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Precise determination of the properties of $X(3872)$ and of its isovector partner $W_{c1}$

High Energy Physics - Phenomenology · Submitted 6 Feb 2025 · Published version

abstract compiled · 2026-09-23 · no language-model review

The authors' main claim It is found as a virtual state at $\left(3.1\pm0.7+ 1.3^{+1.9}_{-0.6}\,i\right)\ \rm MeV$ relative to the $D^+ D^{*-}$ threshold on an unphysical Riemann sheet, strongly supporting a molecular nature of both $X(3872)$ and $W_{c1}$.

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arXiv ID2502.04458 (version 4)
Pith ID2R4YKGTL, Pith's permanent record of this paper and its review
CitationChristoph Hanhart, Feng-Kun Guo, Teng Ji, Ulf-G. Mei{\ss}ner, Xiang-Kun Dong. "Precise determination of the properties of $X(3872)$ and of its isovector partner $W_{c1}$." arXiv:2502.04458 (2025). https://pith.science/paper/2R4YKGTL
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Compiled by classifier-1.13.0 via TypeSafe API, question bank abstract-p1-20260923, 2026-09-23: 1 request, 5,633 input tokens.

What the abstract itself states, as probabilities: claims first 0.18 · states limitation 0.57 · human participants 0.01 · controlled comparison 0.03 · randomized assignment 0.01 · states quantitative result 0.99 · compares with prior results 0.71 · mentions code or data availability 0.02.

The abstract, sentence by sentence

arXiv listing abstract v4. Results and the main claim are underlined; .

We perform a simultaneous fit to BESIII data on $e^+e^-\to \gamma (D^0{\bar{D}^{0}}\pi^0/J/\psi\pi^+\pi^-)$ and LHCb data on $B^+\to K^+(J/\psi\pi^+\pi^-)$ to precisely determine the properties of the $X(3872)$, with full consideration of three-body effects from $D^*\to D\pi$ decay, respecting both analyticity and unitarity. The $X(3872)$ is determined to be a quasi-bound state with a significance of $2.7\,\sigma$, representing the most precise determination to date. Its pole is located at $\left(-160^{+57}_{-74}-125^{+23}_{-38}\,i\right) \rm keV$, relative to the nominal $D^0\bar{D}^{*0}$ threshold. Moreover, we confirm the presence of an isovector partner state, $W_{c1}$. It is found as a virtual state at $\left(3.1\pm0.7+ 1.3^{+1.9}_{-0.6}\,i\right)\ \rm MeV$ relative to the $D^+ D^{*-}$ threshold on an unphysical Riemann sheet, strongly supporting a molecular nature of both $X(3872)$ and $W_{c1}$. As a highly nontrivial prediction we show that the $W_{c1}$ leads to nontrivial lineshapes around 3.88 GeV in $B^0\to K^0 X(3872)\to K^0 D^0\bar D^0\pi^0$ and $K^0J/\psi\pi^+\pi^-$ -- thus the scheme presented here can be tested further by improved measurements.

