---
title: 'Upsilon(10753): Vector Bottomonium Candidate'
url: https://www.emergentmind.com/topics/upsilon-10753
type: topic
---

# Upsilon(10753): Vector Bottomonium Candidate

\(\Upsilon(10753)\) is a vector bottomonium-like resonance observed in \(e^+e^-\) annihilation near \(10.75\) GeV in both \(\pi^+\pi^-\Upsilon(nS)\) and \(\omega\chi_{bJ}(1P)\) final states. It carries \(J^{PC}=1^{--}\), and recent channel-dependent determinations place it at \((10756.3\pm2.7\pm0.6)\) MeV/\(c^2\) with width \((29.7\pm8.5\pm1.1)\) MeV in \(\pi^+\pi^-\Upsilon(nS)\), and at \((10756.1\pm3.4({\rm stat.})\pm2.7({\rm syst.}))\) MeV/\(c^2\) with width \((32.2\pm11.3({\rm stat.})\pm14.9({\rm syst.}))\) MeV in \(\chi_{bJ}\omega\) analyses [2401.12021] [2510.25461]. Its spectroscopic assignment remains unsettled. Proposed descriptions include a \(4S\)–\(3D\) mixed conventional bottomonium, a pure \(3\,{}^3D_1\) level, a dressed hadronic resonance with large \(B^{*}\bar B^{*}\) content, a hybrid bottomonium, and a compact tetraquark [2508.18720] [2403.03770] [2104.03975] [2210.16250].

## 1. Experimental identification and resonance parameters

Belle first established the state as a resonant structure in \(e^+e^- \to \Upsilon(nS)\pi^+\pi^-\) with \(n=1,2,3\), and Belle II later connected the same energy region to \(e^+e^- \to \omega\chi_{bJ}(1P)\) with \(J=1,2\) [2312.02761] [2208.13189]. Production in \(e^+e^-\) annihilation fixes the vector quantum numbers, and the Particle Data Group lists it as a \(J^{PC}=1^{--}\) candidate.

| Measurement channel | Mass and width | Source |
|---|---|---|
| Belle in \(\pi^+\pi^-\Upsilon(nS)\) | \(M=(10752.7 \pm 5.9^{+0.7}_{-1.1})\) MeV, \(\Gamma=(35.5^{+17.6}_{-11.3}{}^{+3.9}_{-3.3})\) MeV | [2312.02761] |
| Belle + Belle II in \(\pi^+\pi^-\Upsilon(nS)\) | \(M=(10756.3\pm2.7\pm0.6)\) MeV/\(c^2\), \(\Gamma=(29.7\pm8.5\pm1.1)\) MeV | [2401.12021] |
| Belle + Belle II in \(\chi_{bJ}\omega\) | \(M=(10756.1\pm3.4({\rm stat.})\pm2.7({\rm syst.}))\) MeV/\(c^2\), \(\Gamma=(32.2\pm11.3({\rm stat.})\pm14.9({\rm syst.}))\) MeV | [2510.25461] |

The experimental picture is therefore internally consistent at the level of mass and total width. A notable feature is that \(\Upsilon(10753)\) sits between the established \(\Upsilon(4S)\) and \(\Upsilon(10860)\) regions, precisely where open-bottom thresholds and strong coupled-channel effects become unavoidable in spectroscopy.

