Observation and Properties of the X(3872) Decaying to J/psi pi+ pi- in p-p(bar) Collisions at sqrt(s) = 1.96 TeV

D0 Collaboration: V.M. Abazov; et al

REVIEW

Observation and Properties of the X(3872) Decaying to J/psi pi+ pi- in p-p(bar) Collisions at sqrt(s) = 1.96 TeV

D0 Collaboration: V.M. Abazov, et al

High Energy Physics - Experiment · Submitted 4 May 2004 · 13 references

Pith's verdict: A clean, independent D0 confirmation of the X(3872) with a solid mass measurement; the only genuinely soft claim is the unquantified 'similar to psi(2S)' statement in the abstract.

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arXiv IDhep-ex/0405004 (version 2)

Pith IDFHATAVF3, Pith's permanent record of this paper and its review

CitationD0 Collaboration: V.M. Abazov, et al. "Observation and Properties of the X(3872) Decaying to J/psi pi+ pi- in p-p(bar) Collisions at sqrt(s) = 1.96 TeV." arXiv:hep-ex/0405004 (2004). https://pith.science/paper/FHATAVF3

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Editor's note

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Quick read on the D0 X(3872) paper. The core is real: an independent observation of the X(3872) in J/psi pi+pi- in 230 pb^-1 of Run II data, 522 +/- 100 candidates at 5.2 sigma, and Delta M = 774.9 +/- 3.1 (stat) +/- 3.0 (syst) MeV. That is a second collider confirming Belle and CDF with its own detector, its own trigger, and a competitive mass. The two-peak fit in Fig. 1 is clean, the psi(2S) peak sits right there as an in-situ control, and the selection is described well enough to follow. Nothing here is hand-waved at the level of the main result. The paper also does something the earlier references did not: it splits the sample by pT, rapidity, decay length, isolation, and the two helicity angles, and puts the X(3872) and psi(2S) yields side by side in Table I. That table is the useful part of the paper and will be what people cite it for. On the mass-scale correction, I think the reader's worry is overblown. The correction is 3.0 MeV and they assign a 100% systematic of 3.0 MeV to it, so even a total failure of the correction moves the central value by less than the quoted total error. It is also the natural multiplicative fix, since both peaks share the same muons. Where I do agree with the reader is the abstract's 'similar to psi(2S)' [abstract:s3]. That is a null result stated without a chi-squared, a p-value, or any statement of how big a difference the data could have detected. The body is more careful ('no significant differences'), but the abstract overstates what was tested. Minor, and fixable with one sentence. Two smaller things. The 5.2 sigma is quoted without the calculation; a reader can roughly reconstruct it from the yield and error, but it should be shown. And the yield's strong dependence on the M(pi+pi-) cut (522 down to 170 as the cut tightens to 0.70) is reported and then dropped, which is a shame, because that is the most physically interesting number in the paper. None of this threatens the observation. This is a competent, honest confirmation paper that deserves referees and will be cited for its mass and its production comparison. Worth your time if you work on exotic charmonium; skippable otherwise.

Referee report

Significance

If the observation holds, this is an independent confirmation of the Belle and CDF signals in a new dataset and detector, with a mass difference measured to about 4 MeV total uncertainty. The paper has real methodological strengths that deserve to be named: the ψ(2S) reference is drawn from the same data with the same trigger and selection, which controls many otherwise dangerous systematic effects; the mass-scale correction is stated explicitly rather than absorbed silently, and is conservatively assigned a 100% systematic equal to the full size of the correction; and Table I publishes the fitted yields in every subregion, which lets a reader redo the comparison rather than take the summary sentence on trust. The result is a useful, self-contained contribution to the X(3872) literature.

