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

Segovia, Jorge; Entem, D. R.; Fernández, F.

doi:10.1007/s00601-016-1063-7

Cited by 7 publications

(5 citation statements)

References 62 publications

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“…This strong disagreement with the HQSS prediction was explained by the contribution of B meson loops or, equivalently, by the presence of a four-quark B B component within the Υ(4S) wave function [24,25]. In the case of transitions to spin-singlet states, there is still no evidence of Υ(4S) → ππh b (1P ), while the Υ(4S) → ηh b (1P ) has been observed recently by Belle to be the largest hadronic transition from the Υ(4S) [26], with a branching fraction in agreement with theoretical arguments [27,28] based on various treatments of the light-quark contributions. At the Υ(5S) energy [29,30], the Υ(5S) → ππh b (mP ) transitions, which were expected to be suppressed by the HQSS violation, have been observed by Belle to be enhanced by the presence of intermediate exotic, four-quark states [31,32].…”

supporting

confidence: 73%

Inclusive study of bottomonium production in association with an $η$ meson in $e^+e^-$ annihilations near $Υ(5S)$

Tamponi,

Guido,

Mussa

et al. 2018

Preprint

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We study bottomonium production in association with an η meson in e + e − annihilations near the Υ(5S), at a center of mass energy of √ s = 10.866 GeV. The results are based on the 121.4 fb −1 data sample collected by the Belle experiment at the asymmetric energy KEKB collider. Only the η meson is reconstructed and the missing-mass spectrum of η candidates is investigated. We observe the e + e − → ηΥJ (1D) process and find evidence for the e + e − → ηΥ(2S) process, while no significant signals of Υ(1S), h b (1P ), nor h b (2P ) are found. Cross sections for the studied processes are reported.

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supporting

confidence: 73%

Inclusive study of bottomonium production in association with an $η$ meson in $e^+e^-$ annihilations near $Υ(5S)$

Tamponi,

Guido,

Mussa

et al. 2018

Preprint

View full text Add to dashboard Cite

show abstract

“…This strong disagreement with the HQSS prediction was explained by the contribution of B meson loops or, equivalently, by the presence of a four-quark BB component within the Υ (4S) wave function [24,25]. In the case of transitions to spin-singlet states, there is still no evidence of Υ (4S) → ππh b (1P), while the Υ (4S) → ηh b (1P) has been observed recently by Belle to be the largest hadronic transition from the Υ (4S) [26], with a branching fraction in agreement with theoretical arguments [27,28] based on various treatments of the light-quark contributions. At the Υ (5S) energy [29,30], the Υ (5S) → ππh b (m P) transitions, which were expected to be suppressed by the HQSS violation, have been observed by Belle to be enhanced by the presence of intermediate exotic, four-quark states [31,32].…”

supporting

confidence: 68%

Inclusive study of bottomonium production in association with an $$\eta $$ η meson in $$e^+e^-$$ e + e - annihilations near $$\varUpsilon (5S)$$ Υ ( 5 S )

et al. 2018

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We study bottomonium production in association with an η meson in e + e − annihilations near the Υ (5S), at a centre-of-mass energy of √ s = 10.866 GeV. The results are based on the 121.4 fb −1 data sample collected by the Belle experiment at the asymmetric-energy KEKB collider. Only the η meson is reconstructed and the missing-mass spectrum of η candidates is investigated. We observe the e + e − → ηΥ J (1D) process and find evidence for the e + e − → ηΥ (2S) process, while no significant signals of Υ (1S), h b (1P), nor h b (2P) are found. Cross sections for the studied processes are reported.The treatment of the non-perturbative regime of Quantum Chromodynamics represents one of the major open problems in particle physics [1]. Quarkonia -bound states of either b andb or c andc quarks -are regarded as one of the most fertile environments in which new theoretical approaches to this quandary can be tested [2], thanks to the intrinsic multiscale nature of their dynamics, which are characterized by the coexistence of hard and soft processes [3]. The richness of this sector has been shown by the wave of new discoveries from the BaBar, Belle and CLEO experiments, and then BESIII and LHCb, that challenged the prevailing theoretical models for quarkonium spectra and transitions. Unexpected neutral and charged states have been observed in both charmonium and bottomonium, together with striking violations of the Okubo-Zweig-Iizuka (OZI) rule [4][5][6] and Heavy Quark Spin Symmetry (HQSS). These have demonstrated that the light-quark degrees of freedom play a crucial role in the description of spectral properties [7] and transitions [8]. For a recent review of the theoretical models of quarkonia, see Refs. [9,10].The study of transitions that violate HQSS, like those on which this work is focused, is therefore part of a broader topic of studying exotic quarkonium-like states. HQSS and the models based on it, like the QCD Multipole Expansion [11][12][13][14][15][16], have been long considered reliable for describing hadronic transitions in bottomonium. In this approach, the transitions can be classified into favoured non-spin flipping, like Υ (nS) → ππΥ (mS), and disfavoured spin-flipping, like Υ (nS) → η Υ (mS), which are suppressed by a factor of (Λ QCD /m b ) 2 . As a result of this suppression, the small ratio of branching fractionsis predicted [17,18] This paper is devoted to the study of one of the missing experimental pieces in the puzzle of the hadronic transitions in bottomonium: the single-η emission from the Υ (5S)The final states with Υ (1S) and Υ (2S) have been studied by theorists using rescattering models [24] or by considering intermediate hybrids [35]. The predictions are affected by large uncertainties but agree within one order of magnitude with a preliminary result reported by Belle [36] that was obtained via the exclusive reconstruction of the Υ (1S, 2S) decay into muons. In a recent work [37], the case of Υ (5S) → ηΥ J (1D) is analyzed in the context of a rescattering model where the Υ (5S) ...

