein, the existence of hybrid mesons with a mass near the one of the decaying resonance 1 .…”

Section: Introductionmentioning

confidence: 99%

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The Role of Spin-Flipping Terms in Hadronic Transitions of $${\Upsilon (4S)}$$ Υ ( 4 S )

2016

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Recent experimental data on the Υ(4S) → Υ(1S)η and Υ(4S) → h b (1P )η processes seem to contradict the naive expectation that hadronic transitions with spin-flipping terms should be suppressed with respect those without spin-flip. We analyze these transitions using the QCD Multipole Expansion (QCDME) approach and within a constituent quark model framework that has been applied successfully to the heavy-quark sectors during the last years. The QCDME formalism requires the computation of hybrid intermediate states which has been performed in a natural, parameter-free extension of our constituent quark model based on the Quark Confining String (QCS) scheme. We show that i) the M1-M1 contribution in the decay rate of the Υ(4S) → Υ(1S)η is important and its suppression until now is not justified; ii) the role played by the L = 0 hybrid states, which enter in the calculation of the M1-M1 contribution, explains the observed enhancement in the Υ(4S) → Υ(1S)η decay width; and iii) the anomalously large decay rate of the Υ(4S) → h b (1P )η transition has the same physical origin.

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Section: Resultsmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

The Role of Spin-Flipping Terms in Hadronic Transitions of $${\Upsilon (4S)}$$ Υ ( 4 S )

2016

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“…The parameters of the quark wave functions must be changed by more than 15% in order to account for these discrepancies [10]. Searches for the π 0 transitions have only yielded upper limits [7,9].…”

Section: B(υ(2s)→υ(1s)η) B(υ(2s)→υ(1s)πmentioning

confidence: 99%

Study of the hadronic transitionsΥ(2S)→(η,π0)Υ(1
Tamponi¹,
Mussa²,
Adachi³
et al. 2013
Phys. Rev. D
10
1
6
0
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We study the rare hadronic transitions Υ(2S) → Υ(1S)η and Υ(2S) → Υ(1S)π 0 using a sample of 158 ×10 6 Υ(2S) decays collected with the Belle detector at the KEKB asymmetric-energy e + e − collider. We measure the ratios of branching fractions (B) Assuming the value B(Υ(2S) → Υ(1S)π − π + ) = (17.92±0.26)%, we obtain B(Υ(2S) → Υ(1S)η) = (3.57 ± 0.25(stat) ± 0.21(syst)) × 10 −4 and B(Υ(2S) → Υ(1S)π 0 ) < 4.1 × 10 −5 (90% CL). B(Υ(2S)→Υ(1S)η) B(Υ(2S)→Υ(1S)πPACS numbers: 14.40. Pq,13.25.Gv In recent years, hadronic transitions between quarkonia have led to an impressive series of discoveries [1]: X(3872), Y (4260), as well as h c and h b were observed in transitions either from or to the ψ and Υ states. The phenomenology of these transitions is commonly described with the QCD Multipole Expansion formalism (QCDME) [2,3], which allows one to classify the transitions in a series of chromoelectric and chromomagnetic multiplets. In particular, theoretical predictions for η and π 0 transitions [4,5] among states are being challenged by experimental measurements. The η and π 0 transitions between vector bottomonia should be mediated either by two M1 gluons or by one E1 and one M2 gluon: both cases imply a spin flip of the b quark. The corresponding amplitude should scale as 1/m b , and its measurement yields information about the chromomagnetic moment of the b quark.By scaling from the ψ(2S) → J/ψη transition, one expects a transition width of:, and therefore a ratio of branching fractions R η,. Within the QCDME formalism, one can calculate R η,π + π − = 2.3 × 10 −3 [4] assuming the b quark mass to be m b = 4.67 GeV/c 2 [6]. A further suppression is expected for the π 0 transition, which violates isospin; here, theory predictsThe Υ(2, 3, 4S) → Υ(1S)η transitions have been studied by CLEO [7] and BaBar [8,9]; the measured branching fractions are either unexpectedly large (Υ(4S)) or too small (Υ(2S) and Υ(3S)). The parameters of the quark wave functions must be changed by more than 15% in order to account for these discrepancies [10]. Searches for the π 0 transitions have only yielded upper limits [7,9].We report here a new measurement of the transition Υ(2S) → Υ(1S)η and a search for Υ(2S) → Υ(1S)π 0 using the Belle detector at the KEKB e + e − collider [11]. The Υ(1S) is reconstructed in both the e + e − and µ + µ − decay modes; we reconstruct the η meson via its decay to γγ and π − π + π 0 , and the π 0 in the γγ final state. As a normalization sample, we reconstruct the dominant transition Υ(2S) → Υ(1S)π − π + , which has a branching fraction of (17.92±0.26)% [6]. The data sample for this analysis includes an integrated luminosity of 24.7 fb −1 at the Υ(2S) resonance peak, corresponding to (158±4)×10 6 Υ(2S) decays, and an additional 1.7 fb −1 at √ s=9.993 GeV used to study the QED continuum backgrounds. The Belle detector is described in detail elsewhere [12]. Here, we summarize the features that are relevant to the current analysis. The momentum of each charged track is measured using a four-layer double-sided Sili...