Major objections (3)

[Abstract, sentence 3; final paragraph; Table I; Fig. 3] The claim that the X(3872) production and decay characteristics are 'similar to those of the ψ(2S)' is a null result reported without any quantitative compatibility test. Table I and Fig. 3 give six two-bin comparisons, but no χ2, no degrees of freedom, no p-value, and no statement of the discriminating power of the test are provided. This matters because the X(3872) yields carry roughly 19% statistical uncertainty, so the comparison is intrinsically coarse: for the isolation bin, for example, the X(3872) fraction is 85/522 = 0.163 ± 0.042 against 257/1192 = 0.216 ± 0.017 for the ψ(2S), a difference of about 1.2σ on a single comparison, and with six comparisons the sensitivity to a genuine difference is limited. Please add an explicit compatibility statistic over the six regions (a χ2/ndf or an equivalent p-value, with the correlations induced by the common fit and common normalization stated), and state what size of difference the data could have detected. If the sample does not support such a statement, the abstract sentence should be softened from 'find them to be similar' to 'are consistent with', which is what the data actually establish.
[Mass-scale correction, paragraph following Fig. 1] The corrected mass difference 774.9 MeV/c2 is the headline number, but the correction cannot be reconstructed from the text. The paper quotes the uncorrected value 771.9 ± 3.1 MeV/c2 and states that the correction is the ratio of the PDG ψ(2S)–J/ψ mass difference to 'our corresponding measured mass difference', yet the measured ψ(2S)–J/ψ ΔM is never given, nor is the numerical scale factor (which must be about 1.0039 for the correction to be +3.0 MeV/c2). Please quote the fitted ψ(2S) ΔM, the PDG reference value used, and the resulting multiplicative factor, and confirm explicitly that the factor is applied multiplicatively to ΔM, which is valid only if the momentum-scale error is common to the two-mass difference. In addition, the entire 3.0 MeV/c2 systematic is the scale correction; please state whether other candidates (track alignment, field-map calibration, fit model and range) were examined and found negligible, so that the reader can see the systematic budget is complete rather than merely dominated by one term.
[Yield versus M(π+π−) requirement, paragraph following Fig. 1] The paper reports that tightening the M(π+π−) requirement to 0.60, 0.65, and 0.70 GeV/c2 reduces the X(3872) yield from 522 ± 100 to 433 ± 98, 336 ± 78, and 170 ± 54, but gives no ψ(2S) counterpart and no interpretation. This is directly relevant to the 'similar to ψ(2S)' claim: if the ψ(2S) yield falls at the same rate, the effect is a selection acceptance and supports the similarity statement; if it falls more slowly, the X(3872) dipion system has a different composition, or the signal has a background component that the nominal fit absorbs. Please report the ψ(2S) yields under the same tightened cuts and state the ratio of the two, with uncertainties.

Minor objections (10)