## 2. Observed decay pattern and line-shape phenomenology

The state is experimentally distinguished not only by its mass but by an unusual channel pattern. Belle II observed \(e^+e^-\to\omega\chi_{bJ}(1P)\) at \(\sqrt{s}=10.745\) GeV with
\[
\sigma_B(e^+e^-\to \omega\chi_{b1})=(3.6^{+0.7}_{-0.7}\pm0.5)\ {\rm pb},
\qquad
\sigma_B(e^+e^-\to \omega\chi_{b2})=(2.8^{+1.2}_{-1.0}\pm0.4)\ {\rm pb},
\]
and found the energy dependence consistent with a resonance centered near \(\Upsilon(10753)\) rather than \(\Upsilon(10860)\) [2208.13189]. The later Belle–Belle II combined analysis sharpened this picture: at \(\sqrt{s}=10.745\) GeV it measured
\[
\sigma_{\rm Born}(e^+e^-\to \chi_{b1}\omega)=(3.8^{+0.6}_{-0.5}\pm0.4)\ {\rm pb},
\]
\[
\sigma_{\rm Born}(e^+e^-\to \chi_{b2}\omega)=(2.6^{+0.8}_{-0.7}\pm0.4)\ {\rm pb},
\]
with
\[
\frac{\sigma_{\rm Born}(e^+e^-\to\chi_{b1}\omega)}
{\sigma_{\rm Born}(e^+e^-\to\chi_{b2}\omega)}
=1.5^{+0.5}_{-0.4}\pm0.2
\]
[2510.25461].

The same combined fit extracted
\[
\Gamma_{ee}\mathcal{B}\big(\Upsilon(10753)\to\chi_{b1}\omega\big)
=(1.46 \pm 0.25_{\rm stat} \pm 0.20_{\rm syst})\,{\rm eV},
\]
\[
\Gamma_{ee}\mathcal{B}\big(\Upsilon(10753)\to\chi_{b2}\omega\big)
=(1.29 \pm 0.38_{\rm stat} \pm 0.31_{\rm syst})\,{\rm eV},
\]
and their ratio
\[
\frac{\Gamma_{ee}\mathcal{B}(\Upsilon(10753)\to\chi_{b1}\omega)}
{\Gamma_{ee}\mathcal{B}(\Upsilon(10753)\to\chi_{b2}\omega)}
=1.13 \pm 0.38_{\rm stat} \pm 0.34_{\rm syst}
\]
[2510.25461]. In the same study, \(\Upsilon(10753)\) was found to decay into \(\chi_{bJ}\omega\) but not into \(\chi_{bJ}(\pi^+\pi^-\pi^0)_{\rm non-\omega}\), with upper limits
\[
\Gamma_{ee}\mathcal{B}\big(\Upsilon(10753)\to\chi_{b1}(\pi^+\pi^-\pi^0)_{\rm non-\omega}\big)<0.08\ {\rm eV},
\]
\[
\Gamma_{ee}\mathcal{B}\big(\Upsilon(10753)\to\chi_{b2}(\pi^+\pi^-\pi^0)_{\rm non-\omega}\big)<0.07\ {\rm eV}
\]
[2510.25461].

In \(\pi^+\pi^-\Upsilon(nS)\), Belle II reported the first observation of \(\Upsilon(10753)\to\pi^+\pi^-\Upsilon(1S)\) and \(\Upsilon(10753)\to\pi^+\pi^-\Upsilon(2S)\), but no evidence for \(\pi^+\pi^-\Upsilon(3S)\) [2401.12021]. At \(\sqrt{s}=10.746\) GeV the measured Born cross sections were
\[
0.64^{+0.12}_{-0.11}\pm0.03\ {\rm pb}
\]
for \(\pi^+\pi^-\Upsilon(1S)\),
\[
1.43^{+0.17}_{-0.17}\pm0.17\ {\rm pb}
\]
for \(\pi^+\pi^-\Upsilon(2S)\), and
\[
0.11^{+0.11}_{-0.09}\pm0.08\ {\rm pb}
\]
for \(\pi^+\pi^-\Upsilon(3S)\) [2401.12021]. The resonance-peak ratios were reported as
\[
\mathcal{R}^{\Upsilon(10753)}_{\sigma(1S/2S)}=0.46^{+0.15}_{-0.12},
\qquad
\mathcal{R}^{\Upsilon(10753)}_{\sigma(3S/2S)}=0.10^{+0.05}_{-0.04},
\]
showing a pronounced suppression of the \(3S\) channel [2401.12021].