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“…The QCD multipole expansion model [6] can be used generally to describe hadronic transition between the lower mass bottomonium levels, while its predictions fail when considering bottomonia above the BB threshold. In particular, the transitions between bottomonium states via an η meson are predicted, for example in [6][7][8], to be highly suppressed, since they require a spin flip of the heavy quark. Among the most unexpected experimental measurements, the BaBar collaboration found an enhancement of the transition Υ(4S) → ηΥ(1S) with respect to the transition via a dipion [1].…”

Section: Introductionmentioning

confidence: 99%

Study of η and dipion transitions in ϒ(4S) decays to lower bottomonia

Guido¹,

Mussa²,

Tamponi³

et al. 2017

Phys. Rev. D

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We study hadronic transitions between bottomonium states using 496 fb −1 data collected at the Υ(4S) resonance with the Belle detector at the KEKB asymmetric energy e + e − collider. We measure:−5 , and B(Υ(4S) → ηΥ(1S)) = (1.70 ± 0.23(stat.) ± 0.08(syst.)) × 10 −4 . We measure the ratio of branching fractions R = B(Υ(4S) → ηΥ(1S))/B(Υ(4S) → π + π − Υ(1S)) = 2.07 ± 0.30(stat.) ± 0.11(syst.). We search for the decay Υ(1 3 D1,2) → ηΥ(1S), 3 but do not find significant evidence for such a transition. We also measure the initial state radiation production cross sections of the Υ(2S, 3S) resonances and we find values compatible with the expected ones. Finally, the analysis of the Υ(4S) → π + π − Υ(1S) events shows indications for a resonant contribution due to the f0(980) meson.

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Single eta production in heavy quarkonia: Breakdown of multipole expansion

Cited by 14 publications

References 29 publications

The Role of Spin-Flipping Terms in Hadronic Transitions of $${\Upsilon (4S)}$$ Υ ( 4 S )

The Role of Spin-Flipping Terms in Hadronic Transitions of $${\Upsilon (4S)}$$ Υ ( 4 S )

Study of the hadronic transitionsΥ(2S)→(η,π0)Υ(1
Tamponi¹,
Mussa²,
Adachi³
et al. 2013
Phys. Rev. D
10
1
6
0
View full text Add to dashboard Cite

Study of η and dipion transitions in ϒ(4S) decays to lower bottomonia

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Single eta production in heavy quarkonia: Breakdown of multipole expansion

Cited by 14 publications

References 29 publications

The Role of Spin-Flipping Terms in Hadronic Transitions of $${\Upsilon (4S)}$$ Υ ( 4 S )

The Role of Spin-Flipping Terms in Hadronic Transitions of $${\Upsilon (4S)}$$ Υ ( 4 S )

Study of the hadronic transitionsΥ(2S)→(η,π0)Υ(1Tamponi1, Mussa2, Adachi3 et al. 2013Phys. Rev. D10160View full textAdd to dashboardCite

Study of η and dipion transitions in ϒ(4S) decays to lower bottomonia

Contact Info

Product

Resources

About

Study of the hadronic transitionsΥ(2S)→(η,π0)Υ(1
Tamponi¹,
Mussa²,
Adachi³
et al. 2013
Phys. Rev. D
10
1
6
0
View full text Add to dashboard Cite