[Fig. 1] The horizontal axis begins at 0.6 GeV/c2, while the ψ(2S) peak lies near 0.589 GeV/c2, so the reference peak used to normalize the entire comparison is truncated at the left edge of the displayed distribution. Please state the actual fit range and show the ψ(2S) peak fully within it.
[Final paragraph] The significance of 5.2 standard deviations is quoted without saying how it was computed. From the numbers given it appears to be the yield divided by its fitted uncertainty; if so, say so, and if a likelihood-ratio or Δχ2 estimate was used, give that instead.
[Table I] The subregion yields do not sum to the totals quoted for the initial selection (for example, the isolation rows give 257 + 942 = 1199 against 1192 ± 55, and the cos θπ rows give 589 + 606 = 1195). Please state whether each subregion is fitted independently and how the fractions plotted in Fig. 3 are normalized, since the choice affects the comparison.
[Fig. 3] The figure compares event-yield fractions but the text does not state the uncertainties drawn on the points, nor whether the X(3872) and ψ(2S) fractions are statistically correlated through the common fit and common normalization. Please state both.
[Fig. 1 inset and mass-scale discussion] The text notes that the J/ψ peak position in Fig. 1 is shifted relative to the accepted value but does not quantify the shift. Please quote the fitted J/ψ mass and its difference from the PDG value, since that shift is the motivation for the scale correction.
[Table I caption] The ψ(2S) and X(3872) widths are fixed to the values from the full-sample fit in the subregion fits. Please quote the fixed ψ(2S) width and state whether it is consistent with the X(3872) width of 17 ± 3 MeV/c2 quoted in the text.
[Selection criteria] The requirement of fewer than 100 tracks per event is stated without motivation. Please give the reason and the fraction of events it removes.
[Helicity comparison, Table I rows (c) and (f)] The comparison is made with a single cut at |cos θ| = 0.4 in each of the dipion and dimuon frames. Please justify the choice of 0.4, or show the full cos θ distributions, since a two-bin split discards most of the shape information that would distinguish helicity states.
[References [2] and [9]] Reference [2], the CDF confirmation that provides essential context for this observation, is listed as submitted; please update its status if it has since appeared. Reference [9], which supports the detector performance figures quoted in the text (for example the 50 µm impact-parameter resolution), is listed as in preparation; consider summarizing the relevant performance numbers in the text so the analysis does not rest on an unpublished document.
[Comparison with prior measurements] The introduction quotes the Belle mass and cites the CDF confirmation, but the discussion never compares the measured ΔM with those values explicitly. Please add a sentence stating the level of agreement with the published Belle and CDF mass differences.

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The paper

The paper claims

D0 sees the X(3872) in its own data and finds it behaves like a known charmonium state.

The reading

The paper sets out to answer two questions about the X(3872), a narrow peak first reported by Belle and then by CDF in the $J/ψπ^+π^-$ channel: does it appear in an independent dataset, and does it look like an ordinary charmonium state or something stranger? Using about 230 pb$^{-1}$ of Run II D0 data at $√s = 1.96$ TeV, with the $J/ψ$ reconstructed in $μ^+μ^-$, the collaboration finds $522 ± 100$ candidates at a significance of 5.2 standard deviations and measures the mass splitting from the $J/ψ$ as $774.9 ± 3.1$ (stat) $± 3.0$ (syst) MeV/$c^2$. It then splits the sample by transverse momentum, rapidity, isolation, effective decay length, and the helicity angles of the dipion and dimuon systems, and compares every yield fraction to the $ψ(2S)$, which appears in the same mass-difference distribution. The point of that comparison is that the $ψ(2S)$ is a well-understood $c̄c$ bound state: if the X(3872) tracks it in every kinematic and lifetime bin, the simplest reading is that the new state is produced and decays the way charmonium is. A confirmation in a third experiment, with a mass good to a few MeV, is what makes the X(3872) a fixed target for any explanation of what it is.

What carries the argument

The load-bearing device is the mass-difference distribution, $ΔM = M(μ^+μ^-π^+π^-) - M(μ^+μ^-)$, rather than the absolute four-body mass. Taking the difference cancels most of the momentum-scale error common to the muons and pions, so a peak position can be quoted to a few MeV even when the absolute $J/ψ$ mass sits visibly off its accepted value. The same distribution contains the $ψ(2S)$ peak, and that coincidence does double duty: it calibrates the residual scale by comparing the measured $ψ(2S)-J/ψ$ splitting to the accepted one, and it supplies a matched reference sample whose behaviour in every kinematic bin can be compared with the X(3872) bin by bin. The comparison variables are chosen so that they separate prompt from long-lived production (effective decay length, isolation) and probe the spin structure of the decay (the helicity angles $θ_π$ and $θ_μ$ obtained by boosting a daughter and the parent into the dipion or dimuon rest frame).