Two further phenomenological features are already clear. First, no evidence was found for \(\pi^\mp Z_b^\pm\) or \(f_0(980)\Upsilon(nS)\) intermediate states in \(\pi^+\pi^-\Upsilon(1S,2S)\) transitions [2401.12021]. Second, the contrast with \(\Upsilon(10860)\) is sharp: Belle and Belle II data indicate that the internal structures of \(\Upsilon(10753)\) and \(\Upsilon(10860)\) may differ, and the ratio
\[
\frac{\sum_{n=1}^3 \mathcal{B}(\Upsilon(10753)\to \Upsilon(nS)\pi^+\pi^-)}
{\sum_{J=1}^2 \mathcal{B}(\Upsilon(10753)\to\chi_{bJ}\omega)} < 0.9,
\]
whereas for \(\Upsilon(10860)\)
\[
\frac{\sum_{n=1}^3 \mathcal{B}(\Upsilon(10860)\to \Upsilon(nS)\pi^+\pi^-)}
{\sum_{J=1}^2 \mathcal{B}(\Upsilon(10860)\to\chi_{bJ}\omega)} > 28
\]
[2510.25461].

## 3. Conventional bottomonium descriptions

A large fraction of the literature treats \(\Upsilon(10753)\) as a conventional \(b\bar b\) state modified by strong threshold dynamics rather than as a manifest exotic. The most developed version is a \(4S\)–\(3D\) mixing scheme in which the physical pair \(\Upsilon(10580)\) and \(\Upsilon(10753)\) arises from the basis \(\Upsilon_{4S}\) and \(\Upsilon_{3D}\):
\[
\begin{pmatrix} \Upsilon(10580)\\[4pt] \Upsilon(10753) \end{pmatrix}
=
\begin{pmatrix} \cos\theta & -\sin\theta\\[4pt] \sin\theta & \cos\theta \end{pmatrix}
\begin{pmatrix} \Upsilon_{4S}\\[4pt] \Upsilon_{3D} \end{pmatrix},
\]
so that
\[
|\Upsilon(10753)\rangle=\sin\theta\,|4S\rangle+\cos\theta\,|3D\rangle
\]
[2508.18720]. In one analysis the dielectron width of \(\Upsilon(10580)\) yields two allowed angles,
\[
\theta=(27\pm4)^\circ,\qquad \theta=(-35\pm4)^\circ,
\]
and predicts
\[
\Gamma_{ee}(\Upsilon(10753))=(93\pm22)\ {\rm eV}
\]
or
\[
(97\pm22)\ {\rm eV}
\]
[2508.18720]. A related study extracted
\[
\theta=(27.7\pm5.0)^\circ
\]
from \(\Gamma_{ee}(\Upsilon(10580))\) and a mass-mixing interval
\[
\theta\in[23.4^\circ,36.1^\circ]
\]
from a quadratic mass relation [2312.02761]. Another hadronic-loop analysis using \(\theta=(33\pm4)^\circ\) quoted
\[
\Gamma_{e^+e^-}(\Upsilon(10753))=(0.159\pm0.030)\ {\rm keV},
\]
which indicates substantial model dependence in the electronic width [2201.12715].

The chief spectroscopic motivation for mixing is that pure \(3D\) quark-model masses tend to lie below the observed resonance. One S–D mixing analysis quotes \(m_{4S}^{\rm QM}\approx10635\) MeV and \(m_{3D}^{\rm QM}\approx10698\) MeV, with level repulsion shifting the physical states to \(\Upsilon(10580)\) and \(\Upsilon(10753)\) [2508.18720]. A different mass-mixing study requires the pure \(4S\) mass in
\[
m_{\Upsilon(4S)}\in[10607,10635]\ {\rm MeV}
\]
and the pure \(3\,{}^3D_1\) mass around
\[
m_{3\,{}^3D_1}\sim10698\text{–}10725\ {\rm MeV}
\]
[2312.02761].