background contribution method result interpretation main claim

What the classifier reports for each sentence. The number is the probability it gave the label.
#sentencerolethe authors' own workstates the main conclusionstrength
s0 We perform a simultaneous fit to BESIII data on $e^+e^-\to \gamma (D^0{\bar{D}^{0}}\pi^0/J/\psi\pi^+\pi^-)$ and LHCb data on $B^+\to K^+(J/\psi\pi^+\pi^-)$ to precisely determine the properties of the $X(3872)$, with full consideration of three-body effects from $D^*\to D\pi$ decay, respecting both analyticity and unitarity. method 0.90 0.96 0.07 asserted 0.97
s1 The $X(3872)$ is determined to be a quasi-bound state with a significance of $2.7\,\sigma$, representing the most precise determination to date. result 1.00 0.94 0.42 asserted 0.98
s2 Its pole is located at $\left(-160^{+57}_{-74}-125^{+23}_{-38}\,i\right) \rm keV$, relative to the nominal $D^0\bar{D}^{*0}$ threshold. result 1.00 0.95 0.17 asserted 1.00
s3 Moreover, we confirm the presence of an isovector partner state, $W_{c1}$. result 0.99 0.92 0.17 asserted 1.00
s4 It is found as a virtual state at $\left(3.1\pm0.7+ 1.3^{+1.9}_{-0.6}\,i\right)\ \rm MeV$ relative to the $D^+ D^{*-}$ threshold on an unphysical Riemann sheet, strongly supporting a molecular nature of both $X(3872)$ and $W_{c1}$. result 0.93 0.96 0.23 asserted 0.97
s5 As a highly nontrivial prediction we show that the $W_{c1}$ leads to nontrivial lineshapes around 3.88 GeV in $B^0\to K^0 X(3872)\to K^0 D^0\bar D^0\pi^0$ and $K^0J/\psi\pi^+\pi^-$ -- thus the scheme presented here can be tested further by improved measurements. future work 0.50 0.92 0.08 asserted 0.98

What kind of paper the classifier reports this is: empirical study 0.47 · evidence from analysis of existing data 1.00.

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Every quoted sentence on this record is the authors'. Every label is from Pith's closed vocabulary, with the probability shown beside it. Every number in the measurements table is the authors', checked by code. Record as JSON

The paper
Original abstract

We perform a simultaneous fit to BESIII data on $e^+e^-\to \gamma (D^0{\bar{D}^{0}}\pi^0/J/\psi\pi^+\pi^-)$ and LHCb data on $B^+\to K^+(J/\psi\pi^+\pi^-)$ to precisely determine the properties of the $X(3872)$, with full consideration of three-body effects from $D^*\to D\pi$ decay, respecting both analyticity and unitarity. The $X(3872)$ is determined to be a quasi-bound state with a significance of $2.7\,\sigma$, representing the most precise determination to date. Its pole is located at $\left(-160^{+57}_{-74}-125^{+23}_{-38}\,i\right) \rm keV$, relative to the nominal $D^0\bar{D}^{*0}$ threshold. Moreover, we confirm the presence of an isovector partner state, $W_{c1}$. It is found as a virtual state at $\left(3.1\pm0.7+ 1.3^{+1.9}_{-0.6}\,i\right)\ \rm MeV$ relative to the $D^+ D^{*-}$ threshold on an unphysical Riemann sheet, strongly supporting a molecular nature of both $X(3872)$ and $W_{c1}$. As a highly nontrivial prediction we show that the $W_{c1}$ leads to nontrivial lineshapes around 3.88 GeV in $B^0\to K^0 X(3872)\to K^0 D^0\bar D^0\pi^0$ and $K^0J/\psi\pi^+\pi^-$ -- thus the scheme presented here can be tested further by improved measurements.

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References
How the literature uses it

17 arXiv papers cite this in 35 sentences

Each citing sentence is taken from the citing paper's LaTeX source and typed by Pith's classifier. A label appears at probability 0.8 or more (0.95 for support), a contest at 0.7 or more; the quoted words are the citing authors'. How each label was checked · JSON

Papers whose main result relates to this one's

Found among the papers closest to this one by title and main claim. Pith's classifier compared each pair's main results and a second model family confirmed the relation; checked against two further families, shown conflicts agreed 118 times in 120 and shown same results 218 times in 239. The quoted sentence is the other paper's main claim.

States a conflicting result 1 paper
  • Our analysis disfavors the interpretation of X(3872) as a loosely bound molecular state if we use the experimental $D^\ast D\pi$ coupling constant $g=0.59$ and a reasonable cutoff around 1 GeV, which is the typical hadronic scale.

    Is X(3872) {\sl Really} a Molecular State? · 0.81

Papers citing it · 21 sentences without a confident label

Uses its method or tool 2 papers
  • The effective potential matrix is constructed in terms of the heavy-quark spin (HQS) and light-flavor SU(3) symmetries [ref] ,[The direct $J/ψπ$ and $J/ψK$ transitions are Okubo-Zweig-Iizuka suppressed and are neglected in the present analysis.