Extended reading notes

Core claim

D0 reports the observation of the X(3872) in the decay chain $X(3872) → J/ψπ^+π^-$, $J/ψ → μ^+μ^-$, in $p̄p$ collisions at $√s = 1.96$ TeV, with $522 ± 100$ candidates extracted from a Gaussian-plus-polynomial fit to the mass-difference distribution $ΔM = M(μ^+μ^-π^+π^-) - M(μ^+μ^-)$. The fitted width of the peak, $17 ± 3$ MeV/$c^2$, is consistent with detector resolution, and the significance is quoted as 5.2 standard deviations. The measured splitting is $ΔM = 774.9 ± 3.1$ (stat) $± 3.0$ (syst) MeV/$c^2$ after a momentum-scale correction anchored on the $ψ(2S)$ peak in the same sample. The second half of the paper is a shape comparison: yields of X(3872) and $ψ(2S)$ are extracted in bins of $p_T$, $|y|$, isolation, effective proper decay length, $cos θ_π$ and $cos θ_μ$, and the resulting yield fractions agree within the (large) statistical errors. The authors conclude that they find no significant differences between the X(3872) and the $c̄c$ state $ψ(2S)$ in production or decay.

Load-bearing premise

The mass-scale correction assumes that the momentum-scale error distorting the $J/ψ$ peak is the same common-mode error that shifts the $ψ(2S)$ peak in the same sample, so that rescaling by the measured $ψ(2S)-J/ψ$ ratio fixes the X(3872) splitting; the authors acknowledge the $J/ψ$ peak sits off its accepted mass and assign a 100 percent systematic to this correction, which means the quoted central value and error bar rest on that bracketing assumption rather than on an independent calibration.

Editorial extensions

If this is right

The X(3872) is confirmed as a real state in a third independent dataset, so any explanation must reproduce a narrow peak at a $J/ψ$ mass splitting near 775 MeV/$c^2$.
The quoted splitting of about 774.9 MeV/$c^2$ with roughly 4 MeV total uncertainty becomes a target that competing measurements and theoretical models must hit.
Because the X(3872) yield fractions across $p_T$, rapidity, isolation and decay length match the $ψ(2S)$, models that predict a markedly different production mechanism, such as a loosely bound molecular state with an unusual lifetime or feed-down pattern, face a constraint.
The absence of an obvious difference in the $cos θ_π$ and $cos θ_μ$ distributions limits how different the X(3872) helicity structure can be from that of the $ψ(2S)$ at this sample size.

Reading between the lines

Editorial extensions of the paper, not claims the author makes directly.

The comparison is statistically soft: with $522 ± 100$ candidates split across six variables, the yield fractions in Fig. 3 carry errors of order 20 percent, so 'similar to the $ψ(2S)$' here means 'not visibly different at this precision' rather than 'demonstrated to be identical'.
A molecular or four-quark interpretation is not excluded by this paper; it would have to arrange for the production and decay-length distributions to mimic charmonium, which is a real but not impossible constraint on such models.
The in-situ $ψ(2S)$ calibration is the kind of trick that becomes much sharper with the far larger samples now available at the LHC, where the same bin-by-bin comparison could turn a null result into a real discriminant.
The proximity of the state to the $D^{*0}D̄^0$ threshold, noted in the paper's references but not tested here, is the natural next question: a threshold-bound interpretation predicts specific decay-rate ratios to $D^{*0}D̄^0$ and $π^+π^-J/ψ$ that this analysis does not address.

Original abstract

We report the observation of the X(3872) in the J/psi pi+pi- channel, with J/psi decaying to mu+mu- in p-p(bar) collisions at sqrt(s) = 1.96 TeV. Using approximately 230 pb^-1 of data collected with the Run II D0 detector, we observe 522 +/- 100 X(3872) candidates. The mass difference between the X(3872) state and the J/psi is measured to be 774.9 +/- 3.1 (stat.) +/- 3.0 (syst.) MeV/c^2. We have investigated the production and decay characteristics of the X(3872), and find them to be similar to those of the psi(2S) state.

The compiled record

The paper's own sentences, arranged, kept beside the review and separate from it. Each label is drawn from a closed vocabulary; the number beside it is the probability the classifier gave that label. Numbers in the tables are the authors', checked by code. No sentence in this record was written by a model.