Decay phenomenology is a more stringent test than mass alone. In the \(\omega\chi_{bJ}\) system, heavy-quark-spin-symmetry tree-level spin counting gives for a pure \(S\)-wave vector
\[
\Gamma_0^S:\Gamma_1^S:\Gamma_2^S = 1:3:5,
\]
while for a pure \(D\)-wave
\[
\Gamma_0^D:\Gamma_1^D:\Gamma_2^D = 20:15:1.
\]
After including open-bottom triangle loops for the \(D\)-wave component, one analysis finds at the \(\Upsilon(10753)\) mass
\[
\Gamma(\Upsilon_D\to\chi_{b0}\omega):\Gamma(\Upsilon_D\to\chi_{b1}\omega):\Gamma(\Upsilon_D\to\chi_{b2}\omega)\approx 29:18:1,
\]
which is incompatible with the experimentally observed near equality of the \(\chi_{b1}\omega\) and \(\chi_{b2}\omega\) rates [2508.18720]. The same work therefore concludes that \(\Upsilon(10753)\) cannot be a pure \(D\)-wave bottomonium and must involve S–D interference.

Within the S–D mixing picture, the \(\omega\chi_{bJ}\) branching fractions inferred from Belle II data fall in the \(10^{-3}\)–\(10^{-2}\) range. For example, with \(\theta=(27\pm4)^\circ\) and the constructive solution,
\[
\mathcal{B}(\Upsilon(10753)\to\chi_{b1}\omega)\approx 6.8\pm5.0\times10^{-3},
\]
\[
\mathcal{B}(\Upsilon(10753)\to\chi_{b2}\omega)\approx 5.7\pm5.3\times10^{-3},
\]
while the destructive solution gives
\[
22\pm10\times10^{-3}
\]
and
\[
14\pm8\times10^{-3}
\]
respectively [2508.18720].

Other hidden-bottom transitions have been modeled in the same framework. For \(\Upsilon(10753)\to\eta_b(1S)\omega,\eta,\eta'\), intermediate \(B^{(*)}\bar B^{(*)}\) loops yield branching fractions that may reach the order of \(10^{-3}\)–\(10^{-2}\) over \(\alpha\in[0.2,1.0]\), with a preferred range \(\alpha\in[0.3,0.5]\) giving partial widths
\[
\Gamma(\Upsilon(10753)\to \eta_b\omega)\approx 5.6\text{–}38.8\ {\rm keV},
\]
\[
\Gamma(\Upsilon(10753)\to \eta_b\eta)\approx 2.8\text{–}23.4\ {\rm keV},
\]
\[
\Gamma(\Upsilon(10753)\to \eta_b\eta')\approx 2.7\text{–}20.2\ {\rm keV}
\]
[2312.02761]. For \(\Upsilon(10753)\to \Upsilon(1^3D_J)\eta\), a separate loop calculation predicts that
\[
\mathcal{B}[\Upsilon(10753)\to\Upsilon(1^3D_{1})\eta]
\]
and
\[
\mathcal{B}[\Upsilon(10753)\to\Upsilon(1^3D_{2})\eta]
\]
can reach the order of magnitude of \(10^{-4}\)–\(10^{-3}\), whereas
\[
\mathcal{B}[\Upsilon(10753)\to\Upsilon(1^3D_{3})\eta]
\]
is around \(10^{-6}\)–\(10^{-5}\) [2205.04049]. Hadronic-loop calculations for \(\Upsilon(10753)\to\Upsilon(nS)\pi^+\pi^-\) likewise obtain branching ratios of order \(10^{-4}\)–\(10^{-3}\) and reproduce Belle \(\Gamma_{e^+e^-}\times\mathcal{B}\) values within the \(4S\)–\(3D\) scenario [2201.12715].

A competing conventional assignment appears in a relativistic screened potential model, which identifies \(\Upsilon(10753)\) as a pure \(\Upsilon_1(3D)\) state with
\[
M_{\rm cal}=10741.3\ {\rm MeV}
\]
and
\[
\Gamma_{ee}(3^3D_1)=3.059\ {\rm eV},
\]
together with a three-gluon width
\[
\Gamma(ggg)=7.54\ {\rm keV}
\]
[2501.03147]. That model treats \(\Upsilon(10753)\) as unmixed \(3\,{}^3D_1\), in contrast to the S–D mixing literature. The tension between these two conventional pictures is one of the central unresolved issues in the subject.