    A femtoscopic tale of two $C$-parities: the $Z_c(3900)$ and the isovector partner of the $X(3872)$ · Formalism · 0.85

  • Therefore, we refrain from considering direct transitions between observation channels, which allows us to reduce the dimension of the potential matrix in Eq. [ref] by introducing an effective potential $V̅$ (Hereinafter, summation over repeated indices is implied unless stated otherwise), [equation] that absorbs the effects of the observation channels [ref] .

    Vector charmonium(-like) states in the energy range of 4.1-4.6 GeV · Lippmann-Schwinger equation · 0.81

Uses its data or values 4 papers
  • We fix these constants $a_i(μ=1 GeV)$ to the values $-2.77$ for $i=1$, and $-2.5$ for $i=2,3$ [ref] .[These subtraction constants, fixed in the state-of-the-art analyses of the $Z_c(3900)$ and $Z_cs(3985)$ [ref] and of the $W_c1$ [ref] , are intimately related to the UV cutoff used in the wave function in Eq. [ref] [ref] .

    A femtoscopic tale of two $C$-parities: the $Z_c(3900)$ and the isovector partner of the $X(3872)$ · Formalism · 0.84

  • A direct calculation for the $X(3872)$ system, using the pertinent parameters extracted from data in Ref. [ref] , namely $E_b=160 keV$ below the neutral threshold on RS$_++$ and $=0.26$, leads to a nearby $I=1$ pole on RS$_+-$ close to the charged threshold at [equation] consistent with Refs. [ref] ; see also Ref. [ref] for support from lattice calculations.

    Amplified Isospin Breaking from Coupled-Channel Dynamics Near Threshold · From Amplification to Partner Poles · 0.87

  • For the effective couplings $g_^'$ of $X(3872)$ to $D^0D̅^*0$ and $D^+D^*-$, we take the values $g_, 0'=(0.26 ±0.02) e^(0.02 ±0.01) i GeV^-1/2$ and $g_, ±' =(0.16 ±0.01) e^(0.02 ±0.01) i GeV^-1/2$ determined recently in Ref. [ref] .

    Production of $1^{-+}$ exotic charmonium-like states in electron-positron collisions · Decay width for $ψ(4360)→γX(3872)$ · 1.00

Compares with it 2 papers
Cites it as support 1 paper
  • A recent study of the BESIII data on $e^+e^-→γ(D^0D̅^0π^0)J/ψπ^+π^-$, and LHCb data on $B^+→K^+(J/ψπ^+π^-)$, with full consideration of three-body effects, respecting analyticity and unitarity, provides strong support for the molecular picture [ref] .

    $KX(3872)$ interaction and correlation function · Introduction · 0.97

Cites it as background 1 paper

What it cites · 49 sentences without a confident label

Contests 11 papers
  • While the Flatté parameterization of Ref. [ref] employed in Refs. [ref] offers improvement by including the nonanalyticity at the $D^0D̅^*0$ threshold, it neglects the three-body effects of the $DD̅π$ system, as discussed in Refs. [ref] for similar systems, which could hinder a precise determination of the $X(3872)$ properties.

    Reconciling the X(3872) with the near-threshold enhancement in the D^0\bar{D}^{*0} final state · Introduction · contest 0.71

  • While the Flatté parameterization of Ref. [ref] employed in Refs. [ref] offers improvement by including the nonanalyticity at the $D^0D̅^*0$ threshold, it neglects the three-body effects of the $DD̅π$ system, as discussed in Refs. [ref] for similar systems, which could hinder a precise determination of the $X(3872)$ properties.

    Three-body $D\bar{D}\pi$ dynamics for the X(3872) · Introduction · contest 0.71

  • While the Flatté parameterization of Ref. [ref] employed in Refs. [ref] offers improvement by including the nonanalyticity at the $D^0D̅^*0$ threshold, it neglects the three-body effects of the $DD̅π$ system, as discussed in Refs. [ref] for similar systems, which could hinder a precise determination of the $X(3872)$ properties.