Compiled by classifier-1.13-20260917 via OpenRouter, question bank abstract-p1-20260923, 2026-09-23: 1 request, 3,801 input tokens, $0.0002 reported.

What the abstract itself states, as probabilities: claims first 0.04 · states limitation 0.08 · human participants 0.01 · controlled comparison 0.26 · randomized assignment 0.01 · states quantitative result 0.99 · compares with prior results 0.65 · mentions code or data availability 0.01.

The abstract, sentence by sentence

arXiv listing abstract v2. Results and the main claim are underlined; show every role.

We report the observation of the X(3872) in the J/psi pi+pi- channel, with J/psi decaying to mu+mu- in p-p(bar) collisions at sqrt(s) = 1.96 TeV. Using approximately 230 pb^-1 of data collected with the Run II D0 detector, we observe 522 +/- 100 X(3872) candidates. The mass difference between the X(3872) state and the J/psi is measured to be 774.9 +/- 3.1 (stat.) +/- 3.0 (syst.) MeV/c^2. We have investigated the production and decay characteristics of the X(3872), and find them to be similar to those of the psi(2S) state.

background contribution method result interpretation main claim

What the classifier reports for each sentence. The number is the probability it gave the label.
#	sentence	role	the authors' own work	states the main conclusion	strength
s0	We report the observation of the X(3872) in the J/psi pi+pi- channel, with J/psi decaying to mu+mu- in p-p(bar) collisions at sqrt(s) = 1.96 TeV.	result 0.73	0.96	0.71	asserted 1.00
s1	Using approximately 230 pb^-1 of data collected with the Run II D0 detector, we observe 522 +/- 100 X(3872) candidates.	result 0.75	0.97	0.14	asserted 1.00
s2	The mass difference between the X(3872) state and the J/psi is measured to be 774.9 +/- 3.1 (stat.) +/- 3.0 (syst.) MeV/c^2.	result 1.00	0.97	0.14	asserted 1.00
s3	We have investigated the production and decay characteristics of the X(3872), and find them to be similar to those of the psi(2S) state.	result 0.72	0.96	0.41	asserted 1.00

What kind of paper the classifier reports this is: empirical study 1.00 · evidence from observation or experiment 0.93.

What was examined, and what was not

sources read

arXiv listing abstract v2

not examined

full text
figures and tables
references and citing sentences
relations to other papers

levels run

P abstract

not run

S sections
T body sentences
C citations
R cross-paper relations

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

Figures

**Figure 1.** shows the distribution in the mass difference ∆M = M(µ +µ −π +π −) − M(µ +µ −), after all selections

**Figure 3.** FIG. 3: Comparison of event-yield fractions for

Showing 2 of the paper's 3 figures. See all figures in the PDF ↗ Figures reproduced from arXiv:hep-ex/0405004 by the authors.

References

Works cited (13)

[1]

S. K. Choi et al. (Belle Collaboration), Phys.\ Rev.\ Lett.\ 91 , 262001 (2003)

View on Pith 2003
[2]

D. Acosta et al. (CDF II Collaboration), submitted to Phys.\ Rev.\ Lett., hep-ex/0312021

View on Pith Pith review arXiv
[3]

F. E. Close, P. R. Page, ``The D^ *0 D^ 0 threshold resonance'', Phys. Lett. B578 , 119 (2004), hep-ph/0309253

View on Pith Pith review arXiv 2004
[4]

E. J. Eichten, K. Lane, and C. Quigg, ``Charmonium levels near threshold and the narrow state X(3872) ^ + ^ - J/ ,'' FERMILAB--Pub--04/001--T, hep-ph/0401210, and references therein

View on Pith Pith review arXiv
[5]

C. Quigg, ``Quarkonium: New developments,'' hep-ph/0403187

View on Pith Pith review arXiv
[6]