## 4. Coupled-channel and dynamical-resonance interpretations

A distinct line of work attributes \(\Upsilon(10753)\) primarily to threshold dynamics. In a lattice-QCD-based diabatic Born–Oppenheimer treatment using string-breaking potentials and an emergent-wave method, the state appears as a pole generated by mixing between a confined \(b\bar b\) channel and open bottom channels [2008.05605]. In the two-channel \(\bar bb+\bar B^{(*)}B^{(*)}\) problem, the relevant pole lies near
\[
M\approx 10.774\ {\rm GeV},\qquad \Gamma\approx 98.5\ {\rm MeV},
\]
with composition
\[
\%\bar QQ\simeq 6\%,\qquad \%\bar MM\simeq 94\%.
\]
After adding the \(\bar B_s^{(*)}B_s^{(*)}\) channel, the pole becomes
\[
M=10.773^{+0.001}_{-0.002}\ {\rm GeV},\qquad \Gamma=15.9^{+2.9}_{-4.4}\ {\rm MeV},
\]
with
\[
\%\bar QQ\approx24\%,\qquad \%\bar MM\approx60\%,\qquad \%\bar M_sM_s\approx16\%
\]
[2008.05605]. In that framework, \(\Upsilon(10753)\) is therefore a dynamical meson-meson resonance with dominant open-bottom content rather than a compact quarkonium.

A constituent-quark-model meson-meson coupled-channel calculation reaches a related but numerically different conclusion [2403.03770]. Including bare \(\Upsilon(4S)\), \(\Upsilon(3D)\), \(\Upsilon(5S)\), \(\Upsilon(4D)\) together with \(B\bar B\), \(B\bar B^\ast\), \(B^\ast\bar B^\ast\), \(B_s\bar B_s\), \(B_s\bar B_s^\ast\), and \(B_s^\ast\bar B_s^\ast\), it finds a pole at
\[
M_5=10712\pm5\ {\rm MeV},\qquad \Gamma_5=41\pm4\ {\rm MeV},
\]
whose wavefunction contains
\[
{\cal P}_{\Upsilon(4S)}=36\%,
\qquad
{\cal P}_{\Upsilon(3D)}=8.8\%,
\qquad
{\cal P}_{B^\ast\bar B^\ast}=43\%
\]
with total quarkonium and meson-meson fractions close to equality [2403.03770]. The paper summarizes this as an equally mixture of a conventional \(b\bar b\) state and \(B^\ast\bar B^\ast\) molecule. It also stresses that poles obtained in the complex energy plane do not have to appear as simple peaks in the relevant cross sections, and that the \(\Upsilon(10750)\) candidate emerges as a dressed hadronic resonance.

An unquenched-quark-model study aimed at the \(\Upsilon(5S)\) question reaches a more conservative conclusion [2507.13882]. Starting from a bare
\[
M_0(5S)=10927.6\ {\rm MeV}
\]
and coupling to \(B^{(*)}\bar B^{(*)}\) and \(B_s^{(*)}\bar B_s^{(*)}\) channels, it obtains a total mass shift
\[
\Delta M_{\rm total}=-31.4\ {\rm MeV}
\]
and
\[
M_{\rm UQM}(5S)=10896.2\ {\rm MeV},
\]
very close to \(\Upsilon(10860)\) but far above \(\Upsilon(10753)\) [2507.13882]. In that framework, coupled-channel effects are important but not large enough to identify \(\Upsilon(10753)\) with \(\Upsilon(5S)\), and \(\Upsilon(10753)\) and \(\Upsilon(10860)\) may be two different states.

These coupled-channel approaches share a common lesson: once explicit \(B^{(*)}\bar B^{(*)}\) and \(B_s^{(*)}\bar B_s^{(*)}\) thresholds are included, the vector bottomonium spectrum above open-bottom threshold is richer than the naïve quenched \(b\bar b\) ladder. Whether \(\Upsilon(10753)\) should be regarded as predominantly dynamical or as a heavily dressed conventional state remains model-dependent.