    2005.13419 · Introduction · contest 0.71

Uses the method or tool of 14 papers
  • The $D^*$ decay widths take the $Dπ$ self-energies into account via the energy-dependent $Γ_α(E;l)$, which introduces the $πDD̅$ three-body cut into the amplitude, and the constant $Γ_α^rad$ is accounting for the radiative $Dγ$ partial width of $D^*$ (see Refs. [ref] for explicit expressions).

    Predicting isovector charmonium-like states from X(3872) properties · Framework · 0.91

  • The $D^*$ decay widths take the $Dπ$ self-energies into account via the energy-dependent $Γ_α(E;l)$, which introduces the $πDD̅$ three-body cut into the amplitude, and the constant $Γ_α^rad$ is accounting for the radiative $Dγ$ partial width of $D^*$ (see Refs. [ref] for explicit expressions).

    Coupled-channel approach to $T_{cc}^+$ including three-body effects · Framework · 0.91

  • This can be done in a way consistent with unitarity [ref] , which gives [equation] where the Latin indices $j=ρ,ω$ represent the channels $J/ψρ,J/ψω$, respectively.

    A practical parametrization for line shapes of near-threshold states · Framework · 0.92

Uses data or values from 6 papers
  • In the BESIII data [ref] for the $J/ψπ^+π^-$ distribution, besides the resonance signal (taken to be from $X(3872)$ in Ref. [ref] ), there is a smooth background.

    Observation of $e^{+} e^{-} \to \gamma X(3872)$ at BESIII · Numerical results · 0.99

  • In the BESIII data [ref] for the $J/ψπ^+π^-$ distribution, besides the resonance signal (taken to be from $X(3872)$ in Ref. [ref] ), there is a smooth background.

    2309.01502 · Numerical results · 0.99

  • To include the effect of the additional decay channels of $X(3872)$ in the analysis, we employ the relative branching ratios reported in Refs. [ref] ,[Although the $W_c1$ contribution was not considered there, we expect them to provide reasonable estimates.] which lead to an estimate of the contributions from other inelastic channels to the $X(3872)$ width to be $≲20$ keV.

    2001.01156 · Numerical results · 0.99

Compares with 4 papers
  • The real part is consistent with the ones obtained in the analyses performed by LHCb [ref] and BESIII [ref] using the generalized Flatté parameterization of Ref. [ref] , but with a significantly reduced uncertainty.

    Lineshapes for composite particles with unstable constituents · Numerical results · 1.00

  • The real part is consistent with the ones obtained in the analyses performed by LHCb [ref] and BESIII [ref] using the generalized Flatté parameterization of Ref. [ref] , but with a significantly reduced uncertainty.

    2005.13419 · Numerical results · 1.00

  • The real part is consistent with the ones obtained in the analyses performed by LHCb [ref] and BESIII [ref] using the generalized Flatté parameterization of Ref. [ref] , but with a significantly reduced uncertainty.

    2309.01502 · Numerical results · 1.00

Cites as support 4 papers
  • Thus the current data are consistent only with a very small or even positive effective range, providing strong support for a molecular nature of $X(3872)$ in line with the reasoning of Refs. [ref] .

    From the lineshape of the $X(3872)$ to its structure · Numerical results · 1.00

  • Thus the current data are consistent only with a very small or even positive effective range, providing strong support for a molecular nature of $X(3872)$ in line with the reasoning of Refs. [ref] .

    Generalization of Weinberg's Compositeness Relations · Numerical results · 1.00

  • Thus the current data are consistent only with a very small or even positive effective range, providing strong support for a molecular nature of $X(3872)$ in line with the reasoning of Refs. [ref] .

    Effective range expansion for narrow near-threshold resonances · Numerical results · 1.00

Cites as background 16 papers

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