N. T\" o rnqvist, ``Isospin breaking of the narrow charmonium state of Belle at 3872 MeV as a deuson'', hep-ph/0402237

View on Pith Pith review arXiv
[7]

K. Hagiwara et al. , Phys. Rev. D 66 , 010001 (2002) and 2003 off-year partial update for the 2004 edition available on the PDG WWW pages (URL: http://pdg.lbl.gov/)

View on Pith 2002
[8]

S. Abachi et al. (D \ Collaboration), Phys. Lett. B370 , 239 (1996); F. Abe et al. (CDF Collaboration), Phys.\ Rev.\ Lett.\ 79 , 572 (1997)

View on Pith 1996
[9]

V. Abazov, et al., in preparation for submission to Nucl. Instrum. Methods Phys. Res. A, and T. LeCompte and H.T. Diehl, ``The CDF and D0 Upgrades for Run II'', Ann. Rev. Nucl. Part. Sci. 50 , 71 (2000)

View on Pith 2000
[10]

S. Abachi, et al. , Nucl. Instrum. Methods Phys. Res. A 338 , 185 (1994)

View on Pith 1994
[11]

The X(3872) particle is

View on Pith
[12]

Visitor from University of Zurich, Zurich, Switzerland

View on Pith
[13]

Visitor from Institute of Nuclear Physics, Krakow, Poland. 0.25cm

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Forward citations

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A parameter-free formalism, based on one color-octet channel, reproduces LHC hadroproduction rates of χc1(3872) and supports its tetraquark interpretation.

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The prompt X(3872) cross section times its J/psi pi pi branching fraction is 1.06 +/- 0.11 (stat) +/- 0.15 (syst) nb for 10 < pT < 30 GeV and |y| < 1.2, well below the NRQCD prediction of 4.01 +/- 0.88 nb.
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A coupled-channel mixture model fitted to the X(3872) and Z(3930) masses predicts the X(3860) at about 3867 MeV, dominated by the charmonium core.
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hep-ph 2009-05 conditional novelty 5.0 of 10

Isospin breaking in a D-D* molecular model of the X(3872) is small, but rho phase space explains the observed J/psi pi pi pi to J/psi pi pi ratio, and a negative C-parity partner state is predicted.
The New Heavy Mesons: A Status Report
hep-ph 2006-01 conditional novelty 5.0 of 10

Eleven new heavy mesons are surveyed against quark-model and lattice expectations, with new coupled-channel calculations arguing that several are weakly bound meson molecules or strongly renormalized quark states.
Probing the structure of $\chi_{c1}(3872)$: Heavy quark symmetries at work
hep-ph 2026-06 unverdicted novelty 4.0 of 10

Heavy-quark large-mass limit applied to E1 transitions of χ_c1(2P) yields decay rates that match LHCb measurements for χ_c1(3872) under the 2P assignment.
The charming case of $X(3872)$ and $\chi_{c1}(2P)$
hep-ph 2025-01 conditional novelty 4.0 of 10

The radiative decay ratio R(X(3872)) = B(X(3872) to psi(2S) gamma)/B(X(3872) to J/psi gamma) is predicted to be 1.7 ± 0.3, matching the LHCb value 1.67, supporting the chi_c1(2P) charmonium assignment.
Four-Quark Hadrons: an Updated Review
hep-ph 2014-11 conditional novelty 4.0 of 10

The XYZ resonances, especially the charged Z(4430) and Zc(3900), are best organized as compact diquark-antidiquark tetraquarks, with a Feshbach-like coupling to open-flavor thresholds selecting which predicted levels ...
X(3872) as a molecular DD* state in a potential model
hep-ph 2009-10 conditional novelty 4.0 of 10

A coupled-channel potential model with a tunable cutoff of about 1.2 GeV produces a bound DD* state with the quantum numbers of the X(3872), and also predicts bound BB* states in the isoscalar limit.
The $XYZ$ states: experimental and theoretical status and perspectives
hep-ex 2019-07 accept novelty 3.0 of 10