## 5. Hybrid and tetraquark proposals

The hybrid interpretation identifies \(\Upsilon(10753)\) with the lowest \(1^{--}\) bottomonium hybrid supported by the \((\Pi_u-\Sigma_u^-)\) static-energy multiplet in Born–Oppenheimer EFT [2209.08548]. In that formulation the state is written as a spin-singlet hybrid,
\[
\Upsilon(10753)\equiv n^1\mathcal{P}_1\ {\rm hybrid},\qquad n=1,
\]
and is paired with \(\Upsilon(11020)\) as the first excited \(1^{--}\) hybrid [2209.08548] [2104.03975]. The transition formalism employs weakly coupled pNRQCD with singlet–octet chromoelectric and chromomagnetic operators,
\[
g\,\mathrm{Tr}\big[S^\dagger\,\mathbf r\!\cdot\!\mathbf E\,O+O^\dagger\,\mathbf r\!\cdot\!\mathbf E\,S\big]
\]
and
\[
\frac{g c_F}{m_Q}\,\mathrm{Tr}\big[S^\dagger(\mathbf S_1-\mathbf S_2)\!\cdot\!\mathbf B\,O+O^\dagger(\mathbf S_1-\mathbf S_2)\!\cdot\!\mathbf B\,S\big],
\]
which enforce characteristic spin-selection rules [2209.08548].

Under this hypothesis, \(\Upsilon(10753)\) has specific exclusive and semi-inclusive decay patterns. The predicted widths include
\[
\Gamma\big[\Upsilon(10753)\to \Upsilon(1S)\pi^+\pi^-\big]
=43.4(\pm 17.3)_{\rm m.e.}(\pm 2.4)_{Z_B}(\pm 8.6)_{\alpha_s}(^{+0.5}_{-0.0})_\kappa\ {\rm keV},
\]
\[
\Gamma\big[\Upsilon(10753)\to \Upsilon(2S)\pi^+\pi^-\big]
=2.75(\pm 1.10)_{\rm m.e.}(\pm 0.15)_{Z_B}(\pm 0.55)_{\alpha_s}(^{+0.13}_{-0.12})_\kappa\ {\rm keV},
\]
\[
\Gamma\big[\Upsilon(10753)\to \Upsilon(3S)\pi^+\pi^-\big]
=0.98(\pm 0.39)_{\rm m.e.}(\pm 0.05)_{Z_B}(\pm 0.19)_{\alpha_s}(\pm 0.03)_\kappa\ {\rm eV},
\]
\[
\Gamma\big[\Upsilon(10753)\to \Upsilon(1S)K^+K^-\big]
=3.98(\pm 1.59)_{\rm m.e.}(\pm 0.22)_{Z_B}(\pm 0.79)_{\alpha_s}(^{-0.50}_{+0.67})_\kappa\ {\rm keV},
\]
as well as a semi-inclusive width
\[
\Gamma^{\rm NLO}_{\Upsilon(10753)\to \Upsilon(1S)}=9.7(\pm3.8)_{\alpha_s}\ {\rm MeV}
\]
[2209.08548]. The hybrid papers treat these channels as discriminants of explicit gluonic excitation rather than of ordinary quarkonium.

The tetraquark interpretation has also been developed quantitatively in a chiral quark model with scalar nonet exchange [2210.16250]. In that study conventional \(\Upsilon(5S)\) is calculated near \(10.86\) GeV and found unsuitable for the \(10.753\) GeV resonance, while a full-channel-coupling calculation over molecular \(b\bar b-q\bar q\), molecular \(b\bar q-q\bar b\), and diquark–antidiquark configurations produces a stable resonance
\[
{}^1R_1(10770)
\]
with width
\[
\Gamma\big({}^1R_1(10770)\big)\approx16\ {\rm MeV}
\]
[2210.16250]. Its internal composition is dominated by about \(45\%\) diquark–antidiquark and about \(37\%\) hidden-color octet–octet components, with compact rms distances, and it is proposed as a candidate for the experimental \(\Upsilon(10753)\) [2210.16250].