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“…They are very hard to calculate in QCD from first principles when the quarkantiquark pair is open-flavor; however, it is worth mentioning herein that there exist non-relativistic effective field theories [80][81][82] and lattice-regularised QCD [83][84][85] computations of, at least, the first multiplet of quarkgluon hybrid mesons when the quark and antiquark are of the same heavy flavor. We shall take a reasonable model which has been already used for the study of similar hadronic transitions in the charmonium and bottomonium sectors [45,86,87], and it will be explained below.…”

Section: Spin-nonflip ππ and η Transitionsmentioning

confidence: 99%

“…It is also important to mention here that the above parameters are considered theoretically as Wilson coefficients and thus they depend on the characteristic energy scale of the physical process. They have been fixed in our previous studies of hadronic transitions within the charmonium and bottomonium sectors [86,87] and, in order to gain predictive power, we use here the values corresponding to the bottomonium case.…”

Section: Spin-nonflip ππ and η Transitionsmentioning

confidence: 99%

“…An extension of the non-relativistic constituent quark model described above to include hybrid states was presented in [86] (see also Refs. [45,87]). This extension is inspired on the Buchmuller-Tye quark-confining string (QCS) model [89][90][91] in which the meson is composed of a quark and antiquark linked by an appropriate color electric flux line (the string).…”

Section: A Model For Hybrid Mesonsmentioning

confidence: 99%

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Towards the discovery of novel $B_c$ states: radiative and hadronic transitions

Martín-González,

Ortega,

Entem

et al. 2022

Preprint

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The properties of the Bc-meson family (c b) are still not well determined experimentally because the specific mechanisms of formation and decay remain poorly understood. Unlike heavy quarkonia, i.e. the hidden heavy quark-antiquark sectors of charmonium (cc) and bottomonium (b b), the Bcmesons cannot annihilate into gluons and they are, consequently, more stable. The excited Bc states, lying below the lowest strong-decay BD-threshold, can only undergo through radiative decays and hadronic transitions to the Bc ground state, which then decays weakly. As a result of this, a rich spectrum of narrow excited states below the BD-threshold appear, whose total widths are two orders of magnitude smaller than those of the excited levels of charmonium and bottomonium. In a different article, we determined bottom-charmed meson masses using a non-relativistic constituent quark model which has been applied to a wide range of hadron physical observables, and thus the model parameters are completely constrained. Herein, continuing to our study of the Bc sector, we calculate the relevant radiative decay widths and hadronic transition rates between c b states which are below BD-threshold. This shall provide the most promising signals for discovering excited Bc states that are below the lowest strong-decay BD-threshold. Finally, our results are compared with other models to measure the reliability of the predictions and point out differences.

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

Cited by 7 publications

References 62 publications

Inclusive study of bottomonium production in association with an $η$ meson in $e^+e^-$ annihilations near $Υ(5S)$

Inclusive study of bottomonium production in association with an $η$ meson in $e^+e^-$ annihilations near $Υ(5S)$

Inclusive study of bottomonium production in association with an $$\eta $$ η meson in $$e^+e^-$$ e + e - annihilations near $$\varUpsilon (5S)$$ Υ ( 5 S )

Towards the discovery of novel $B_c$ states: radiative and hadronic transitions

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