A book-length review cataloguing the experimental evidence for exotic charmonium- and bottomonium-like states and the theoretical frameworks, from quark models to effective field theory and lattice QCD, proposed to ex...
Exotics: Heavy Pentaquarks and Tetraquarks
hep-ph 2017-06 accept novelty 3.0 of 10

A comprehensive review of the charmonium- and bottomonium-like exotics and the two LHCb pentaquarks, covering the experimental evidence state by state and the four competing theoretical explanations for them.
Heavy-Quark QCD Exotica
hep-ph 2016-10 accept novelty 3.0 of 10

About 30 charmoniumlike and bottomoniumlike states that do not fit the ordinary quark-antiquark or three-quark scheme have been reported since 2003, and no single theoretical picture yet explains them all.
Multiquark States
hep-ph 2017-11 accept novelty 2.0 of 10

Exotic multiquark hadrons have now been observed, almost all involving heavy quarks, and the evidence favors loosely bound hadronic molecules over tightly bound tetraquarks and pentaquarks.
Non-Standard Heavy Mesons and Baryons, an Experimental Review
hep-ph 2017-08 accept novelty 2.0 of 10

A 2017 experimental review finds that many heavy-quark hadron candidates conflict with conventional quark-model assignments, so the spectroscopy of all but the simplest hadrons remains unexplained.
Exotic Hadrons with Heavy Flavors -X, Y, Z and Related States-
hep-ph 2016-03 accept novelty 2.0 of 10

The review argues that X(3872) and the Zb(10610)/Zb(10650) states are hadronic molecules whose near-threshold dynamics are organized by chiral and heavy-quark symmetry.
The hidden-charm pentaquark and tetraquark states
hep-ph 2016-01 accept novelty 2.0 of 10

A comprehensive review argues that the charged Zc/Zb states and the LHCb Pc(4380)/Pc(4450) pentaquarks are multiquark candidates, and catalogues the molecular, tetraquark, and diquark interpretations along with their ...
Quarkonium at the Frontiers of High Energy Physics: A Snowmass White Paper
hep-ph 2013-07 conditional novelty 2.0 of 10

A community white paper argues that exotic quarkonium spectroscopy and large-transverse-momentum quarkonium production are the two areas where the next decade of experiments will most change our understanding of QCD.
Production of exotic hadrons in $pp$ and nuclear collisions
hep-ph 2024-11 conditional novelty 1.0 of 10

A review of exotic-hadron production in pp, pbar-p, and nuclear collisions, arguing that such measurements can discriminate between hadronic-molecule and compact-tetraquark interpretations of states like the X(3872).
Heavy-flavour and quarkonium production in the LHC era: from proton-proton to heavy-ion collisions
nucl-ex 2015-06 accept novelty 1.0 of 10

The review concludes that open charm and beauty production is well described by perturbative QCD across collision systems, while quarkonium production and polarisation remain unexplained by any single model.
An overview of $XYZ$ new particles
hep-ph 2013-12 conditional novelty 1.0 of 10

The review compiles the experimental status and the competing theoretical interpretations of the 23 charmoniumlike and bottomoniumlike XYZ states observed since 2003.

How the literature uses it

107 arXiv papers cite this in 117 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 the same result 1 paper

We report the observation of a narrow state decaying into $J/\psi\pi^+\pi^-$ and produced in $220 pb^{-1}$ of $\bar{p} p $ collisions at $\sqrt{s}=1.96 TeV$ in the CDF II experiment.

Observation of the Narrow State $X(3872)\to J/\psi\pi^{+}\pi^{-}$ in $\bar{p}p$ Collisions at $\sqrt{s}=1.96 \TeV$ · 0.96

Papers citing it · 61 sentences without a confident label

Uses its data or values 7 papers

Measurements of the mass of the $X(3872)$ by the Belle, CDF, Babar, and D0 collaborations [ref] , combined with a new measurement of the $D^0$ mass by the CLEO collaboration [ref] , imply that the mass is extremely close to the $D^*0 D̅^0$ threshold:

An Estimate of the Partial Width for X(3872) into p p-bar · Introduction · 0.87
Measurements of its mass in the decay mode $J/ψ π^+ π^-$ indicate that it is below the threshold for $D^*0 D̅^0$ by $0.42 ±0.39$ MeV [ref] .