These proposals differ sharply in ontology. The hybrid picture emphasizes a \(b\bar b\) pair bound to excited glue on \(\Pi_u\) and \(\Sigma_u^-\) adiabatic surfaces, whereas the tetraquark calculation emphasizes a compact \(b\bar q q\bar b\) resonance with large diquark–antidiquark content. Both are motivated by the difficulty of accommodating all observed properties in a single simple \(b\bar b\) assignment.

## 6. Present status, tensions, and decisive observables

Several misconceptions can already be excluded. The first is that \(\Upsilon(10753)\) is straightforwardly the same state as \(\Upsilon(10860)\). Belle II’s exclusive-channel program shows the opposite: \(\Upsilon(10753)\) decays into \(\chi_{bJ}\omega\) but not into \(\chi_{bJ}(\pi^+\pi^-\pi^0)_{\rm non-\omega}\), whereas \(\Upsilon(10860)\) decays into \(\chi_{bJ}(\pi^+\pi^-\pi^0)_{\rm non-\omega}\) but not into \(\chi_{bJ}\omega\) [2510.25461]. The second is that a pure \(3D\) interpretation automatically explains the \(\omega\chi_{bJ}\) data. It does not: Belle II measured
\[
\frac{\sigma_B(e^+e^-\to \omega\chi_{b1})}{\sigma_B(e^+e^-\to \omega\chi_{b2})}=1.3\pm0.6
\]
at \(\sqrt{s}=10.745\) GeV [2208.13189], and the later \(\Gamma_{ee}\mathcal{B}\) ratio
\[
1.13 \pm 0.38_{\rm stat} \pm 0.34_{\rm syst}
\]
is very far from the pure \(D\)-wave expectation of \(1/15\) and only consistent with the quoted S–D-mixed expectation \(0.2\) at the \(1.8\sigma\) level [2510.25461].

The most important unresolved quantity is the electronic width. A pure \(3\,{}^3D_1\) model gives
\[
\Gamma_{ee}\approx 3\ {\rm eV}
\]
[2501.03147]; one S–D mixing analysis gives
\[
\Gamma_{ee}\approx 93\text{–}97\ {\rm eV}
\]
[2508.18720]; another mixed-state loop treatment quotes
\[
\Gamma_{ee}=(0.159\pm0.030)\ {\rm keV}
\]
[2201.12715]. This wide spread indicates that \(\Gamma_{ee}\) is currently one of the clearest theory discriminants. A precise direct determination would immediately constrain the allowed wave-function composition.

Open-bottom and radiative channels are equally decisive. In the coupled-channel picture of [2403.03770], the \(\Upsilon(10753)\) candidate should decay predominantly to \(B^\ast\bar B^\ast\), with \({\cal BR}_{B^\ast\bar B^\ast}\approx90\%\). In the pure-\(3D\) screened-potential picture, the characteristic signatures are a very small \(\Gamma_{ee}\), a three-gluon width near \(7.5\) keV, and sizable E1 transitions to \(\chi_{bJ}(2P,3P)\) with widths of order \(10\)–\(20\) keV [2501.03147]. In the \(4S\)–\(3D\) mixing literature, promising tests include \(\eta_b\omega\), \(\eta_b\eta\), \(\eta_b\eta'\), \(\Upsilon(1^3D_J)\eta\), and \(\gamma X_b\), the last with a predicted branching fraction of \(10^{-4}\) in one loop model [2312.02761] [2205.04049] [2403.01676].

The present evidence therefore supports a narrower conclusion than a definitive assignment. \(\Upsilon(10753)\) is a well-established vector resonance with a distinctive \(\chi_{bJ}\omega\) signature, suppressed non-\(\omega\) three-pion modes, observed \(\pi^+\pi^-\Upsilon(1S,2S)\) decays, and no evidence so far for \(Z_b\)-dominated dipion substructure [2401.12021] [2510.25461]. These facts disfavor a simple pure-\(D\)-wave description and indicate that threshold dynamics are essential. Whether the dominant language should be mixed bottomonium, dressed hadronic resonance, hybrid, or tetraquark remains an active problem in heavy-quark spectroscopy.

Source: https://www.emergentmind.com/topics/upsilon-10753