Estimating the Production Rate of Loosely-bound Hadronic Molecules using Event Generators · Introduction · 0.96
Using the most recent measurements of the mass of the $X(3872)$ in the $J/ψ π^+ π^-$ decay channel by the Belle, CDF, Babar, and D0 Collaborations [ref] , the combined average for the position of the $X(3872)$ resonance relative to the $D^*0 D̅^0$ threshold is

Using Line Shapes to Discriminate between Binding Mechanisms for the X(3872) · Introduction · 1.00

Cites it as background 49 papers

After Belle, CDF and D0 confirmed the $X(3872)$ in proton-antiproton collisions [ref] .

Is the X(3872) Production Cross Section at Tevatron Compatible with a Hadron Molecule Interpretation? · Introduction · 0.80
The discovery of the narrow charmoniumlike state with a mass of about 3.872 GeV [ref] , now known as the $χ_c1(3872)$, led to a renewed interest in exotic hadrons since their existence were prophesized in the 1960s [ref] .

Hadroproduction data support tetraquark hypothesis for $\chi_{c1} (3872)$ · Introduction · 0.98
It has been almost ten years since the narrow $$ state was discovered in $B^+$ decays by the Belle experiment [ref] .[The inclusion of charge-conjugate states is implied in this Letter.] Subsequently, its existence has been confirmed by several other experiments [ref] .

Determination of the X(3872) meson quantum numbers · Introduction · 0.98

Discussion

Disagree with the review, or know something it missed? Leave a comment, highlight any passage above to comment on it, or challenge this review formally.

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S. K. Choi et al. (Belle Collaboration), Phys.\ Rev.\ Lett.\ 91 , 262001 (2003)

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D. Acosta et al. (CDF II Collaboration), submitted to Phys.\ Rev.\ Lett., hep-ex/0312021

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F. E. Close, P. R. Page, ``The D^ *0 D^ 0 threshold resonance'', Phys. Lett. B578 , 119 (2004), hep-ph/0309253

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E. J. Eichten, K. Lane, and C. Quigg, ``Charmonium levels near threshold and the narrow state X(3872) ^ + ^ - J/ ,'' FERMILAB--Pub--04/001--T, hep-ph/0401210, and references therein

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C. Quigg, ``Quarkonium: New developments,'' hep-ph/0403187

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N. T\" o rnqvist, ``Isospin breaking of the narrow charmonium state of Belle at 3872 MeV as a deuson'', hep-ph/0402237

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K. Hagiwara et al. , Phys. Rev. D 66 , 010001 (2002) and 2003 off-year partial update for the 2004 edition available on the PDG WWW pages (URL: http://pdg.lbl.gov/)

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S. Abachi et al. (D \ Collaboration), Phys. Lett. B370 , 239 (1996); F. Abe et al. (CDF Collaboration), Phys.\ Rev.\ Lett.\ 79 , 572 (1997)

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V. Abazov, et al., in preparation for submission to Nucl. Instrum. Methods Phys. Res. A, and T. LeCompte and H.T. Diehl, ``The CDF and D0 Upgrades for Run II'', Ann. Rev. Nucl. Part. Sci. 50 , 71 (2000)

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S. Abachi, et al. , Nucl. Instrum. Methods Phys. Res. A 338 , 185 (1994)

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The X(3872) particle is

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[12] [12]

Visitor from University of Zurich, Zurich, Switzerland

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[13] [13]

Visitor from Institute of Nuclear Physics, Krakow, Poland. 0.25cm

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